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  • 1.
    Abdellaoui, G.
    et al.
    Telecom Laboratory, Faculty of Technology, University Abou Bekr Belkaid, Tlemcen, Algeria.
    Bolmgren, Karl
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Fuglesang, Christer
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Marchi, A. Zuccaro
    RIKEN, Wako, Japan.
    EUSO-SPB1 mission and science2024In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 154, p. 102891-, article id 102891Article in journal (Refereed)
    Abstract [en]

    The Extreme Universe Space Observatory on a Super Pressure Balloon 1 (EUSO-SPB1) was launched in 2017 April from Wanaka, New Zealand. The plan of this mission of opportunity on a NASA super pressure balloon test flight was to circle the southern hemisphere. The primary scientific goal was to make the first observations of ultra-high-energy cosmic-ray extensive air showers (EASs) by looking down on the atmosphere with an ultraviolet (UV) fluorescence telescope from suborbital altitude (33 km). After 12 days and 4 h aloft, the flight was terminated prematurely in the Pacific Ocean. Before the flight, the instrument was tested extensively in the West Desert of Utah, USA, with UV point sources and lasers. The test results indicated that the instrument had sensitivity to EASs of ⪆3 EeV. Simulations of the telescope system, telescope on time, and realized flight trajectory predicted an observation of about 1 event assuming clear sky conditions. The effects of high clouds were estimated to reduce this value by approximately a factor of 2. A manual search and a machine-learning-based search did not find any EAS signals in these data. Here we review the EUSO-SPB1 instrument and flight and the EAS search.

  • 2. Agarwal, Anurag
    et al.
    Dowling, Ann P.
    Shin, Ho-Chul
    Graham, Will
    Sefi, Sandy
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Ray-tracing approach to calculate acoustic shielding by a flying wing airframe2007In: AIAA Journal, ISSN 0001-1452, E-ISSN 1533-385X, Vol. 45, no 5, p. 1080-1090Article in journal (Refereed)
    Abstract [en]

    The "silent aircraft" is in the form of a flying wing with a large wing planform and a propulsion system that is embedded in the rear of the airframe with intakes on the upper surface of the wing. Thus a large part of the forward-propagating noise from the intake ducts is expected to be shielded from observers on the ground by the wing. Acoustic shielding effects can be calculated by solving an external acoustic scattering problem for a moving aircraft. In this paper, acoustic shielding effects of the silent aircraft airframe are quantified by a ray-tracing method. The dominant frequencies from the noise spectrum of the engines are sufficiently high for ray theory to yield accurate results. It is shown that, for low-Mach number homentropic flows, a condition satisfied approximately during takeoff and approach, the acoustic rays propagate in straight lines. Thus, from Fermat's principle it is clear that classical geometrical optics and geometrical theory of diffraction solutions are applicable to this moving-body problem as well. The total amount of acoustic shielding at an observer located in the shadow region is calculated by adding the contributions from all the diffracted rays (edge-diffracted and creeping rays) and then subtrading the result from the incident field without the airframe. The three-dimensional ray-tracing solver is validated by comparing the numerical solutions with analytical high-frequency asymptotic solutions for canonical shapes. Experiments on a model-scale geometry have been conducted in an anechoic chamber to test the applicability of the ray-tracing technique. The results confirm the accuracy of the approach, which is then applied to a CAD representation of a prototype silent aircraft design. As expected, the flying wing configuration provides very significant ground shielding (in excess of 10 dB at all locations) of a source above the airframe.

  • 3.
    Aghaali, Habib
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Turbocharged SI-Engine Simulation with Cold and Hot-Measured Turbocharger Performance Maps2012In: Proceedings of ASME Turbo Expo 2012, Vol 5, ASME Press, 2012, p. 671-679Conference paper (Refereed)
    Abstract [en]

    Heat transfer within the turbocharger is an issue in engine simulation based on zero and one-dimensional gas dynamics. Turbocharged engine simulation is often done without taking into account the heat transfer in the turbocharger. In the simulation, using multipliers is the common way of adjusting turbocharger speed and parameters downstream of the compressor and upstream of the turbine. However, they do not represent the physical reality. The multipliers change the maps and need often to be different for different load points. The aim of this paper is to simulate a turbocharged engine and also consider heat transfer in the turbocharger. To be able to consider heat transfer in the turbine and compressor, heat is transferred from the turbine volute and into the compressor scroll. Additionally, the engine simulation was done by using two different turbocharger performance maps of a turbocharger measured under cold and hot conditions. The turbine inlet temperatures were 100 and 600°C, respectively. The turbocharged engine experiment was performed on a water-oil-cooled turbocharger (closed waste-gate), which was installed on a 2-liter gasoline direct-injected engine with variable valve timing, for different load points of the engine. In the work described in this paper, the difference between cold and hot-measured turbocharger performance maps is discussed and the quantified heat transfers from the turbine and to/from the compressor are interpreted and related to the maps.

  • 4. Ahlgren, Niklas
    et al.
    Karlsson, Thomas
    Larsson, Robin
    Spacecraft Department, OHB Sweden, Sweden.
    Noteborn, Ron
    PRISMA Mission Extension: Adapting Mission Operations to New and Changing Mission Objectives2012In: SpaceOps 2012 Conference, American Institute of Aeronautics and Astronautics, 2012Conference paper (Refereed)
    Abstract [en]

    The PRISMA in-orbit test-bed was launched in June 2010 to demonstrate strategies and technologies for formation flying and rendezvous. OHB Sweden is the prime contractor for the project which is funded by the Swedish National Space Board (SNSB) with support from DLR, CNES, and DTU. In early September of 2011, 15 months after launch, all primary mission objectives of the PRISMA formation flying satellites had been achieved and mission success was declared. Since a significant amount of delta-V capability still remained an open call for new experiments was issued, inviting both old and new experimenters to use the capabilities of the formation. Several interested parties took the opportunity to perform their own experiments with an existing platform, each coming with new mission objectives not previously planned to be flown on the PRISMA satellites. Some of these experiments were close to what had already been achieved within the nominal mission, but some included new ways of using the formation not envisioned by the spacecraft designers. The new experiments span from data collection in specific relative orbits, with a separation from a few meters to several kilometers, to entirely new modules within the on-board software. Changing from a pre-planned technology demonstration mission to operating a commercial resource required adaptation of the original operational concept, taking into account the different levels of experience of the customers and managing the satellites between experiments. This paper describes how these new mission objectives were integrated in operations and how a sometimes very short turn-around between initial concept and experiment execution was implemented with the aid of well established validation processes, high degrees of on-board autonomy and a flexible operations team.

  • 5.
    Ahn, Myeonghwan
    et al.
    Mechanical Engineering Research Institute, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea.
    Lee, Duck-Joo
    Mihaescu, Mihai
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics.
    A numerical study on near-field pressure fluctuations of symmetrical and anti-symmetrical flapping modes of twin-jet using a high-resolution shock-capturing scheme2021In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, p. 107147-107147, article id 107147Article in journal (Refereed)
    Abstract [en]

    Screeching supersonic jets appears at off-design operating conditions and is perceived as an intense tonal noise. In a twin nozzle configuration, mutual interactions between the two jet plumes may occur with various coupling modes developing depending on the operating conditions and lateral distance between the jets. The investigation of the detailed flow behaviors and near-field pressure fluctuations with relevance to the twin jets system, the analysis of the developed instabilities, will enhance understanding of fundamental features associated with jets located close to each other.

    In the present study, the single jet is considered first to assess the large eddy simulation (LES) approach used and the near-field pressure fluctuation predictions. Based on the validated solver, twin jets are simulated. Two different twin-nozzle configurations having different separation distance or nozzle-to-nozzle centerline spacing are scrutinized for the same Mach number of 1.358. Notably, the twin jets are screeching by the coupling mode for both set-ups; however, the case of closer inter-nozzle distance presents a symmetrical dominant flapping mode, while the other case shows an anti-symmetrical flapping mode. The strength of the pressure fluctuation at the fundamental frequency changes depending on the location of the observer point (upstream or downstream) and the reference plane (twin-jet and normal to the twin-jet plane). The screech tones of the two cases, observable in the upstream region, are significantly different in the normal to the twin-jet plane direction because of the phase difference of fluctuating pressure. However, the first harmonic component remains strong, regardless of the flapping mode. It is also observed that, at the fundamental frequency, the amplitude of the pressure fluctuation at downstream locations is found to be strong in the normal to the twin-jet plane when the symmetrical flapping mode occurs. This feature is also observed in the twin-jet plane in the case of the opposite mode. By analyzing the developed vertical structures and performing correlation analyses of pressure fluctuations along jet shear layers, the periodicity of the flow in the downstream region with relevance to the fundamental frequency is revealed.

  • 6.
    Ahn, MyeongHwan
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Mihaescu, Mihai
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Effects of Temperature on the Characteristics of Twin Square Jets by Large Eddy Simulations2022In: AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022, American Institute of Aeronautics and Astronautics (AIAA) , 2022, article id AIAA 2022-0681Conference paper (Refereed)
    Abstract [en]

    In this study, we investigate the effects of temperature on the aerodynamic and aeroacoustics characteristics of twin square jets. Implicit Large Eddy Simulations (ILES) are performed for twin jets with a fixed nozzle pressure ratio (NPR) of 3.0 and temperature ratios (TR) of 1.0, 2.0, 4.0, and 7.0. A second-order central scheme is used to resolve acoustic waves, and an artificial dissipation model is applied to capture shock waves and to suppress non-physical oscillations. In addition, the variation of a specific heat ratio as function of temperature is considered under the chemical equilibrium assumption. The numerical results show that the length of potential core is reduced with the increase of temperature due to the enhanced mixing in jet shear layers which can be estimated by turbulent kinetic energy (TKE). Meanwhile, the fluctuations of the transverse velocity show different trends between the cases within the corresponding potential core length, which can be associated with the screeching phenomena of the twin-jet. As temperature increases, the convection Mach number in the jet shear layers is also increased so that the Mach wave is generated for TR of 2.0, 4.0, and 7.0. However, a crackle noise is only observed for TR of 4.0 and 7.0, whose generation is identified by the skewness and kurtosis factors. Relatively low temperature jets (TR of 1.0 and 2.0) are screeching so that peaks are observed in the spectra obtained upstream. On the other hand, broadband component is gradually increased when the jets are heated, and the largest increase is observed at the location exposed to the Mach wave radiation.

  • 7.
    Ahn, MyeongHwan
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Mihaescu, Mihai
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Karnam, Aatresh
    University of Cincinnati.
    Gutmark, Ephraim
    Aerospace Engineering, University of Cincinnati.
    Large-eddy simulations of flow and aeroacoustics of twin square jets including turbulence tripping2023In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 35, no 6Article in journal (Refereed)
    Abstract [en]

    In this study, we investigate the flow and aeroacoustics of twin square (i.e., aspect ratio of 1.0) jets by implicit large-eddy simulations (LESs) under a nozzle pressure ratio of 3.0 and a temperature ratio of 1.0 conditions. A second-order central scheme coupled with a modified Jameson's artificial dissipation is used to resolve acoustics as well as to capture discontinuous solutions, e.g., shock waves. The flow boundary layer inside of the nozzle is tripped, using a small step in the convergent section of the nozzle. The time-averaged axial velocity and turbulent kinetic energy of LES with boundary layer tripping approaches better to particle image velocimetry experimental data than the LES without turbulence tripping case. A two-point space–time cross-correlation analysis suggests that the twin jets are screeching and are coupled to each other in a symmetrical flapping mode. Intense pressure fluctuations and standing waves are observed between the jets. Spectral proper orthogonal decomposition (SPOD) confirms the determined mode and the relevant wave propagation. The upstream propagating mode associated with the shock-cell structures is confined inside jets. Far-field noise obtained by solving Ffowcs Williams and Hawkings equation is in good agreement with the measured acoustic data. The symmetrical flapping mode of twin jets yields different levels of the screech tone depending on observation planes. The tonalities—the fundamental tone, second and third harmonics—appear clearly in the far-field, showing different contributions at angles corresponding to the directivities revealed by SPOD.

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  • 8.
    Akbarpour, Sahar
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lightweight Structures. KTH.
    Enhanced Composite Joint Performance through Interlacement of Metal Inserts2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work in this thesis investigates bolted joints in fibre reinforced composites with particular focus on a novel insert concept. The concept is characterised by replacing all composite plies with stacked metal patches, locally around a bolt hole, so that they jointly form a solid metal reinforcement. An extensive experimental study is presented together with finite element analysis of the studied cases.

    Reinforcing bolt holes with high-strength metals improves the bearing load capacity of the composite laminates. True enhancement of the joint performance however requires that the open-hole tensile strength is improved as well. The work started with tests of pin-loaded and open-hole tensile specimens with inserts, and significant improvement of the bearing load capacity was found. The initial tests enabled more informed design, and insert configurations having sufficient open-hole tensile strength could thereby be manufactured and tested. In parallel, composite-metal joints were numerically modelled to simulate and analyse the mechanical performance of the joints and gain a better understanding of the governing damage mechanisms.

    The performance of the joints was eventually investigated by means of experiments on single-shear, single- and double-bolt specimens, with and without inserts. The allowable bolt distance and the influence from the bolt tightening torque were also examined.

    The initial samples had inserts of stainless steel. Later, specimens with titanium alloy inserts were also included in the test series. Various insert configurations were designed to study the effects of different features in the composite-metal bond lines. The numerical simulations of the composite--metal interfaces were performed with two types of models, one joining the two materials directly to each other, without modelling any adhesive film in between, and the other including an elastic representation of the adhesive layer. The experimental results were then used to support verification of the results from the simulations.

    The final assessment of the concept was performed on insert configurations designed either for pure tensile loading or for more general (bi-directional) loading conditions, and the bearing load capacity, open-hole tensile strength and the performance of bolted joints were compared for cases with different inserts. While higher bearing strength improvement was achieved when the holes were reinforced with inserts of stainless steel, reinforcement with inserts of titanium was even more successful since it improved virtually all studied aspects of the joints considerably.

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  • 9.
    Akbarpour, Sahar
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lightweight Structures.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lightweight Structures.
    Strength improvement of bolted joints in composite materials by use of patched metal inserts2020In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 52, article id 112628Article in journal (Refereed)
    Abstract [en]

    Metal inserts are occasionally used to improve bearing load capacity of bolted joints in laminated composite materials. This paper investigates a new reinforcement concept where inserts are built by locally replacing composite plies with metal patches of various diameters, surrounding the holes. The inserts are built during composite manufacturing by alternately placing the metal patches through the thickness of the laminate at locations where holes are to be drilled after consolidation. An extensive experimental study including pin‐ loaded, open–hole tensile, and single‐shear testing of bolted specimens is presented. Considerable improve- ment of the bearing strength – 50‐60% – is attained for pin‐loaded specimens with inserts, demonstrating the potential of the reinforcement concept. The open–hole tensile tests show that the by‐pass strength can be maintained or even improved with up to 20% if the inserts are properly designed. Finally, the results from the single‐shear tests of bolted joints show more than 25% improvement in strength for reinforced single‐ and double‐bolt specimens. It is possible that the inserts would maintain clamping pressure over time, which could then almost double the imrovement (47%) for bolted joints.

  • 10.
    Alaniz, Monica
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Belyayev, Serhiy
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Bergman, David
    Casselbrant, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Honeth, Mark
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Huang, Jiangwei
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Ivchenko, Nickolay
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Laukkanen, Mikko
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Michelsen, Jacob
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Pronenko, Vira
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Paulson, Malin
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Schlick, Georg
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Tibert, Gunnar
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Valle, Mario
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    The SQUID sounding rocket experiment2011In: Proceedings of the 20th ESA Symposium on European Rocket and Balloon Programmes and Related Research, European Space Agency, 2011, p. 159-166Conference paper (Refereed)
    Abstract [en]

    The objective of the SQUID project is to develop and in flight verify a miniature version of a wire boom deployment mechanism to be used for electric field measurements in the ionosphere. In February 2011 a small ejectable payload, built by a team of students from The Royal Institute of Technology (KTH), was launched from Esrange on-board the REXUS-10 sounding rocket. The payload separated from the rocket, deployed and retracted the wire booms, landed with a parachute and was subsequently recovered. Here the design of the experiment and post fight analysis are presented.

  • 11.
    Alarcón, José Faúndez
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Sasaki, Kenzo
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Hanifi, Ardeshir
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Larsson, Roger
    Saab Aeronautics, Bröderna Ugglas gata, SE-58188, Linköping, Sweden, Bröderna Ugglas gata.
    Henningson, Dan S.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    REACTIVE CONTROL OF BYPASS TRANSITION IN A WING BOUNDARY LAYER2022In: 33rd Congress of the International Council of the Aeronautical Sciences, ICAS 2022, International Council of the Aeronautical Sciences , 2022, p. 3037-3047Conference paper (Refereed)
    Abstract [en]

    This investigation deals with the numerical implementation of a data-driven method for reactive control of the boundary-layer over a NACA0008 airfoil. The aim of this work is to evaluate the performance of controller in damping the flow disturbances and its efficiency in delaying laminar-turbulent transition. We focus our attention on the bypass transition scenario caused by free-stream turbulence. In this scenario, the perturbations in the wing boundary-layer develop into streaky structures. We show that this data-driven method is effective in decreasing the wall shear stress and disturbance energy at the objective location, and this damping is sustained downstream of the objective location. However, further downstream, the fluctuations grow again reaching amplitudes similar to those in the uncontrolled case.

  • 12.
    Allam, Sabry
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Åbom, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Advanced experimental procedure for in-duct aero-acoustics2006In: 13th International Congress on Sound and Vibration 2006, ICSV 2006, 2006, p. 1185-1192Conference paper (Refereed)
    Abstract [en]

    The purpose of this paper is to present a method for characterization of in-duct aero-acoustic sources that can be described as active acoustic two-ports. The method is applied to investigate the sound produced from an orifice plate. The motivation is to obtain better data for the development of improved prediction methods for noise from flow singularities, e.g., in HVAC systems on aircrafts. Most of the earlier works fall into two categories; papers modeling the scattering of acoustic waves and papers modeling the sound generation. Concerning the scattering it is possible to obtain estimates of the low frequency behavior from linear perturbations of the steady state equations for the flow. Concerning the sound generation most of the presented work is experimental and follows a paper by Nelson&Morfey, which present a scaling law procedure for the in-duct sound power based on a dipole model of the source. One limitation with the earlier works is that the sound power only was measured on the downstream side. Also data was only obtained in 1/3-octave bands, by measuring the sound radiated from an open duct termination. Assuming plane waves and linear acoustics the flow duct singularity can be completely modeled as an active 2-port. The experimental determination of its properties is done in a two steps procedure. In the first step the passive data, i.e., the scattering matrix S, is determined using external (independent) sources. In the second step the S matrix is used and the source vector is determined by testing the system with known acoustic terminations.

  • 13.
    Alshahrani, Ali
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Flight Dynamics.
    Analysis and Initial Optimization of The Propeller Design for Small, Hybrid-Electric Propeller Aircraft2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis focuses on the optimization of the electric aircraft propeller in order to increaseflight performance. Electric aircraft have limited energy, particularly the electricmotor torque compared to the fuel engine torque. For that, redesign of the propeller forelectric aircraft is important in order to improve the propeller efficiency. The airplanepropeller theory for Glauert is selected as a design method and incorporated with Brattimprovements of the theory. Glauert theory is a combination of the axial momentum andblade element theory. Pipistrel Alpha Electro airplane specifications have been chosen asa model for the design method. Utilization of variable pitch propeller and the influence ofnumber of blades has been investigated. The obtained design results show that the variablepitch propellers at cruise speed and altitude 3000 m reducing the power consumptionby 0.14 kWh and increase the propeller efficiency by 0.4% compared to the fixed pitchpropeller. Variable pitch propeller improvement was pretty good for electric aircraft. Theoptimum blade number for the design specifications is 3 blades.

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  • 14.
    Ambre, Rombaut
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Landing the Propellant Stage of a launcher2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To reduce the cost of launch, several aerospace companies are exploring the possibility of partly reusable launchers. In order to be reusable with minimum refurbishment cost the reusable part of the launcher has to suffer little damage and land in optimal conditions. In this paper, a guidance algorithm to achieve the return of the reusable vehicle on ground through a vertical landing is described. Different mission scenarios are taken into account and the performance of the guidance algorithm is assessed using a 6 Degrees Of Freedom simulator.

  • 15.
    Amini, Kasra
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Janabadi, Ehsan Dehghani
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Fayaz, Rima
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Lighting and illumination investigation of long-term residence on Mars for the case of a set of designed Martian Habitat Units (MHUs)2022In: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030, Vol. 192, p. 210-232Article in journal (Refereed)
    Abstract [en]

    Addressing the subject matter of human missions on Mars, the Martian Habitat Units (MHUs) are presented as a comprehensive solution. MHUs are designed in clusters of 10 units, each capable of serving as long-term habitats for 9 scientific crew members. The life-style requirements of the units are targeted at an imitation of cultural thriving life we all know of, and not a mere survival-type shelter expecting the first people to step foot on Mars. One aspect of many challenging issues to be addressed in such complex settings is the lighting and illuminance condition of the said habitats, which in the context of Mars, and generally deep space missions being far from the sun will certainly lead to an arduous task. To check the validity of the argument and assess the extent to which the natural light level available on the surface of Mars will be sufficient for the daily requirements of the crew and mission in terms of illuminance, the current manuscript presents thorough and detailed simulations and analyses on the availability evaluation of natural lighting in the site location of MHUs, namely Valles Marineris, Melas Chasma. In this paper solar irradiation parameters on Mars are calculated based on the previous research which resulted in global, direct and diffuse irradiance at 12 different Martian solar times. The simulations are distributed over the Martian year and its day-time, and for two extreme orientations of MHUs in their circular surrounding cluster, namely East/West and South/North units. The distribution of illuminance for each case, and trend comparison studies are then accompanied by numerical values and analyses on the percentage to which the natural lighting conditions on Mars have been shown to be sufficient as a fraction of the whole lighting load of the habitats, which is to be compensated using artificial sources. The corresponding values are shown to fall well in the range of 35-45% of the total lighting loads. Also, as the results of the simulations show, due to the consistency of the glazed parts of the designed facade through all exterior surface of the MHU, natural lighting sufficiency percentage does not show a significant difference between two simulated orientations. This fact further approves the circular orientation premise of the MHUs in their cluster.

  • 16.
    Amini, Kasra
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics. Univ Stuttgart, Inst Aerosp Thermodynam ITLR, Stuttgart, Germany..
    Moradi, Mojgan
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Teymoori, Peyman Ebadi Belfeh
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Vossoughi, Bahareh
    Rhein Westfal TH Aachen, Fac Mech Engn, Aachen, Germany.;Rhein Westfal TH Aachen, Inst Combust Engines Verbrennungskraftmaschinen, Aachen, Germany..
    Janabadi, Ehsan Dehghani
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Fayaz, Rima
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Design of a set of habitat units and the corresponding surrounding cluster for long-term scientific missions in the pre-terraforming era on mars2022In: Icarus, ISSN 0019-1035, E-ISSN 1090-2643, Vol. 385, p. 115119-, article id 115119Article in journal (Refereed)
    Abstract [en]

    We are living in a point in the history of science and technology, where space travel for research and settlement is inevitable. As the utmost crucial technology pieces for leaving Earth and travelling into the cosmos is being established one after another, it is just a matter of decades, until it all gets integrated together, solving the engineering problems ahead of the way and being able to step on the planets and moons of the solar system. In this quest, as has been the case for most of the technological advancements so far, there ought to be mind experiments, in which one skips one step, assumes the availability of responses to the skipped-over step, and searches for the solution to the questions of the next level. This way, by getting passed the first, i.e. current step, the solution to the next one is already available. The current manuscript is addressing this very 'next step', on the long path to eventually colonize Mars and inhabit it for long-term research-based missions; let it be for terraforming, or other agenda to be defined by the research strategists, then. And as mentioned earlier, the current step; being setting foot on Mars, is well-deservedly taken for granted, as is to come forth undoubtedly. Having that realized, we might find ourselves faced by the engineering complexities of surviving and thriving on Mars, which is the subject matter of the current research, from the aspect point of space technological and architectural design. The design procedure beginning from setting the philosophy of design upon the concerns of sustaining in the hostile environment of Mars, to the stepwise emergence of the final design of a cluster of Martian Habitat Units (MHUs) considering the high-criteria of the case, is the subject matter covered in this manuscript.

  • 17.
    Amini, Kasra
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Moradi, Mojgan
    Department of Architectural Technology, Faculty of Architecture and Urban Planning, University of Art, Tehran, Iran.
    Vossoughi, Bahareh
    Faculty of Mechanical Engineering, RWTH Aachen University, Aachen, Germany.
    Janabadi, Ehsan Dehghani
    Department of Architectural Technology, Faculty of Architecture and Urban Planning, University of Art, Tehran, Iran.
    Space-technological and architectural methodology and process towards design of long-term habitats for scientific human missions on mars2023In: MethodsX, ISSN 1258-780X, E-ISSN 2215-0161, Vol. 11, article id 102270Article in journal (Refereed)
    Abstract [en]

    Centered on the core idea of long duration habitat design for research crew on Mars, the Martian Habitat Units (MHUs) are designed as a cluster of 10 units each with the maximum capacity of 9 crew members to live and carry on with the local challenges of scientific and exploratory life, while enjoying their lives as intellectual, social individuals in the harsh environment of Mars for durations in the order of magnitude of several years. This approach to the concept of a living environment in sharp contradiction to that of a shelter with the minimal capabilities to meet the requirements of terrestrial life to the point of survival, has led the outcoming design to be a fulfilling environment for the inhabitants of the units to evolve and thrive culturally, while being on a years-long mission. This manuscript provides detailed insight on the lessons learned of the aforementioned comprehensive design attempt with, but not limited to, the following core concerns: • The initial stand-point of such a design procedure relies on an ever increasing and comprehensive list of concerns, be it classically discussed in the literature and predictable, or unforeseen on the face of it, but to be prevented anyhow. The manuscript discusses the most crucial ones of such criteria/concerns. • The infamous saying of “Whatever that can go wrong, will go wrong” demands a rather complex level of redundancies in all layers of the design and the thought procedure behind its all aspects. The manuscript addresses the adequate steps towards its realization. • Modularity in all layers of the design plays a key role in reducing construction, maintenance, and installation costs, as for any deep space mission the mentioned expenses are astronomically high themselves. The manuscript presents our solution for geometric modularity of the design.

  • 18. Amoignon, Olivier
    et al.
    Pralits, Jan O.
    Hanifi, Ardeshir
    Swedish Defence Research Agency.
    Berggren, M.
    Henningson, Dan S.
    KTH, School of Engineering Sciences (SCI), Mechanics, Stability, Transition and Control.
    Shape optimization for delay of laminar-turbulent transition2006In: AIAA Journal, ISSN 0001-1452, E-ISSN 1533-385X, Vol. 44, no 5, p. 1009-1024Article in journal (Refereed)
    Abstract [en]

    A method using gradient-based optimization is introduced for the design of wing profiles with the aim of natural laminar How, as well as minimum wave drag. The Euler equations of gasdynamics, the laminar boundary-layer equations for compressible flows on infinite swept wings, and the linear parabolized stability equations (PSE) are solved to analyze the evolution of convectively unstable disturbances. Laminar-turbulent transition is assumed to be delayed by minimizing a measure of the disturbance kinetic energy of a chosen disturbance, which is computed using the PSE. The shape gradients of the disturbance kinetic energy are computed based on the solutions of the adjoints of the state equations just named. Numerical tests are carried out to optimize the RAE 2822 airfoil with the aim to delay simultaneously the transition, reduce the pressure drag coefficient, and maintain the coefficients of lift and pitch moments. Constraints are also applied on the geometry. Results show a reduction of the total amplification of a large number of disturbances, which is assumed to represent a delay of the transition in the boundary layer. Because delay of the transition implies reduction of the viscous drag, the present method enables shape optimization to perform viscous drag reduction.

  • 19.
    Andersson, Kenny
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.
    Risk Assessment for Space Debris Collisions2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The increasing reliance on space infrastructure and its rapid expansion necessitate the development and enhancement of tools for space debris and fragmentation research. Accurate prediction of the risks associated with satellite fragmentation requires comprehensive understanding of the dynamics involved. To address this need, the widely used NASA Standard Breakup Model (SBM) is employed in this thesis to predict fragment characteristics resulting from breakup events. Additionally, a novel method is introduced to determine the direction of these fragments, something not directly covered by the SBM. Furthermore, the principle of kinetic gas theory is applied to calculate the overall, long-term collision risk between debris and a predetermined satellite population. The results from this reveal the limitations of the SBM in accurately simulating fragmentations for certain satellite types. However, the newly implemented fragment directionality method aligns well with observed data, suggesting its potential for further research. Similarly, the risk model exhibits strong correspondence with ESA's MASTER, a model used for assessing collision risks with debris, with the deviations likely due to different impact velocity models used. Finally, the validated fragmentation and risk models are combined, and the combined model is used to analyse a real-world fragmentation event.

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  • 20.
    Andersson, Klas
    a Dept. of Mech. and Astronautical Eng., Naval Postgraduate School, Monterey, CA, United States.
    Extending Endurance for Small UAVs by Predicting and Searching for Thermal Updrafts2009Conference paper (Refereed)
  • 21.
    Andersson, Klas
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Robotics, Perception and Learning, RPL.
    Improving Fixed Wing UAV Endurance, by Cooperative Autonomous Soaring2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The ever-expanding use and development of smaller UAVs (Unmanned Aerial Vehicles) has highlighted an increasing demand for extended range and endurance for this type of vehicles. 

    In this thesis, the development of a concept and system for autonomous soaring of cooperating unmanned aerial vehicles is presented. The purpose of the developed system is to extend endurance by harvesting energy available in the atmosphere in the form of thermal updrafts, in a similar way that some birds and manned gliders do. By using this “free” energy, considerable improvements in maximum achievable endurance can be realized under a wide variety of atmospherical and weather conditions. 

    The work included theoretical analysis, simulations, and finally flight test- ing of the soaring controller and the system. The system was initially devel- oped as a single-vehicle concept and thereafter extended into a system consist- ing of two cooperating gliders. The purpose of the extension to cooperation, was to further improve the performance of the system by increasing the ability to locate the rising air of thermal updrafts. 

    The theoretical analysis proved the soaring algorithm’s thermal centering controller to be stable. The trials showed the concept of autonomous soaring to function as expected from the simulations. Further it revealed that, by applying the idea, extensive performance gains can be achieved under a fairly wide variety of conditions. 

    The cooperative soaring, likewise, functioned as anticipated and the glid- ers found, cooperated, and climbed together in updrafts. This represents the first and presumably only time cooperative autonomous soaring in this way, has been successfully demonstrated in flight. To draw further conclusions on the advantages of cooperative soaring additional flight trials would, however, be beneficial. 

    Possible issues and limitations were highlighted during the trials and a number of potential improvements were identified. 

    As a part of the work, trials were conducted to verify the viability to implement the system into “real world” operational scenarios. As a proof of concept this was done by tasking the autonomous gliders to perform data/communications relay missions for other UAV systems sending imagery to the ground-station from beyond line of sight (BLOS). The outcome of the trials was positive and the concept appeared to be well suited for these types of missions. The comms relay system was further developed into a hybrid system where the optimal location concerning relay performance was autonomously sought out, after-which the attentiveness then switched to autonomous thermal soaring in the vicinity of this ideal relay position. The hybrid system was tested in simulation and partially flight tested. 

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  • 22.
    Andersson, Klas
    et al.
    KTH, School of Computer Science and Communication (CSC). the Dept. of Mech. & Aeronautical Eng. Naval Postgraduate School, Monterey, CA 93940 USA.
    Jones, Kevin
    Dobrokhodov, Vladimir
    Kaminer, Isaac
    Thermal highs and pitfall lows - notes on the journey to the first cooperative autonomous soaring flight2012In: 2012 IEEE 51st IEEE Conference on Decision and Control (CDC), Institute of Electrical and Electronics Engineers (IEEE), 2012, p. 3392-3397Conference paper (Refereed)
    Abstract [en]

    This paper discusses the development and flight testing of an algorithm for cooperative soaring by multiple autonomous gliders. Flight test results confirmed that the algorithm functioned as expected and that the gliders worked cooperatively to find and utilize the same updrafts during the test. However, the flight also indicated that the effectiveness of the strategy depends largely on the existing thermal conditions in combination with how restrictively the limits of separation be tween the cooperating gliders are set. To the best of the authors' knowledge this was the world's first cooperative autonomous thermal soaring flight.

  • 23.
    Andersson, Klas
    et al.
    Naval Postgraduate School, Monterey, California 93943.
    Kaminer, Isaac
    Naval Postgraduate School, Monterey, California 93943.
    Dobrokhodov, Vladimir
    Naval Postgraduate School, Monterey, California 93943.
    Cichella, Venanzio
    Universita’ di Bologna, 40126 Bologna, Italy.
    Thermal Centering Control for Autonomous Soaring; Stability Analysis and Flight Test Results2012In: Journal of Guidance Control and Dynamics, ISSN 0731-5090, E-ISSN 1533-3884, Vol. 35, no 3, p. 963-975Article in journal (Refereed)
  • 24.
    Andersson, Klas
    et al.
    Naval Postgraduate Shool.
    Kaminer, Issac
    Naval Postgraduate Shool.
    Jones, Kevin
    Naval Postgraduate Shool.
    Dobrokhodov, Vladimir
    Naval Postgraduate Shool.
    Lee, Deok-Jin
    Naval Postgraduate Shool.
    Cooperating UAVs Using Thermal Lift to Extend Endurance2009Conference paper (Refereed)
  • 25.
    Anton, Nicholas
    et al.
    Scania CV AB, SE-15138 Sodertalje, Sweden..
    Genrup, Magnus
    Lund Univ, Energy Sci, SE-22100 Lund, Sweden..
    Fredriksson, Carl
    Scania CV AB, SE-15138 Sodertalje, Sweden..
    Larsson, Per-Inge
    Scania CV AB, SE-15138 Sodertalje, Sweden..
    Christiansen Erlandsson, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    AXIAL TURBINE DESIGN FOR A TWIN-TURBINE HEAVY-DUTY TURBOCHARGER CONCEPT2018In: PROCEEDINGS OF THE ASME TURBO EXPO: TURBOMACHINERY TECHNICAL CONFERENCE AND EXPOSITION, 2018, VOL 2B, ASME Press, 2018, article id UNSP V02BT44A008Conference paper (Refereed)
    Abstract [en]

    In the process of evaluating a parallel twin-turbine pulse-turbocharged concept, the results considering the turbine operation clearly pointed towards an axial type of turbine. The radial turbine design first analyzed was seen to suffer from sub-optimum values of flow coefficient, stage loading and blade speed-ratio. Modifying the radial turbine by both assessing the influence of "trim" and inlet tip diameter all concluded that this type of turbine is limited for the concept. Mainly, the turbine stage was experiencing high values of flow coefficient, requiring a more high flowing type of turbine. Therefore, an axial turbine stage could be feasible as this type of turbine can handle significantly higher flow rates very efficiently. Also, the design spectrum is broader as the shape of the turbine blades is not restricted by a radially fibred geometry as in the radial turbine case. In this paper, a single stage axial turbine design is presented. As most turbocharger concepts for automotive and heavy-duty applications are dominated by radial turbines, the axial turbine is an interesting option to be evaluated for pulse charged concepts. Values of crank-angle-resolved turbine and flow parameters from engine simulations are used as input to the design and subsequent analysis. The data provides a valuable insight into the fluctuating turbine operating conditions and is a necessity for matching a pulse-turbocharged system. Starting on a 1D-basis, the design process is followed through, resulting in a fully defined 3D-geometry. The 3D-design is evaluated both with respect to FEA and CFD as to confirm high performance and durability. Turbine maps were used as input to the engine simulation in order to assess this design with respect to "on-engine" conditions and to engine performance. The axial design shows clear advantages with regards to turbine parameters, efficiency and tip speed levels compared to a reference radial design. Improvement in turbine efficiency enhanced the engine performance significantly. The study concludes that the proposed single stage axial turbine stage design is viable for a pulse-turbocharged six cylinder heavy-duty engine. Taking into account both turbine performance and durability aspects, validation in engine simulations, a highly efficient engine with a practical and realizable turbocharger concept resulted.

  • 26.
    Antonio, D'Anniballe
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.
    Catalogue initialization: assessing optical tracklet-to-tracklet association methods2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Space surveillance and tracking is paramount to enable collision avoidance alert systems and avoid fragmentation events and the consequent generation of debris. This thesis work was performed within the framework of the EU SST, a network of sensors and processing capabilities of the European Union dedicated to space tracking. Using tools developed at CNES, a performance analysis of a correlation assessment algorithm based on the Lambert’s problem was carried out. The algorithm was tested on a simulated population orbiting the GEO region using different dynamical models. The performance of the algorithm was also tested for varying values of the sensor noise. A modification to the algorithm accounting for orbit perturbations was proposed and tested, showing improved results under certain conditions. Finally, the catalogue initialization capabilities of the algorithm were assessed in terms of correlation assessment and orbit determination accuracy by testing it on real data collected by the TAROT network of telescopes.

  • 27.
    Aoudia, Thomas
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Aircraft Performance Monitoring on Contaminated Runways2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Operations on contaminated runways are a permanent challenge for the aviation community. Among the stakeholders, Airbus has decided to improve its knowledge by developing a fast post-processing software aiming at quickly identifying the runway state on operational recordings. First and foremost, the context of operations on contaminated runways is presented, with a particular emphasis on runway condition assessment methods. In a second part, the models embedded in this function are validated against simulation and more elaborated flight test analysis software. Then, the identification algorithm is validated by comparing its outputs to actual operational conditions. Finally, the robustness of the identification is assessed.

  • 28.
    Aribowo, Agus
    et al.
    Research Center for Aeronautics Technology, National Research and Innovation Agency (BRIN), Bogor 16350, Indonesia.
    Adhynugraha, Muhammad Ilham
    Research Center for Aeronautics Technology, National Research and Innovation Agency (BRIN), Bogor 16350, Indonesia.
    Megawanto, Fadli Cahya
    Directorate of Strengthening and Partnership of Research and Innovation Infrastructure, BRIN, Bogor 16912, Indonesia.
    Hidayat, Arif
    Research Center for Advanced Material, BRIN, Banten 15314, Indonesia.
    Muttaqie, Teguh
    Research Center for Hydrodynamics Technology, BRIN, Surabaya 60117, Indonesia.
    Wandono, Fajar Ari
    Research Center for Aeronautics Technology, National Research and Innovation Agency (BRIN), Bogor 16350, Indonesia.
    Nurrohmad, Abian
    Research Center for Aeronautics Technology, National Research and Innovation Agency (BRIN), Bogor 16350, Indonesia.
    Chairunnisa,
    Research Center for Energy Conversion and Conservation, BRIN, Banten 15314, Indonesia.
    Saraswati, Sherly Octavia
    Research Center for Process and Manufacturing Industry Technology, BRIN, Banten 15314, Indonesia.
    Wiranto, Ilham Bagus
    Research Center for Process and Manufacturing Industry Technology, BRIN, Banten 15314, Indonesia.
    Al Fikri, Iqbal Reza
    Research Center for Process and Manufacturing Industry Technology, BRIN, Banten 15314, Indonesia.
    Saputra, Muhammad Dito
    KTH, School of Engineering Sciences (SCI). Research Center for Rocket Technology, National Research and Innovation Agency (BRIN), Bogor 16350, Indonesia.
    Finite element method on topology optimization applied to laminate composite of fuselage structure2023In: Curved and Layered Structures, ISSN 2353-7396, Vol. 10, no 1Article in journal (Refereed)
    Abstract [en]

    This research applies a numerical study of topology optimization of laminate composite structures by using a finite element method (FEM). In this methodology, the plies orientation is excluded from the optimization. The geometry-based optimization from frames of a MALE UAV fuselage structure is presented. The minimum strain energy with an optimization constraint of 20% of weight reduction is used in the objective function. Before the primary analysis, benchmark studies of topology optimization without considering orientations from previously published literature are performed. The convergence studies were taken to acquire the appropriate mesh size in the FEM technique, which utilized a four-noded shell element. The finite element analysis and optimization results showed that the structural design of the newly framed composite fuselage MALE UAV meets the structural strength requirements specified in the airworthiness standard STANAG 4671.

  • 29.
    Arnal, Daniel
    et al.
    ONERA.
    Tran, Dac
    Dassault Aviation.
    Hein, Stefan
    DLR.
    Hanifi, Ardeshir
    KTH, School of Engineering Sciences (SCI), Mechanics, Stability, Transition and Control. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Engelbrecht, T.
    SUPERsonic TRAnsition Control Contract N° AST4-CT-2005-516100: Final Technical Report2008Report (Other academic)
  • 30.
    Arrieus, Benjamin
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Flight Dynamics.
    Hydraulic systems on AS350 helicopters: description, post-crash examination and contribution to accidentology2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This paper presents the work done during a Master Thesis at Airbus Helicopters company in theaccident investigation team. The focus of that internship was the hydraulic systems on AS350 helicoptersthat assist flight controls and may have an impact on accidents. It led to a "lessons learned" analysis basedon accident rates and protective/ corrective measures taken by Airbus Helicopters after hydraulics relatedaccidents. A detailed protocol for hydraulic circuit expertise has been written and a tool-case for functionalpost-crash hydraulic tests has been developed. This paper will present how helicopters fly, are controlledand how hydraulics are involved in flight controls. The above cited missions will then be explained.

  • 31.
    Arulkrishnan, Arjhun
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Space Technology.
    Low Thrust Trajectory Optimization2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years, researchers realized the advantages of using low thrust propulsion system to navigate the spacecraft through the solar system. Designing a trajectory through space using low thrust propulsion system involves solving complex non-linear equations. Also, it often incorporates optimization of certain parameters like time of flight or propellant consumption, making it more complex. There are commercially available software like SEPSPOT and GMAT, which solves trajectory optimization problems. But these software are computationally tedious and requires a deeper understanding of concepts and software. This paper tries to bridge the gap by analyzing different simpler methods available for solving optimization problem. An Analytical method and the Indirect Optimization methods were examined in this investigation with the goal of assessing each approach, thereby determining the quicker yet accurate method. A few approximations like Directional Adaptive Guidance (DAG) and Orbital Averaging techniques were used to reduce the computational load. Results from both the methods were compared with each other and validated with results available from literature. Various missions like Geosynchronous Transfer Orbit (GTO) to Geostationary Earth Orbit (GEO), Low Earth Orbit (LEO) to Medium Earth Orbit (MEO) and pure orbital changes were taken and analyzed. It was concluded that by making proper approximations, one can get solutions quickly without compromising the accuracy of the solution. An error of 4% was observed between the two methods, which can be ignored for getting near estimates. After validating the methods,the analytical method was used to produce a non-dimensionalized contour graph which can be used as an estimate for getting time optimal solution for most of the missions within the sphere of influence of Earth.

  • 32.
    Ask, Jacob
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Space Technology.
    Selected Trends and Space Technologies Expected to Shape the Next Decade of SSC Services2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Since the early 2000s the space industry has undergone significant changes such as the advent of reusable launch vehicles and an increase of commercial opportunities. This new space age is characterized by a dynamic entrepreneurial climate, lowered barriers to access space and the emergence of new markets. New business models are being developed by many actors and the merging of space and other sectors continues, facilitating innovative and disruptive opportunities. Already established companies are adapting in various ways as efforts to stay relevant are gaining attention. The previous pace of development that was exclusively determined by governmental programs are now largely set by private and commercial ventures. Relating to all trends, new technologies and driving forces in the space industry is no trivial matter. By analyzing and examining identified trends and technologies the author has attempted to discern those that will have a significant impact on the industrial environment during the next decade. Market assessments have been summarized and interviews have been carried out. Discussions and conclusions relating to the services provided by the Swedish Space Corporation are presented. This report is intended to update the reader on the current status of the space industry, introduce concepts and provide relevant commentary on many important trends.

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  • 33.
    Astruc, Maxime
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Space Technology.
    Mission Programming for the Mars Moon eXplorer Mission2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis presents a way to maximise the photographic coverage of Phobos, one of the two Martian moons, as part of the space mission Mars Moon eXplorer. This coverage is performed by the French hyperspectral imager MacrOmega, and two criteria are selected: the area covered and the resolution of the pictures. The approach considered is a greedy algorithm, and elements of basic theory are provided. This greedy approach is compared to a chronological algorithm, whose results were already approved for the mission.

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  • 34. Austrin, L.
    et al.
    Torabzadeh Tari, Mohsen
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Larsson, A.
    Analysis of a feasible pulsed-power supply system for an Unmanned Aerial Vehicle2006In: ICAS-Secretariat, 2006, p. 3605-3612Conference paper (Refereed)
    Abstract [en]

    More Electric Aircraft technology enables the power supply of electric energy weapons such as high-power microwave and laser weapons. Aspects of electric power generation, energy storage, distribution and pulse-conditioning systems for the power supply of directed energy weapons in Unmanned Aerial Vehicle are addressed in this paper. A trend in aircraft design is to electrify more parts of the aircraft via the concept of More Electric Aircraft (MEA) and its technology which allows for increased electric power consumption. Thus, MEA technology enables the power supply of weapons and protection systems that are using electric energy. Among these devices directed energy weapons such as high-power microwave (HPM) and laser weapons are feasible. Such systems require high power pulsed electric energy with, thus imposing new requirements of on-board power supplies. In the demonstrated concept it is important to analyze power losses and efficiency as well as weight and volume in order to evaluate the possibility to adapt the system in an UAV.

  • 35.
    Axelsson, Mathias
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.
    Design of a Satellite Constellation Intended for Use with a Small User Terminal2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Satellite constellations intended for communications services are becoming increasingly relevant with multiple companies such as Starlink and OneWeb launching constellations consisting of hundreds or thousands of satellites. This thesis investigated how such a constellation can be designed for a small user terminal with a diameter of approximately 15 cm. Four constellations, two at 8 500 km altitude and two at 1 200 km altitude, were proposed. Methods for systematic placement of satellites in orbital planes, aspects going into the link budget, and relevant regulations on the international level were investigated. It was found that the most favourable constellation was a medium Earth orbit constellation with a minimum elevation of 30°. The primary reason for this choice was the limited budget which did not allow for a large number of satellites being launched. Finally, the concept of a hybrid constellation with both geostationary satellites and non-geostationary satellites was considered.

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  • 36.
    Azad, Kevin
    et al.
    KTH, School of Engineering Sciences (SCI).
    Fungula, Felix
    KTH, School of Engineering Sciences (SCI).
    Electrical Propulsion System Design of a Blended Wing Body UAV2022Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The conventional tube-and-wing aircraft has been around since the 1950s, with little to no innovative progress being made towards redesigning the conventional aircraft. The blended wing body (BWB) shape fuses the wing of the aircraft with the fuselage increasing structural strength while also increasing potential surface area to create lift, making it more efficient than conventional wing shapes. Today aviation has a 2 % CO2 contribution to global emissions. Aircraft manufacturers are predicting a steady rise for the aviation industry. The contribution of green-house gases is set to increase exponentially. Hydrogen fuel cells could deem a good fit between traditional combustion engine aircraft and electrical aircraft having a high efficiency but also being fuel-based. This report investigates the possibility of a prototype model of the Project ''Green Raven'' from KTH of creating a hybrid fuel cell BWB UAV with a 4 m wingspan. The analytical data is from literature and available benchmark data. First, an electrically driven subscale prototype is made and tested, and then the full-scale model is made. The prototype is pro-posed to be driven by a single two-bladed propeller with 10 x 4.7-inch dimensions running at 10000-13000 rpm with a takeoff weight of 4 kg, where 0.75 kg of the weight was from 5 Li-Po batteries. Performance parameters were calculated by given data with a given cruise speed of 30 m/s and a cruise endurance of 1 hour. The prototype will fly for close to maximum load at climb with an angle of 6°. With the Li-Po batteries with a total of 11 Ah, the aircraft has more than 10 % to spare for safety reasons.

     

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  • 37.
    Balani, Elena
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Flight Dynamics.
    A Safety Device for an Unmanned Aerial System2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Optionally piloted aircraft are conceived to operate either through manned or remote piloting. However, as long as they are under testing with remote controls, a safety pilot is usually present on board. The consequence is that the crew shall be protected from failures of the automated flight systems. For this reason, specific safety devices that serve as monitors were designed. An instance of such devices is the Fault Detection System for small rotorcrafts. The goal of this work is to adapt this monitor to a new actuation set. The existing code is adjusted to fit the updated actuators' hardware and the new code is then tested and improved based on an iterative validation process. The final outcome is a system that can successfully intervene to mitigate failures of other components in accordance with the safety requirements.

  • 38.
    Ballard, Claire
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Conceptual lay-out of small launcher2012Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 39.
    Ballard, Claire
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Conceptual lay-out of small launcher2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The objective of this diploma thesis is to perform a conceptual lay-out of a small launcher. Re- quirements have been defined in order to realize this first preliminary study and design of a small launcher. In that frame, a MATLAB code has been written in order to simulate the rocket tra- jectories. An optimization program on launcher staging has been written as well. To validate this code, the VEGA and Ariane 5 launchers have been used. Then from studies on existing launchers, simulations have been performed in order to find an optimum small launcher and later on to design more precisely the small launcher. As a requirement an upper stage has been newly designed for the purpose of the study. At the end, two small launchers have been considered: a three-stage launcher using the Zefiro 23 as a first stage, the Zefiro 9 as a second stage, and an upper stage using a 3kN thrust engine; a two-stage launcher using the Zenit booster engine in the first stage, and an upper stage using a 22kN thrust engine.

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  • 40. Balmer, G.
    et al.
    Berquand, A.
    Company-Vallet, E.
    Granberg, V.
    Grigore, V.
    Ivchenko, Nickolay
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    Kevorkov, R.
    Lundkvist, E.
    Olentsenko, Georgi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    Pacheco-Labrador, J.
    Tibert, Gunnar
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Yuan, Yunxia
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    ISAAC: A REXUS STUDENT EXPERIMENT TO DEMONSTRATE AN EJECTION SYSTEM WITH PREDEFINED DIRECTION2015In: EUROPEAN ROCKET AND BALLOON: PROGRAMMES AND RELATED RESEARCH, 2015, p. 235-242Conference paper (Refereed)
    Abstract [en]

    ISAAC - Infrared Spectroscopy to Analyse the middle Atmosphere Composition was a student experiment launched from SSC's Esrange Space Centre, Sweden, on 29th May 2014, on board the sounding rocket REXUS 15 in the frame of the REXUS/BEXUS programme. The main focus of the experiment was to implement an ejection system for two large Free Falling Units (FFUs) (240 mm x 80 mm) to be ejected from a spinning rocket into a predefined direction. The system design relied on a spring-based ejection system. Sun and angular rate sensors were used to control and time the ejection. The flight data includes telemetry from the Rocket Mounted Unit (RMU), received and saved during flight, as well as video footage from the GoPro camera mounted inside the RMU and recovered after the flight. The FFUs' direction, speed and spin frequency as well as the rocket spin frequency were determined by analyzing the video footage. The FFU-Rocket-Sun angles were 64.3 degrees and 104.3 degrees, within the required margins of 90 degrees +/- 45 degrees. The FFU speeds were 3.98 m/s and 3.74 m/s, lower than the expected 5 +/- 1 m/s. The FFUs' spin frequencies were 1.38 Hz and 1.60 Hz, approximately half the rocket's spin frequency. The rocket spin rate slightly changed from 3.163 Hz before the ejection to 3.117 Hz after the ejection of the two FFUs. The angular rate, sun sensor data and temperature on the inside of the rocket module skin were also recorded. The experiment design and results of the data analysis are presented in this paper.

  • 41.
    Barrére, Vincent
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Viability of CREO Simulate: (CAD software’s module) as a thermal simulation software2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The analysis of the reliability of CREO simulate will be done step by step. First of all, the precisionof the simulation has to be measured thus a comparison with simple theoretical computations willbe done. Then, the scope of the capacity of the software will be analyzed and if elements deemednecessary to thermal simulations are missing, back up solutions are to be found. Also, the influenceof the meshing will be studied and measured to ensure that the software guarantee convergence evenin the hand of persons unfamiliar with simulations.In parallel, one will experiment with realistic hardware that could be used to compare reality withthe simulations. Those experiments will be handmade using regular materials from the company.

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  • 42.
    Basaran, Hasan
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Space Technology.
    Comparison of Control Approaches for Formation Flying of Two Identical Satellites in Low Earth Orbit2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Formation flying of satellites describes a mission in which a set of satellites arrange their position with respect to one another. In this paper, satellite formation flying guidance and control algorithms are investigated in terms of required velocity increment Delta-v, and tracking error for a Chief/Deputy satellite system. Different control methods covering continuous and impulsive laws are implemented and tested for Low Earth Orbit (LEO). Sliding Mode, Feedback Linearization and Model Predictive Controllers are compared to an Impulsive Feedback Law which tracks the mean orbital element differences. Sliding Mode and Feedback Linearization controllers use the same dynamic model which includes Earth Oblateness perturbations. On the other hand, Model Predictive Control with Multi-Objective Cost Function is based on the Clohessy–Wiltshire equations, which do not account for any perturbation and do not cover the eccentricity of the orbit. The comparison was done for two different missions both including Earth Oblateness effects only. A relative orbit mission, which was based on the Prisma Satellite Mission and a rendezvous mission, was implemented. The reference trajectory for the controllers was generated with Yamanaka and Ankersen’s state transition matrix, while a separate method was used for the Impulsive Law. In both of the missions, it was observed that the implemented Impulsive Law outperformed in terms of Delta-v, 1.2 to 3.5 times smaller than the continuous control approaches, while the continuous controllers had a smaller tracking error, 2 to 8.3 times less, both in terms of root mean square error and maximum error in the steady state. Finally, this study shows that the tracking error and Delta-v has inversely proportional relationship.

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    fulltext
  • 43.
    Bashir, Zain
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.
    Lokat, Murtaza
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.
    Thermal & Air management for aBus Engine Compartment: A method for determining boundary conditions for computational fluid dynamics simulation2021Independent thesis Advanced level (degree of Master of Fine Arts (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In today's procedures of bus development in Scania CV, physical tests are the most common and reliable source of confirmation for new concepts. As of now, the majority of the physical tests are conducted in various places around the globe such as Spain, Brazil, and Sweden in order to subject the buses to various climates and environments. Naturally, these tests around the globe demand a lot of resources and are very time-consuming leading the bus development department to look for alternative ways of confirmation for these tests. An alternative to testing is in the eld of Computational Fluid Dynamics (CFD), by using 3D models to simulate in order to save resources and time. Today, the method of simulating using CFD is becoming more frequent in the development phase. However, it needs improvements. The purpose of this master's thesis is to develop a method in which the application of CFD can be successfully relied upon, by identifying a set of boundary conditions used as initial data for the CFD simulation. The boundary conditions in this project are the driving conditions and the surface temperatures of the heat sources inside the engine compartment. Initially, a physical test is conducted, in which the surface and surrounding temperatures are measured. Surrounding temperatures will act as a comparison between the physical tests and the simulations. Once the boundary conditions have been measured through physical tests, the data acquired is then used for the simulation as initial values. The goal is to achieve a maximum of10% difference between the results of the physical test and those of the simulations. From the final results, the difference between the physical tests and the simulations is 24% for one of the driving conditions which is considered the best case. However, the results are an improvement compared to the old method used currently by Scania. The method developed in this masters thesis shows an improvement of 21% compared to the old method for the same driving condition which implies a step in the right direction for reliable simulations.

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    fulltext
  • 44.
    Bayati, Arastoo
    et al.
    KTH, School of Engineering Sciences (SCI).
    Reinders, Peter
    KTH, School of Engineering Sciences (SCI).
    Conceptual Design of a Small Size Unmanned Air Vehicle: Part B: Flight Performance and Flight Mechanics2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report summarizes the task of conceptually designing an UAV suited for agricultural observation of Swedish farmland. The design of the UAV was divided into two parts. This report focuses on the flight mechanics, performance analysis, and cost analysis of the UAV, whereas the other part centers around the aerodynamic performance. Therefore, some elements, such as the wing selection, will not be subject to discussion in this report. A set of different requirements were posed, such as having a flight time longer than two hours, being able to between 5-10 m/s, able to perform vertical take-off and landing, fly at a maximum of 100 meters, and weighing less than 5 kg. By using different sources of literature, reasonable assumptions, and Matlab analytics, a UAV was designed that met all constraints demanded. The cost analysis yielded a result that was reasonable, which overall makes this conceptual UAV a realistic product that could be manufactured using the project design.

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  • 45.
    Becourt, Pierre-Olivier
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.
    Design of a suction wing for wind propulsion of ships: Pre-sizing and calculations2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As emissions of polluting substances due to shipping are growing, newsolutions for ship propulsion are emerging. One of them is the suctionwing, a vertical wing designed to generate lift forward, and made even moreefficient than classical wings by the suction of its boundary layer. Thisproject allowed for the participation, within a team of mechanical engineers,in the early design of a pilot model of such a system, ultimately intendedto be industrialised. The design process was followed in order to define thesolutions to match the performances of each function of the wing, basedon a set of specifications, and to verify the sustainability of those solutions.Also, a particular interest in the furniture and/or manufacturing of thosesolutions was given. For those instances, the suction system was defined withthe collaboration of manufacturers. Also, the wing orientation system wasdefined and its integration was verified with respect to the deformation ofthe components at its interfaces. Then, The flap was designed in order todefine solutions to allow mobility transmission, taking into account its stressconditions. The solution for the sealing of the system was also worked upon.Finally, the main mast of the wing was designed so to maintain its integrity,with respect to its stress charges and its strong stress concentrations.

  • 46.
    Belloni, Valeria
    et al.
    Sapienza Univ Rome, Geodesy & Geomat Div DICEA, Rome, Italy..
    di Tullio, Marco
    Sapienza Univ Rome, Geodesy & Geomat Div DICEA, Rome, Italy..
    Ravanelli, Roberta
    Sapienza Univ Rome, Geodesy & Geomat Div DICEA, Rome, Italy..
    Fratarcangeli, Francesca
    Sapienza Univ Rome, Geodesy & Geomat Div DICEA, Rome, Italy..
    Nascetti, Andrea
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Crespi, Mattia
    Sapienza Univ Rome, Geodesy & Geomat Div DICEA, Rome, Italy..
    Cosmo-skymed range measurements for displacement monitoring using amplitude persistent scatterers2020In: IGARSS 2020 - 2020 IEEE international geoscience and remote sensing symposium, Institute of Electrical and Electronics Engineers (IEEE) , 2020, p. 2495-2498Conference paper (Refereed)
    Abstract [en]

    Synthetic Aperture Radar (SAR) satellite data are widely used to monitor deformation phenomena impacting the Earth's surface (e.g. landslides, glacier motions, subsidence, and volcano deformations) and infrastructures (e.g. bridges, dams, buildings). The analysis is generally performed using the Differential SAR Interferometry (DInSAR) technique that exploits the phase information of SAR data. However, this technique suffers for lack of coherence among the considered stack of images, and it can only be adopted to monitor slow deformation phenomena. In the field of geohazards monitoring and glacier melting, the Offset Tracking technique has been also widely investigated. This approach is based on the amplitude information only but it reaches worse accuracy compared to DInSAR. To overcome the limitations of DInSAR and Offset Tracking, in the last decade, a new technique called Imaging Geodesy has been investigated exploiting the amplitude information and the precise orbit of the modern SAR platforms (i.e. TerraSAR-X, COSMO-SkyMed). In this study, an investigation of using COSMO-SkyMed data for Earth surface monitoring was performed. The developed approach was applied to a set of imagery acquired over the Corvara (Northern Italy) area, which is affected by a fast landslide with yearly displacements up to meters. Specifically, two well identifiable and stable human-made Amplitude Persistent Scatterers (APSs) were considered to estimate the residual errors of COSMO-SkyMed sensor during the acquisition period between 2010 and 2015. Then, the same methodology was applied to estimate the displacement of a Corner Reflector (CR) located in the landslide area. Finally, the results were compared to the available GPS reference trend showing a good agreement.

  • 47.
    Beneitez Galan, Miguel
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Duguet, Yohann
    LISN-CNRS, Campus Universitaire d'Orsay, Université Paris-Saclay, F-91400 Orsay, France.
    Schlatter, Philipp
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Henningson, Dan S.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Instability of the optimal edge trajectory in the Blasius boundary layer2023In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 971, article id A42Article in journal (Refereed)
    Abstract [en]

    In the context of linear stability analysis, considering unsteady base flows is notoriously difficult. A generalisation of modal linear stability analysis, allowing for arbitrarily unsteady base flows over a finite time, is therefore required. The recently developed optimally time-dependent (OTD) modes form a projection basis for the tangent space. They capture the leading amplification directions in state space under the constraint that they form an orthonormal basis at all times. The present numerical study illustrates the possibility to describe a complex flow case using the leading OTD modes. The flow under investigation is an unsteady case of the Blasius boundary layer, featuring streamwise streaks of finite length and relevant to bypass transition. It corresponds to the state space trajectory initiated by the minimal seed; such a trajectory is unsteady, free from any spatial symmetry and shadows the laminar-turbulent separatrix for a finite time only. The finite-time instability of this unsteady base flow is investigated using the 8 leading OTD modes. The analysis includes the computation of finite-time Lyapunov exponents as well as instantaneous eigenvalues, and of the associated flow structures. The reconstructed instantaneous eigenmodes are all of outer type. They map unambiguously the spatial regions of largest instantaneous growth. Other flow structures, previously reported as secondary, are identified with this method as relevant to streak switching and to streamwise vortical ejections. The dynamics inside the tangent space features both modal and non-modal amplification. Non-normality within the reduced tangent subspace, quantified by the instantaneous numerical abscissa, emerges only as the unsteadiness of the base flow is reduced.

  • 48.
    BENETHUILLERE, Quentin
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Revision Of The Aircraft Engines Preliminary Design Platform Of First Level2014Independent thesis Advanced level (degree of Master (Two Years)), 20 HE creditsStudent thesis
    Abstract [en]

    In the highly competitive aerospace industry, engine manufacturers must react very quickly and precisely to any demand emerging from aircraft manufacturers if they want to be positioned on the offer. This is especially true when answering to Requests For Information (RFI) based on preliminary design investigations of first level. In order to reduce the time needed to perform these costly operations while improving the performances achieved, Snecma wishes to develop tools for dimensioning the engine and also for assessing key parameters such as mass, emissions, fuel burn, costs, etc. Unfortunately, the set of tools and the process used at the present time for preliminary design investigations of first level are not sufficient to meet the high standards sought-after by the company in terms of time and performances. As a consequence, efforts must be spent on redefining the whole process and the tools it is based on; here is the mission that has been conferred upon me.

     

    Multiple exchanges with performances engineers and specialists allowed to draw the current process for preliminary design investigations of first level and raise all the associated concerns. At the same time, a status of the existing tools (called modules in this report), mainly developed under Excel, has been realised in order to identify the range of action for today's investigations. A prototype has been developed under SDK Python with the aim of proving the feasibility of a solution to a difficulty that shows up in the process for each new investigation: the one of generating the workflow on the optimisation software Optimus. A target process has finally been discussed considering all the information collected, and would allow dividing by five the time needed to perform investigations compare to now. The prototype developed lead to interesting results and this solution could thus probably be integrated in the target process as it would allow saving one day of work for an engineer for each study to be carried out.

     

    Solutions have been proposed to all the concerns identified in the process and they will have to be discussed with many actors and investigated further in the near future in order to set the target process that will allow meeting the final objective of answering all types of RFIs emitted by aircraft manufacturer in a very short time with a high level of confidence in the results.

    Download full text (pdf)
    Benethuillere_Quentin_EGI2014_080MSCEKV1050.pdf
  • 49.
    BENETHUILLERE, Quentin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Revision Of The Aircraft Engines Preliminary Design Platform Of First Level2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the highly competitive aerospace industry, engine manufacturers must react very quickly and precisely to any demand emerging from aircraft manufacturers if they want to be positioned on the offer. This is especially true when answering to Requests For Information (RFI) based on preliminary design investigations of first level. In order to reduce the time needed to perform these costly operations while improving the performances achieved, Snecma wishes to develop tools for dimensioning the engine and also for assessing key parameters such as mass, emissions, fuel burn, costs, etc. Unfortunately, the set of tools and the process used at the present time for preliminary design investigations of first level are not sufficient to meet the high standards sought-after by the company in terms of time and performances. As a consequence, efforts must be spent on redefining the whole process and the tools it is based on; here is the mission that has been conferred upon me.

     

    Multiple exchanges with performances engineers and specialists allowed to draw the current process for preliminary design investigations of first level and raise all the associated concerns. At the same time, a status of the existing tools (called modules in this report), mainly developed under Excel, has been realised in order to identify the range of action for today's investigations. A prototype has been developed under SDK Python with the aim of proving the feasibility of a solution to a difficulty that shows up in the process for each new investigation: the one of generating the workflow on the optimisation software Optimus. A target process has finally been discussed considering all the information collected, and would allow dividing by five the time needed to perform investigations compare to now. The prototype developed lead to interesting results and this solution could thus probably be integrated in the target process as it would allow saving one day of work for an engineer for each study to be carried out.

     

    Solutions have been proposed to all the concerns identified in the process and they will have to be discussed with many actors and investigated further in the near future in order to set the target process that will allow meeting the final objective of answering all types of RFIs emitted by aircraft manufacturer in a very short time with a high level of confidence in the results.

     

    Download full text (pdf)
    Benethuillere_Quentin_EGI2014_080MSCEKV1050.pdf
  • 50.
    BENETHUILLERE, Quentin
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Revision Of The Aircraft Engines Preliminary Design Platform Of First Level2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the highly competitive aerospace industry, engine manufacturers must react very quickly and precisely to any demand emerging from aircraft manufacturers if they want to be positioned on the offer. This is especially true when answering to Requests For Information (RFI) based on preliminary design investigations of first level. In order to reduce the time needed to perform these costly operations while improving the performances achieved, Snecma wishes to develop tools for dimensioning the engine and also for assessing key parameters such as mass, emissions, fuel burn, costs, etc. Unfortunately, the set of tools and the process used at the present time for preliminary design investigations of first level are not sufficient to meet the high standards sought-after by the company in terms of time and performances. As a consequence, efforts must be spent on redefining the whole process and the tools it is based on; here is the mission that has been conferred upon me.

     

    Multiple exchanges with performances engineers and specialists allowed to draw the current process for preliminary design investigations of first level and raise all the associated concerns. At the same time, a status of the existing tools (called modules in this report), mainly developed under Excel, has been realised in order to identify the range of action for today's investigations. A prototype has been developed under SDK Python with the aim of proving the feasibility of a solution to a difficulty that shows up in the process for each new investigation: the one of generating the workflow on the optimisation software Optimus. A target process has finally been discussed considering all the information collected, and would allow dividing by five the time needed to perform investigations compare to now. The prototype developed lead to interesting results and this solution could thus probably be integrated in the target process as it would allow saving one day of work for an engineer for each study to be carried out.

     

    Solutions have been proposed to all the concerns identified in the process and they will have to be discussed with many actors and investigated further in the near future in order to set the target process that will allow meeting the final objective of answering all types of RFIs emitted by aircraft manufacturer in a very short time with a high level of confidence in the results.

    Download full text (pdf)
    Benethuillere_Quentin_EGI2014_080MSCEKV1050.pdf
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