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  • 51.
    Fruth, Florian
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian M.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Bladh, R.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Unsteady forcing vs. efficiency - The effect of clocking on a transonic industrial compressor2013Ingår i: ASME 2013 Fluids Engineering Division Summer Meeting: Volume 1A, Symposia: Advances in Fluids Engineering Education; Advances in Numerical Modeling for Turbomachinery Flow Optimization; Applications in CFD; Bio-Inspired Fluid Mechanics; CFD Verification a., ASME Press, 2013, s. V01AT02A010-Konferensbidrag (Refereegranskat)
    Abstract [en]

    A numerical investigation on the impact of clocking on the efficiency and the aerodynamic forcing of the first 1.5 stages of an industrial transonic compressor was conducted. Using unsteady 3D Navier-Stokes equations, seven clocking positions were calculated and analyzed. Efficiency changes due to clocking were up to 0.125%, whereas modal excitation changes up to 31.7%. However, no direct correlation between the parameters of efficiency, stimulus and modal excitation was found as reported by others. It was found that potential forced response risks can be reduced by clocking, resulting only in minor efficiency penalties. Assuming almost sinusoidal behavior of efficiency and stimulus changes, as found in this investigation, both parameters can be set into correlation by using an ellipse interpolation. Direct impact of design changes on efficiency and stimulus through clocking can be deducted from that graph and quick estimations about extrema be made using only 5-6 transient simulations. Results however also stress the importance of considering modal excitation when optimizing for aerodynamic forcing, for which the ellipse interpolation is not necessarily possible. Highest efficiency is achieved with the IGV wake impinging on the stator blade leading edge at mid-span. It was found however that this alone is not a sufficient criteria in case of inclined wakes, as wake impingement at different span positions leads to different efficiencies.

  • 52.
    Fruth, Florian
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian M.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Influence of the blade count ratio on aerodynamic forcing part II: High pressure transonic turbine2012Ingår i: Proceedings of the ASME Turbo Expo, New York: American Society of Mechanical Engineers , 2012, s. 1343-1354Konferensbidrag (Refereegranskat)
    Abstract [en]

    The influence of the Blade Count Ratio (BCR) on the aerodynamic forcing of a transonic high pressure turbine has been investigated numerically. Main focus here was put on the change in unsteady aerodynamics, modal properties and the mode excitation. Using a scaling technique, six different transonic turbine stages with different numbers of scaled blades but maintained steady aerodynamics were generated and further analyzed. In the analysis a non-linear, time marching CFD solver was used and the unsteady, harmonic forces projected onto the mode shapes. For this transonic turbine the unsteady pressure at the rotor blade decreases in amplitude and spanwise distribution from low to high blade count ratios. In chordwise direction a local minimum for intermediate blade count ratios was found for the rotor and stator blades. Mode frequencies decreased monotonically with an increasing BCR. Significant mode changes for modes 5 and 6 of the different BCRs were captured  using the Modal Assurance Criteria. It was found that for these transonic turbines the blade count ratio and reduced frequency are amongst others key parameters for a reduction in aerodynamic forcing. Even though an almost monotonic trend was found for the stator blade excitation, the rotor blade excitation behaves highly non-monotonic. A maximum value in excitation potential was found close to reported blade count ratio values. Optimization of certain modes is possible but case dependent, due to the non-monotonic nature. Moreover it was found that for a minor increase in upstream blade count the mean unsteady forces on the rotor blades is reduced, but the mode excitation not necessarily has to decrease.

  • 53.
    Fruth, Florian
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian M.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mårtensson, Hans
    Volvo Aero. Researchers.
    Mayorca, Maria A.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    INFLUENCE OF THE BLADE COUNT RATIO ON AERODYNAMIC FORCING PART I: HIGHLY LOADED TRANSONIC COMPRESSOR2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    The influence of the Blade Count Ratio (BCR) on the aerodynamic forcing of a highly transonic compressor has been investigated. The focus has been put on the unsteady aerodynamics as well as mode excitability and thus High Cycle Fatigue (HCF) risk. A number of compressor stages were investigated that differed in blade count of the stator blade row. Time-resolved aerodynamic forcing results were acquired using a non-linear CFD approach. The results were decomposed into frequency content and combined with modal properties of the various components. It is found that the BCR is a key parameter to reduce generalized force and consequently vibratory HCF stresses. Furthermore a potential in avoiding and/or alleviating potential resonant crossings in the Campbell diagram is reported. The dependency of these aspects from BCR is largely non-linear and for the first time discussed in detail on the basis of a transonic compressor stage.

  • 54. Gao, Zhan
    et al.
    Raza, Rizwan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Development of Direct Methanol Low Temperature Fuel Cells from a Polygeneration, Perspective2011Ingår i: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 35, s. 690-696Artikel i tidskrift (Refereegranskat)
  • 55. Geraimchuk, I.M
    et al.
    Geraimchuk, M.D
    Kazachkov, I.V
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Virtual university environment: Swedish-Ukrainian network for design and implementation of Internet-based education software2010Konferensbidrag (Övrigt vetenskapligt)
  • 56. Geraimchuk, M.D
    et al.
    Kazachkov, I.V
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Development and implementation of multimedia educational systems for universities and schools2007Konferensbidrag (Refereegranskat)
  • 57.
    Gezork, Tobias
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Gutierrez, Mauricio
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Groth, Pieter
    GKN Aerospace Sweden AB.
    Vogt, Damian M.
    Institut für Thermische Strömungsmaschinen und Maschinenlaboratorium, University of Stuttgart.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Unsteady blade force computation sensitivity in a transonic turbine to rotor tip gap, hub and shroud cavity model detail2015Ingår i: Proceedings of the 14th International Symposium on Unsteady Aerodynamics, Aeroacoustics & Aeroelasticity of Turbomachines, 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    The influence of including geometric detailing features on blade forcing predicted by CFD calculations is investigated. Various features such as rotor tip gap, rotor tip shroud cavity with substantial leakage flow and large rotor upstream hub rim cavity are investigated. The test case is based on a single stage transonic test turbine rig in which the unsteady aerodynamics and blade forcing have previously been investigated numerically.

    Including the tip gap and the tip shroud leakage in the computational model resulted in an overall increase in unsteady forcing. The change in forcing is mainly due to a change in secondary flow structure, but also due to a change of the stage flow condition. Conversely, it is shown that including the hub cavity in the computational model, even without the presence of purge-flow, reduces the unsteady force. Lastly, even though there are changes in unsteady blade loading, the blade response amplitude is only changed marginally (maximum 7%) due to forcing variations alone.

  • 58.
    Gezork, Tobias
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mayorca, M. A.
    Groth, P.
    Vogt, D. M.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Influence of tip shroud cavity detailing on turbine blade forcing calculations2014Ingår i: ASME Turbo Expo 2014: Turbine Technical Conference and Exposition, ASME Press, 2014, Vol. 7B, s. V07BT35A021-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Forced response in turbomachinery refers to the vibration of a component due to an excitation originating from another component. Obstacles, such as struts and blade rows in the upstream and downstream flow path of a turbomachine engine lead to engine order (EO) excitations. To be able to predict the severity of these excitations, both aerodynamic and structural calculations are performed. There is a risk of critical high cycle fatigue (HCF) failure when the force acts at a resonance frequency. Customarily, forcing calculations exclude detailing features, such as leakage flows. The current investigation uses a two stage subsonic model steam turbine configuration with shrouded rotor blades to demonstrate the influence of neglecting flow through seal cavities for blade forcing predictions. Upstream and downstream vanes are the excitation sources on the rotor blade. Calculation results are compared for a configuration including and excluding the tip shroud cavity. Computed data is compared to available pressure data from tests in the model turbine. The investigation shows for the first blade passing excitation at design point that the axial and circumferential rotor forcing change by +22%, respectively +4% when including the tip shroud cavity for the investigated configuration. The change in forcing arises from the interaction of the leakage flow with the main stream flow. For highly loaded designs this can be of importance if there is a critical excitation.

  • 59.
    Gezork, Tobias
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Petrie-Repar, Paul
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    A NEW VISUALIZATION METHOD FOR HARMONIC UNSTEADY FLOWS IN TURBOMACHINERY2016Ingår i: PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2016, VOL 7B, AMER SOC MECHANICAL ENGINEERS , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Understanding unsteady flow processes is key in the analysis of challenging problems in turbomachinery design such as flutter and forced response. In this paper a new visualization method for harmonic unsteady flow is presented. The method illustrates the direction in which unsteady waves are traveling and transporting energy by the direct visualization of the propagating pressure waves in terms of field lines constructed from the wave group velocity. The group velocity is calculated from the unsteady flow solution by assuming that the local unsteady pressure perturbation of interest can be represented by a single harmonic unsteady wave. The applicability of the method is demonstrated for three test cases including a linear cascade of two-dimensional flat plates and a linear cascade of two-dimensional compressor blade profiles.

  • 60.
    Ghaem Sigarchian, Sara
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik. European Institute of Innovation and Technology, Sweden.
    Malmquist, Anders
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Modeling and control strategy of a hybrid PV/Wind/Engine/Battery system to provide electricity and drinkable water for remote applications2014Ingår i: Energy Procedia: 2013 ISES Solar World Congress, Elsevier, 2014, Vol. 57, s. 1401-1410Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper a small-scale energy system called emergency container is presented. This container has lots of applications and can be designed as stationary solution in remote areas such as rural electrification and a mobile solution for disaster situation, military purposes and exploration teams. In this study the container is a hybrid PV/wind/engine energy system that is designed to provide electricity and drinkable water for 1000 person in disaster situations. A transient model implemented in Transient Simulation System (TRNSYS) program is developed and performance of the system during one-year operation for two locations (Nairobi in Kenya and Nyala in Sudan) with relatively high solar insolation is analyzed. The result of the model is significantly important in order to choose the right size of the different components. Due to the fluctuations of solar and wind energy as well as the importance of the battery life cycle, there is a need to have a smart power management and an appropriate fast response control system. In order to achieve it and to fulfill the energy demand as much as possible through renewable energies, a dispatch strategy is introduced and a control algorithm is applied to the model. This control algorithm has increased system reliability and power availability. The transient simulation shows that the share of power generation by solar energy is 63% and 80% and the share of wind power is 27% and 12% in Nairobi and Nyala respectively. It means that most of the energy demand (around 90%) can be covered by renewable energy. This results in significant mitigation of environmental issues compared to using only diesel engine that is a common solution in disaster situations.

  • 61.
    Glodic, Nenad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Bartelt, Michael
    Vogt, Damian
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Aeroelastic Properties of Combined Mode Shapes in an Oscillating LPT Cascade2009Konferensbidrag (Refereegranskat)
  • 62.
    Glodic, Nenad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Experimental and numerical investigation of mistuned aerodynamic influence coefficients in an oscillating LPT cascade2012Ingår i: Proceedings of the ASME Turbo Expo, New York: American Society of Mechanical Engineers , 2012, s. 1355-1367Konferensbidrag (Refereegranskat)
    Abstract [en]

    The effect of aerodynamic mistuning on the aerodynamic damping in an oscillating Low-Pressure Turbine (LPT) cascade is investigated. The considered aerodynamic mistuning is caused by blade-to-blade stagger angle variations. The study is carried out experimentally and numerically by employing the influence coefficient method. On the experimental side a sector cascade is used where one of the blades is made oscillating in three orthogonal modes. The unsteady blade surface pressure is acquired on the oscillating blade and two neighbour blades and reduced to aeroelastic stability data. By gradually de-staggering the oscillating blade, aerodynamically mistuned influence coefficients are acquired. On the numerical side full-scale time-marching RANS CFD simulations are performed using nominal and de-staggered blades. The study shows that variations in blade-to-blade stagger angle affect the aerodynamic influence coefficients and as a consequence overall aeroelastic stability. Whereas discrepancies are found in the exact prediction of mistimed influence coefficients compared to measured, the overall magnitude and trends are well captured.

  • 63.
    Glodic, Nenad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Influence of Tip Clearance Modelling in Predictions of Aeroelastic Response in an Oscillating LPT Cascade2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    The present study investigates the influence of tip clearance modelling in predictions of the aeroelastic response in an oscillating Low-Pressure Turbine (LPT) cascade. The study was carried out through validation of different numerical models against experimental data. On the experimental side a sector cascade was used, where one of the blades was oscillated in axial bending mode. Unsteady pressure measurements were performed at several spanwise positions on the non-oscillating blades and at mid-span of the oscillating blade. On the numerical side full-scale time-marching RANS CFD simulations were performed employing models with and without tip clearance. The study showed that the model without tip clearance provides reliable result up to 70%. In the near-tip region difference induced due to the absence of tip clearance in the model amounts to about 25% of minimum stability value, relative to the nominal tip clearance model. It has also been shown that the resolution of the tip clearance mesh in spanwise direction of the gap might have a considerable impact of prediction accuracy. Imposed small variations in the tip clearance size have not led to substantial changes in predicted aeroelastic response of the cascade.

  • 64. Green, Jeff
    et al.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Scaling of Turbine Blade Unsteady Pressures for Rapid Forced Response Assessmen2006Ingår i: Proceedings of the ASME Turbo Expo 2006, Vol 5, Pts A and B, 2006, s. 1081-1089Konferensbidrag (Refereegranskat)
    Abstract [en]

    High Cycle Fatigue caused by high vibration levels continues to be a major concern in gas turbine design. The use of Computational Fluid Dynamics methods is becoming more commonplace for calculating the vibration amplitude of turbomachinery blades during the design process. A typical calculation approach would be to calculate the unsteady aerodynamic loads at the resonance condition for each vibration mode of interest. In this paper it is proposed that, for a choked high pressure (HP) turbine, an unsteady flow prediction can be scaled across a wide engine operating range using a few simple parameters.

    There is a fixed relationship between the turbine inlet pressure and the HP shaft speed (when expressed nondimensionally) which can be used to scale the flow conditions. The effects of altitude, variation in the ratio of shaft speeds, compressor bleed flows and schedule of the variable vanes are secondary, having only a small influence on the behaviour.

    This paper demonstrates that the steady flow distribution around both stator and rotor is virtually constant across the speed range of the engine and the rotor unsteady surface pressure distribution shows only small differences. Further, the parameter which is of prime interest for vibration assessment, the modal force, can be scaled very well using turbine inlet pressure. For modes of vibration with high amplitudes the errors introduced by scaling are of the order of 6% which is considered acceptable for design predictions.

  • 65.
    Guedez, Rafael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Optimization of Thermal Energy Storage Integration Strategies for Peak Power Production by Concentrating Solar Power Plants2014Ingår i: PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE, 2014, Vol. 49, s. 1642-1651Konferensbidrag (Refereegranskat)
    Abstract [en]

    The integration of thermal energy storage systems in concentrating solar thermal power plants allows power production to be shifted from times where there is low demand to periods where electricity prices are higher. Although increasing the total investment, thermal energy storage can therefore enhance profitability of the solar power plant. The present study presents optimum power plant configurations for a given location considering different price-based grid integration strategies. Such optimum plant configurations were determined using a thermo-economic optimization approach where the operating strategy was set such that electricity was generated once the market price exceeds a given price level, defined as the minimum price selling indicator. Plants were optimized for different indicator values to cover designs from base load and peak power production. For each of these price-operating strategies, optimum plant configurations were found by varying two solar-related design parameters, namely the solar multiple and the storage size, whilst simultaneously evaluating the economic performance of each design. Finally, an economic analysis was performed for each of the optimum power plants, assuming financial conditions throughout the lifetime of the power plant. Results show that the optimum plant configurations vary with respect to the chosen operating strategy. Optimum configurations for peak power production yielded relatively smaller storage units than that of the optimum baseload plants. Furthermore, the study demonstrates that under current cost estimations, and for the specified location, concentrating solar thermal power is not an attractive option for utility-grid investors. However, it is shown that when considering a reduction in investment costs or the possibility of having renewable electricity incentives such as the investment tax credit treasury cash grant, concentrating solar thermal power plants can become an economically viable technology.

  • 66.
    Gutierrez, Mauricio
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Gezork, Tobias
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Yang, Shu
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Andersson, C.
    Vogt, D. M.
    Forced response analysis of a transonic turbine using a free interface component mode synthesis method2015Ingår i: 11th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2015, European Conference on Turbomachinery (ETC) , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Assessing forced response is crucial during the design phase of turbomachines. Since the analyses are computationally expensive and time-consuming when using full models, Reduced Order Models (ROM) are utilized to decrease the number of Degrees Of Freedom (DOF) and consequently analysis time and cost. The ROM used in the current analysis belongs to the component mode synthesis (CMS) method with a free-interface approach known as Craig-Chang. A transonic high pressure turbine is investigated featuring large ranges of disk and blade dominated modes depending in the Nodal Diameter (ND). The free-interface approach will be assessed in the disk and blade dominated regions with a detailed study of the frequencies and mode shapes. In addition, a forced response analysis within the blade dominated region is evaluated in the paper. Moreover, a study of the amount of modes required in the basis for the reduced order transformation matrix is presented.

  • 67.
    Gutierrez Salas, Mauricio
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Bladh, R.
    Martensson, H.
    Petrie-Repar, Paul
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, D. M.
    Forced response analysis of a mistuned compressor blisk comparing three different reduced order model approaches2016Ingår i: Proceedings of the ASME Turbo Expo, ASME Press, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Accurate structural modeling of blisk mistuning is critical for the analysis of forced response in turbomachinery. Apart from intentional mistuning, mistuning can be due to the manufacturing tolerances, corrosion, foreign object damage and in-service wear in general. It has been shown in past studies that mistuning can increase the risk of blade failure due to energy localization. For weak blade to blade coupling, this localization has been shown to be critical and higher amplitudes of vibration are expected in few blades. This paper presents a comparison of three reduced order models for the structural modeling of blisks. Two of the models assume cyclic symmetry while the third model is free of this assumption. The performance of the reduced order models for cases with small and large amount of mistuning will be examined. The benefits and drawbacks of each reduction method will be discussed.

  • 68.
    Gutierrez Salas, Mauricio
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Bladh, Ronnie
    Martensson, Hans
    Petrie-Repar, Paul
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian M.
    Forced Response Analysis of a Mistuned, Compressor Blisk Comparing Three Different Reduced Order Model Approaches2017Ingår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 139, nr 6, artikel-id 062501Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Accurate structural modeling of blisk mistuning is critical for the analysis of forced response in turbomachinery. Apart from intentional mistuning, mistuning can be due to the manufacturing tolerances, corrosion, foreign object damage, and in-service wear in general. It has been shown in past studies that mistuning can increase the risk of blade failure due to energy localization. For weak blade to blade coupling, this localization has been shown to be critical and higher amplitudes of vibration are expected in few blades. This paper presents a comparison of three reduced order models (ROMs) for the structural modeling of blisks. Two of the models assume cyclic symmetry, while the third model is free of this assumption. The performance of the reduced order models for cases with small and large amount of mistuning will be examined. The benefits and drawbacks of each reduction method will be discussed.

  • 69.
    Guédez, Rafael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Reducing the Number of Turbine Starts in Concentrating Solar Power Plants through the Integration of Thermal Energy Storage2013Ingår i: Proceedings of the ASME TurboExpo 2013, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The operation of steam turbine units in solar thermal power plants is very different than in conventional base-load plants. Due to the variability of the solar resource, much higher frequencies of plant start-ups are encountered. This study provides an insight to the influence of thermal energy storage integration on the typical cycling operation of solar thermal power plants. It is demonstrated that the integration of storage leads to significant reductions in the annual number of turbine starts and is thus beneficial to the turbine lifetime. At the same time, the effects of storage integration on the electricity costs are analyzed to ensure that the designs remain economically competitive. Large storage capacities, can allow the plant to be shifted from a daily starting regime to one where less than 20 plant starts occur annually. Additionally, the concept of equivalent operating hours is used to further analyze the direct impact of storage integration on the maintenance planning of the turbine units.

  • 70.
    Hosseini, Seyed Mohammad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fruth, Florian
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Effect of Scaling of Blade Row Sectors on the Prediction of Aerodynamic Forcing in a Highly-Loaded Transonic Turbine Stage2012Ingår i: Proceedings of the ASME Turbo Expo 2011, Vol 6, Parts A And B, New York: American Society of Mechanical Engineers , 2012, s. 1297-1307Konferensbidrag (Refereegranskat)
    Abstract [en]

    The viability of a scaling technique in prediction of forced response of the stator and rotor blades in a turbine stage has been examined. Accordingly the so called parameter, generalized force, is defined which describes the excitation of a modeshape due to the unsteady flow forces at a certain frequency. The capability of this method to accurately predict the generalized forces serves as the viability criterion. The scaling technique modifies the geometry to obtain an integer stator, rotor blade count ratio in an annulus section while maintaining steady aerodynamic similarity. A non-scaled configuration is set up to serve as the reference case. Further configurations with different scaling ratios are also generated for accuracy comparison. Unsteady forces are calculated through 3D Navier-Stokes simulations by VolSol, which is based on an explicit, time-marching. A general purpose finite element model of blades is also provided to enable modal analysis with the harmonic forces. The generalized forces of stator and rotor blades revealed high sensitivity towards modification of stator blades while acceptable accuracy was obtained by moderate modifications of the rotor blades for first harmonic forces. Moreover the influence of variable blade's structural characteristics proved to be remarkable.

  • 71.
    Jayasuriya, Jeevan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Ersson, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Fredriksson, Jan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Ultra Low Emission Gas Turbine Combustion: An Expoerimental Investigation of Catalytically Stabilizws Lean Pre-mixed Combustion on Modern Gas Turbine Conditions2004Konferensbidrag (Refereegranskat)
  • 72.
    Jayasuriya, Jeevan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Ersson, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Fredriksson, Jan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Catalytic Combustion Developments for Ultra Low Emission Gas Turbine Combustion2003Konferensbidrag (Refereegranskat)
  • 73.
    Jayasuriya, Jeevan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Ersson, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Fredriksson, Jan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Experimental Investigations of High Pressure Catalytic Combustion of Methane2003Konferensbidrag (Refereegranskat)
  • 74.
    Jayasuriya, Jeevan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fredriksson, Jan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Persson, Katarina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Thevenin, Philippe
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Bench Scale Experimental Test Rig  for High Pressure Catalytic Combustion2002Konferensbidrag (Refereegranskat)
  • 75.
    Jayasuriya, Jeevan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Manrique, Arturo
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fakhrai, Reza
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fredriksson, Jan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Experimental investigations of catalytic combustion for high-pressure gas turbine applications2006Ingår i: Proceedings of the ASME Turbo Expo 2006, Vol 1, 2006, s. 763-771Konferensbidrag (Refereegranskat)
    Abstract [en]

    Catalytic combustion has proven to be a suitable alternative to conventional flame combustion in gas turbines for achieving Ultra-Low Emission levels (ULE). In the process of catalytic combustion, it is possible to achieve a stable combustion of lean fuel/air mixtures which results in reduced combustion temperature in the combustor. The ultimate result is that almost no thermal-NOx is formed and the emissions of carbon monoxide and hydrocarbon emissions are reduced to single-digit limits. Successful development of catalytic combustion technology would lead to reducing pollutant emissions in gas turbines to ultra-low levels at lower operating costs. Since the catalytic combustion prevents the pollutant formations in the combustion there is no need for costly emission cleaning systems.

  • 76.
    Jayasuriya, Jeevan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Manrique Carrera, Arturo
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fakhrai, Reza
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fredriksson, Jan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Gasified biomass fuelled gas turbine: Combustion stability and selective catalytic oxidation of fuel-bound nitrogen2006Ingår i: Proceedings of the ASME Turbo Expo 2006, Vol 1, 2006, s. 773-780Konferensbidrag (Refereegranskat)
    Abstract [en]

    Low heating value of gasified biomass and its fuel bound nitrogen containing compounds challenge the efforts on utilizing gasified biomass on gas turbine combustor. Low heating value of the gas brings along combustion stability issues and pollutant emission concerns. The fuel bound nitrogen present in gasified biomass could completely be converted to NOx during the combustion process. Catalytic combustion technology, showing promising developments on ultra low emission gas turbine combustion of natural gas could also be the key to successful utilization of biomass in gas turbine combustor. Catalysts could stabilize the combustion process of low heating value gas while the proper design of the catalytic configuration could selectively convert the fuel bound nitrogen into molecular nitrogen. This paper presents preliminary results of the experimental investigations on combustion stability and nitrogen selectivity in selective catalytic oxidation of ammonia in catalytic combustion followed by a brief description of the design of catalytic combustion test facility. The fuel-NOx reduction strategy considered in this study was to preprocess fuel in the catalytic system to remove fuel bound nitrogen before real combustion reactions occurs. The catalytic combustion system studied here contained two stage reactor in one unit containing fuel preprocessor (SCO catalyst) and combustion catalysts. Experiments were performed under lean combustion conditions (lambda value from 6 up to 22) using a simulated mixture of gasified biomass. The Selective Catalytic Oxidation approach was considered to reduce the conversion of NH3 into N-2. Results showed very good combustion stability, higher combustion efficiency and good ignition performances under the experimental conditions. However, the selective oxidation of fuel bound nitrogen into N-2 was only in the range of 20% to 30% under the above conditions.

  • 77.
    Jayasuriya, Jeevan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Manrique, Carrera
    Fakhrai, Reza
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fredriksson, Jan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    High Pressure Catalytic Combustion of Methane in a Multi Segmented Catalytic Combustor2005Konferensbidrag (Övrigt vetenskapligt)
  • 78.
    Jayasuriya, Jeevan
    et al.
    KTH, Skolan för industriell teknik och management (ITM).
    Manrique, Carrera
    Fredriksson, J
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Ersson, A.T
    Järås, S
    Gasified Biomass Fuelled Gas Turbine: Combustion Stability and Selective Catalytic Oxidation of Fuel-bound Nitrogen2004Konferensbidrag (Refereegranskat)
  • 79. Jocker, M.
    et al.
    Hillion, F. X.
    Fransson, Torsten H.
    KTH, Tidigare Institutioner                               , Energiteknik.
    Wahlen, U.
    Numerical unsteady flow analysis of a turbine stage with extremely large blade loads2002Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 124, nr 3, s. 429-438Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the detailed numerical analysis including parametric studies on the aerodynamic excitation mechanisms in a turbine stage due to the unsteady stator-rotor interaction, The work is part of the predesign study of a high-pressure subsonic turbine,for a rocket engine turbopump. The pressure level in such turbines can be remarkably high (in this case 54 MPa inlet total pressure). Hence, large unsteady rotor blade loads can be expected, which impose difficult design requirements, The parameter studies are performed at midspan with the numerical flow solver UNSFLO, a 2-D/Q3-D unsteady hybrid Euler/Navier-Stokes solver. Comparisons to 2-D and steady, 3-D results obtained with a fully viscous solver VOLSOL, are made. The investigated design parameters are the axial gap (similar to8-29 percent of rotor axial chord length) and the stator vane size and count (stator-rotor pitch ratio similar to1-2.75), For the nominal case the numerical solution is analyzed regarding the contributions of potential and vortical flow disturbances at the rotor inlet using rotor gust computations. It was found that gust calculations were not capable to capture the complexity of the detected excitation mechanisms, but the possibility to reduce excitations by enforcing cancellation of the vortical and potential effects has been elaborated. The potential excitation mechanism in the present turbine stage is found dominant compared to relatively small and local wake excitation effects. The parameter studies indicate design recommendations for the axial gap and the stator size regarding the unsteady rotor load.

  • 80.
    Jöcker, Markus
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Kessar, Alexandros
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Kah, G.
    Rehder, H. J.
    Comparison of models to predict low engine order excitation in a high pressure turbine stage2006Ingår i: Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines / [ed] Hall, KC; Kielb, RE; Thomas, JP, 2006, s. 145-159Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper compares three numerical strategies to predict the aerodynamic rotor excitation sources of "Low Engine Order" (LEO) in a high-pressure turbine stage. Main focus is laid on methods to compute the stator exit flow. The aim is to evaluate computationally cheap approaches to avoid modeling the whole circumference of the stator. A single passage viscous strategy, a single passage inviscid linear blade movement strategy, and a viscous multi-passage sector strategy are compared and evaluated. The assessment of the prediction quality is made by comparison of the computed stator exit flow to experimental data. The main result is that only the global behavior of the stator exit flow is estimated right, both the level and amplitude of Mach number and pressure are computed with poor agreement to experiments. Future evaluations of the resulting rotor excitation pressure are needed to estimate the level of necessary agreement to give acceptable predictions of the low engine order forced response.

  • 81. Kazachkov, I.V
    et al.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Popa, Marianne Salomon
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Development of the mobile computer and special notebook tools and technologies for the electronic educational international network2009Rapport (Övrigt vetenskapligt)
  • 82. Kazachkov, I.V
    et al.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Salomon Popa, Marianne
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Virtual university environment: swedish-ukrainian network for design of internet-based education software2011Rapport (Övrigt vetenskapligt)
  • 83. Kazachkov, I.V
    et al.
    Geraimchuk, M.D
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Development and implementation of multimedia educational systems for universities and secondary schools2007Konferensbidrag (Övrigt vetenskapligt)
  • 84.
    Kessar, Alexandros
    et al.
    KTH.
    Jöcker, Markus
    KTH.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Rehder, Hans Jürgen
    Kost, Friedrich H.
    Flow Measurements for Low Engine order Excitations in a High Pressure Turbine stage2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper demonstrates and evaluates unique flow measurement results obtained in a high pressure test turbine, in order to analyze the effect of Low Engine Order (LEO) excitations. A stator was modified to induce LEO flow variations by either imposing a throat width variation or a blockage of the trailing edge cooling flow from some of the vanes. Laser Two Focus (L2F) and pressure probe measurements were performed at subsonic and transonic flow conditions, without and with the rotor installed and operated. Time resolved velocity data was obtained in front and inside of rotor passages covering the Low Engine Order variation period. The presented results evaluation focuses only on L2F measurements and show that the LEO variation of flow velocity and turbulence intensity is most visible in the gap between stator and rotor and at the first measurement location inside the rotor passage. The overall trend is that stator exit flow Mach numbers are higher behind the passages with smaller pitch and vice versa.

  • 85. Kielb, R.
    et al.
    Barter, J.
    Chernycheva, Olga
    KTH, Tidigare Institutioner, Energiteknik.
    Fransson, Torsten H.
    KTH, Tidigare Institutioner, Energiteknik.
    Flutter of low pressure turbine blades with cyclic symmetric modes: A preliminary design method2004Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 126, nr 2, s. 306-309Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A current preliminary design method for flutter of low pressure turbine blades and vanes only requires knowledge of the reduced frequency and mode shape (real). However many low pressure turbine (LPT) blade designs include a tip shroud that mechanically connects the blades together in a structure exhibiting cyclic symmetry. A proper vibration analysis produces a frequency and complex mode shape that represents two real modes phase shifted by 90 deg. This paper describes an extension to the current design method to consider these complex mode shapes. As in the current method, baseline unsteady aerodynamic analyses must be performed for the three fundamental motions, two translations and a rotation. Unlike the current method work matrices must be saved for a range of reduced frequencies and interblade phase angles. These work matrices are used to generate the total work for the complex mode shape. Since it still only requires knowledge of the reduced frequency and mode shape (complex), this new method is still very quick and easy to use. Theory and an example application are presented.

  • 86.
    Laumert, Björn
    et al.
    KTH, Tidigare Institutioner, Energiteknik.
    Mårtensson, H.
    Fransson, Torsten H.
    KTH, Tidigare Institutioner, Energiteknik.
    Investigation of unsteady aerodynamic blade excitation mechanisms in a transonic turbine stage - Part I: Phenomenological identification and classification2002Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 124, nr 3, s. 410-418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Based on the results of time-dependent 3-D viscous computations the aerodynamic mechanisms that cause the unsteady pressure fluctuations on the vane and rotor blade surface of a high-pressure transonic turbine are identified and separately classified in a phenomenological manner. In order to be able to describe separately the influence of wake, potential and shock distortions on the blade surface pressure tit design operation conditions, the stator exit Mach number is increased as to enhance the shock distortions and lowered as to enhance potential anti wake distortions, In a comprehensive approach the observations from the off-design conditions are utilized to classify every major perturbation observed in the perturbation space-time maps tit design operation conditions. The spanwise variations caused by the inherent 3-D nature of the flow field and promoted by the 3-D shape of the rotor blade are addressed.

  • 87.
    Laumert, Björn
    et al.
    KTH, Tidigare Institutioner, Energiteknik.
    Mårtensson, H.
    Fransson, Torsten H.
    KTH, Tidigare Institutioner, Energiteknik.
    Investigation of unsteady aerodynamic blade excitation mechanisms in a transonic turbine stage - Part II: Analytical description and quantification2002Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 124, nr 3, s. 419-428Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a study of the blade pressure perturbation levels and the resulting blade forces in a high-pressure transonic turbine stage based on 3-D time dependent viscous computations. Globally, the blade pressure unsteadiness is quantified with the RMS of the pressure perturbations integrated in both time and along the blade surface. Operation point as well as spanwise variations are addressed. Locally, the relative strength of the pressure perturbation events on the vane and rotor blade surface is investigated. To obtain information about the relative strength of events related to the blade passing frequency and higher harmonics, the pressure field is Fourier decomposed in time at different radial positions along the blade arc-length. The amplitude peaks are then related to the pressure events in space-time maps. With the help of the observations and results from the blade pressure study, the radial variations of the unsteady blade force and torque acting on a constant span blade profile section are investigated. The connection between the first and second vane passing frequency pressure amplitudes on the rotor blade surface and the resulting force and the torque amplitudes for three selected blade modes was investigated in detail. In this investigation the pressure was integrated over defined rotor blade regions to quanti,, local force contributions. Spanwise as well as operation point variations are addressed.

  • 88.
    Laumert, Björn
    et al.
    KTH, Tidigare Institutioner, Energiteknik.
    Mårtensson, Hans
    Volvo Aero Corporation.
    Fransson, Torsten H.
    KTH, Tidigare Institutioner, Energiteknik.
    Investigation of the Flowfield in the Transonic VKI Brite EURAM Turbine Stage with 3D Steady and Unsteadu N-S Computations2000Ingår i: ASME TURBO EXPO LAND SEA & AIR 2000, Munich, Germany, 2000, 2000Konferensbidrag (Refereegranskat)
  • 89.
    Lucio, Monaco
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Bergmans, John
    Vogt, Damian
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    A Remotely Operated Aeroelastically Unstable Low Pressure Turbine Cascade for Turbomachinery Aeromechanics Education and Training-Remote Flutter Lab2015Ingår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, nr 3, artikel-id 032507Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of advanced pedagogical methodologies in connection with advanced use of modern information technology for delivery enables new ways of communicating, of exchanging knowledge, and of learning that are gaining increasing relevance in our society. Remote laboratory exercises offer the possibility to enhance learning for students in different technical areas, especially to the ones not having physical access to laboratory facilities and thus spreading knowledge in a world-wide perspective. A new "Remote Flutter Laboratory" has been developed to introduce aeromechanics engineering students and professionals to aeroelastic phenomena in turbomachinery. The laboratory is world-wide unique in the sense that it allows global access for learners anywhere and anytime to a facility dedicated to what is both a complex and relevant area for gas turbine design and operation. The core of the system consists of an aeroelastically unstable turbine blade row that exhibits self-excited and self-sustained flutter at specific operating conditions. Steady and unsteady blade loading and motion data are simultaneously acquired on five neighboring suspended blades and the whole system allows for a distant-based operation and monitoring of the rig as well as for automatic data retrieval. This paper focuses on the development of the Remote Flutter Laboratory exercise as a hands-on learning platform for online and distant-based education and training in turbomachinery aeromechanics enabling familiarization with the concept of critical reduced frequency and of flutter phenomena. This laboratory setup can easily be used "as is" directly by any turbomachinery teacher in the world, free of charge and independent upon time and location with the intended learning outcomes as specified in the lab, but it can also very easily be adapted to other intended learning outcomes that a teacher might want to highlight in a specific course. As such it is also a base for a turbomachinery repository of advanced remote laboratories of global uniqueness and access. The present work documents also the pioneer implementation of the LabSocket System for the remote operation of a wind tunnel test facility from any Internet-enabled computer, tablet or smartphone with no end-user software or plug-in installation.

  • 90.
    Manrique Carrera, Arturo
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fakhrai, Reza
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Catalytic Combustion of Gasified Biomass for Gas Turbine Applications: Experimental Study for Reducing Fuel NOx Formation2005Ingår i: 14th European Biomass Conference & Exhibition, 2005, Vol. 100Konferensbidrag (Refereegranskat)
  • 91.
    Manrique Carrera, Arturo
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Jayasuriya, Jeevan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fakhrai, Reza
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Persson, Katarina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Järås, Sven
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Catalytic Combustion of Gasified Biomass for Gas Turbine Applications: Experimental Investigation at High Pressure2005Ingår i: Proceedings of the 6th International Workshop on Catalytic Combution, 2005, Vol. 100, s. 9-14Konferensbidrag (Refereegranskat)
  • 92. Manyumbu, E.
    et al.
    Martin, V
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Simple mathematical modeling and simulation to estimate solar-regeneration of a silica gel bed in a naturally ventilated vertical channel for Harare, Zimbabwe2014Ingår i: Energy Procedia, 2014, s. 1733-1742Konferensbidrag (Refereegranskat)
    Abstract [en]

    Passive air conditioning (humidity and temperature control) in buildings is more desirable on sustainable basis. One of the challenges of passive humidity control is regeneration of the materials applied for the purpose. This paper looks at solar regeneration of a silica gel layer (bed) for typical seasons of the year in Harare, Zimbabwe. This bed forms the primary system that is then used for drying room internal surfaces during the night. The extent of silica gel solar drying is the main attention of this investigation. Solar regeneration of a silica gel bed that forms a solar 'absorber' surface of a rectangular solar channel is investigated. Simple mathematical models are developed and subsequent spreadsheet simulations are carried out. Silica gel sorption models are from literature or estimated through curvefitting of available data. Solar radiation falling on a vertical surface at a given orientation is evaluated from the global solar radiation data using a developed simulator based on correlations obtained from literature and measured solar radiation data from the local meteorological department. For a vertical solar channel of an air gap of 20mm, and a height of 3m, silica gel is regenerated to some quite low moisture content of circa 0.06kg/kg. Comparable degree of regeneration is achieved for both seasons.

  • 93. Manyumbu, Edson
    et al.
    Martin, Viktoria
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    A parametric analysis on the regeneration performance of silica gel in a proposed comfort provision strategy for a typical office space in Harare, Zimbabwe2016Ingår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 126, s. 104-112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports the influence, design and climate parameters have on the regeneration performance of a proposed strategy for passive comfort provision for an office space. Solar regeneration of an external silica gel bed is later followed by regeneration of internal surfaces laden with silica gel. The internal surfaces regeneration is effected utilizing air dried by the external bed. External bed regenerating air conditions are evaluated based on simple energy balance and buoyancy models. Thermal efficiency is formulated based on its fundamental definition. Silica gel drying models are obtained from literature. MS Excel Spreadsheet program is applied in the present simulations. Internal surfaces regeneration depends largely on; ventilation rate, initial dryness and mass of external silica gel bed. There is an optimum ventilation rate for a given mass of silica gel in the external bed for particular initial moisture content. Channel depth is quite critical to the regeneration effect on the external silica gel bed, with an average influence coefficient of 200%. The specific humidity of the regenerating air has the least coefficient of influence of 82%. Considering the foregoing, the design of the proposed system calls for simulation to estimate performance.

  • 94.
    Martin, Andrew
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Gronli, Morten
    Bredesen, Arne M.
    SUSPOWER and ENGAS: Two major European research infrastructures in the gas turbine and energy conversion fields2006Ingår i: Proceedings of the ASME Turbo Expo 2006, Vol 1, 2006, s. 1015-1022Konferensbidrag (Refereegranskat)
    Abstract [en]

    Since the mid-1990's the European Commission (EC) has provided funding for transnational access schemes that open up existing major research facilities to outside users. In the current 6th Framework Program, two out of 14 funded projects - SUSPOWER and ENGAS - are of prime interest to the gas turbine community. SUSPOWER (KTH, Stockhom, Sweden) encompasses unique large-scale experimental facilities within the area of sustainable thermal power generation. Topics of key interest include high-temperature air combustion, catalytic combustion, gasification, aeroelasticity of turbine/compressor blades, film cooling aerodynamics, and stator/rotor interactions. ENGAS (NTNU, Trondheim, Norway) includes a complex array of specialized laboratories in the topic of environmental gas management. Relevant research topics include combustion of hydrogen and hythane, biomass gasification, CO2 absorption and sequestration, membranes for hydrogen and CO2 separation, gas storage in rock caverns, and hydrogen production and storage. This paper presents information on these projects along with a brief overview of previous EC transnational access activities as related to gas turbine research and development.

  • 95.
    Mayorca, Maria Angelica
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian M.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mårtensson, H.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Prediction of Turbomachinery Aeroelastic Behavior From a Set of Representative Modes2013Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 135, nr 1, s. 011032-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method is proposed for the determination of the aeroelastic behavior of a system responding to mode-shapes which are different from the tuned in vacuo ones, due to mistuning, mode family interaction, or any other source of mode-shape perturbation. The method is based on the generation of a data base of unsteady aerodynamic forces arising from the motion of arbitrary modes and uses least square approximations for the prediction of any responding mode. The use of a reduced order technique allows for mistuning analyses and is also applied for the selection of a limited number of arbitrary modes. The application of this method on a transonic compressor blade shows that the method captures the aeroelastic properties well in a wide frequency range. A discussion of the influence of the mode-shapes and frequency on the final stability response is also provided.

  • 96.
    Mayorca, Maria Angelica
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian M.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mårtensson, Hans
    VOLVO Aero Corporation.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Prediction of Turbomachinery Aeroelastic Behavior from a Set of Representative Modes2012Ingår i: Proceedings of the ASME Turbo Expo 2011, Vol 6, Parts And B / [ed] Presented by ASME International Gas Turbine Institute, Vancouver, Canada: American Society of Mechanical Engineers , 2012, s. 1449-1461Konferensbidrag (Refereegranskat)
    Abstract [en]

    A method is proposed for the determination of the aeroelastic behavior of a system responding to mode-shapes different to the tuned in-vacuo ones, due to mistuning, mode family interaction or any other source of mode-shape perturbation. The method is based on the generation of a data base of unsteady aerodynamic forces arising from the motion of arbitrary modes and uses Least Square approximations for the prediction of any responding mode. The use of a reduced order technique allows for mistuning analyses and is also applied for the selection of a limited number of arbitrary modes. The application on a transonic compressor blade shows that the method captures well the aeroelastic properties in a wide frequency range. A discussion of the influence of the mode-shapes and frequency on the final stability response is also provided.

  • 97.
    Mayorca, María A.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    De Andrade, Jesus A.
    Vogt, Damian M.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mårtensson, Hans
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Effect of Scaling of Blade Row Sectors on the Prediction of Aerodynamic Forcing in a Highly Loaded Transonic Compressor Stage2011Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 133, nr 2, s. 021013-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An investigation of the sensitivity of a geometrical scaling technique on the blade forcing prediction and mode excitability has been performed. A stage of a transonic compressor is employed as a test object. A scaling ratio is defined, which indicates the amount of scaling from the original geometry. Different scaling ratios are selected and 3D Navier-Stokes unsteady calculations completed for each scaled configuration. A full-annulus calculation (nonscaled) is performed serving as reference. The quantity of interest is the generalized force, which gives a direct indication of the mode excitability. In order to capture both up- and downstream excitation effects, the mode excitability has been assessed on both rotor and stator blades. The results show that the first harmonic excitation can be predicted well for both up-and downstream excitations using moderate amounts of scaling. On the other hand, the predictions of second harmonic quantities do show a higher sensitivity to scaling for the investigated test case.

  • 98.
    Mayorca, María A.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian M.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mårtensson, H.
    A New Reduced Order Modeling for Stability and Forced Response Analysis of Aero-Coupled Blades Considering Various Mode Families2012Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 134, nr 5, s. 051008-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the description and application of a new method for stability and forced response analyses of aerodynamically coupled blades considering the interaction of various mode families. The method, here referred as multimode least square, considers the unsteady forces due to the blade motion at different modes shape families and calculates the aerodynamic matrixes by means of a least square (L2) approximations. This approach permits the prediction of mode families' interaction with capabilities of structural, aerodynamic and force mistuning. A projection technique is implemented in order to reduce the computational domain. Application of the method on tuned and structural mistuned forced response and stability analyses is presented on a highly loaded transonic compressor blade. When considering structural mistuning the forced response amplitude magnification is highly affected by the change in aerodynamic damping due to mistuning. Analyses of structural mistuning without aerodynamic coupling might result in over-estimated or under-estimated response when the source of damping is mainly aerodynamic. The frequency split due to mistuning can cause that mode families' interact due to reducing their frequencies separation. The advantage of the present method is that the effect of mode family interaction on aerodynamic damping and forced response is captured not being restricted to single mode families.

  • 99.
    Mayorca, María A.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian M.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mårtensson, Hans
    VOLVO Aero Corporation, Trollhättan, Sweden.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    A New Reduced Order Modeling for Stability and Forced Response Analysis of Aero-Coupled Blades Considering Various Mode Families2010Ingår i: Proceedings of ASME Turbo Expo 2010: Scottish Exhibition & Conference Centre / [ed] ASME 2010, Glasgow, UK: ASME 2010 , 2010, s. 1-10Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the description and application of a new method for stability and forced response analyses of aerodynamically coupled blades considering the interaction of various mode families. The method, here referred as MLS (Multimode Least Square), considers the unsteady forces due to the blade motion at different modes shape families and calculates the aerodynamic matrixes by means of a least square (L2) approximations. This approach permits the prediction of mode families’ interaction with capabilities of structural, aerodynamic and force mistuning. A projection technique is implemented in order to reduce the computational domain. Application of the method on tuned and structural mistuned forced response and stability analyses is presented on a highly loaded transonic compressor blade. When considering structural mistuning the forced response amplitude magnification is highly affected by the change in aerodynamic damping due to mistuning. Analyses of structural mistuning without aerodynamic coupling might result in over-estimated or under-estimated response when the source of damping is mainly aerodynamic. The frequency split due to mistuning can cause that mode families’ interact due to reducing their frequencies separation. The advantage of the present method is that the effect of mode family interaction on aerodynamic damping and forced response is captured not being restricted to single mode families.

  • 100.
    Mayorca, María Angélica
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    De Andrade, Jesús A.
    Universidad Simon Bolivar - USB Laboratorio de Conversión de Energia Mecánica Sartenejas, Miranda, Venezuela.
    Vogt, Damian
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Mårtensson, Hans
    VOLVO Aero Corporation, Trollhättan, Sweden.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Effect of scaling of blade row sectors on the prediction of aerodynamic forcing in a highly-loaded transonic compressor stage2009Ingår i: PROCEEDINGS OF THE ASME TURBO EXPO 2009, VOL 6, PTS A AND B, 2009, s. 535-546Konferensbidrag (Refereegranskat)
    Abstract [en]

    An investigation of the sensitivity of a geometrical scaling technique on the blade forcing prediction and mode excitability has been performed. A stage of a transonic compressor is employed as test object. A scaling ratio is defined which indicates the amount of scaling from the original geometry. Different scaling ratios are selected and 3D Navier Stokes unsteady calculations completed for each scaled configuration. A full annulus calculation (non-scaled) is performed serving as reference. The quantity of interest is the generalized force, which gives a direct indication of the mode excitability. In order to capture both up- and downstream excitation effects the mode excitability has been assessed on both rotor and stator blades. The results show that first harmonic excitation can be predicted well for both up- and downstream excitation using moderate amount of scaling. On the other hand, the predictions of second harmonic quantities do show a higher sensitivity to scaling for the investigated test case.

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