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  • 1.
    Bouchouireb, Hamza
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Pignier, Nicolas
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    O'Reilly, Ciarán J.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Boij, Susann
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Dahan, Jeremy A.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. Siemens PLM, United Kingdom.
    Identification of noise sources on a realistic landing gear using numerical phased array methods applied to computational data2017In: 23rd AIAA/CEAS Aeroacoustics Conference, American Institute of Aeronautics and Astronautics, 2017Conference paper (Other academic)
    Abstract [en]

    The aerodynamic sound sources on a realistic landing gear are investigated using numerical phased array methods, based on array data extracted from compressible Detached-Eddy Simulations of the flow. Assuming monopole or monopole in a moving medium propagation, the sound sources are identified in the source region through various beamforming approaches: dual linear programming (dual-LP) deconvolution, orthogonal beamforming and CLEAN-SC. The predicted source locations are in good agreement with previous experimental results performed on the same nose landing gear configuration by industrial and academic partners within the ALLEGRA project. Additionally, the modeled sources are used to generate far-field spectra which are subsequently compared to the ones obtained with the Ffowcs Williams-Hawkings acoustic analogy. The results of the dual-LP approach show a good match between the far-field spectra up to a certain frequency threshold cor- responding to the quality of the mesh used. The results demonstrate the potential of numerical phased array methods as a legitimate modeling tool for aeroacoustic simulations in general and as a tool to gain insight into the noise generation mechanisms of landing gear components in particular. 

  • 2. Choudhari, M.
    et al.
    Lockard, D. P.
    Jenkins,
    Neuhart,
    Choudhari,
    Cattafesta,
    Murayama,
    Yamamoto,
    Ura,
    Ito,
    Vilela de Abreu, Rodrigo
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Hoffman, Johan
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Jansson, Johan
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Lockard,
    Ueno,
    Knacke,
    Thiele,
    Dahan, Jeremy
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Tamaki,
    Imamura,
    Tanaka,
    Amemiya,
    Hirai,
    Ashton,
    West,
    Mendonca,
    Housman,
    Kiris,
    Ribeiro,
    Fares,
    Casalino,
    Terracol,
    Ewert,
    Boenke,
    Simoes,
    Bonatto,
    Souza,
    Medeiros,
    Bodart,
    Larsson,
    Moin,
    Assessment of slat noise predictions for 30P30N high- lift configuration from Banc-III workshop2015In: 21st AIAA/CEAS Aeroacoustics Conference, American Institute of Aeronautics and Astronautics, 2015Conference paper (Refereed)
    Abstract [en]

    This paper presents a summary of the computational predictions and measurement data contributed to Category 7 of the 3rd AIAA Workshop on Benchmark Problems for Airframe Noise Computations (BANC-III), which was held in Atlanta, GA, on June 14-15, 2014. Category 7 represents the first slat-noise configuration to be investigated under the BANC series of workshops, namely, the 30P30N two-dimensional high-lift model (with a slat contour that was slightly modified to enable unsteady pressure measurements) at an angle of attack that is relevant to approach conditions. Originally developed for a CFD challenge workshop to assess computational fluid dynamics techniques for steady high-lift predictions, the 30P30N configurations has provided a valuable opportunity for the airframe noise community to collectively assess and advance the computational and experimental techniques for slat noise. The contributed solutions are compared with each other as well as with the initial measurements that became available just prior to the BANC-III Workshop. Specific features of a number of computational solutions on the finer grids compare reasonably well with the initial measurements from FSU and JAXA facilities and/or with each other. However, no single solution (or a subset of solutions) could be identified as clearly superior to the remaining solutions. Grid sensitivity studies presented by multiple BANC-III participants demonstrated a relatively consistent trend of reduced surface pressure fluctuations, higher levels of turbulent kinetic energy in the flow, and lower levels of both narrow band peaks and the broadband component of unsteady pressure spectra in the nearfield and farfield. The lessons learned from the BANC-III contributions have been used to identify improvements to the problem statement for future Category-7 investigations.

  • 3.
    Dahan, Jeremy A.
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    O'Reilly, Ciarán
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Efraimsson, Gunilla
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Numerical investigation of a realistic nose landing gear2014In: 20th AIAA/CEAS Aeroacoustics Conference, American Institute of Aeronautics and Astronautics, 2014Conference paper (Other academic)
    Abstract [en]

    A hybrid approach is used to study the noise generated by a realistic full-scale nose land- ing gear configuration. Compressible Detached-Eddy Simulations are performed to com- pute the flow field and the far-field noise is evaluated with the Ffowcs Williams-Hawkings acoustic analogy. Preliminary Reynolds-Averaged Navier-Stokes simulations are performed to evaluate the sensitivity of the steady solution to the computational grid. It is found that mesh independence is not obtained with the grids considered, although the agreement between the medium and fine grids is reasonable. The time-dependent solution obtained via DES is examined and the main noise sources on the gear surfaces are identified. The power spectral density of pressure uctuations on the tyre surface is found to be rather broadband on the noisier sides of the tyre, while distinct humps and a sharp peak near 1kHz are identified in the quieter regions of the tyre. This sharp peak is observed again in the far-field noise. Further work is needed to clarify the cause of this peak. Its frequency is too high to link it with shedding from a gear component, although it could be associated with unsteadiness near the tyre corner.

  • 4.
    Dahan, Jeremy A.
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    O'Reilly, Ciarán J.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Efraimsson, Gunilla
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Numerical investigation of the flow around a realistic nose landing gearManuscript (preprint) (Other academic)
    Abstract [en]

    Detached-eddy simulations of the flow around a realistic two- wheeled nose landing gear are conducted, at a Reynolds number corresponding to the final approach phase for a regional aircraft. The main focus is on the flow and associated sound fields in the inter-wheel region and in the wake of the landing gear. Three unstructured grids are designed to evaluate the sensitivity of the solution to grid resolution. The three flow solutions agree well, although the turbulent wake requires a fine mesh. In addition, comparisons with available experimental data on two other nose landing gear models, the PDCC and LAGOON gears, yield a good qualitative agreement. The wake of the landing gear assembly is strongly three-dimensional and exhibits a complex behaviour. The effect of the torque links and wheel axle on the flow dynamics and sound sources were examined via simulations on different configurations. The presence of the torque links and the wheel axle, often simplified or omitted in numerical landing gear studies, were found to strongly modify the flow in the inter-wheel region and in the wheel wakes. The noise was propagated to the far-field using the convective form of the FWH integral. The far- field noise at sideline receivers agrees well with wind-tunnel measurements and the overhead noise sources in the inter-wheel region are identified by considering the integrand of the FWH analogy. 

  • 5.
    Dahan, Jeremy
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aerodynamics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Futrzynski, Romain
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aerodynamics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    O'Reilly, Ciarán
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Efraimsson, Gunilla
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aerodynamics.
    Aero-acoustic source analysis of landing gear noise via dynamic mode decomposition2014In: 21st International Congress on Sound and Vibration, ICSV21: / [ed] Malcolm J. Crocker, Marek Pawelczyk, Jing Tian, 2014, Vol. 2, p. 1245-1252Conference paper (Refereed)
    Abstract [en]

    In this paper, we apply dynamic mode decomposition (DMD) on time accurate simulationsof the pressure distribution on a realistic full-scale noselanding gear configuration in order toidentify noise generating structures on landing gear surfaces. The simulated pressure data isobtained from DES simulations using the commercial software STAR-CCM+ by CD-adapco.The dynamics of the surface pressure on a tyre are discussed and the DMD modes are com-puted from instantaneous pressure snapshots. The far-fieldnoise is determined via the FfowcsWilliams-Hawkings analogy, where a given frequency band source term can be reconstructedby choosing an appropriate number of DMD modes.

  • 6.
    Neri, Eleonora
    et al.
    Trinity College Dublin, Department of Mechanical and Manufacturing Engineering, Ireland.
    Kennedy, John
    Trinity College Dublin, Department of Mechanical and Manufacturing Engineering, Ireland.
    Bennett, Gareth J.
    Trinity College Dublin, Department of Mechanical and Manufacturing Engineering, Ireland.
    O'Reilly, Ciarán
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Dahan, Jeremy
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Esposito, Marco
    Tecknosud, Italy.
    Bruno, Massimiliano
    Magnaghi Aeronautica, Italy.
    Bianco, Antonello
    Pininfarina, Italy.
    Amoroso, Francesco
    Eurotech, Italy.
    Di Giulio, Massimiliano
    Allenai Aermacchi, Italy.
    Characterization of low noise technologies applied to a full scale fuselage mounted nose landing gear2015In: 44th International Congress and Exposition on Noise Control Engineering, INTER-NOISE, The American Society of Mechanical Engineers (ASME) , 2015, Vol. 3, p. 1869-1878Conference paper (Other academic)
    Abstract [en]

    The negative impact of aircraft noise includes effects on population's health, land use planning and economic issues such as building restrictions and operating restrictions for airports. Thus, the reduction of noise generated by aircraft at take-off and approach is an essential consideration in the development of new commercial aircraft. Among the different aircraft noise sources, landing gear noise is one of the most significant during approach. This research presents results from the European Clean Sky funded ALLEGRA project, which investigated a full-scale Nose Landing Gear (NLG) model featuring the belly fuselage, bay cavity and hydraulic dressing. Tests were performed for a variety of wind speeds and yaw angles. In this paper, a characterization of the noise generated by the full-scale Nose Landing Gear (NLG) model is presented and the different techniques used for characterizing acoustic sources on the NLG are described. The landing gear noise source is characterized in terms of OASPL, directivity, source spectra, PNL and PNLT. A comparison between the NLG with and without the application of low noise technology is presented.

  • 7.
    Pignier, Nicolas
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Dahan, Jeremy
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    O'Reilly, Ciarán
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Boij, Susann
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Aeroacoustic analysis of a NACA duct2015In: 10th European Congress and Exposition on Noise Control Engineering, Euronoise, 2015Conference paper (Other academic)
    Abstract [en]

    An initial aeroacoustic study of a typical NACA inlet is presented. In this paper, the shape of the NACA inlet is based on the experimental work of the National Advisory Committee for Aeronautics. The study is performed at low Mach numbers. A time-averaged solution is obtained through a RANS simulation and validated against experimental results. The results show good agreement both in terms of overall performance of the inlet and in terms of local surface pressures. From the steady simulations, a broadband noise source model is applied to get an estimate of the location of the noise source regions on the surface of the inlet. This model of the NACA inlet will be used for a future acoustic analysis based on unsteady detached eddy simulation (DES) of the flow and on the Ffwocs Williams-Hawkings integral.

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