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- Andersson, Niklas, 1976, et al.
(författare)
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A Study of Mach 0.75 Jets and Their Radiated Sound Using Large-Eddy Simulation
- 2004
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Ingår i: AIAA 2004-3024, proc. of 10th AIAA/CEAS Aeroacoustics Conference, May 10-12, 2004.
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Konferensbidrag (refereegranskat)abstract
- Large-Eddy Simulations (LES) of a compressible nozzle/jet configuration have been carried out. Two jets were simulated, an isothermal jet and a jet with a higher temperature than the quiescent surrounding air. The Mach number was in both cases 0.75 and the jet Reynolds number was 50,000. Sound pressure levels in far-field observer locations were evaluated using Kirchhoff surface integration. The Favre filtered Navier-Stokes equations were solved using a finite volume method solver with a low-dissipation third-order upwind scheme for the convective fluxes, a second-order centered difference approach for the viscous fluxes and a three-stage second-order Runge-Kutta technique in time. The computational domain was discretized using a block structured boundary fitted mesh with approximately 3,000,000 cells. The calculations were performed on a parallel computer, using message-passing interface (MPI). A compressible form of Smagorinsky's subgrid scale model was used for computation of the subgrid scale stresses. Absorbing boundary conditions based on characteristic variables were adopted for all free boundaries. Velocity components specified at the entrainment boundaries were estimated from corresponding Reynolds Averaged Navier-Stokes (RANS) calculations, which enable the use of a rather narrow domain. This, furthermore, ensures that the correct amount of fluid is entrained into the domain. Two-point space-time correlations were obtained for locations in the shear layer center, from which length and time scales of turbulence structures were evaluated. Predicted near-field flow statistics and far-field sound pressure levels (SPL) are both in good agreement with experiments. Predicted (SPL) are for all observers locations, where evaluated, within a 3.0 [dB] deviation from measured levels and for most locations within a 1.0 [dB] deviation. Experimental data used for validation were provided by Laboratoire dEtude Aeròdynamiques, Poitiers, France.
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| 2. |
- Andersson, Niklas, 1976, et al.
(författare)
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Large-Eddy Simulation of a Mach 0.75 Jet
- 2003
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Ingår i: AIAA 2003-3312, proc. of 9th AIAA/CEAS Aeroacoustic Conference, May 12-14, 2003.
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Konferensbidrag (refereegranskat)abstract
- A large-eddy simulation (LES) of a compressible nozzle/jet configuration has been carried out. A cold Mach 0.75 jet was simulated. The Reynolds number based on the jet velocity at the nozzle exit plane and the nozzle diameter was 50,000. The Favre filtered Navier-Stokes equations were solved using a finite volume method with a low dissipative third order upwind scheme for the convective fluxes, a second order centered difference approach for the viscous fluxes and a three-stage second order Runge-Kutta time marching technique. A compressible form of Smagorinsky's sub-grid scale model was used for computation of the sub-grid scale stresses. The calculations were performed using a block structured boundary fitted mesh with approximately 3,000,000 cells. The calculations have been performed on a parallel computer, using message-passing interface (MPI). Absorbing boundary conditions based on characteristic variables were adopted for all free boundaries. Velocity components specified at the entrainment boundaries were estimated from a corresponding Reynolds Averaged Navier-Stokes (RANS) calculation. In order to diminish disturbances caused by the outlet boundary a buffer layer was added at the domain outlet. Kirchhoff surface integration has been utilized to obtain far-field sound pressure levels in a number of observer locations using instantaneous pressure from the LES. Aerodynamic results and predicted sound pressure levels are both in good agreement with experiments. Experimental data were provided by Laboratoire dEtude Aeròdynamiques, Poiters, France.
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| 9. |
- Wollblad, Christian, 1978, et al.
(författare)
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Semi-implicit Preconditioning for Wall-bounded Flow
- 2004
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Ingår i: 34th AIAA Fluid Dynamic Conference and Exhibit. - Reston, Virigina : American Institute of Aeronautics and Astronautics. - 9781624100314
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Large eddy simulations (LES) of high speed compressible viscous flow require high space resolution as well as short time steps if explicit time stepping is used. A semi-implicit preconditioning scheme specially suitable for wall-bounded flow is developed which, when combined with an explicit time stepping algorithm, makes much larger time steps possible than with the explicit scheme alone. The method is validated for developing turbulent channel flow and applied to a transonic flow with shock wave turbulent boundary layer interaction. In both cases, the computational time saved is measured. Finally possible developments of the method are discussed.
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| 10. |
- Eriksson, Lars-Erik, 1950, et al.
(författare)
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Development of a Cooled Radial Flameholder for the F404/RM12 Afterburner: Part III Afterburner Rumble Prediction and Suppression
- 2003
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Ingår i: ISABE-2003-1060, proc. of 16th ISABE Conf, Cleveland Ohio, September 2003.
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Konferensbidrag (refereegranskat)abstract
- One-dimensional methods used for solving acoustic instabilities are of doubtful value in the design of afterburner systems. In this paper a three-dimensional method developed and used at Volvo Aero Corporation is described. The method deals with the mean flow and the perturbation flow separately. The perturbation part is based on the linearized Euler equations (time domain) for compressible multi-species flow together with a spectrum trans-formation and Arnoldis method for eigenmode extraction.
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