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IMPLICIT LARGE EDDY SIMULATION OF A SUPERSONIC TURBULENT BOUNDARY LAYER OVER A COMPRESSION-EXPANSION RAMP

Muzio Grilli
Lehrstuhl fur Aerodynamik und Stromungsmechanik Technische Universitat Munchen Boltzmannstr 15, D-85748 Garching, Germany

Stefan Hickel
Institute of Aerodynamics and Fluid Mechanics Technische Universitat Munchen Boltzmannstr. 15, 85748 Garching bei Munchen, Germany; Chair of Computational Aerodynamics Faculty of Aerospace Engineering, TU Delft Kluyverweg 1, 2629 HS Delft, Netherlands

Nikolaus A. Adams
Chair of Aerodynamics and Fluid Mechanics, Department of Mechanical Engineering, Technical University of Munich, 85748 Garching bei München, Germany

Аннотация

Results of a large-eddy simulation (LES) of a supersonic turbulent boundary layer flow along a compression-expansion ramp configuration are presented. The numerical simulation is directly compared with an available experiment at the same flow conditions. The compression-expansion ramp has a deflection angle of β = 25°. The flow is characterized by a free-stream Mach number of Ma = 2.88 and the Reynolds number based on the incoming boundary layer thickness is Reδ0 = 132840. The Navier Stokes equations for compressible flows are solved on a cartesian collocated grid. About 32.5 × 106 grid points are used to discretize the computational domain. Subgrid scale effects are modeled implicitly by the adaptive local deconvolution method (ALDM). A synthetic inflow-turbulence technique is used, which does not introduce any low frequency into the domain, therefore avoiding any possible interference with the shock/boundary layer interaction system. Statistical samples are gathered over 1000 characteristic time scales δ0/U. The numerical data is in good agreement with the experiment in terms of mean surface-pressure distribution, skin-friction, mean velocity profiles, velocity and density fluctuations. The computational results confirm theoretical and experimental results on fluctuation-amplification across the interaction region. In the wake of the main shock a shedding of shocklets is observed. Results show the development of Gortler-like vortices in the reattachment region. The LES provide a reliable and detailed flow information, which helped to improve considerably the understanding of shock-boundary-layer interaction.