An important aspect of the design of supersonic aircraft is the minimization of aerodynamic and thermal loads onto the vehicle's surface. Unfortunately local contour discontinuities are generally unavoidable in the design, although a smooth aerodynamic shape of the surface is attempted. Examples of such discontinuities occur at positions where control devices and the intake of the propulsion system are integrated. Generic geometries of these contour discontinuities are, for example, kinks, fins, windshield, door edges, compression or expansion corners, and forward- or backward-facing steps. These geometries will induce shock wave/boundary-layer interactions and the flow separation from the surface, resulting in an increase of pressure and heat flux level in the vicinity of the obstacle at supersonic speeds. A common geometry that often occurs on the vehicle surface is the forward-facing step. The flow characteristic around forward-facing step is an important part of the vehicle design. Thus, in the present work, a numerical investigation is carried out to determined the flow characteristic around a forward-facing step. A new approach for the computation of unsteady compressible flows has been developed. The new scheme employs upwinding of the convective flux based on particle velocity and has been termed the particle velocity upwinding (PVU) scheme. The PVU scheme is an explicit two-step predictor-corrector scheme, in which the convective fluxes are evaluated on cell faces using a first-order upwinding method. The scheme is accurate and stable, giving solutions free from oscillations near the discontinuities without any explicit addition of artificial viscosity. The PVU scheme has an edge over state-of-the-art high-resolution schemes in terms of simplicity of implementation in multidimensional flows and problems involving complex domains. The numerical scheme is validated for both Euler and Navier-Stokes equations. Furthermore, thePVUscheme is used to investigate laminar supersonic viscous flow over a forward-facing step. The results are obtained for Minfinity = 1.5-3.5 in steps of 0.5 and for Reinfinity =104. Step heights Hs of 10 and 20% of the characteristic length of the problem are considered. The effect of step height and the incoming freestream Mach number on the spatial flow structure and on the important design parameters such as wall pressure, skin friction, heat transfer, and length of separated region are investigated.
New scheme for the computation of compressible flows
Neues Verfahren zur Simulation kompressibler Strömungen
AIAA Journal (online) ; 44 , 5 ; 1025-1039
2006
15 Seiten, 20 Bilder, 22 Quellen
Article (Journal)
English
New Scheme for the Computation of Compressible Flows
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