A general schematic flow representation that explains the mechanism of inviscid gas separation in time-dependent and three-dimensional gas flows is presented. The scenario of gas flow separation from a body surface or a mixing layer is described as a vortex which induces in the flowfield a velocity opposing to that of the main flow, thus decelerating it. Within the framework of this scenario the analytical conditions of separation are obtained for conical and self-similar gas flows which coincide with the results of experimental and numerical simulations.

The fundamental properties of separation in unsteady supersonic ideal gas flows

On the theory of supersonic inviscid flow separation in gasdynamic problems

This paper presents a numerical study of shock wave diffraction at a sharp ninety degrees edge, using an explicit second-order Godunov-type Euler scheme based upon the solution of a generalized Riemann problem (GRP). The Euler computations produce flow separation very close to the diffraction edge, leading to a realistic development of the separated shear layer and subsequent vortex roll-up. The diffracted shock wave, and the secondary shock wave, are both reproduced well. In addition a pair of vortex shocks are shown to form, extending well into the vortex core.

Computation of shock wave diffraction at a ninety degrees convex edge

Most aerospace vehicles, although designed for hypersonic cruise at low angles of attack, often have to perform rapid maneuvers at high angles of attack from low supersonic down to low subsonic speeds. There is, therefore, a need for rapid prediction of the nonlinear high-alpha vehicle dynamics of slender-wing aircraft in that speed range. The present paper describes such a prediction method, which can account for the nonlinear dynamic effects of leading-edge vortices at angles of attack, yaw, and roll. A comparison with existing experimental results shows that the accuracy of the prediction is satisfactory for preliminary design as long as breakdown of the leading-edge vortices does not occur.

The fundamental properties of separation in unsteady supersonic ideal gas flows

Citations

On the theory of supersonic inviscid flow separation in gasdynamic problems

References

Computation of shock wave diffraction at a ninety degrees convex edge

Rapid prediction of high-alpha unsteady aerodynamics of slender-wingaircraft

Vortical singularity behind a highly yawed cone

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