ON THE STRUCTURE OF AN UNSTEADY TYPE-IV INTERACTION AT MACH-8

The unsteady laminar how due to a Type IV shock-on-shock interaction a t Mach 8 is examined with a flux-split scheme based on a modified Steg er-Warming method. A sequence of meshes is utilized to perform a grid resolution study and the results are compared with available experimen tal data. The formulation is cell-centered finite-volume with second o rder accuracy obtained with the MUSCL approach in conjunction with a l imiter to prevent unphysical spatial oscillations. Viscous terms are c entrally differenced. The solution is advanced with implicit Gauss-Sei del line relaxation. The calculations indicate unsteady behavior on al l meshes. The coherent structure of the asymptotic solution is examine d. The impinging supersonic jet limit cycle exhibits a relatively regu lar oscillatory behavior with a dominant frequency of about 30 kHz. Th is is accompanied by sizeable movement of the terminating jet shock an d associated variation in surface pressure and heat transfer rates.