Viscous Hypersonic Flow over Simple Blunt Bodies; Comparison of a Second-Order Theory with Experimental Results.

摘要

For the case of plane hypersonic flow over a cylinder with blunt cross-section the second-order terms account for the effects of wall curvature, velocity slip and temperature jump at the surface and displacement interaction. An implicit finite-difference procedure similar to the one used by Blottner and Flugge-Lotz is used to solve both the first- and second-order equations. Complete solutions are obtained for two simple blunt bodies, a circular cylinder and a slab with a circular leading edge. Two different solutions for the circular cylinder corresponding to the exact theoretical and the experimental pressure distributions respectively are compared to Tewfik and Giedt's experimental results from a low density wind tunnel. The agreement between the measured and predicted heat-transfer rates is somewhat unsatisfactory. The theoretical pressure distribution when corrected for displacement interaction agrees, on the other hand, well with the measured values. On the basis of the second-order solution it is possible to assess the validity of the asymptotic expansion of the Navier-Stokes equations. From the numerical results obtained it appears that the boundary-layer approximation breaks down upstream of the shoulder (theta = 90 degrees) for a highly curved body such as the circular cylinder. The consequence of this apparent breakdown and a possible remedy is discussed. (Author)