Heat Transfer Analysis over Disc and Hemispherical Spike Attached to Blunt-Nosed Body at Mach 6

摘要

Aero-spike attached to a blunt body significantly alters its flow field and influences aerodynamic drag at high speeds. The dynamic pressure in the recirculation area is highly reduced and this leads to the decrease in the aerodynamic drag. Consequently, the geometry of the aero-spike has to be simulated in order to obtain a large conical recirculation region in front of the blunt body to get beneficial drag reduction. Axisymmetric compressible Navier-Stokes equations are solved using a finite volume discretization in conjunction with a multistage Runge-Kutta time stepping scheme. The effect of the various types of aero-spike configurations on the reduction of aerodynamic drag is evaluated numerically at Mach 6 at a zero angle of attack. The computed density contours agree well with the schlieren pictures. Additional modification to the tip of the spike to get the different type of flow field such as formation of shock wave, separation area and reattachment point are examined flat-disk spike and hemispherical disk spike attached to the blunt nosed body. One of the critical heating areas is at the stagnation point of a blunt body, where the incoming hypersonic flow is brought to rest by a normal shock and adiabatic compression. Therefore the problem of computing the heat transfer rate near the stagnation point needs a solution of the entire flow field from the shock to the spike body. The bow shock distance ahead of the hemispherical and flat-disc is compared with the analytical solution and an agreement found between them. The influence of the shock wave generated from the spike is used to analysis the pressure distribution, the coefficient of skin friction and the wall heat flux facing the spike surface to the flow direction. The numerical analysis gives complete flow field information over the spike surface including the stand-off distance shock, sonic line, and velocity gradient along the surface of the spike.