Study of surface roughness effect on forebody aerothermodynamics

Abstract

In this study, the surface aerothermodynamics phenomenon on blunt forebody model according to the model surface condition was verified experimentally and validate numerically. The aerothermodynamic phenomenon of the model surface considered the flow of the hypersonic nozzle in consideration of the environment in the ground test facility. The model surface aerodynamics influence according to various nozzle flow profiles through numerical analysis was considered. The study was based on the measurement results of the model surface aerodynamics according to the nozzle flow in the Mach 4 environment of the Ludwieg tube. Five nozzle flows, including contour nozzle and conical nozzle flow, were considered, and numerical analysis confirmed that the non-uniformity of nozzle flow affected the pressure and shock wave shape of the forebody model surface. Based on this observation, the effective test section and the size of the effective model were confirmed, in the shock tunnel test facility through the manufacture of the Mach 6 contour nozzle for the shock tunnel and the flow uniformity test. In the shock tunnel environment, the aerothermodynamics change of the forebody model surface was measured. The aerothermodynamic effect of the roughness of the model surface and the model size was experimentally confirmed, and compared and verified by numerical analysis and theoretical methods. Pressure and heat flux amount were measured on the forebody surface, and it was confirmed that good agreement with the theoretical and numerical analysis results. No observable pressure change was showed as the surface roughness increased, however it was verified that the heat flux increased in proportion to the surface roughness. As a result of the measurement according to the model size, it was confirmed that the increase in heat flux due to the surface roughness showed a constant increase regardless of the model size. In the case of the influence of the model size, it was confirmed that the surface heat flux was inversely proportional to the model size, as at the stagnation point in theory.