Effects of surface topology on blunt body heat transfer

Abstract

This master thesis presents the work conducted on the effects of surface rough topology on heat transfer experienced by a flat-faced rigid body in a low enthalpy flow. The whole work consists of two parts. The foremost part is a numerical modelling, complimented by an experimental validation of the code. The CFD technique is based on the in-house CLithium2 code of Queen Mary University of London (QMUL). The code was modified for the hypersonic conditions used at the KAIST Hypersonic Laboratory, and was verified correspondingly for the distance of the detached shock wave and the developed boundary layer against existing analytic, numerical, and experimental techniques. The free-stream conditions for nominal Mach number 6 are used in order to agree with accompanying shock tube tests. The numerical results are obtained for laminar conditions due to the very short time scales looked at it. The rough topology modelling is simulated with the levels ranging from 2000 microns to 8 microns. The results show that topology with the higher roughness level yields an increase in the stagnation heat transfer and stagnation pressure over the body. However, this trend in heat transfer belongs to roughness level higher than 1000 microns. In addition, a relatively low temperature (< 2000 K) conditions justified the use of ideal gas model and the continuum assumption used in the code.