Experimental and Numerical Study of Gap Heating on a HYFLEX Tile Model in the Arc Heated Facility L3K

Abstract

Gap heating tests were performed on a HYFLEX tile model with gaps of the flight configuration in the arc heated facility L3K. The width of the longitudinal and traversal gaps of the model were varied systematically at the same flow condition. The homogeneity of the hypersonic nozzle flow was proved by Pitot pressure profile measurement. The gap geometry was found to have a direct influence on the temperature development in the gap. A strong temperature decrease along the longitudinal gap in flow direction and relatively lower surface temperatures at the stagnation point of the T-gap indicate a significant decrease in kinetic energy for the gap flow. The results of the test with a stepwise increase of the surface heat flux rate show that the gap heating is a slow process compared to the surface responses. Tests at higher angle of attack, i.e. higher surface pressure, confirm the result of other tests concerning the dependency of the gap temperature on the pressure level. Moreover, numerical simulation of the L3K high enthalpy tests on the HYFLEX tiles model was performed with a Navier-Stokes approach assuming chemical nonequilibrium. The knowledge of gap heating distribution was provided through 2D investigations focusing on the transversal gap. Computations allowed to get representation of the complex cavity physics into gaps and to provide convective heating distribution almost completely located at the 20% first part of the gap walls since the rest remains rather adiabatic.