Experimental Investigation of Hexcomb-Pattern Roughness Effects on Transition Onset and Turbulent Heating Augmentation at Mach 6

Hollis, Brian R

关键词: ABLATION;    AEROTHERMODYNAMICS;    ATMOSPHERIC ENTRY SIMULATION;    BOUNDARY LAYER TRANSITION;    COMPUTATIONAL FLUID DYNAMICS;    CORRELATION;    FLOW DISTRIBUTION;    HEAT SHIELDING;    HYPERSONIC WIND TUNNELS;    REYNOLDS NUMBER;    SURFACE ROUGHNESS;    THERMAL PROTECTION;    TURBULENT FLOW;    TURBULENT HEAT TRANSFER;    WIND TUNNEL TESTS;   

RP-ID  :  NASA/TM−2019-220424,L-21079,NF1676L-34982

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来源: NASA Technical Reports Server

【 摘 要 】

An experimental investigation of hexcomb-patterned surface roughness effects on boundary-layer transition and turbulent heating has been performed. Two representative entry vehicle geometries, a spherical- cap aeroshell and a sphere-cone aeroshell, were considered. Multiple cast ceramic models of each geometry were fabricated with varying roughness pattern densities and depths that simulated an ablated hexcomb-structure thermal protection system. Wind tunnel testing was performed at Mach 6 over a range of Reynolds numbers sufficient to produce laminar, transitional, and turbulent flow. Aeroheating and boundary-layer transition onset data were obtained using global phosphor thermography. The experimental heating data are presented herein, as are comparisons to laminar and turbulent smooth-w ll heat transfer distributions from computational flow field simulations.