Fin leading-edge sweep effect on shock-shock interaction at Mach 6

The effects of fin leading-edge sweep on peak heating rates due to shock-shock interaction have been experimentally examined in the NASA Langley Research Center 20-Inch Mach 6 Tunnel. The shock interaction was produced by the intersection of a planar incident shock (16.8-deg shock angle relative to the freestream, generated by a 9-deg wedge) with the bow shock formed around a 0.5-in.-diam cylindrical leading-edge fin. Heating distributions along the leading-edge stagnation line have been obtained using densely spaced thin-film resistive-type sensors. Schlieren images were obtained to illustrate the very complex shock-shock interactions. The fin leading-edge sweep angle was varied from 15 deg swept back (relative to the normal to the freestream) to 45 deg swept forward for a freestream unit Reynolds number of 2 X 10(6)/ft. Two models were utilized during the study, one with 0.025-in. spacing between gauge centers, and the other with 0.015-in. spacing Gauge spatial resolution on the order of 0.015 in. appeared to capture the narrow heating spike accurately. Peak heating due to shock interaction was maximized when the fin was swept forward 15 and 25 deg, both promoting augmentations over seven times the baseline value. The schlieren images for these cases revealed type IV and Type III interactions, respectively.