Transitional Shock Wave Boundary Layer Interactions and Surface Heat Transfer on a Hollow-Cylinder/Flare at Mach 5

Abstract

A hollow-cylinder model with a 15◦ half-angle flare is tested at Mach 5 for fivedifferent Reynolds numbers ranging from 4.10 × 105 < ReL < 1.62 × 106 . The laminar boundary layer separates due to the shock-induced pressure rise and reattaches downstream of the flare corner. Reattachment is associated with transition to turbulence and the formation of hot streaks. Surface heat transfer is measured using a FLIR infrared camera and five custom Ahmic thin-film gauges while pressure fluctuations are measured with two Kulites and three PCBs. For sufficiently transitional cases, heat transfer reaches a maximum near reattachment and moves upstream for increasing Reynolds number. Steady heat transfer trends along x/L between IR and thin-film gauges match qualitatively and the discrepancies between each diagnostic are discussed. In the premultiplied pressure spectra, two peaks were identified at f ≈ 14 kHz and f ≈ 100 kHz and their potential sources are discussed. Unsteady heat transfer measurements are discussed in regards to their viability for detecting reattachment and transition.