Ground Test Measurements of Boundary-Layer Instabilities and Transition for HIFiRE-5 at Flight-Relevant Attitudes

摘要

A 2:1 elliptic cone model was tested in a Mach-6 quiet wind tunnel at both low and elevated freestream noise levels. Simultaneous measurements were made using an infrared camera and pressure sensors that were mounted flush with the model surface. The model was inclined at angles-of-attack and yaw angles similar to those in the HIFiRE-5b flight test. As in flight, it was observed that crossflow transition was significantly more sensitive to yaw angle than angle-of-attack. With respect to the yaw angle, the windward side of the model was more unstable to crossflow than the lee side. Changing the yaw angle by 1° in quiet flow resulted in a 20% decrease in the minimum crossflow transition Reynolds number. Angle-of-attack had a larger effect on transition for mixed yaw and angle-of-attack orientations than for pure angle-of-attack. Positive yaw angles had little effect on the amplitude of traveling crossflow waves. Negative yaw angles resulted in a substantial suppression of traveling crossflow. High-frequency disturbances were detected near the model centerline for several model orientations in quiet flow that moved the crossflow-unstable region of the model near the centerline. These disturbances may be secondary instabilities of stationary crossflow vortices.