Measurement of HIFiRE-5 Boundary-Layer Transition in a Mach-6 Quiet Tunnel with Infrared Thermography

Abstract

The principal goal of the Hypersonic International Flight Research Experimentation (HIFiRE) flight Five is to measure hypersonic boundary-layer transition on a three-dimensional body. The HIFiRE flight tests are supported by a ground test campaign; this paper presents measurements of heat flux and boundary-layer transition in the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT). This facility has been developed to provide quiet flow at high Reynolds number, with low noise levels comparable to flight. Previously, the global heat flux and location of the transition front were measured with TemperatureSensitive Paint (TSP). Two modes of transition were observed: transition starting in close proximity to the centerline and transition roughly halfway between the centerline and leading edges, probably due to the breakdown of crossflow vortices. One drawback of the TSP was the unavoidable step at the edge of the painted area, which has an unknown effect on the subsequent complex transition front. A new 38.1%-scale HIFiRE-5 model was built with a flush PEEK shell, which makes it suitable for infrared-thermographic heatflux measurements. Quiet-flow tests at Reynolds numbers of 8–12·106 /m and zero angle of attack were conducted and indicate a centerline transition location within 5% of the earlier TSP results, on the order of the uncertainty of the two techniques. This good agreement with independent instrumentation on the flush-walled model reinforces confidence in the earlier measurements.