Aerothermodynamic Ground Tests in Support of the Boundary Layer Transition Flight Experiment

Abstract

The U.S. Air Force Research Laboratory/U.S. Air Force Office of Scientific Research has sponsored the Boundary Layer Transition (BOLT) experiment to investigate hypersonic boundary-layer transition on a low-curvature, concave surface with swept leading edges. This paper provides a review of aerothermodynamic ground-test contributions by NASA Langley Research Center to the design of the BOLT flight experiment. Several test entries into the NASA Langley Aerothermodynamics Laboratory 20 Inch Mach 6 Air Tunnel are discussed. Global surface heating distributions on subscale BOLT models were measured using either phosphor thermography or infrared thermography at a range of model attitudes and freestream Reynolds numbers. An initial test entry provided the first experimental measurements of transition on the BOLT geometry. A second test entry investigated the effects of distributed surface roughness along the swept leading edges. A third test entry provided an evaluation of the aeroheating environment on the aerodynamic fairings and a portion of the flight vehicle downstream of the BOLT experiment. These entries were intended to support the development and design of flight hardware and instrumentation for the BOLT flight experiment.