Investigation of the Flow Field of a 2D SCRAM-Jet Inlet at Mach 7 with optional Boundary Layer Bleed

Abstract

The current measurement campaign at Mach 7 has been carried out in the hypersonic wind tunnel H2K at the German Aerospace Center (DLR) in Cologne to investigate the viscous flow effects in a fixed geometry SCRAM-jet inlet operating at Mach 7.5. This campaign was part of a research training group financed by the German National Research Council (DFG). To reduce the risk of inlet un-start, a optional passive boundary layer bleed has been integrated at the throat and successfully tested. The passive bleed reduces the lip shock induced separation bubble on the ramp significantly. The obtained experimental resultws are discussed and compared with CFD calculations. To investigate the compression behavior, different back pressures have been applied and the effects on the internal flow structure are analyzed by means of Schlieren pictures and Pitot pressure profiles at the exit of the isolator. The heat transfer coefficient to the inner side wall of the isolator is calculated using the time dependent surface temperature, measured with an infrared system and 2D Stanton number distributions are presented.