Internal Flowfield Investigation of a Hypersonic Inlet at Mach 6 with Bleed

To study the influence of viscous effects on the performance and, especially the internal flowfield, of scramjet engines, an experimental study has been carried out on a fixed geometry scramjet inlet operating at Mach 6. The tests have been performed using a hypersonic blowdown wind-tunnel facility. To reduce the risk of inlet unstart, a 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 results are discussed and compared with computational fluid dynamics calculations. To investigate the compression behavior, different backpressures have been applied and the effects on the internal flow structure are analyzed by means of schlieren change in pitot pressure and calculated Mach number profile base don the geometrical shape of the internal flowpath. The heat transfer coefrficient to the inner sidewall of the isolator is calculated using the time-dependent surface temperature, measured with an infrared system. The variation of the Stanton number based on different flow phenomena could be resolved successfully.