A Novel Test of Starting Characteristics of Hypersonic Inlets in Shock Tunnel

Abstract

The unsteady effects in the shock tunnel flow establishment can aid hypersonic inlet starting. An unself-starting inlet may be started in the shock tunnel initial operation. To confirm the hypersonic inlet self-starting ability in shock tunnel, a new test method has been developed. It adopts a light obstacle to choke the inlet flow for unstarting the inlet at the initial stage of the shock tunnel operation. The obstacle can then be fast blown out to determine whether the inlet will be restarted under steady test flow conditions. Shutterlike fast response is required for the flow blockage generated by the obstacle because of the short steady flow duration of the shock tunnel. With the help of the shutter-like obstacle, the inlet could be ”pre-set” in either started or unstarted state prior to the steady test flow. Generic hypersonic inlets with different internal contraction ratios have been developed for inlet starting experiments. Various flow characteristics in the inlet starting process were achieved by applying a high speed schlieren system. The internal contraction ratio limits for inlets self-starting and unstarting were obtained and compared with literature. The effect of leading edge bluntness on the inlet starting characteristics were also examined. It was found that the leading edge bluntness play quite important roles in the inlet starting process.