Starting Characteristics of Hypersonic Inlets in Shock Tunnel

The starting-characteristic of inlet is one of the key factors that govern the performance of hypersonic airbreathing propulsion system. For efficient operation, the inlets must operate in a started mode. Inlet starting has been extensively studied,[1][2] however, it is difficult to accurately predict whether the inlet is started or unstarted. Therefore, it will be useful to find an easy way that is capable of testing various behaviors of the inlet starting process. Pulse facilities could play an important role in these ground tests. But it has been shown that the inlet could be started with larger internal contraction ratio (ICR) in pulse facilities,[1] such as a shock tunnel, because of the unsteady effects in flow establishment of the facility[3] which have strong capability of helping inlet to start. So, there is a large discrepancy compared with conventional facilities. However, every coin has two sides. Whether the strong help-to-start capability of pulse facility can be switched ’on’ and ’off’? The present paper reports our recent progress related to the above ideas.