Theoretical Prediction And Flow Control Of Hypersonic Inlet Starting

Reliable starting of the inlet is of critical importance for the successful operation of scramjet engines. To research the mechanism of inlet auxiliary start, the prediction theory of hypersonic inlet starting is analyzed in this paper. Then some research is conducted on the inlet starting process assisted by the moving door’s dynamic motion. Last, a flow control concept to inhibit the recirculation zone is explored.At first, the steps of designing perforation area distribution were summarized through the derivation of the mass spillage starting theory. The perforation area distribution for a certain inlet was designed by following these steps. Numerical simulation was conducted on this design result. It turns out that the inlet can’t start and needs bigger perforation area. Therefore, a correction factor k is introduced. The results show that the corrected perforation area distribution can make the inlet starting.Then, unsteady numerical simulation was carried out to study the influence of the moving door’s rotation on the inlet starting process by adopting the dynamic mesh. The results indicate that the auxiliary start doesn’t have ideal effect and the main factor leading to the inlet unstarting is the recirculation zone behind the door.Next, a flow control concept was explored to inhibit the recirculation zone by using high-speed inflow through the slots on the door. The results indicate that high speed inflow can inhibit recirculation zone effectively and the inlet starts successfully while the door closing to the bottom plate.At last, some research was carried on the auxiliary start and the recirculation inhibition of inward turning inlet. It turns out that with low inlet Mach number, the stream pressure before the door is lower than the one in recirculation zone. In this condition, the recirculation zone develops upstream and leads to the inlet unstarting.