Investigations On A High Performance Submerged Inlet With Second Flow Control

Compared with conventional inlets like nacelle-mounted or S-shaped inlets, the submerged inlethas unique advantages, including less external drag, decreased aircraft weight and lower observability.However, due to the entire embedment into the air vehicle body, it is hard for the freestream flowentering the inlet and the fuselage boundary layer is ingested into the inlet extensively, which resultsin low total pressure recovery coefficient and high flow distortion. Thus, it is necessary to investigatea high performance submerged inlet to satisfy the need of the engine in a wide range of operatingconditions.Firstly, this thesis studies the baseline submerged inlet without any control methods to obtain itsbasic performance and flow structure with numerical method. The ingested fuselage boundary layeraround the entrance and the vortex pair originated from the side edges of the inlet are confirmed to bethe two main causes for the high total pressure losses and flow distortion. Thus, two new controlconcepts, blowing on the fuselage and bleeding in the duct, are brought forward in this thesis. Theeffects of different control methods on the performance of the submerged inlet and characteristics ofthe flow field are obtained. The influential laws of different control methods on the inlet are alsostudied and the results indicate that the control methods brought forward in present thesis are alleffective to increase the total pressure recovery coefficient and decrease the flow distortion index. Atlast, the method bleeding in the duct is investigated by experiment and the results confirm the controlmethod is effective with the total pressure recovery coefficient increased by2.2%~3.8%and thedistortion index decreased by20%~60%as compared with the baseline inlet.