Flow Characteristics And Flow Control Of A Rectangular Low-Boom Supersonic Inlet

Supersonic inlets make up much of the windward area of an civil aircraft,and the shock generated by which comes as the main source of the overall sonic boom.Therefore,the study of the low-boom inlets is of great significance to minimize the sonic boom from civil supersonic vehicles.In this paper,a rectangular low-boom supersonic inlet was designed,which features a zero-angle cowl and relaxed isentropic compression forebody.After that,several numerical simulations were also carried out to study the flow control for the designed inlet,as well as its flow characteristics.Results indicate that,the forebody relaxed compression wave of the low-boom inlet impinges on the inner surface of the cowl and reflects in an irregular way,resulting in a curve shock and a corresponding subsonic region formed near the entrance of the inlet.This kind of flow structure could reduce the critical total pressure recovery by 2.3% and 5.5% in the cases of Mach 1.8 and 2.0 respectively,and make total pressure recovery become sensitive at Mach 2.5.Through parametric investigations of the low-boom inlet,it is found that the bigger of the deflection angle of forebody isentropic compression surface?2 and the second cowl angle ?2,or the smaller of the relaxed degree of compression wave hc/h0 and the radius of shoulder arc R,the curve shock formed by irregular reflection becomes stronger,which results in the reduces of the mass flow rate of the inlet by 1.8% at maxim.While the critical total pressure recovery of the inlet would be increased or decreased by 1.06% or 2.22% at maxim,because of the increase of ?2 or the increase of hc/h0 respectively.On the other hand,the boom strength of this low-boom inlet,which could be reduced by 98.6% compared with the external compression supersonic inlet,would also increase significantly once the design parameters are changed,the incoming Mach number is reduced or the subcritical state is reached.Finally,during studies on the flow control for this low-boom inlet,it is found that,the highly swept microramps can effectively suppress the lateral flow in the channel,as well as the segregation caused by cowl shock/boundary layer interactions,and in the meanwhile,lower the height of the low energy flow region in the outlet cross section,by strengthening the mix between the low energy flow and the main flow region.Furthermore,the backward movements and height increases of the highly swept microramps can increase its flow control performance in a certain range.