Research On Shock Wave/boundary Layer Interactions And Flow Control In The Internal Contraction Duct Of Hypersonic Inlets

The severe shock wave/boundary layer interactions significantly affect the flowfield structures and the aerodynamic performances of low-cowl drag two-dimensional hypersonic inlets.A flow control method of inserting a splitter in the internal contraction section of the inlet was proposed in this paper.Numerical simulations were conducted to study the flow characteristics and the aerodynamic performances with and without splitter over the wide flight Mach numbers.First,based on the flow characteristics of the shock wave/boundary layer interactions in the internal contraction section of low-cowl drag two-dimensional hypersonic inlets,a flow control concept was put forward and verified over the wide Mach number range.The results show that a splitter located in the internal contraction portion of the low-cowl drag hypersonic inlet can obviously suppress the large scale separation which is induced by severe shock wave/boundary layer interactions and improve flowfield structures in the inlet.The flow control mechanism of the splitter mainly lies in that the severe shock wave/boundary layer interaction induced by the strong cowl shock in the baseline inlet is splitted by splitter into several weaker shock wave/boundary layer interactions and shock intensity and boundary layer thickness are also decreased.When the flow Mach number M₀ is 4,5 and 6 respectively,compared with the baseline inlet,the total pressure recovery of the inlet with the splitter is increased by 51.9%,60.0%and 88.5%,and the mass flow ratio is increased by 24.0%,8.8%and 1.7%,correspondingly.Three-dimensional results of the two-dimensional inlet with sidewall indicate that the splitter can also suppress the large scale separation which is induced by severe shock wave/boundary layer interactions in the internal contraction duct of the real three-dimensional configuration.Second,the impact of the splitter positions on the flowfield characteristics and aerodynamic performances of the inlet were analyzed over the wide Mach number range.The effective control area of splitter in the typical low-cowl drag two-dimensional hypersonic was obtained.The results show that incident points of shock wave and the internal contraction ratio of the upside and downside passages in the internal contraction section of the inlet have a great impact on the control effect of the splitter.In order to maximize the control effect of the splitter within the wide Mach number range,it is necessary to ensure that the shock waves hit on the boundary layer of the wall separately,and the contraction ratio of upside and downside passages should be consistent.Last,in order to study the impact of a splitter located in the internal contraction portion on the maximum sustainable backpressure of low-cowl drag hypersonic inlets,two groups of different internal contraction ratio of low cowl-drag two-dimensional hypersonic inlets with and without splitter were simulated to study the backpressure characteristics.The results show that the maximum sustainable backpressure of the ICR1.667 inlet with splitter increased by 60.5%?36.7%?15.9%,and the maximum sustainable backpressure of the ICR1.566 inlet with splitter increased by 32.3%?10.1%?4.2%,with the incoming Mach number M₀=4,5,6 respectively,which means that the splitter can significantly improve the maximum sustainable backpressure of low cowl-drag hypersonic inlets and widen the stable operation range of hypersonic inlets.In addiation,the splitter located in the internal contraction portion helps to improve the uniformity of airflow parameters distribution,so as to make the shock train propagate upstream sysmetrically,which is benifical to increase the maximum sustainable backpressure of the inlet.