涡发生器对高超声速轴对称进气道外部流动的影响

采用三维CFD黏性模拟考察涡发生器对高超声速轴对称进气道外部流动的影响.针对前缘钝化半径0.8 mm和3.2 mm的轴对称进气道外部流场，以涡发生器高度与当地位移边界层厚度比值为影响参数，考察流场结构与性能参数的影响规律.结果表明，涡发生器产生的干扰波系使得前缘激波向外偏移，下游近壁面流动与主流区出现明显的交换，下游流动出现明显的展向非均匀性.涡发生器对流动的影响沿流向逐渐减弱.在气流压缩性能方面，涡发生器下游压比、动压比沿流向开始增大，随后逐渐恢复到无涡发生器工况；Mach数、总压恢复系数开始降低，随后逐渐向无涡发生器工况趋近.涡发生器高度与当地位移边界层厚度的比值h可作为衡量其影响的重要参数.当h≤1.5时，进气道流场结构、性能参数的变化几乎可忽略，h≤3.0时进气道入口处性能参数几乎能够恢复到无涡发生器工况. 

Effects of Vortex Generators on the External Flows of an Axisymmetric Hypersonic Inlet

Effects of vortex generators on the external flows of an axisymmetric hypersonic inlet were investigated by three-dimensional CFD simulations. Effects on the flow structures and performance parameters were analyzed on two configurations, of which noses were 0.8 mm radius and 3.2 mm radius, respectively. The results show that the induced shock waves of vortex generators cause outward displacements of the external shock waves. The momentum exchanges between the near wall flows and external main flows are enhanced, which results in evident spanwise non-uniformity in the downstream flowfield. The effects of vortex generators degrade in the streamwise orientation. The pressure ratio and dynamic pressure ratio of spanwise cross sections increase at first, then the increments gradually degrade and recover to the values of no vortex generator conditions. The Mach number and the recovery coefficients of total pressure also decrease at first and gradually recover in the streamwise orientation. The parameter h, which is the ratio of vortex generator heights to the displacement thicknesses of the local boundary layers, can be used to characterize the influence intensity of vortex generators. For both configurations, variations of flowfield and performance parameters are negligible as h ≤ 1.5. The performance parameters can recover to the values of no vortex generator conditions by the inlet entrance as h ≤ 3.0.