"A Study on Shock Wave Self-Excited Oscillation in Supersonic Flows"

本文的目的是研究超声速流动中激波的自激振荡。因此，对许多带激波的超音速流动进行了实验和计算研究。重点是建立在对超声速流动中激波自激振荡的流动结构和流动物理的物理认识的基础上。对于研究项目，本研究选择了以下八个主题进行研究，并完成了本研究的目标。(1)研究了激波/湍流边界层中激波的自激振荡。流动分离不均匀，相当不稳定。非定常特性与马赫数无关。在密度轮廓测量中采用了新的流场可视化技术。(2)研究了超声速流动中对向射流激波的自激振荡。数值模拟结果与实验结果吻合较好。更多的红色压力波动表明主导频率的变化是由射流总压力引起的。(3)研究了超声速射流与壁面的相互作用流场。由于喷管出口与壁面的距离不同，相互作用的流型和激波振荡型发生了很大的变化。(4)研究了超声速混合流场。数值模拟结果与实验结果吻合较好。提出了超声速混合的新技术，并证明了它的可行性。(5)在热力学和化学非平衡条件下研究了激波诱导气动加热。揭示了高温对气动加热的影响。(6)研究了钝体前方激波产生的气动冲击问题。气膜冷却已被证明具有足够的降低气动热的能力。(7)在峰值压力和峰值加热条件下，研究了再入飞行器瓦片间隙产生的空腔流动。捕获了嵌入激波的振荡腔流动。(8)对塞式喷管周围嵌入激波的超音速流动进行了研究。研究了塞式喷嘴形状对阻力的影响，并通过优化喷嘴形状实现了阻力的大幅度降低。少

The purpose of the present study is to investigate the shock wave self-excited oscillation in supersonic flows. Hence, many supersonic flows with shock waves have been experimentally and computationally studied. The emphasis is based on the physical understanding of the flow structure and flow physics of shock wave self-excited oscillation in supersonic flows. For the research projects eight topics are selected and studied in the present study as follows and the objectives of the present study have been completed. :(1) Self-induced oscillation of shock wave in shock wave/turbulent boundary layer have been studied. The flow separation is not uniform and quite unsteady. Also the unsteady features are independent on mach number. The new flow visualization technique by LIF is installed for the measurement of density contour.(2) Self-induced oscillation of shock wave in opposing jet in supersonic flow have been studied. Numerical simulations show quite good agreement with experiments. Measu … More red pressure fluctuations show that dominant frequency changes due to total pressure of jet.(3) Interacting flow field between supersonic jet and wall has been studied. The interacting flow pattern and shock wave oscillation pattern changes drastically due to the distance between the nozzle exit and wall.(4) The supersonic mixing flow fields have been studied. Numerical simulations have been also conducted resulting quite good agreement with experiments. The new technique for supersonic mixing has been proposed and demonstrated its capability.(5) Shock wave induced aerodynamic heating has been studied with thermally and chemically nonequilibrium conditions. High temperature effects on aerodynamic heating have been revealed.(6) Aerodynamic haeting problems generated from shock wave ahead of the blunt body have been studied. Film cooling has proved to have sufficient capability for reducing aerodynamic heating.(7) Cavity flow generated by the gap of the tile of the reentry vehicle has been studied with peak pressure and peak heating. Oscillatory cavity flows with embedded shock waves have been captured.(8) Supersonic flows with embedded shock wave around plug nozzle have been studied. The effect of the shape of plug nozzle on the drag is investigated and the drastic reduction of the drag is obtained by optimal nozzle shape. Less