轴向入射激波反射聚焦的实验和数值模拟

为研究两级脉冲爆震发动机凹腔入口宽度对第2级凹腔中激波聚焦过程的影响，设计轴向入射激波聚焦的实验系统，对不同入口宽度下激波反射聚焦的过程进行了实验和数值模拟。采用纹影系统拍摄凹腔中的流场结构，并测量了凹腔顶点处的动态压力。采用保持强稳定性（SSP）的Runge Kutta格式、weighed essential non oscillation（WENO)格式和块结构网格自适应加密（SAMR）算法对激波反射、衍射和聚焦的过程进行了数值模拟，数值模拟结果和实验吻合较好。通过分析比较相同马赫数激波通过不同宽度凹腔的反射聚焦过程，发现较小宽度凹腔入口下激波反射和聚焦较强，顶点的压力峰值较高，激波聚焦诱导的射流较强。 

Experiment and numerical simulation of axial incident shock wave reflection and focusing process

To study the effects of the shock wave focusing on the second stage process of the two stage pulse detonation engine by the cavity entrance widths, an experimental system was designed to research axially incident shock focusing on the different cavity entrance widths. And experiment and numerical simulation were carried out to investigate the process and the effects of the reflected shock wave focusing. The schlieren system was used to photograph the structure of the cavity flow field, and the dynamic pressure on the vertex was measured. Strong stability preserving (SSP) Runge Kutta method, and weighed essential non oscillation (WENO) scheme and block structured dynamically adaptive mesh refinement (SAMR) algorithm were adopted to simulate the shock wave reflection, diffraction and focusing process. Good agreement between experiments and numerical results was observed. By analyzing and comparing the shock wave reflection and focusing process under the conditions of the same Mach shock wave through different entrance cavity widths, the enhancement of the reflection and focusing and the increase of the vertex pressure with a smaller width were found. Meanwhile, the jet enhancement was induced by the shock wave focusing.