开式风洞超声速压气机流场起动的数值研究

在开式风洞超声速平面叶栅试验中，从试验启动到叶栅建立超声速流动状态的过程，即超声速流场起动问题，已成为公认的难题。为建立可行的开式风洞超声速流场起动方法，奠定开式超声速风洞的使用基础，基于某超声速风洞，以超声速压气机平面叶栅为研究对象，开展三维数值仿真研究；分析试验条件下超声速流场起动失败的原因，制定三种流场起动方案。结果表明：起动失败的原因为叶栅前缘形成了一道强正激波；仅提高风洞进口总压无法建立叶栅超声速流动状态；仅增大下壁溢流缝宽度可起动超声速叶栅流场，但有效叶栅流道数量减少，壁面附面层增厚；保持上、下壁溢流缝宽度在1 倍栅距以上，在栅前上、下壁设置超声速墙并进行抽吸，可有效起动超声速流场，相邻流道出口马赫数最大波动0.01，出口气流角最大波动0.09°，周期性可满足试验需求。

Numerical Research on Starting Problem of Supersonic Compressor in Outlet-Opening Wind Tunnel

The process from test starting to supersonic flow state established in an outlet-opening wind tunnel, i.e. the starting problem of supersonic flow, has become a recognized challenge. The aim is to establish feasible flow field starting method, laying the foundation for the use of outlet-opening wind tunnel. Three-dimensional numerical research on starting problem of supersonic compressor cascade was carried out in the supersonic wind tunnel at Shenyang Engine Research Institute. The failure reason of supersonic flow field starting on experimental condition was analyzed, three flow field starting schemes were established. The results show that: The starting failure reason is the formation of a strong normal shock wave at the leading edge of the cascade. Increasing the inlet total pressure alone cannot establish the supersonic flow; The supersonic cascade flow field can be started by increasing the overflow gap width on lower wall side, but the number of effective cascade passages decreases and the boundary layer thickness increases; Maintaining the width of overflow gap on the upper and lower walls at more than 1.0 pitch, setting upper and lower supersonic walls in front of cascade and conducting suction can effectively start the supersonic flow field. The maximum fluctuation of outlet Mach number is 0.01, the maximum fluctuation of outlet flow angle is 0.09°. The periodicity can meet the experimental requirements.