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在Ma=3.0的超声速风洞中,分别对上游边界层为超声速层流和湍流,压缩角度为25和28的压缩拐角流动进行了实验研究.采用纳米粒子示踪平面激光散射(NPLS)技术获得了流场整体和局部区域的精细结构,边界层、剪切层、分离激波、回流区和再附激波等典型结构清晰可见,测量了超声速层流压缩拐角壁面的压力系数.从时间平均的流场结构中测量出分离激波、再附激波的角度和再附后重新发展的边界层的增长情况,通过分析时间相关的流场NPLS图像,可以发现流场结构随时间的演化特性.实验结果表明:在25的压缩角度下,超声速层流压缩拐角流动发生了典型的分离,边界层迅速增长失稳转捩,并引起一道诱导激波,流场中出现了K-H涡、剪切层和微弱压缩波结构,而超声速湍流压缩拐角流动没有出现分离,湍流边界层始终表现为附着状态;在28的压缩角度下,超声速层流压缩拐角流动进一步分离,回流区范围明显扩大,诱导激波、分离激波向上游移动,再附激波向下游移动,分离区流动结构复杂,相比之下,超声速湍流压缩拐角流动的回流区范围明显较小,边界层增长缓慢,流场中没有出现诱导激波、K-H涡和压缩波,流动分离区域的结构也相对简单,但分离激波的强度则明显更强.
In the supersonic wind tunnel with Ma = 3.0, the experimental results on the compression corner flow with supersonic laminar flow and turbulent flow in the upstream boundary layer and the compression angles of 25 and 28 respectively were obtained. The results of nanoparticle tracer planar laser light scattering (NPLS) The detailed structure of the whole and part of the flow field, the boundary layer, the shear layer, the separation shock, the recirculation zone and the reattached shockwave are clearly visible, and the pressure coefficient of the laminar compression supersonic wall is measured. From the time average And the growth of the boundary layer re-developed after reattachment, the evolution of the flow field structure over time can be found by analyzing the time-dependent NPLS images The experimental results show that at the compression angle of 25, the corner flow in the supersonic laminar flow splits in a typical way, and the boundary layer grows rapidly and induces a shock wave, and the KH vortex and shear appear in the flow field Layer and weakly compressional wave structure, while the turbulent flow in the supersonic turbulent flow does not appear to separate, and the turbulent boundary layer always shows the attached state. At the compression angle of 28, the supersonic laminar flow compression corner After further separation, the range of recirculation zone was obviously enlarged, the shock wave was induced, the shock wave was separated and moved upstream, and then the shock wave was moved downstream. The flow structure in the separation zone was complex. In contrast, the recirculation zone of supersonic turbulent flow compression corner was obvious Smaller boundary layer growth is slow. There is no induced shock wave, KH vortex and compression wave in the flow field. The structure of the flow separation area is relatively simple, but the intensity of the separation shock wave is obviously stronger.