A Study on Mixing Enhancement of Shear Layer by Streamwise Vortex Formed in a Supersonic Flow.

实验研究了弯曲后缘对可压缩“单”剪切层生长的影响。将计算结果与可压缩“双”剪切层的计算结果进行了直接比较。几种类型的正弦曲线后缘被用来在剪切层中诱导流向涡流。正弦曲线的波长变化很大。结果表明，与可压缩双剪切层相比，主不稳定性引起的展向涡更加隐蔽，间距变化较大。结果表明，利用弯曲的尾缘，可以在流动中诱导出流向涡。利用弯曲的后缘，可压缩单剪切层的生长速度略有增加。然而，与可压缩双剪切层相比，增长速率的增加要小得多。结果表明，曲线后缘只有在用于可压缩双SH…时才能有效地增强混合。数值研究了可压缩剪切流的二次失稳引起的流向涡结构。本文采用对流马赫数为0.4的平行剪切流。通过线性稳定性分析，确定了流向涡结构分量的存在，并确定了最大放大倍率的尺度比。此外，通过三维计算对空间演化的剪切流进行了研究。观测到了与线性稳定性分析结果类似的流向涡结构。在引入类白噪声扰动的情况下，估算了剪切层的生长速率，并研究了流向涡结构对剪切层生长的影响。由于二次不稳定引起的流向涡结构，三维计算的增长速率大于二维情况，因此在六种空腔的超燃冲压发动机燃烧室中进行了煤油超音速燃烧实验研究。将煤油注入马赫数为2的垂直于空腔前方气流方向的气流中。通过使用氮气作为瓶装气体或使用氮气和先导氢气在雾化状态下注入煤油。结果表明，影响煤油自燃的因素不仅有空腔的大小，还有冲击波的相互干扰。此外，型腔尺寸对低温条件下的火焰保持也有很大影响。此外，气泡雾化技术的罐装气体压力对煤油的着火和阻燃有显著影响。较少

Effects of a curved trailing edge on growth of a compressible "single" shear layer are investigated experimentally. The results are directly compared with those for a compressible "double" shear layer. Several types of sine-curved trailing edges are used to induce streamwise vortices into the shear layer. The wavelength of the sine curve is varied widely. It is shown that spanwise vortices due to the primary instability are much more obscure and the spacing varies widely, when compared with those for the compressible double shear layer. And it is shown that, by use of the curved trailing edge, streamwise vortices are induced into the flow. By use of the curved trailing edge, the growth rate of the compressible single shear layer slightly increases. However, when compared with the compressible double shear layer, the increase in the growth rate is much smaller. It is shown that the curved trailing edge is effective for mixing enhancement only when it is used for a compressible double sh … More ear layer.Streamwise vortex structure induced by secondary instability of compressible shear flow was numerically investigated. Parallel shear flow with convective Mach number 0.4 was used in the present study. From linear stability analysis, existence of streamwise vortex structure components was confirmed, and scale ratio which gives maximum amplification rate was specified. In addition, spatially evolving shear flow was investigated by three-dimensional calculation. Streamwise vortex structure similar to that gotten from liner stability analysis was observed. In the case where white-noise-like disturbance was introduced, growth rate of shear layer was estimated and effect of streamwise vortex structure on growth of shear layer was investigated. Due to streamwise vortex structure induced by secondary instability, growth rate in three-dimensional calculation was larger than the case of two-dimensional case.An experimental research on supersonic combustion of kerosene was conducted in a model scramjet combustor with six kinds of cavities. Kerosene was injected into a Mach 2 vitiated air stream perpendicular to the direction of the air flow ahead of a cavity. Kerosene was injected at an atomized state by using nitrogen as barbotage gas or using nitrogen and pilot hydrogen. As a result, it became apparent that not only the size of cavity but also mutual interference of shock waves had much effect on a kerosene auto-ignition. And the cavity size had also a considerable impact on a flame-holding at low temperature conditions. Moreover, the barbotage gas pressure for an effervescent atomization technique had a significant effect on the ignition and the flame-holding of kerosene. Less