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

实验研究了弯曲尾缘对可压缩“单”剪切层增长的影响。结果直接与可压缩的“双”剪切层。几种正弦曲线后缘被用来诱导流向涡进入剪切层。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，由主不稳定性引起的展向涡更加模糊，涡间距变化很大。计算结果表明，弯曲尾缘可以在流动中诱导出流向涡。通过使用弯曲后缘，可压缩单剪切层的增长率略有增加。然而，当与可压缩双剪切层相比时，增长率的增加要小得多。结果表明，弯曲尾缘只有在可压缩双涡时才能有效地增强混合， ...更多信息 对可压缩剪切流二次不稳定性诱导的流向涡结构进行了数值研究。对流马赫数为0.4的平行剪切流用于本研究。通过线性稳定性分析，证实了流向涡结构分量的存在，并确定了放大率最大的尺度比。此外，通过三维计算，研究了剪切流的空间演化。观察到了与线性稳定性分析结果相似的流向涡结构。在引入类白噪声扰动的情况下，估算了剪切层的增长速率，并研究了流向涡结构对剪切层增长的影响。由于二次不稳定性诱导的流向涡结构，三维计算中的增长率大于二维计算。在一个具有6种凹腔的超燃冲压发动机模型燃烧室中进行了煤油超声速燃烧的实验研究。将K2CO3注入到垂直于空腔前方气流方向的马赫数2的污浊气流中。通过使用氮气作为barbotage气体或使用氮气和引燃氢气，在雾化状态下注入K2CO3。结果表明，空泡的大小和激波的相互干扰对煤油自燃有很大的影响。凹腔尺寸对低温条件下的火焰稳定性也有相当大的影响。此外，对于煤油雾化技术，高压气体压力对煤油的着火和火焰稳定性有显著的影响。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