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

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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