凹腔上游横向喷流混合过程的实验研究

利用基于纳米粒子的平面激光散射(NPLS)技术研究了超燃冲压模型发动机中凹腔上游横向喷注乙烯燃料时凹腔附近的流场,主要研究了燃料射流与主流的混合过程;对比了在不同喷注压力下燃料射流穿透度的变化;研究了不同凹腔参数对燃料与主流混合过程的影响。通过研究发现,喷注压力对燃料射流与主流混合效果的影响主要体现在两个方面,射流的穿透度和射流的扩散;对燃料射流来说,与主流混合的主要阶段为大涡的形成直至破碎阶段;在喷注总压相同下,喷注位置靠近凹腔有利于燃料射流与主流的混合和向凹腔内的输运;凹腔构型对燃料射流的影响主要在于大尺度结构开始发展破碎的阶段。

Experimental Study of the Mixing Process of Transverse Fuel Injection in the Upper Part of a Cavity

Based on the technology of Nano-based Planar Laser Scattering(NPLS), the ambient flow field of a cavity was studied in the research, in which the ethene fuel was injected perpendicularly in the upper part of a cavity placed in a scramjet engine model. The study focused on the mixing process of the fuel jet and its mainstream, the comparison of the changes in the fuel jet penetrability under different injection stagnation pressures, as well as the effect of the cavity geometry parameters on the mixing process of the fuel jet and its mainstream. Through the study, the effect of the injection stagnation pressures on the mixing of the fuel jet and its mainstream was found mainly in two aspects: the penetrability and the diffusion of the fuel jet. As for the fuel jet, this study indicated that the main phase of the mixing process with the mainstream begins when the eddies come forth and ends when the eddies break up. Moreover, this study showed that a closer location of the injector helps to produce a better mixing of fuel jet and mainstream and a higher-quality transportation of the fuel jet to the cavity. In addition, the influence of the cavity configuration on the fuel jet primarily starts from the stage of the breaking up of the large-sized eddies.