超声速气流中凹槽结构煤油喷射和掺混研究

Studies on kerosene injection and mixing with cavity in supersonic flow

关键词:  凹槽  喷射  掺混  高速阴影法  平面激光诱导荧光(PLIF)

Key words:  Cavity  Injection  Mixing  High-speed shadowgraphy  PLIF

摘要:

针对凹槽超声速气流中的喷射掺混现象开展了实验和数值计算研究。实验中采用了高速阴影法和PLIF(Plane laser induced fluorescence)方法详细地记录了实验现象。结合高速阴影得到的喷射和掺混随时间的流动变化过程,分析了其流动结构和机理。针对在凹槽内喷射的方案研究了喷射压力(1.0 MPa,3.0 MPa,4.0 MPa)、喷射角度(45°,90°)、来流总压和马赫数对掺混的影响。结果表明:在高速气流中,煤油破碎雾化机理依赖于大速度差、强剪切气流作用。煤油雾化区和来流空气混合边界存在涡结构。对小孔(d=0.4 mm)喷射,即使在高压(4.0 MPa)垂直喷射条件下,煤油射流产生的弓形激波强度也较弱。由于剪切层的存在导致上述参数变化对煤油穿透深度的影响较小。

Abstract:

The investigation for kerosene injection and mixing with cavity in supersonic flow has been performed experimentally and numerically.High-Speed Shadowgraphy and PLIF were used to record the experimental phenomena.The flow structure and mechanism were analyzed based on the results obtained by high-speed shadowgraphy for the injection and mixing process.The effects of injection pressure,injection angles,total pressure of coming flow and Mach numbers on the fuel injection and mixing were studied.Results showed that velocity gradient and shear in the flow played an important role in the process of kerosene break up and atomization in high speed flow.There were vortexes on the border between plume area and free flow.When kerosene was injected vertically from small hole,the intensity of bow shock was low although the injection pressure was up to 4.0 MPa.The shear reduced the effects of injection pressure,injection angles,total pressure of coming flow and Mach numbers on penetration.