简化微小液滴在超声速气流横向喷射中的运动探索

The study for the motion of simplified little droplet and transversely injection in supersonic flow

从研究超声速气流中简化液滴(刚性小球)的气动力着手,比较分析使用CFD方法与使用两相流理论中已有的颗粒阻力系数模型得到的简化液滴气动力结果,得出Charles B.Henderson给出的阻力系数经验关系式适用于计算简化液滴在超声速气流中的运动。进一步,对不同直径简化液滴的运动开展工程方法的计算。在来流Ma=2.7的二维平板超声速流场中选取一个截面,作为气相流场,结果显示:(1)简化液滴与主气流存在相对超声速运动,当简化液滴直径dk≤0.12mm时,纵向相对超声速运动区域约为0.15m^0.4m,当dk>0.12mm时,作用区域明显增大;(2)以10m/s喷射出的简化液滴,其横向穿透深度与纵向运动距离比约为0.004m/1m^0.021m/1m;(3)以100m/s的速度喷射出的30~120μm直径简化液滴,其横向穿透深度与纵向运动距离比约为0.02m/1m^0.055m/1m,实际过程中,小尺寸简化液滴的汽化很快,其穿透深度很小。

Beginning from the study for the aerodynamic force on simplified droplet （little rigid sphere） in supersonic flow, the results of aerodynamic force, using by CFD method and by the drag coefficient models in the two phase flow theory, are compared and analyzed. So it is concluded that the drag coefficient formula given by Charles B. Henderson is suitable to simulate the simplified droplet movement in supersonic airflow. Further more, the calculation of different diameter simplified droplet movement is carried out by using engineering calculation method. One section of two dimensional supersonic flat flow with Ma2.7 inflow is chosen as gas flow field and the results show that, （1） there exits relative supersonic movement between the simplified droplet and the main gas flow, the lengthways movement distance of which is about 0.15-0.4m for the simplified droplets with dk≤0. 12mm diameters and increases obviously for those with dk〉0. 12mm diameters, （2） for the simplified droplets injected with 10m/s velocity the ratios of the transverse penetration deepness to the lengthways movement distance are about 0. 004m/lm-0. 021m/lm, （3） for the 30μm- 120μm simplified droplets injected with 100m/s velocity the ratios of the transverse penetration deepness to the lengthways movement distance are about 0.02m/lm-0.055m/lm. In the actual process the evaporation of little size simplified droplet is fast and its penetration deepness is short.