液体射流撞壁液膜表面波形成演变机理及其影响  

Formation mechanism and its influence of surface wave on liquid film by jet impingement

作　　者：王慧君 施浙杭 李伟锋[1] 林庆国 WANG Huijun;SHI Zhehang;LI Weifeng;LIN Qingguo(Institute of Clean Coal Technology,East China University of Science and Technology,Shanghai 200237,China;Shanghai Institute of Space Propulsion,Shanghai 201112,China)

机构地区：[1]华东理工大学洁净煤技术研究所,上海200237 [2]上海空间推进研究所,上海201112

出　　处：《推进技术》2024年第6期200-208,共9页Journal of Propulsion Technology

基　　金：国家自然科学基金(U21B2088)。

摘　　要：为揭示液体火箭发动机推力室内撞壁液膜形成演变机理,并优化液膜冷却设计,采用高速摄像技术实验研究了液体射流撞壁液膜表面波特征,考察了射流雷诺数(1255<Re<14116,1.6 m/s<u<18 m/s)和撞击距离L/d=30,60和90(d为喷嘴直径)对表面波频率、波间距及液滴飞溅的影响。结果表明,撞击点附近主要存在由射流动能引起的撞击波,高Re下液膜表面波前缘横向弯曲变形,呈现不规则锯齿状。当1960<Re<3920时,随Re的增加液膜表面波主频增大,频谱分布范围变宽。自撞击点向下游运动过程中波的主频、波速和波间距均不断减小。当撞击距离大于射流破碎长度,射流撞壁转变成连续液滴撞壁。对于连续液滴撞壁和高Re射流撞壁,表面波边缘沿壁面法线方向形成冠状薄膜,由于惯性力和表面张力的作用,薄膜破碎拉丝形成液滴,液滴溅射率随撞击距离的增加而增大。本文揭示了液膜撞击点附近大尺度波主要由射流表面扰动引起,并阐明了大部分飞溅液滴由表面波边缘薄液膜的破碎产生。In order to reveal the formation and evolution mechanism of liquid film in thrust chamber of liquid rocket engine and optimize the design for liquid film cooling,the characteristics of the surface wave on liquid film by liquid jet impingement were studied using high-speed camera.The effects of jet Reynolds number(1255<Re<14116,1.6 m/s<u<18 m/s)and impact distance L/d=30,60,90(d refers to diameter of the nozzle)on surface wave frequency,the distance between waves and droplet splashing were investigated.Results show that there are mainly impact waves caused by jet kinetic energy near the impact point.At higher Re,the wavefronts are transversely bent and deformed,eventually sawtooth shape structures with irregular wavefronts become dominant downstream.For 1960<Re<3920,when Re increases,the main frequency of the surface wave near the impact point increases and the bandwidth of surface wave frequency becomes wider.The main frequency,wave velocity and distance between two waves decrease when fluid flows downstream from the impact point.When the impact distance is larger than the jet breakup length,the jet breaks into continuous droplets before impinging on the plate.For continuous droplets impingement and jet at high Re impingement,a liquid crown along normal direction of the wall is formed at the edge of the surface wave,then the crown is broken into droplets because of inertia force and surface tension.The droplet splashing rate increases with the increase of the impact distance.This study reveals that the formation of large-scale waves near the impact point depends on surface disturbance of the jet,and the splashing droplets are generated by the breaking up of thin film around the edge of the surface wave.

关 键 词：液体火箭发动机 射流 撞壁液膜 表面波 飞溅 高速摄像 

分 类 号：V434[航空宇航科学与技术—航空宇航推进理论与工程]