Injection Characteristic And Breakup Process Of Transverse Liquid Jet In Crossflow

The present research focused on the breakup process and injection characteristic ofliquid jet in crossflow.Numerical simulation and experimental observation method wereemployed in present study. Two different two phase flow numerical simulation methodsused in the paper were Euler-Euler method and Euler-Lagrange method. There werethree kinds of experimental observation methods which were high speed photographytechnology, high speed shadowgraph photograph and Particle Image Velocity (PIV). Anoriginal Image Process was developed in the study. The original image processemployed in the present work was based on Matlab and the method was used to get themost unstable point in the boundary on the phase surface. So the penetration curveobtained in the present research was not quite similar to those got by others.Two kinds of phase surface capture methods; specifically Volume of Fluids (VOF)method and Couple Level Set&Volume of Fluids (CLSVOF) method were comparedand estimated. Results showed that in comparison with VOF method the CLSVOFmethod was a superior phase surface capture method. Applying the CLSVOF method,the column breakup process of liquid jet in low speed crossflow was studied in detail.The simulation results showed that the Weber Number of the crossflow and theReynolds Number of the liquid jet determined the jet breakup point. The momentumflux ratio of the liquid jet and the crossflow was the determining factor of the jetpenetration height. Experimental results show that the column breakup model turned tothe shear breakup model as the growing of Weber number and Renolds number.The effects of three key factors, i.e. the pressure drop of the liquid jet, the diameterof the injector and the angle of the transverse liquid jet, on the injection characteristic oftransverse liquid jet in cold supersonic cross air flow were analyzed in detail. It can beobtained that with the pressure drop getting lager, the penetration height and thespanwise expansion area of the jet increased. At the same time, enlarging the diameterof the injector would increase the penetration height and broaden the spanwiseexpansion. The penetration height was proportion to the angle betweenthe jet and thecrossflow. As to the shock wave caused by the injection of the liquid fuel, the angle ofthat shock wave went down proportionally to the decrease of the three key factorsmentioned above. The total pressure drop of the crossflow decreased simultaneouslywith the decrease of the jet pressure drop, the reductionof the injector diameter and thediminishing of the injecting angle.Employing the jet penentration height definition and jet flow boundary extractionmethod put forward in the essay and combining multi groups of experimental results,the empirical formulae of the penetration curve of vertical injection and the penetrationheight curve considering injection angle effect were summarized as below: The injection characteristic of double and three assembled injectors were studiedboth numerically and experimentally. The results in the present research showed that thespanwise assembled injectors were more favorable to increase the spanwise expansion.Compared with the injection of the single injector case, the penetration height of theliquid jet in spanwise assembled went up slightly but the total pressure drop of thecrossflow increased obviously. The streamwise assembled double injectors wouldcontribute to the increase of the penetration height while cut down the total pressure ofthe crossflow much more. Comparing those two kinds of assembled injectors, thestreamwise assembled case could get larger penetration height while the spanwiseassembled case could make the jets boundry grow wider in the tunnel.