Quasi-Direct Numerical Simulation on Atomization Characteristics of Impinging Jets Injector
LI Jia-nan;FEI Jun;YANG Wei-dong;ZHOU Li-xin;LIU Chang-bo;Science and Technology on Liquid Rocket Engine Laboratory;
In order to realize numerical simulation of impinging jets atomization and to investigate the effects of geometry and working parameters on atomization characteristics,Quasi-Direct Numerical Simulation of atomization process was carried out based on tree-structure adaptive mesh refinement algorithm and VOF(Volume-of-Fluid) method. The whole process of a pair of jets from ejecting to liquid sheet formation and breakup of liquid sheet into ligaments and droplets was obtained. The information of breakup length of liquid sheet and Sauter mean diameter of droplets and atomization frequency were also obtained. The simulations were validated by comparing numerical results of typical cases with experimental data. The simulation precision was also given.The formation mechanism of impact wave was explored. Diameter distribution of droplets and the effects of impinging angle,ratio of diameter,jet velocity,ratio of momentum on atomization characteristics were also analyzed.The results show that the multi-phase,multi-scale process of atomization can be numerically simulated with the algorithm used in the paper. The formation of impact wave is the result of uncomplete balance of inertia force when impinging happens. The diameter distribution of droplets approximately obeyed Rosin-Rammler distribution. The increase of impinging angle and jet velocity will lead to decrease of breakup length of liquid sheet and mean droplet diameter. However,the increase of impinging angle will lead to decrease of atomization frequency while increase of jet velocity will lead to increase of atomization frequency. When ratio of momentum is one and ratio of diameter is not one,there forms hollow liquid sheet and to some extent the atomization field also declines. The ratio of momentum mainly affects decline degree of atomization field.
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