相间滑移对喷油器喷孔内空化现象数值模拟研究的影响  

Effects of Slip Velocity on the Modeling of Cavitation Phenomenon in Injector Nozzle

作　　者：麻斌[1] 高莹[1] 刘宇[1] 刘洪岐[1] 陈伟[1] 徐英健 MA Bin GAO Ying LIU Yu LIU Hongqi CHEN Wei XU Yingjian(State Key Laboratory of Automobile Simulation and Control, Jilin University, Changchun 130025, China)

机构地区：[1]吉林大学汽车仿真与控制国家重点实验室,长春130025

出　　处：《西安交通大学学报》2017年第1期59-64,78,共7页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(51306069)

摘　　要：针对喷孔内空化现象影响喷雾特性进而影响发动机经济及排放性能的问题,利用ANSYS_Fluent 15.0软件,在湍流计算采用realizable k-ε模型、空化计算采用S-S模型(Schnerr and Sauer Model)的基础上,基于均相流及双欧拉两相流模型建立了2种喷油器喷孔内空化现象数值模拟模型。基于均相流的模型认为液相与蒸汽相流速相同,即不考虑相间滑移的影响;基于双欧拉两相流的模型认为液相与蒸汽相拥有不同的流速,即考虑相间滑移的影响。2种模型的计算与试验结果对比分析显示:在相同边界条件下,2种模型的计算结果存在显著差异,考虑相间滑移的计算结果与试验结果吻合良好,既能反映喷孔内空化现象的变化趋势,也可获得准确的空化特征长度,未考虑相间滑移的计算结果仅可反映喷孔内空化现象的变化趋势,但2种模型均不能捕捉到喷孔内空化区域末端的小型空化团分离现象。该结果表明,在空化现象数值模拟研究中,强湍流作用下蒸汽相的运动状态完全受液相支配,而液相运动状态不受蒸汽相影响的这一结论,并非在所有流动状态下均成立。Fuel spray atomization is significantly influenced by nozzle cavitation.Two simulation models are established to analyze nozzle cavitation by ANSYS_Fluent 15.0.The two models based on the homogeneous equilibrium scheme and Eulerian-Eulerian scheme employ the realizable k-ε model for turbulence computation and Schnerr and Sauer model for cavitation computation.The slip velocity between different phases is ignored in the model from the homogeneous equilibrium scheme and taken into account in the Eulerian-Eulerian scheme.Simulation results are compared with the experimental ones,and it is found that there are obvious differences between the simulations of the two models with the same boundary conditions,and the model considering slip velocity gives more accurate results,where both the specific cavitation length and the changing trend of the cavitation length are obtained.The model ignoring slip velocity only gives accurate changing trend of the cavitation length.The small scale cavitationcloud separated from the whole cavitation sheet cannot be simulated by the two models.The simulations indicate that the assumption that under very strong turbulence the fluid carrier influences the vapor phase via drag but the vapor phase has no influence on the fluid carrier does not hold true in all flow states.

关 键 词：喷油器 空化 数值模拟 相间滑移 

分 类 号：TK417[动力工程及工程热物理—动力机械及工程]