环下润滑结构中非圆柱液流在横向气流中脱落现象分析

Analysis of the Phenomenon of Non Cylindrical Liquid Flow Falling Off in Transverse Air Flow in Under-Race Lubrication

为分析靠圆柱孔一侧射出的弓形截面非圆柱液流在横向气流中的脱落现象,使用CLSVOF(Couple Level Set VOF)多相流模型与大涡模拟(LES)模型相结合的方法,对非圆柱液流的脱落过程进行数值模拟。结果表明:非圆柱液流在横向气流中的脱落现象是由迎风面上气液密度差产生的Rayleigh-Taylor(R-T)不稳定性和液流边缘气液速度差产生的Kelvin-Helmholtz(K-H)不稳定性共同形成的表面波引起的,同时液流边缘外侧产生的连续漩涡也促进了液流的脱落;横向气流速度增加时,由于表面波增强液流的脱落量增大,横向气流方向改变时由于迎风面上的表面波现象减弱脱落量降低,说明了迎风面上形成的不稳定性表面波是引起液流脱落的主要因素。

In order to study the shedding mechanism of non-cylindrical liquid flow with bow cross-section injected from one side of a cylindrical hole in cross-flow,a method combining CLSVOF multiphase flow model with large eddy simulation(LES)model was used to simulate the shedding process of non cylindrical liquid flow.The results show that the shedding phenomenon of non cylindrical liquid flow in cross-flow is caused by the surface wave formed by the Rayleigh-Taylor(R-T)instability because of the gas-liquid density difference on the windward surface and the K-H(Kelvin-Helmholtz)instability because of the gas-liquid velocity difference on the edge of the liquid flow.The continuous vortex generated at the outside edge of the liquid flow also promotes the shedding of the liquid flow.When the transverse airflow velocity in⁃creases,the shedding of liquid flow increases due to the increase of surface wave.When the transverse airflow direction changes,he shedding of liquid flow decreases due to the decrease of surface wave on the windward side.It is shown that the instability surface wave formed on the windward surface is the main factor causing the shedding phenomenon.