非对称压差下三角形微孔摩擦副的两向异性应用

Application of Anisotropy of Sliders with Triangular Dimples Under Asymmetric Pressure Differences

带有方向性微孔的平行摩擦副在不同运动方向有不同的摩擦性能,但在两向运动时,利用方向性微孔的两向异性去适配两向不同压差的研究仍然缺乏。基于Fluent多相流空化模型,针对带有等边三角形微孔的平行摩擦副,建立了其中一个微孔周期的间隙流体的3维数值计算模型,研究了如何应用三角形的两向异性以减小摩擦系数。首先,使用了流动因子判定流动状态,网格无关性分析确定网格尺寸,并与文献计算结果对比,保证了数值计算模型的正确性;然后,描述了三角形微孔的两向异性,并解释了三角形微孔两向异性产生的原因是由于两向运动时的不同楔效应;随后,研究了运动速度和微孔深度对两向异性的影响;最后,在不同的两向运动工况下,将三角形微孔摩擦副的两向平均摩擦系数与圆形微孔的两向平均摩擦系数进行了对比。研究结果表明:三角形微孔摩擦副的两向异性主要出现在压差较低的区域,摩擦系数差异最大可达31.68%;增大速度会使具有明显两向异性的压差区间增大;不同的孔深对两向异性的影响取决于孔深对动压的影响,孔深为3μm时摩擦性能最好;圆形微孔摩擦副的摩擦系数介于三角形摩擦副两向运动的摩擦系数之间,与正向运动时的三角形微孔摩擦副的摩擦系数最大相差17.96%;当两向运动时,应将三角形微孔尖端朝向压差较低侧,利用三角形微孔的两向异性,最多能够比圆形微孔减少13.3%的两向平均摩擦系数。

Parallel sliders textured with oriented dimples have different frictional performances when moving in different directions.However,the anisotropy of dimples is hardly studied to adopt the different working conditions at bidirectional movements.Therefore,based on the multiphase flow cavitation model in Fluent,a three-dimensional numerical model of the lubricant between the parallel sliders with equilateral triangular dimples was developed for reducing the friction coefficient with the anisotropy of triangle dimples.Firstly,the fluid factor was calculated for checking the flow pattern,and the grid independence test was done for determining the grid size.The calculation result was also compared with the reference in order to ensure the accuracy of the model.Secondly,the anisotropy of triangle dimples was described.The reason of anisotropy is the different wedge effects at different moving direction.Thirdly,the influences of the velocity and the depth of dimples on the anisotropy were studied.Finally,the average friction coefficient of the sliders with triangular dimples was compared with that with circular dimples under different bidirectional movement conditions.The results showed that the anisotropy of sliders with triangular dimples is obvious in the low pressure region,with a maximal friction coefficient difference 31.68%.The increase of velocity widens the pressure range where obvious anisotropy appeared.The effect of dimple depth on the anisotropy depends on the effect of the dimple depth on the dynamic pressure,and the best depth for friction performance is 3μm.The friction coefficient of sliders with circular dimples is between that with triangular dimples moving forward and backward,and the maximum difference is 17.96%.When the working conditions of the two directions are different,the friction coefficient of sliders with triangular dimples can be reduced by 13.3%.