粘性泵性能的数值模拟与理论分析

Numerical Simulation and Theoretical Analysis of Viscous Pump Performance

针对曲轴油泵中的粘性泵部分,利用经过试验验证的数值模拟手段研究粘性泵几何设计参数对出口体积流量的影响规律,发现粘性泵出口体积流量随螺旋升角增大而单调减小,随螺旋凹槽宽度的增大而增大,并存在最优的螺旋凹槽深度使得体积流量达到最大。据此利用流体力学理论,建立粘性泵的理论模型,得到出口体积流量的解析表达式,该表达式预测的体积流量与数值模拟结果符合得较好。利用理论模型分析发现,螺旋升角的增大使得粘性驱动力减小而重力阻滞作用增大,导致体积流量的降低;宽度的变化对粘性力的影响不大,只会线性改变截面面积,因此体积流量随凹槽宽度线性变化;粘性驱动力和重力阻滞作用随凹槽深度的变化速率不一致,导致存在最优的螺旋凹槽深度使得体积流量达到最大。该粘性泵理论模型可用于工作机理类似的泵类机构的研究分析和工程设计中。

The influence of geometry parameters on the outlet volume flow rate is studied for the viscous pump section of crankshaft pump by using numerical method which is validated by experimental data.It is found that the volume flow rate monotonously decreases with the increase of spiral angle,and increases with the increase of spiral groove width;there is an optimum spiral groove depth to maximize the volume flow rate.Whereafter,a theoretical model of viscous pump based on fluid dynamics is established,and an analytic formulation of outlet volume flow rate is obtained.The volume flow rate predicted by the theoretical model agrees well with the numerical simulation result.Based on the theoretical model,it is found that the increase of spiral angle will reduce the viscous driving force and simultaneously strengthen the gravitational blocking effect,which leads to the decrease of volume flow rate;the variation of groove width has little effect on the viscous force and only linearly changes the area of transverse section,so the volume flow rate increases with the increase of groove width;the variation rates of viscous driving force and gravitational blocking effect with the variation of groove depth are not identical,which results in an optimum groove depth to maximize the volume flow rate.This theoretical model of viscous pump can be applied in research and design of pumps with similar working mechanism.