离心泵内小间隙环流瞬态流体力计算

Computation of transient fluid induced force of small clearance flow in centrifugal pump

基于湍流润滑理论建立小间隙环流数学模型,计算层流假设时层流、过渡流及湍流3种流态下环流内压力分布情况,并与实验结果进行对比.结果显示采用层流模型进行计算时,层流工况下求得结果与实验吻合很好,但当雷诺数增加导致小间隙环流发展至过渡态及湍流状态时,数值计算结果与实验结果相比有较大偏差.利用几种典型湍流模型及过渡流模型对数值结果进行修正,修正后的数值结果与实验结果吻合较好;引用过渡区域摩擦因子对模型进行修正后的计算结果可修正采用层流模型和湍流模型时产生的误差,更接近于实验结果.针对离心泵启动的瞬态过程,求解考虑转子涡动角速度及涡动幅值变化时小间隙环流内压力分布,结果显示,涡动角速度及涡动幅值的变化对环流内正压区及负压区分布均有明显影响.

The small clearance flow was modeled based on turbulent lubrication theory. Pressure distribution of small clearance flow which in laminar, transition and turbulent regime state were calculated and then compared with experiment results. Based on comparison results, small clearance flow model was optimized. A typical turbulent lubrication theory and a transition flow model were used to simulate superlaminar flow in small clearance channel. After optimization process the numerical results had a better agreement with experiment results. Pressure distribution of small clearance flow in transient process was obtained when whirling motion and amplitude changing of shaft were considered, and the results showed that peak values of pressure distribution increased markedly when transient effects were considered. Peak values of positive pressure region and negative pressure region in small clearance flow both increased linearly with increased angular velocity of whirling motion. When amplitude increase of whirling motion was considered, pressure curves of small clearance flow entirely up offset, which enhance stability of rotor systems.