离心泵双密封环平衡系统泄漏特性预测方法研究

Leakage Prediction Method for Double Wear-Rings Balancing System of Centrifugal Pumps

关键词:  离心泵  双密封环  平衡系统  泄漏量  Navier-Stocks方程

Key words:  Centrifugal pump  Double wear-rings  Balancing system  Leakage flow rate  Navier-Stokes equations

摘要:

为了准确预测离心泵双密封环平衡系统的泄漏特性，通过分析该平衡系统的几何特征和液体流动特点，对其主要过流部件进行简化，将泵腔液体流动简化为由圆周剪切流和径向压差流叠加而成的轴对称二维粘性层流运动，同时将密封环间隙液体流动简化为两平行平板间的定常不可压缩粘性流体层流运动。然后，利用N-S方程分别建立了泵腔和密封环间隙的液体流动模型，并通过泄漏量相等建立了双密封环平衡系统泄漏量预测模型。为了验证该预测模型的可靠性，以IS80-50-315型离心泵为模型，对不同工况下的双密封环平衡系统泄漏特性进行实验测量，并与预测结果进行比较。结果显示，在不同平衡孔直径和密封环间隙条件下，预测结果与实验数据的相对误差在设计工况下均小于3%，在非设计工况下均小于10%。研究表明，不仅在设计工况下，而且在非设计工况下，本文提出的预测模型均可以较准确地预测离心泵双密封环平衡系统的泄漏特性。

Abstract:

In order to accurately predict the leakage characteristics of the double wear-rings balancing system of centrifugal pumps， the main flow passage components are simplified by analyzing the geometric features and liquid flow characteristics. The liquid flow in the pump side chamber is simplified as an axisymmetric two-dimensional viscous laminar flow composed of circumferential shear flow and radial differential pressure flow. At the same time， the liquid flow in the wear-rings clearance is simplified as laminar flow of incompressible viscous fluid between two parallel plates. Then， the liquid flow models of the pump side chamber and the wear-rings clearance are established by using the N-S equations. According to the condition that the leakage flow rate is equal for the main flow passage components， the leakage prediction model of double wear-rings balancing system is established. In order to verify the reliability of the prediction model， the IS80-50-315 type centrifugal pump was selected to measure the leakage flow rate of the balancing system. The leakage characteristics of the double wear-rings balancing system under different working conditions were obtained and compared with the predicted results. The relative error between the predicted and experimental results is less than 3% at the design condition and less than 10% at the off-design condition under different balancing hole diameters and wear-rings clearances. The research shows that the leakage characteristics of the double wear-rings balancing system can be accurately predicted by the leakage prediction model in present work， not only at the design condition but also at the off-design condition.