黏度对低比转速离心泵性能的影响

The Effect of Viscosity on Performance of a Low Specific Speed Centrifugal Pump

利用CFD对整个泵输送水和黏油进行了流体动力学模拟,重点研究了液体黏度对泵水力性能的影响以及黏度引起的口环中的量纲一化角速度和泄漏率,并将CFD结果与实验数据进行了对比,结果表明:输送黏性流体时低比速离心泵扬程、流量和效率严重下降;在小流量工况下,黏度对泵性能的影响程度小于设计工况下和大流量工况下;但是随着雷诺数减少,通过口环和平衡孔的泄漏量明显降低,容积效率显著增加,由于盖板处的量纲一化旋转角速度明显减少,随着黏度增加圆盘摩擦损失显著增加。研究结果对输送黏性液体的离心泵设计具有指导意义。

By considering water and viscous oils respectively as transported fluids,CFD software was used to simulate the fluid dynamics of the whole pump.The effect of liquid viscosity on the pump performance was particularly addressed,and dimensionless angular velocity and leakage rate were investigated in sidewall gap.The results were compared with the experimental data.The results show that the pump lift,flow rate and efficiency are seriously reduced when the viscous fluid is transported.Under the condition of small flow rate,the influence of viscosity on pump performance is less than that under the design condition and under large flow condition.Increasing viscosity improves the volumetric efficiency by reducing internal leakage through wear rings and balance holes.Due to the obvious decrease of the dimensionless rotational angular velocity of the cover plate,the friction loss of the disc increases significantly with the increase of viscosity.The results lead to some recommendations for designing centrifugal pumps which may be used in transferring viscous fluids.