关死点处离心泵启动过程的数值模拟

Numerical Simulation of Unsteady Flow in Centrifugal Pump During Startup Period at Shut-Off Condition

离心泵在瞬态过程中的瞬态性能正受到越来越多的关注,其中启动特性是目前研究与应用最为广泛的。为防止功率过载,离心泵通常在关闭出口阀门状态下启动。为研究瞬态性能,本文通过数值模拟技术,对一台低比转速离心泵在闭阀快速启动过程中的内部流场进行了不可压缩、非定常、粘性流动的数值模拟。其中压力与速度的耦合采用SIMPLE算法实现。研究表明:随着启动过程中转速的不断提高,动静干涉效应将更为明显;无量纲扬程在启动初始阶段存在极大值,随后快速减少至最小值,而后缓慢上升至稳定的波动值,该过程表现出明显的瞬态效应;准稳态假设不适合用来进行准确瞬态行为预测。总之本研究将为各类涡轮机械的瞬态特性研究提供了参考。

The research on the transient performance of centrifugal pumps has attracted increasing attention during operating periods, wherein the study and application of the startup performance are most wide. To avoid power overload, centrifugal pumps usually start in the case of closed discharge valve. The numerical simulation of incompressible, unsteady, and viscous flow were carried out for a low-specific- speed centrifugal pump to analyze the transient behavior during startup period in the case of closed dis- charge valve. The SIMPLE algorithm was used to accomplish the coupling calculation between pressure and velocity. The results show that rotor-stator interaction becomes stronger with the growing rotational speed. The maximum of non-dimensional head presents at the very beginning of startup, and fast falls be- low quasi-steady value, then rises to quasi-steady value again. The whole process presents obvious transi- ent behavior. Quasi-steady hypothesis can be not competent of predicting the transient characteristics well. In conclusion, the present study provides the valuable reference for the research on transient behav- ior in all kinds of turbomachineries.