内射流对离心泵进口流场及压力脉动影响

Influence of Internal Jet on the Flow Field and Pressure Pulsation at the Inlet of a Centrifugal Pump

为探究内射流对离心泵进口流场及压力脉动的影响,本文以一台有内射流循环回路的模型泵为研究对象,采用数值方法对泵全流道进行定常和非定常计算。结果表明:无内射流时泵性能模拟与实验值基本吻合,设计点扬程误差在1%以内;有内射流时泵扬程略有下降,效率最大下降1.8%。内射流流量与射流孔轴向平均速度随流量增加而减小。内射流对泵进口流场影响显著,其存在使得进口段轴向速度、压力、涡量及湍流强度均发生变化。小流量时内射流对进口流场的影响范围更大。距射流孔越远,轴向速度梯度越小。进口段内射流流场呈周期性变化,压力脉动频谱图中存在的低频信号f=9.13Hz为内射流轴向速度场周期变化频率。

In order to explore the influence of internal jet on the flow field and pressure pulsation at the inlet of a centrifugal pump, with a model pump with an internal jet circulation loop as the research object,the method of numerical calculation was used to simulate steady and unsteady cases of the full channel flow of the centrifugal pump. The results show that the performance simulation of the pump without internal jet was basically consistent with the experimental value,and the head error at design point was less than 1%. The head of the pump with internal jet decreased slightly and the efficiency decreased by 1.8%. The internal jet flow rate and axial average velocity of jet hole decreased with the increase of flow rate. The internal jet had significant influence on the flow field at the pump inlet and its presence made the axial velocity,pressure,vorticity and turbulence intensity change. At small flow,the range of influence of inner jet on inlet flow field was larger. The further away from the jet hole,the smaller the axial velocity gradient.The flow field of the internal jet in the inlet section changed periodically. The low frequency signal f = 9.13 Hz present in the spectrum diagram of pressure pulsation was the cyclically varying frequency of the axial velocity field of the internal jet.