复合式离心泵汽蚀特性的数值模拟与试验分析

Numerical simulation and experimental analysis for cavitation in composite centrifugal pump

为研究某型航天离心泵汽蚀特性,基于Mixture多相流模型与汽蚀模型相结合对长短复合叶轮离心泵内乙二醇水溶液进行不同的进口负压下汽液两相定常数值模拟并进行不同进口压力下的汽蚀性能特性试验,结果表明汽化区域随进口负压的增大而扩大.当进口负压在-50kPa,泵进出口压差在155kPa,已经接近额定压差的3%限制范围,此时离心泵的出口压力105kPa为临界汽蚀出口压力;进口负压到-60kPa时,出口流量突变为300L/h,该泵产生临界汽蚀状态,小于技术要求的最小进口压力10kPa,因此该泵在其工作范围内不会发生汽蚀现象,并证得本文数值模拟的可靠性.

In order to study the cavitation of certain type of aerospace centrifugal pump, the multiphase model on the basis of Mixture was used together with cavitation model.The steady constant value of vapor-liquid phases was simulated under the condition of different negative pressures at inlet of water glycol inside the centrifugal pump with long and short composite impellers, and the cavitation test was conducted with different inlet pressures. The results indicate that the vaporization area expands along with the increase of negative pressure. In case the negative pressure at inlet is-50 kPa and the pressure difference at pump inlet and outlet is 155 kPa,already approaching the 3% allowance of rated pressure difference, the pressure at outlet of centrifugal pump is 105 kPa which is the critical cavitation pressure at outlet. In case the negative pressure at inlet is-60 kPa, the flow rate at outlet suddenly changes to 300 L/h, the critical cavitation state occurs to the pump, and the inlet pressure is less than 10 kPa that is the minimum pressure required in technical specification. Therefore, cavitation will not occur when the pump operates at its working range, and reliability of the value simulation in this paper is also verified.