关键词: 离心泵, 压力脉动, 空化, 叶片载荷, 数值模拟

Abstract: To study the cavitation characteristics of a centrifugal pump under the condition of large flow rates with a head decrease by 3%, the numerical simulation result of flow characteristics and pressure pulsation in the impeller section was discussed, and the reason of pressure on the blades fluctuates was analyzed. The results show that under cavitation, significant differences occur in the vortex structure in the impeller channel, especially obvious flow separation at the diaphragm, and an increase in the flow rate reduces the nonuniformity of the impeller channel flow. Under different cavitation conditions, pressure pulsation at the impeller outlet is dominated by the blade frequency, and its low-frequency and wide-frequency components vary with an increasing flow rate. Under the rated working conditions, pressure pulsations in the low band of 0-290 Hz are significant at each monitoring point. An increase in the flow significantly inhibits the low frequency and broadband pulsations, and fluctuations in other frequencies such as double and triple blade passing frequencies also weaken with the increasing flow. Through a certain orthogonal decomposition of the blade load, the dynamic and static interference between the tongue and the impeller can be considered the main cause of large pressure fluctuations on the blades, and vortex shedding in the flow channel is also a factor that strengthens the pulsations. An in-depth analysis of the characteristics of flows in the impeller section of a centrifugal pump under large flow conditions is provided, which is useful for improvement and optimization of its structure.

Key words: centrifugal pump, pressure pulsation, cavitation, blade load, numerical simulation