Numerical simulation of transient characteristics of mixed-flow pump during start-up process
ZHAO Wenbin1, LI Wei2*, WANG Xingyuan3, JI Leilei2
1. School of Energy and Power Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2. National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 3. Kunming Branch of 705 Research institute of China Shipping Heavy Industry Group Co. Ltd., Kunming, Yunnan 650101, China
Abstract：To study the transient characteristics of the start-up process of a mixed-flow pump, a model and method for solving the transient flow of a mixed-flow pump was developed by using the experimental test speed and flow rate as the solution boundary conditions. The comparison between the head obtained by quasi-steady state and transient numerical methods and the experimental head is used to verify the accuracy of the numerical methods. The evolution of the transient flow field during the start-up of the mixed flow pump and the effect of the start-up acceleration on the internal flow field were analyzed. It was found that the used numerical calculation method was more accurate in reflecting the transient characteristics of the start-up process and the transient head presents significant transient effects. The quasi-steady state method has large errors, and the quasi-steady state method based on similarity law was not applicable in transient performance studies. Due to the effect of angular acceleration and fluid inertia, the inlet pressure gradient at the blade working surface is more pronounced du-ring acceleration, and significant vortices are generated at the blade tip and at the trailing edge of the blade outlet side. It leads to transient external characteristics different from that quasi-steady state conditions. The start-up acceleration has a greater impact on the impact head, the acceleration magnitude determines the peak of the impact head, and the flow lag is also significantly different.
