Inlet pre-whirl for contrarotating axial-flow water-jet pump
HUANG Zhenjie1, PAN Zhongyong 1, SHEN Zhanhao2, PAN Xiwei3
1.National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2.School of Jingjiang, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 3.Mechanics Institute, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
To study the reason why water-jet propulsion pump efficiency at a small flow rate decreased rapidly, the computational fluid dynamics method was applied to the numerical simulation of water-jet pump at a small flow rate. Based on different flow rates and rotation rate control methods,the emergence and development of inlet pre-whirl was studied and the relation between the rotation rate and the inlet pre-whirl was analyzed. The results show that in the working condition, circumferential component of the absolute velocity of the front inlet impeller is close to 0 and changes hardly following the flow channel, and the inlet pre-whirl can be neglected. In the 0.8 Qd working condition, the increase along with the change of flow channel is very small, there is a small pre-whirl only at the rim. At the beginning of 0.6 Qd, the change in inlet pre-whirl becomes obvious, the lower the flow is, the greater the change is. Under the low flow, reducing the front impeller speed can effectively improve the inlet pre-whirl and also can improve the efficiency of the pump. Regulating the impeller speed can effectively improve the inner flow of the pump. The results are of important guiding significance to the inlet pre-whirl analysis of other specific speed water-jet propulsion pumps.
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