1. National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China;2. School of Mechanical Engineering, Nantong University, Nantong, Jiangsu 226000, China
Abstract：Taking the XB4.3/240-300LC vertical long shaft fire pump as the research object, under the condition that the blade wrap angle, the inlet and outlet placement angle, the width of the impeller outlet, the axial distance from the middle position of the impeller outlet to the impeller inlet and the radial distance from the rotating shaft, cross-sectional area of outlet flow and the radial coordinate value of the intersection of the blade inlet edge and the front cover streamline are constant, and various schemes are designed. The shear stress transfer(SST)model is used to carry out numerical simulation and internal flow field analysis for different schemes, so as to find the optimal impeller outlet inclination angle when the pump hydraulic characteristics is the best. The results show that by changing the tilt angle of the impeller outlet, the head and efficiency increase slightly under low flow conditions, while the increase is relatively large under high flow conditions. When the inclination angle of the impeller is 15°, the head and efficiency appears peak values. If the inclination angle continues to increase, the two will decrease instead. If the inclination angle is 15°, it is considered as the optimal impeller outlet inclination angle, and compared with the original plan, the head and efficiency are increased by 5.95% and 1.19%, respectively. The circumferential and radial components of the absolute velocity at the outlet of the impeller have good consistency in the large flow conditions,and the inclination angle of the impeller outlet has little effect on it. The two components of the absolute velocity of each scheme have poor distribution regularity in the flow channel under small flow conditions. The inclined outlet of the impeller has great influence on the distribution of turbulent kinetic energy inside the annular space and the space guide vane.
