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Influence of balancing drum clearance on axial thrust and pressure in rear chamber of last stage impeller of multistage centrifugal pump |
QIAN Chen*, YANG Congxin, HU Xiaojie, ZHANG Yang, HOU Kaiwen |
School of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China |
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Abstract In compressible viscous fluid flows in an axial-split multistage centrifugal pumps were numerically calculated by using the Fluent software based on the SST k-ω turbulence model at six drum radial clearances 0, 0.1, 0.2, 0.3, 0.4, 0.5 mm to study effects of the clearance on pump efficiency, axial thrust and pressure in the rear chamber of the last stage impeller under design condition.The calculated results show that the fluid pressure in the rear chamber increases gradually in the radial direction, and the pressure on the hub nearly impeller outlet is distributed more unevenly along the circumferential direction with increasing drum clearance. The minimum pressure in the mid-span plane of the rear chamber is declined with increase of drum clearance, but the maximum pressure increment along the radius is the lowest at 0.2 mm clearance, then rises rapidly with increasing clearance. The axial thrust is the smallest at 0.3 mm clearance.The pump efficiency decreases with increasing leakage flow rate through the drum gap; particularly, as the leakage flow rate is 0.887 kg/s, the efficiency has been lowered significantly.
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Received: 29 November 2018
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