Effect of the Circumferential Position of Balance Holes on the Cavitation Performance and Cavitation Erosion of Centrifugal Pump

Abstract

The flow field of a low specific speed centrifugal pump is investigated in the present work based on numerical simulation to establish the effect of circumferential positions of balance holes on cavitation behaviour and cavitation erosion of the centrifugal pump. The distribution of the pressure around balance holes is studied, the initiation and development of cavitation at different balance hole schemes are compared, and the distribution of cavitation erosion for the original pump and the ideal scheme is also predicted. The results show that when the NPSHa is high, there is low pressure zone in balance hole, which leads to cavitation in the pump. The cavitation performance of pump is improved by gradually moving balance holes away from blade suction surface, as this reduces low pressure zones around the balance hole and incipient cavitation. Under critical cavitation conditions, the cavitation shows a tendency to collapse as the angle (φ) of circumferential position of balance holes decreases, and the proportion of the higher vapor volume fraction in cavitation core zones also decreases. The cavitation erosion zones on blade surfaces are predicted by using the Erosive Power Method (EPM). The erosion impact of the original pump is more pronounced in the comparative results.

Keywords

• centrifugal pump
• balance hole
• circumferential position of balance hole
• cavitation erosion
• the erosive power method (epm)