Experimental and Numerical Study of Cavitation Breakdown in a Centrifugal Pump

A low specific speed centrifugal pump was constructed to measure cavitation flow characteristics. Pressure distribution over blade surfaces and wall static pressure were measured dynamically and cavitation behavior were photographed by using high speed video and a digital camera. Cavitation flow inside the impeller was computed by commercial CFD code CFX-TASCflow. Head drop characteristics were measured in detail and compared to CFD results. In the case of the best efficiency point flow, bubble cavitation increases along the suction side while decreasing NPSH. When bubble cavitation reaches the throat, another cavity appears on pressure side and the head breakdown occurs steeply. At the high flow rate, cavitation bubbles appear incipiently at the throat on pressure side and head drops gradually. At best efficiency point flow, cavitation phenomena are well captured by CFD.