A systematic investigation on flow characteristics of impeller passage in a nuclear centrifugal pump under cavitation state

• The flow characteristics on the impeller of a nuclear centrifugal pump under the cavitation state have been investigated numerically by CFD.
• The flow patterns both under the steady cavitation state and the transient cavitation process are acquired accurately through simulation results.
• The measured results verify the validity in simulating the flow characteristics of the impeller.

Cavitation is a greatly harmful flow phenomenon for nuclear centrifugal pumps, and it should be attached importance when the pump is designed. Under cavitating conditions the flow patterns in the pump are complex and highly turbulent flow can be induced. In this paper the flow characteristics in the impeller passage of a nuclear centrifugal pump model were systematically investigated under steady and transient cavitation conditions. At moderate cavitation levels the results show that the fluctuations of the radial force on the impeller are mainly affected by rotor-stator interaction effects, but are strongly influenced by cavitation under developed cavitation conditions. At inception vapor is mainly generated near the leading edge of the blade, and spreads on the suction side of the impeller at higher cavitation levels. The vapor generation, development and burst under transient cavitation conditions have a strong influence on the flow patterns in the impeller passage. The trends of the simulations are in accordance with the measured results, thus confirming the validity of the numerical model used for predicting the characteristics of the flow through the impeller.