The cavitation performance analysis of the RCP under LBLOCA at inlet

Abstract

The reverse pump mode is an extreme working condition which is very likely to happen when LBLOCA (large break loss-of-coolant accident) occurs at the inlet of RCP (nuclear reaction coolant pump). In order to study the cavitation performance of the RCP under this kind of extreme working condition, the accuracy of the numerical data is verified by comparing it with the experimental data. Then, the GVF (gas volume fractions) of the RCP under different flow rates are analyzed by numerical simulation. A new method based on the average GVF to estimate the cavitation of the RCP under the reverse pump mode is proposed. In the process of numerical study, the cavitation of the RCP is promoted by changing the inlet pressure, and the cavitation performance of the RCP is studied by the new estimate method. The results show that the head increases at each flow rate with the decrease of inlet pressure under the incipient cavitation state and cavitation development state. When the increase rate of the head reaches the maximum, the RCP is in the full cavitation state. When the pressure drops to a certain value, the average GVF on the impeller blade surface reaches 2%, and the head of the RCP drops sharply like it under the pump mode. Finally, the cavities are widely distributed in the inlet of impeller, it will cause severe mechanical vibration and erosion to flow passage component, and even lead to serious accidents. The present work provides a useful reference for the further study of the operation of the RCP under the LBLOCA.