In industrial fields, pumps are required to operate under gas-liquid two-phase flow conditions, but because performance degradation and instability occur as the amount of gas increases, it is important to clarify the performance during two-phase flow and the flow patterns inside the impeller. Therefore, in this research, we conducted two-phase flow performance test to clarify the effect of gas mixing on performance for a vertical centrifugal pump with a downward-facing suction direction and a chamber area above the impeller, which has not been studied before. The experimental results confirmed that the total head decreases linearly as the gas-liquid mixture ratio increases, and then decreases gradually until the pump is no longer able to pump water. Furthermore, to investigate the flow patterns inside the impeller, we performed a numerical analysis of the two-phase flow condition and were able to reproduce the decrease in total head with an increase in the gas-liquid mixture ratio.
NISHIO et al. (Wed,) studied this question.