Design optimization of a synchronal rotary multiphase pump

Design optimization analyses of a synchronal rotary multiphase pump (SRMP) were performed to improve the pump performance. A comprehensive mathematical model of the SRMP was first developed to calculate various pump performance parameters, including the volume flow rate, shaft power consumption, and pump efficiency. The accuracy of the established model was verified by comparisons between the simulated and experimental results. A design optimization procedure coupled with the mathematical model was then developed by employing a direct search optimization technique-complex method. The optimization calculations for the optimum pump performance and the relevant design variables were implemented under three kinds of operating conditions that differed in their inlet gas volume fractions (GVFs). The calculated results showed that the pump efficiency was effectively improved by the set of optimum design variables obtained in the optimization search. The optimum design variables differed with inlet GVF. Under the condition of a lower inlet GVF, the optimum design variables inclined to values that gave a higher mechanical efficiency. When the inlet GVF increased, the effect of leakage loss on the pump efficiency increased, and as a result the optimum design variables inclined to values that gave a higher volumetric efficiency. The research results suggest that a narrow but taller cylinder is better for the operating condition of a lower inlet GVF and a wide but shorter cylinder is better for the operating condition of a higher inlet GVF.