Abstract: The axial clearance leakage of liquid ring pump impeller intensifies the complexity and polytropy of the gas-liquid flow structure within the pump, which leads to the decrease of pump performance and operation stability. Therefore, the plasma excitation technology is introduced to control the pump clearance leakage flow, and the regulation mechanism of plasma excitation on the clearance leakage flow under different flow conditions is explored. The research results show that the plasma excitation with a 15 kV excitation voltage increases the relative value of efficiency of the liquid ring pump by 3.6%, 4%, and 0.6% under flow rates of 0.01 kg/s, 0.03 kg/s, and 0.05 kg/s, respectively. The leakage vortex with a flow rate of 0.03 kg/s moves forward in the opposite direction of the leakage flow under the action of plasma excitation, which effectively reduces the complexity of the turbulent structure near the wall area, resulting in a decrease in the hydraulic loss and pressure fluctuation intensity of the clearance leakage, and has a significant effect of efficiency enhancement and stability expansion. Under the operation of 0.05 kg/s flow rate, the leakage flow is a wavy flow pattern under the plasma excitation and it appears multiple secondary flow structures in the flow process, which leads to the insignificant effect of plasma suppression. The leakage flow can be effectively suppressed when the plasma excitation position is located in the axial tip region of the blade under different flow rates. As the excitation position gradually moves downstream of the leakage flow, the flow control effect gradually weakens due to the full development of the leakage flow. The research results can provide a theoretical reference for the performance optimization of liquid ring pump.

Key words: liquid ring pump, different flow rate conditions, axial clearance leakage, plasma excitation, flow control