Study on mechanism of unsteady gas-liquid two-phase flow in liquid-ring vacuum pump

To investigate the gas-liquid two-phase flow mechanism in liquid-ring vacuum pump, the large-eddy simulation coupled with volume-of-fluid method (LES-VOF) was used to numerically simulate the unsteady gas-liquid flow characteristics in pump. The structure of gas-liquid flow within pump and its dynamic evolution characteristics were studied, and the hydraulic excitation characteristics induced by gas-liquid flow were analyzed. The result shows that the channel vortex inside the impeller on the pump suction side gradually flows out of the flow passage with the rotation of the impeller, and continuously mixes with the wake vortex at the outlet of the impeller and the separation vortex at the inner wall of the casing. The evolution and development of vortex structures with different intensities and scales near the inner wall of the suction side casing have a relatively large contribution to pressure fluctuation. The wake vortex at the impeller outlet of the exhaust side gradually enters the flow passage and dissipates gradually with time. There is an obvious high-intensity backflow vortex in the exhaust section due to the pressure difference between the flow channels near the leading edge of the exhaust port, which leads to obvious rotor-stator interaction in the exhaust section.