The spatiotemporal distribution characteristics analysis and suppression of the axial tip clearance leakage flow for the liquid-ring vacuum pump

Abstract

The clearance leakage flow of liquid-ring pump has complex spatiotemporal distribution characteristics, and it has severe negative impact on its performance. In order to suppress the axial blade tip leakage flow of liquid-ring pump, the spatiotemporal distribution characteristics of leakage flow was analyzed in detail by numerical simulation method. The composite tip of winglet and squealer was introduced to the liquid-ring pump, and its suppression mechanism was analyzed. The RNG k-ε turbulence model and VOF multiphase flow model were selected to simulate transient flow in liquid-ring pump. The results show that the leakage flow in the suction zone gradually decreases from hub to rim, and the leakage flow intensity gradually increases along the rotation direction of the impeller. The gas leakage velocity of compression zone is the highest, and the leakage flow intensity gradually increases along the rotation direction of the impeller. In the exhaust zone, the reverse leakage flow forms near the hub, which flows from the clearance suction side to the pressure side, and the leakage flow intensity gradually decreases from the hub to the rim. Near the rim, the leakage flow direction changes, flowing from pressure side to suction side. In the transition zone, as the impeller flow passage approaching suction zone gradually, the pressure decreases continuously. The pressure on the clearance suction side is greater than that of the pressure side, and the reverse leakage flow forms near the hub. The composite tip blade of winglet and squealer not only lengthens the clearance channel but also blocks the clearance by the pressure side squealer corner vortex and the squealer vortex, thus the leakage flow was effectively suppressed. To some extend the composite tip can suppress the leakage flow, the vacuum values are improved by 3.5%, 3.9%, and 5.3% under different conditions respectively.