Abstract: The movement of fluid in a part-filled hydrodynamic coupling belongs to two-phase flow in centrifugal field, and the distributional pattern of liquid phase directly influences the output characteristic of turbine wheel. In order to acquaint the liquid distribution law, the movement of working medium is regarded as separated layer flow in a hydrodynamic coupling, and water-air interfaces of a standard peach shaped chamber coupling with effective diameter 562 mm in different working conditions are investigated by solving the volume of fluid(VOF) two-phase model. The periodic 3D flow channel model is built, the realizable k-ε turbulence model and PISO algorithm are employed in the numerical model, and the interior face is used to simulate the interaction between the pump wheel and turbine wheel. Water distribution on pump wheel blade is very similar to test result in the literature. The simulation results show that with the increasing of slip between pump wheel and turbine wheel, the incline of water-air interface becomes rapid and large circulation forms at last, and the distributing area of liquid on the pressure side of pump wheel blade increases while that on the suction side decreases. The results also show that low retainer has smaller influence on the circulation pattern than high one which seriously blocks the flow and stops the large circulation.

Key words: Hydrodynamic coupling, Interface tracking, Part-filled, Volume of fluid