Numerical analysis of the flow field around a Ribbed helix lip seal

In this study, a direct numerical simulation model has been developed to aid in the understanding of the pumping mechanism of a ribbed helix lip seal. A SIMPLEC numerical algorithm with the staggered-grid arrangement is employed to simulate the flow field around the contact region between the lip and the shaft in the environment of a pumping-rate test rig, where both air and oil sides are filled with oil initially. The streamline pattern and pressure field are examined. Complicate three-dimensional streamline topology is analyzed. The vortex generated next to the lip on the oil side rotates such to create an inward pumping effect. On the air side, pressure built up on the windward faces of ribbed helices next to the lip also help pumping oil back to the sump. The pumping rates are calculated at shaft speeds, ranging from 1000 to 6000 rpm, and compared to the measured values from the test rig. Good agreement is observed. Both calculated and measured pumping rates increase as shaft speed and sump temperature increase and as the sealed fluid viscosity decreases. The current results demonstrate the promising application of CFD in the design of radial lip seals.