Prediction of lubrication condition transition for spiral groove rotary seal rings

For the lubrication condition transition with speed variety of spiral groove rotary seal ring, a theoretical lubrication model is established. By applying the finite volume method to numerical discretization, and based on boundary fitted coordinate transformation and mass conservation boundary conditions, a film lubrication model is obtained. In the mixed lubrication state, the asperity contact properties are described by fractal contact model. Mixed and hydrodynamic lubrication are involved in the theoretical model, by which the variation of the frictional coefficient in the whole speed range is acquired and verified by experiment. separation speed is obtained, and the curve of separation speed changes with the oil pressure of entrance is fit. The curve can effectively judge the speed of the lubrication state change for the spiral groove rotary seal ring.