Abstract: For JFO and Reynolds cavitation boundary conditions, a theoretical lubrication condition model of spiral-groove rotary seal is established. Lubrication state transitions are analyzed by theoretical model based on different cavitation conditions. In the mixed lubrication state, the asperity contact properties are described by fractal contact model. The results show that Reynolds boundary condition can be used to predict larger fluid carrying capacity, but apparently underestimate the cavitation area especially in high speed conditions; In steady operating state, JFO boundary condition can be used to predict higher separation speed which makes the rotary seal transfer from mixed lubrication to hydrodynamic lubrication. The experimental results indicate that the theoretical leakages of two cavitation boundary conditions and the experimental results have the same variation tendency. However, compared with Reynolds boundary condition, JFO boundary condition is used to predict smaller leakages, which are more close to the experiment results, particularly in high speed condition.

Key words: ordnance science and technology, rotary seal, JFO cavitation boundary condition, Reynolds cavitation boundary condition, lubrication condition