In this study, a spiral groove liquid film vaporization model based on the viscosity–temperature equation, fluid internal friction, saturation temperature, and pressure relationship equation was established. Using a multiphase flow model based on the finite volume method, the influence of the change in the mass transfer coefficient on the vaporization of the liquid film was studied. Moreover, the influence law of structural parameter changes in liquid film vaporization characteristics and sealing performance was analyzed. The results indicate that, with an increase in the mass transfer coefficient, the average vapor phase volume fraction first increases and then gradually stabilizes. When calculating the average vapor phase volume fraction, it is necessary to consider the influence of the mass transfer coefficient, whereas its effect on the opening force and leakage can usually be neglected. Under the optimal mass transfer coefficient conditions, the average vapor phase volume fraction increases with an increase in the helix angle, groove-weir ratio, and groove depth. By comparison, with an increase in the groove-diameter ratio, the average vapor phase volume fraction first increases and then decreases. The opening force decreases with an increase in the helix angle, groove-to-weir ratio, and groove depth. On the other hand, it first decreases and then increases with an increase in the groove-diameter ratio. The leakage rate increases first and then stabilizes with an increase in the helix angle. Moreover, it increases continuously with an increase in the groove-diameter ratio, groove-weir ratio, and groove depth.

Aiming at the problem of researching the reliability of dynamic-pressure mechanical seals, this paper proposes a reliability evaluation method for dynamic-pressure mechanical seals based on the Monte Carlo method. Based on the influence of the mass transfer coefficient on vaporization phase transition, a liquid film vaporization model of a hydrodynamic mechanical seal’s end face is established, and the working condition parameters and groove structure parameters are designed using the experimental design method. The vaporization characteristics of the liquid film under various parameters are analyzed, and the functional functions of the vaporization characteristics are obtained by fitting. Combined with the maximum vapor phase volume fraction when the dynamic-pressure mechanical seal changes from the liquid miscible phase to the vapor miscible phase, the limit state equation of the vapor phase volume fraction is obtained. Finally, based on the Monte Carlo simulation method, the sealing reliability under specific groove structure parameters is calculated. Our research shows that this method has practicability and effectiveness for the reliability evaluation of mechanical seals with different working conditions and different groove structures.

As a key basic component for leakage prevention in rotating machinery, research on the reliability of mechanical seals has always been the focus of theoretical and practical investigations. A reliability evaluation method for the dynamic pressure mechanical seal based on liquid film vaporization phase transition is proposed. To investigate the affect of the mass transfer coefficient on the vaporization phase transition, a liquid film vaporization model of the hydrodynamic mechanical seal seal face has been established. The working condition parameters and groove structure parameters are selected based on experimental testing. The evaporation characteristics of liquid film under different parameter combinations are analyzed, and as a result, the function of the vaporization characteristics is obtained. The limit state equation of gas phase volume fraction is obtained by using the maximum gas phase volume fraction when the dynamic pressure mechanical seal state changes from liquid phase miscibility to gas phase miscibility. The structural parameters of the groove are sampled based on the Monte Carlo method, and the reliability is calculated using the sampling results and the limit state equation. Finally, the proposed method is used to numerically analyze the reliability of the slot under specific structural parameters.