The fluid leakage channel found in contact mechanical seals belongs to the microchannel category. Thus, upon further inspection, the influence of surface wettability and other factors neglected in previous studies becomes obvious. The porous leakage model of contact mechanical seals considering the surface wettability presented in this paper was based on the Cassie model and slip theory. The variations of the microchannel slip length and the velocity under various wettability conditions were studied and the relationship between the slip length and the apparent contact angle was established. Moreover, using porous media theory, the theoretical model of the leakage rate in contact mechanical seals considers the surface wettability depending on various parameters. The observed parameters included the surface contact angle, sealing medium pressure, viscosity coefficient, fractal dimension, and maximum pore diameter. The simulation results obtained using the proposed model have shown that the leakage rate increases with the increase of the apparent contact angle. Particularly when the contact pressure is small, the influence of the surface wettability is more significant. Furthermore, the leakage rate results obtained via the proposed model were compared to those of existing models. The comparison confirmed that the proposed model is applicable and that the necessity of considering wettability significantly affects the leakage rate calculation accuracy. The proposed model lays a foundation for further improving the calculation accuracy, making it easier for both the researchers and practitioners to suppress the leakage in contact mechanical seals.

The simulation of porous media flow holds significant importance in resource development, environmental protection, and engineering applications. Traditional numerical methods, such as the finite difference method and finite element method, often face challenges in handling complex pore structures and heterogeneous properties. The lattice Boltzmann method based on the Shan–Chen pseudopotential model offers a novel tool for addressing multiphase flow and mass transfer problems in porous media. This paper provides a comprehensive review of the theoretical foundations and application advances of the Shan–Chen model in porous media. Key topics include the optimization of pseudopotential functions, improvements to the equation of state, enhancement of numerical stability under high-density ratio conditions, and its applications in multiphase flow, wettability effects, pore structure influences, and energy and environmental fields. Specific examples include shale reservoir development, CO2 geological sequestration, and fluid behavior studies in fuel cells and electrolyzers. Furthermore, the potential of graphics processing unit (GPU) parallel computing and deep learning techniques in improving the efficiency of the Shan–Chen model and predicting complex fluid behaviors is discussed. The study also outlines future research directions, such as high-density ratio flow simulation, multiscale modeling, and data-driven approaches, providing theoretical support and guidance for the development of porous media flow simulation.

Under the condition of convergence, a textured non-parallel 2D slider bearing model was established, and the tribological properties of textured surface under the convergence gap were numerically studied with the load-carrying capacity as an indicator. Firstly, whether the convergence ratio parameter can accurately characterize the joint effects of film thickness difference and oil film thickness on the surface tribological properties was verified, and the effects of film thickness difference and oil film thickness on the load-carrying capacity of textured and non-textured surface were studied, respectively. The results show that the efficiency of improving the load-carrying capacity of the surface structure first increases and then decreases with the increase of the oil film thickness. In the case of large film thickness difference, the surface texture will reduce the efficiency of improving the load-carrying capacity. In addition, the effects of texture depth, texture width, and sliding velocity on the load-carrying capacity under the convergence gap are also studied. In particular, an optimal texture width to maximize the load-carrying capacity exists.

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.

Leakage across contact mechanical seal faces develops within rough, confined microgaps under a driving pressure difference and rotating-ring tangential shear, making it a two-phase interfacial process governed by capillary invasion, interfacial pinning, and pore-scale connectivity with wettability acting as a primary control; however, how rotational shear reshapes this control remains unclear. Here, a two-dimensional pseudopotential multiple-relaxation-time lattice Boltzmann model with a Peng–Robinson equation of state and curved-boundary wettability calibration resolves interface migration, wall adhesion, breakthrough, and shear redistribution on the measured, contact-deformed topography of a real seal face, with rotating-ring traction imposed via a depth-averaged Couette–Poiseuille closure. Leakage exhibits a non-monotonic dependence on wettability: moderate hydrophobicity produces the longest breakthrough delay, whereas stronger hydrophobicity weakens wall adhesion and redirects the advancing front into better-connected pathways. Steady-state leakage follows a wettability-dependent transition from a shear-maintained film-spreading state sustaining no axial pressure difference to a channelized through-flow state. Larger pressure differences weaken the hydrophobic suppression of steady-state leakage by re-activating liquid-connected pathways, whereas higher viscosity primarily delays leakage initiation and makes the latest-breakthrough window less distinct at the maximum viscosity. Incorporating the out-of-plane capillary pinning between the seal faces as an equivalent source term preserves these mechanisms while strengthening the monotonic decrease in leakage with increasing hydrophobicity. These results demonstrate that the wettability regulation of two-phase seal leakage must be evaluated jointly with the driving pressure difference and medium viscosity.

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.