Gas Film Lubrication Characteristics of Dry Gas Seals with Varying Groove Depths

To address the stringent sealing requirements of specialized equipment in extreme deep-sea environments, where traditional unidirectional sealing structures often fail to accommodate complex bidirectional pressure fluctuations, this study focuses on bidirectional T-groove dry gas seals. The primary objective is to elucidate the influence of groove depth evolution on gas film lubrication characteristics. Based on gas film lubrication theory, a hydrodynamic lubrication governing equation was established. Furthermore, a compressible gas film thickness equation was proposed to characterize the stepwise evolution of the groove geometry, accurately describing the evolution of the gas film thickness with varying groove profiles. Through numerical simulations, key performance parameters—including opening force, leakage, gas film stiffness, and stiffness-to-leakage ratio—were systematically evaluated for six T-groove structures with varying depths. The results reveal a competitive mechanism between operating conditions and sealing performance: while elevated pressure enhances the hydrodynamic effect and gas film stiffness, it simultaneously increases the leakage rate. Similarly, higher rotational speeds improve load-carrying capacity but exacerbate gas flow and leakage. A comparative analysis of the stiffness-to-leakage ratio across the six models indicates that Type 4 and Type 3 achieve the optimal balance between gas film stiffness and leakage control. This study confirms that rational groove design can effectively balance the opening force and leakage rate, thereby enhancing sealing stability. Ultimately, this research uncovers the specific mechanisms by which bidirectional T-groove structures influence gas film lubrication performance, providing a theoretical foundation for optimizing the sealing structures of high-end deep-sea equipment.