Thermal fluid–structure interaction analysis of the leakage characteristics and deformation mechanism in labyrinth seals

While labyrinth seals are extensively employed in rotating machinery, prior studies have predominantly quantified the leakage performance of seal geometries, with less attention given to the multiphysics coupling fluid flow and structural deformation within the critical tooth tip clearance region. This work employs a thermal fluid–structure interaction framework to unravel the leakage characteristics and thermoelastic deformation mechanisms in labyrinth seals. The effects of pressure differences, inlet temperature, and structural Young’s modulus have been comprehensively studied, with an explicit focus on how heat transfer induces tooth deformations of seals. Our results indicate that leakage mass flow increases with pressure differences, while slightly decreases with inlet temperature. Higher pressure differences boost fluid velocity and reduce pressure and temperature, whereas the inlet temperature only significantly affects the temperature distribution in the runner due to the cavity and throttling effect. In addition, the axial deformation of the seal mainly depends on the pressure differences, while the radial deformation is proportional to the inlet temperature with the deformation, peaking at the first tooth. Leakage mass flow initially rises with Young’s modulus due to flexible material deformation and then stabilizes as stiffness limits displacement. Teeth deformations inversely correlate with Young’s modulus, while the seal temperature remains unaffected. In particular, prediction models combining leakage and deformation can provide a basis for selecting seals, validated with less than 5% error. This study provides a reference for designing and improving the efficiency of sealing systems in engineering applications, enabling higher stability and lower leakage rates.