Investigation on the thermo-hydrodynamic lubrication characteristics of segmented annular seal with Rayleigh pockets based on conjugate heat transfer: Numerical modelling and experimental validation

To enhance the accuracy of solving for the leakage flow characteristics in a segmented annular seal (SAS) with Rayleigh pockets, a solution model considering conjugate heat transfer was established to solve the seal’s thermo-hydrodynamic lubrication (THL) characteristics. A test rig was constructed to measure the leakage characteristics of the SAS. Based on the experimental verification of the accuracy of the solution model, a comparative analysis was carried out regarding the impacts of operating condition parameters under isothermal and conjugate heat transfer models on the pressure distribution, lif t force, and leakage of SAS with Rayleigh pockets, as well as the influence of operating condition parameters in the conjugate heat transfer model on gas temperature rise. The results indicate the sealing performance of the SAS with Rayleigh pockets is primarily achieved through the throttling effect on the main sealing surface. The gas temperature rise mainly results from the work done by the high-speed rotation of the rotor raceway on the airflow. The conjugate heat transfer exhibits a relatively minor influence on the pressure distribution and lift force of SAS with Rayleigh pockets, while exerting a substantial influence on the leakage. The conjugate heat transfer impacts the leakage by influencing the density of the sealing medium and the axial flow velocity of the fluid at the outlet. The gas temperature rise of the SAS with Rayleigh pockets increases with the increasing rotational speed while decreases with the increasing pressure ratio. When the seal clearance is 5μm, the rotational speed ranges from 10000 to 20000 r/min, the gas temperature rise surges from 91.78 K to 377.39 K, with a pressure ratio ranging from 2 to 5, the gas temperature rise decreases from 399.27 K to 165.17 K.