The aerodynamic force between a bristle pack and a rotor should be considered in order to predict the stability of a rotor brush seal system. The high pressure flow region in a brush seal makes the interaction of bristle pack, leakage flow and rotor complicated. It provides a challenge to the study of rotor brush seal system dynamic characteristics. To analyze the rotordynamic coefficients of a rotor brush seal system, a 3D CFD rotor labyrinth brush seal computational model was created using Reynolds-averaged Navier-Stokes (RANS) solutions coupled with a non-Darcian porous medium model. The results show that for the same geometry parameters the radial force rises when the pressure ratio increases, the tangential force rises when the pressure ratio increases, and the radial force is much greater than the tangential force. And the flow leakage will increase when the pressure load increases and the mass flow rate increases with the clearance increase. Direct and cross-coupled stiffness and direct damping and cross-coupled damping under different operating condition are discussed. The direct damping and cross-coupled damping both increase when the clearance increases. The cross-coupled stiffness will increase when the inlet pressure increases.

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