Numerical prediction of impact of clearance on rotordynamic coefficients for labyrinth brush seal

The clearance has an obvious influence on the rotordynamic characteristics of brush seals. In order to better know the influence of brush seal on the stability of the rotor bearing system, the rotordynamic coefficients of labyrinth brush seal under different clearance cases and operating conditions are numerically analyzed using CFD RANS solutions coupling with a non-Darcian porous medium model. The results show that at the same geometry parameter the radial force and tangential force will increase when the pressure ratio rises. And when the clearance increases, the direct stiffness decreases sharply at first and then rises slightly. The variation of cross-coupled stiffness is complex. Moreover, at the same operating condition the value of direct damping coefficients increases when clearance increases, which add a stable factor to the rotor.