The effects of clearance sizes on labyrinth brush seal leakage performance using a Reynolds-averaged Navier-Stokes solver and non-Darcian porous medium model

Effects of clearance sizes on the pressure and leakage characteristics in a shaft labyrinth brush seal were numerically investigated using Reynolds-averaged Navier-Stokes (RANS) and non-Darcian porous medium model solutions. The leakage flow characteristics in the referenced design shaft labyrinth seal of turbomachinery was initially studied using the RANS solution. The initial shaft labyrinth seal was redesigned into the multi-stage labyrinth brush seal. The reliability and accuracy of the RANS and the non-Darcian porous medium model for leakage flow in brush seals were demonstrated through comparison of the experimental data. Then, the leakage flowrate of the redesigned shaft labyrinth brush seal was calculated at four sizes of bristle pack tip clearances (0, 0.1, 0.3, and 0.5 mm) and compared with the referenced shaft labyrinth seal. The numerical results show that the leakage flowrate increases rapidly with increasing clearance between the bristle pack tip and the rotor surface for the shaft labyrinth brush seal. The leakage flow pattern in the referenced labyrinth seal and the redesigned shaft labyrinth brush seal was also illustrated.