Abstract: As a new sealing technology, the leakage performance has been one of the hot topics in sealing field. The leakage through the micro voids at the contact interface between rough surfaces of finger element is regarded as the finger seal side leakage, a method of calculating the permeability of porous medium is proposed based on the pressure flow factor and Hagen-Poiseuille law, and the numerical model for calculating the side leakage based on the porous medium theory is established. Then taking into account the finger seal side leakage, the analysis method for total leakage of finger seal is developed. Finally, the influence of the surface topography parameters and the operating conditions on the side leakage, the main leakage and the total leakage is analyzed. In addition, the proportions of the side leakage and main leakage are also studied. The results show that the finger seal side leakage increases with the increase of the RMS roughness and the pressure difference between upstream and downstream finger seal, and when the finger element surface roughness texture direction changes from transverse to longitudinal, the finger seal side leakage also increases. On the other hand, the side leakage becomes dominant as the surface of finger element is rough enough, but the main leakage dominates when the radial displacement excitation of the rotor is larger. This research contributes to the improvement of the theoretical system of the finger seal leakage analysis.

Key words: finger seal, porous medium, roughness, texture feature, pressure flow factor