Numerical analysis of a double interlocking padded finger seal performance based on thermo-fluid-structure coupling method

Abstract

Non-contacting finger seals represent an advanced non-contacting and compliant seal in gas turbine sealing technology. This paper proposes a new structure of non-contacting finger seals with double interlocking pads. The numerical analysis model based on the thermo-fluid-structure coupling method for the new type finger seal was established. The influence of working conditions on leakage of the seal was studied and compared with the single padded non-contacting finger seal. The results show that the interface between the bottom of the finger pad and rotor surface is the main leakage path that forms the gas film with obvious variations of pressure and flow velocity. Under high temperature and high pressure operating conditions, the hydrodynamic effect of the gas film is enhanced, and lifting force is significantly improved. The deformation of fingers is composed of elastic deformation and thermal deformation. At room temperature, the deformation of fingers is mainly elastic deformation and points to the center of the rotor, which reduces the gas film clearance. The deformation of fingers at high temperature and high pressure creates a circumferentially convergent gap between the bottom of the pad and the rotor, which is beneficial to improve the loading capacity and to reduce leakage of the seal. Compared with the typical single padded non-contacting finger seal, the double interlocking padded finger seal proposed in this paper reduces the leakage factor by about 37%, which provides an advanced seal concept with the potential to improve sealing performance under high temperature and high pressure working conditions.