An anisotropic porous media model for leakage analysis of finger seal

Abstract

Finger seal is a new type of compliant seal configuration, which is an important part of an aero-engine and its accessory systems. It has superior sealing performance compared with conventional labyrinth seals and a lower manufacturing cost than brush seals. However, numerical simulation of the leakage characteristics of an entitative finger seal structure are very difficult to implement, because the finger laminates are in close contact with one another and the radial deformation of the fingers caused by interference between seal and rotor as well as the centrifugal and thermal expansion of the rotor can change the geometric structure of seal. The published leakage analysis models of finger seal ignore the leakage throughout the interstices between fingers or finger laminates. In view of this, the authors propose an anisotropic porous media model for leakage analysis of finger seal. The model considers the effects of the seal structure parameters, upstream and downstream axial pressure differences and the fit status between seal and rotor. First, the equations of the model and their parameters were obtained by theoretical derivations, while the correction factors were determined based on experiment leakage data in the literature. Second, the accuracy of the model was validated by calculating the leakage of a known seal structure in the literature and comparing these results with the experimental data. At last, a comparison between the anisotropic and isotropic porous media model is carried out. The results of the validation examples show that the model can simulate the leakage of finger seal very well with the errors between numerical results and experimental data are less than 10% for two-thirds of the data points.