Calculation of Labyrinth Seals in the Secondary Air System of Aircraft Engine

Abstract

The labyrinth seals perform the important functions in the aircraft engine systems operation, which aim to reduce the air leakages and the mutual system interference reduction. The calculation of the labyrinth seal characteristics is performed simply by using the analytical relationships or the modern tools of numerical analysis. However, the seal operation specificity within the system of operating engine secondary streams imposes some additional difficulties manifested in the rotor and stator elements deformation forming a gap. In this paper, we analyzed the formation cases of axis symmetric and asymmetric forms of labyrinth seal gaps. For the case of symmetrical cone gaps formation the correction factors were obtained by using the Fluent analysis to assess the seal characteristics with the conical form of the gaps, compared with the seal with cylindrical shape concentric gaps at the minimum radial clearance. The algorithm of axis symmetric seal deformation at the calculation of the engine secondary air system is described. The asymmetric components of deformations for the rotor and the high-pressure compressor housing are analyzed separately. The high rigidity of the elements contributed to the emergence of low level asymmetric deformation, allowing exclude them at the calculation of the seal characteristics.