THERMAL STRESS ANALYSIS OF CERAMIC GAS-PATH SEAL COMPONENTS FOR AIRCRAFT TURBINES.

Stress and temperature distributions were evaluated numerically for a blade-tip seal system proposed for gas turbine applications. The seal consists of an abradable ceramic layer on a metallic backing with intermediate layers between the ceramic layer and metal substrate. The most severe stresses in the seal, as far as failure is concerned, are tensile stresses at the top of the ceramic layer and shear and normal stresses at the layer interfaces. A parametric study was carried out to evaluate the influence of various design parameters on these critical stress values. The influences of material properties and geometric parameters of the ceramic, intermediate, and backing layers were investgated. After the parametric study was completed a seal system was designed which incorporated materials with beneficial elastic and thermal properties in each layer of the seal. An analysis of the proposed seal design showed an appreciable decrease in the magnitude of the maximum critical stresses over those obtained with earlier configurations.