Optimized blade tip clearance process for a rub tolerant design

Abstract

A process for optimizing a blade tip clearance for a rub tolerate design in a gas turbine engine that includes evaluating a selection of candidate materials for galling and heat generation, selecting a subset of the candidate materials and analyze engine transient tip clearance for the subset materials, verifying the optimum material cooling and heat shielding for tip clearance and structures, and analyze and select an engine break-in procedure for the optimum tip clearance between turbine and compressor. If one of the subset materials results in a poor performance, than another material from the candidate materials is selected and reanalyzed until the best materials have been found. When the best materials are found, then a finite element method of analysis is performed from the blade and the static parts that form the tip clearance is performed to evaluate the materials for damage. If required, the blade and tip squealer configuration is altered to reduce stress, or blade tip coating is used. If a micro-crack in the static part will propagate, then the configuration of the hooks, scallops and the part thickness is reconfigured to reduce stress. Then, a #D analysis is performed for out-of-roundness, centerline bending and rotor sag. The design configuration and manufacturing is reiterated in order to optimize out-of-roundness.