Characterization of Failed First-Stage Turbine Blade Cooling Passage of Gas Turbine Engine

摘要

The cooling passages of the first-stage high-pressure turbine blades of gas turbine engines are located and drilled at the manufacturing stage. The external wall thickness is a critical blade strength parameter and has to be inspected accurately and regularly when blades are routed through repair work shops. This paper investigates a case of two blades from two different blade sets that experienced cooling passage failure during repair, after serving less than 20,000 operating hours. The investigation covered material microstructure, hardness condition, and material thickness residual assessment, using an ultrasonic nondestructive technique between the first cooling passage and the external blade surface. It was concluded that the first cooling passage was inappropriately drilled during manufacturing.