Evaluation of premature failure of a gas turbine component

Abstract

A case study of certain gas turbine stator vanes which fail prematurely is presented, with a view to determining whether operational procedure might have caused the failures. The engines had been operated from a ‘hot-and-high’ environment, and this could have contributed to the failures. Computational fluid dynamics (CFD) techniques were employed in order to obtain an accurate design point thermal history. The resulting convection boundary conditions were then interpolated over a finite element mesh. Transient thermal and stress analyses were performed. At the same time, micro structural analyses of the service-exposed material were carried out to estimate the maximum temperature seen by the component. These showed that higher than expected vane metal temperatures were experienced. Emphasis was placed on the procedures outlined in the USAF Engine Structural Integrity Program, since little detail was known about the actual engine operating histories.