Designing turbine engine components for high cycle fatigue robustness can significantly reduce operating costs and improve safety. However, obtaining an optimum design and getting the new hardware into service using traditional methods is an expensive process. A process that combines state-of-the-art computational fluid dynamics (CFD) analytical simulations with subcomponent rig testing has been developed and demonstrated on a gas turbine engine. The analytical method involves spatial Fourier decomposition of vane exit total pressure from steady flow calculations. This provides an efficient method to reduce the design space and eliminate poor designs, resulting in a small subset of near-optimum designs. To confirm that the remaining candidate designs provide less unsteady forcing and to validate the CFD analysis, a unique experimental test rig was constructed. The experiments consisted of flowing ambient air through a subsection of the engine, while measuring the exit total pressure flow field around the turbine rotor exit annulus with a unique traversing probe. The measured exit total pressure was then Fourier decomposed in space to understand the resulting unsteady forcing on the blade. The costs of the flow rig and producing numerous sets of candidate hardware were much less expensive than full-scale engine or rotating rig tests. New hardware designs tested in the rig were manufactured using a rapid prototyping procedure, which allowed for extremely quick turn around in going from design concept to experimental validation. Good correlation between analysis and test was found, except in a few cases. The majority of these discrepancies were attributed to excitation sources that were impractical to include in the CFD models. This finding indicated that there are still circumstances for which the analytical tools were insufficient and hence experimental validation is still important. Both the analysis and experiments confirmed up to a 50% reduction in the amplitude of unsteady pressure for this particular engine test case.

This content is only available via PDF.
You do not currently have access to this content.