Experimental evaluation of service-exposed Nozzle Guide Vane damage in a Rolls Royce A-250 gas turbine.

摘要

A comprehensive study was conducted to evaluate the degradation of damaged Nozzle Guide Vanes in a transonic annular cascade in the short duration facility at RMC. A custom test section was designed which featured a novel rotating instrumentation suite. This permitted 360° traverse measurements downstream of two unmodified turbine NGV rings from a Rolls-Royce/Allison A-250 turbo-shaft engine. Downstream total pressure was measured at four span-wise locations on both an undamaged reference and a damaged test article. Three performance metrics were developed in an effort to determine characteristic signatures for such common operational damage as trailing edge bends or cracked trailing edges. The highest average losses were observed in the root area, while the lowest occurred closer to the NGV tips. The results from this study indicated that multiple span-wise traverses were required to detect localized trailing edge damage. Recommendations have been made for future tests and test rigs, and for ideas to improve the performance metrics.;Keywords: Gas Turbine, Nozzle Guide Vane, Stator, High Pressure Turbine, Transonic, Annular Cascade IV.