Combustor Rebuild Effects on Gas Turbine Performance
The Institute for Aerospace Research of the National Research Council of Canada (NRCC), has established a program for the evaluation of component deterioration on gas turbine engine performance. The effort is aimed at investigating the effects of typical in-service faults on the performance characteristics of each individual engine component. As part of this project, a study of the effects of combustor rebuild tolerances on overall engine performance was undertaken. This study investigated the range of performance changes that might be expected for simply disassembling and reassembling the combustor module of a gas turbine engine, and how these changes would influence the results of any component modification testing. To evaluate the effects of rebuilding the combustor on the performance of a single spool engine, such as an Allison T56 turboprop engine, a series of three rebuilds was carried out. This study was performed in a similar way to two previous NRCC studies on the effects of compressor and turbine rebuilding. While the compressor and turbine rebuild studies found performance changes in the order of I% on various engine parameters, the effects of rebuilding the combustor have proven to be of similar magnitude. Based on the results of the combustor rebuild study, new methods to improve the assurance of the best possible tolerances during the rebuild process are currently being addressed. This paper describes the project objectives, the experimental installation, and the results of the performance evaluations. Discussed are performance variations due to combustor rebuilds on engine performance characteristics. As the performance changes were significant, a rigorous measurement uncertainty analysis is included.