Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Abstract:
This paper presents the development and the application of fatigue cycles accumulation model suitable for industrial gas turbines operation. The model is developed from a model used by the US Air Force for aircraft engines. In industrial gas turbines, one fatigue cycle is counted in operating the engine to peak power level and shut down; also, daily operation and shut down constitutes one fatigue cycle. But greater variation in engine speed within any period of engine operation leads to greater fatigue life consumption; The developed model takes cognizance of this. The fatigue cycles are estimated from the variation of total stress resulting from the centrifugal stress and the bending momentum stresses imposed on the component concerned. The model is applied to the high pressure turbine blades of the GE LM2500+ type engine using real engine operation data and the fatigue cycles are estimated at the blade mean section. More fatigue cycles are obtained from the model compared to the aircraft model since the developed model takes into account every transition of engine shaft speed. The developed is intended to replace the traditional one fatigue cycle per engine shut down being practiced and provide results which are in line with the nature of engine operation.

Keywords: fatigue cycles, turbine blades, centrifugal stress, bending moment stresses, fatigue failure.

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