Structural Dynamic Analysis Approach Used in a GE Heavy Duty Gas Turbine Combustor for MTBM Enhancement

Gas turbine combustors are subjected to vibrations due to combustion dynamics pressure and rotor imbalance force which results in forced excitation of hardware. Such structural vibration leads to high cycle fatigue and wear out of contact interfaces of combustor, thus limiting hardware durability with reduced maintenance intervals. To have more realistic hardware life prediction for both failure modes, it is vital to understand structural dynamic behavior of combustor assembly in the presence of vibratory loads. This paper describes the methodology used in developing MS5002D LHE combustor assembly linearized finite element dynamic models, the strategy to calibrate them with experimental data and the approach used to perform a forced responded analysis with harmonically varying combustion dynamics pressure and rotor imbalance force. Study shows that with adopted approach, an acceptable modal correlation between the model and the experimental test rig can be achieved. The forced dynamic response analysis results, in terms of dynamic stress distribution, interface sliding displacements and contact loads, represent the needed inputs for life prediction and for addressing the design improvements.