Modelling, Fatigue Crack Growth Assessment and Modal Analysis for a Gas Turbine Compressor Blade

In this research, the fracture mechanics analysis for the 16th stage of a V94.2 gas turbine compressor blade under mechanical and thermal stresses due to rotation, pressure and temperature distributions in the full load steady state condition is studied using ANSYS finite element software. Modelling asymmetric sector of a balde-disk assembly with a ratio of 1 to 79, applying thermomechanical loading, boundary conditions and initial conditions, locations with high stress levels on the blade airfoil are recognized. Then, using ANSYS software to model some cracks with different sizes in two specified locations on the airfoil, the stress intensity factors are calculated. Moreover, by applying Paris relation, crack growth rate with respect to the stress intensity factors are drawn to estimate remaining life in the fatigue crack growth for the cracks with initial dimensions in these two locations. Finally, doing modal analysis, the operating frequencies of the blade are calculated and the Kampbell diagram, the interacting frequencies for the blade are also specified. The obtained results show that for these two cracks locations on the pressure side of the blade airfoil, by increasing the distance along the root of the compressor blade, the remaining life of the cracked compressor blade increases, accordingly.