effect of damping element damage under erosion on vibration behavior of an industrial gas turbine group-blades

The last stage blade rows of modern low-pressure gas turbines are subjected to high static and dynamic loads. the centrifugal forces primarily cause the static loads due to the gas turbine’s rotational speed. dynamic loads can be caused by stationary gas forces, for example. a primary goal in designing modern and robust blade rows is to prevent high cycle fatigue caused by dynamic loads due to synchronous or non-synchronous excitation mechanisms. damping elements are one of the most common structures to alleviate excessive vibration amplitudes in turbomachinery applications. this paper deals with fracture investigations of the gas turbine blade of a 15 mw gas injection station in the national iranian south oil company in the southwest of iran. macroscopic and scanning electron microscopy images of the fracture section of the tube show two phenomena erosion and fatigue. therefore, to more accurately identify the cause of the failure, stress and vibration analysis of the blade is performed individually and coupled with other blades by the connecting tube using ansys software. to validate finite element results, the modal test of a single blade and group of blades is done. according to the observation of fatigue at the section of the tube failure and the possibility of error in the design, the sensitivity measurement of the diameter and installation position of the tube is done.