Author :

K Ravi Prakash Babu, B Raghu Kumar, K Mallikarjuna Rao

Abstract :

The study of vibration response of a turbine blade helps the crack presence in a blade which alters its dynamic characteristics. The change is characterized by changes in the modal parameters associated with natural frequencies. In this paper, comparison of vibration response is made between first stage LP steam turbine blade and last stage LP steam turbine blade in the presence of a crack like defect. Turbine blade is initially assumed as a cantilever beam. Utilizing ANSYS software first stage blades are modeled as thick beams where as last stage blades are modeled as thin beams. From the analysis, it has been observed that the crack depth and its location have noticeable effect on the modal parameters. The natural frequencies of thick beams are high compared to thin beams. It is also observed, for the same crack depth ratio and crack location ratio the modal parameters have more appreciable change for thick beam when compared to that of thin beam.

Keywords :

Vibration response, Finite element analysis, Turbine blade