Analysis of Fatigue Crack Propagation and Life Estimation of Pelton Turbine Bucket by Finite Element Method
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Date
2020-11
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Addis Ababa University
Abstract
The Pelton turbine bucket is subjected to different loads under the turbine operating conditions of
high rotational speed. One of the most catastrophic failures that could occur in a Pelton turbine is
the fracture of the bucket, where the hydraulic jet force is at its maximum and applied for various
cycles. The continual application of this cyclic load will result in nucleation and then fatigue crack
propagation. This failure of Pelton turbine bucket has a great influence on durability of the turbine.
The aim of this thesis is to analyze fatigue crack propagation and estimating the life of Pelton
turbine bucket. To do this, a governing equation for crack propagation and life estimation was
derived and a Pelton turbine bucket was designed.
The three-dimensional model of Pelton turbine bucket was modeled by commercial software
SOLIDWORKS. The modeled bucket was then imported to ANSYS 19 workbench. Finite
Element analysis was done after meshing, boundary conditions and applying load. Then, static
stress analysis and fatigue crack propagation of the turbine bucket was investigated using stress
intensity factors.
The stress-intensity factor was evaluated for each increment of crack depth and it was related with
fatigue crack growth rate. The fatigue crack life was then calculated for each crack increment. As
the result obtained, analysis of fatigue crack propagation and life estimation of the bucket are
discussed. And few recommendations are made for the future study.
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Keywords
Pelton turbine, Kinetic Energy, Potential Energy, Dynamic Loading, J-Integral, Stress Intensity Factor, Fatigue, Crack Propagation, Fatigue Life