Numerical Investigation of Fatigue Growth Rate and Fracture Lifetime Estimation of Kaplan Hydraulic Turbine Runner Blade
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Date
2024-12
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Addis Ababa University
Abstract
Kaplan turbines are the most widely used hydraulic turbines around the world. Suitable for low head and high flow conditions. With these specific features Water sources are known for their efficiency in producing electricity. Kaplan turbine failures are often related to material defects, design flaw, Manufacturing errors, corrosion, fatigue, cavity wear, water erosion. The purpose of this thesis is to estimate the fracture life of Kaplan turbine blades by analyzing the growth rate of fatigue cracks. This includes the derivation of the governing equations for crack initiation, propagation and age estimation as well as designing Kaplan turbine blades. The model is developed and analyzed using ANSYS 2020R1 followed by static stress analysis and fatigue crack growth rate investigation using stress intensity factor and J-integral. The stress-intensity factor is evaluated for each increase in crack depth and is related to the growth rate of fatigue cracks. The lifespan of the fatigue rate and fracture life of runner blades is then calculated based on this relationship. Based on the result obtained, analysis of the fatigue crack growth rate and the estimated fracture life of runner blades are discussed and some recommendation have been discussed for further study.
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Keywords
kaplan turbine, Fatigue, fracture, runner blade, stress- intensity factor