Design and Analysis of a Kaplan Turbine Runner Wheel

The demand for renewable energy sources such as hydro, solar and wind has been rapidly growing over the last few decades due to the increasing environmental issues and the predicted scarcity of fossil fuels. Among the renewable energy sources, hydropower generation is one of the primary sources which date back to 1770s. Hydropower turbines are in two types as impulse and reaction where Kaplan turbine is a reaction type which was invented in 1913. The efficiency of a turbine is highly influenced by its runner wheel and this work aims to study the design of a Kaplan turbine runner wheel. First, a theoretical design was performed for determining the main characteristics where it showed an efficiency of 94%. Usually, theoretical equations are generalized and simplified and also they assumed constants of experienced data and hence a theoretical design will only be an approximate. This was confirmed as the same theoretical design showed only 59.98% of efficiency with a computational fluids dynamics (CFD) evaluation. Then, the theoretically proposed design was further analysed where pressure distribution and inlet/outlet tangential velocities of the blades were analysed and corrected with CFD to improve the efficiency of power generation. The original design could be improved to achieve an efficiency of 93.01%. In general, the blades’ inlet/outlet angles showed a significant influence on the turbine’s power output. Finally, a comparison of the optimised and theoretical design is presented.