Empirical relationship with experimental model test results on change of blade number of Kaplan turbine on flow and efficiency characteristics

Abstract Axial flow Kaplan turbines with moveable guide vanes and rotating runner blades presents a complex flow. Turbine performance is dependent on loss and flow characteristics of different components. The runner is the heart of turbine and its design being the most dominant effect on performance of turbine characteristics in the turbine space. Blade design is combination of profile and solidity, the solidity was changed by changing number of blades and its effect on characteristics was investigated by model testing. In this paper an empirical relationship has been derived based on actual model test as per IEC 60193:2019 of all three types of Kaplan model with vertical runner, Tubular model with horizontal runner, and Bulb turbine model with horizontal runner. The relationship was investigated by changing the runner blade numbers 3, 4 or 5 on flow & efficiency characteristics. The experimental results analysis depicted a relationship in all three types of models having different blade profiles. Relationship among unit parameters like specific speed (n QE ) Discharge factor (Q ED ) and Speed factor (n ED ) were derived by regression analysis of test data.