Determination of hydraulic losses in the flow passage between the guide vanes and runner of the Kaplan turbine

Abstract

Hydraulic losses in the region between the guide vanes and runner of a Kaplan turbine are commonly either neglected or considered a part of the total guide vanes losses. This paper focuses on the determination of these losses for a relevant range of operating modes of the Kaplan turbine model. The research was performed by numerical simulations using two turbulence models, wherein some of the results were validated by the available experimental data. The impact of swirl flow parameters, defined for referent inlet of the researched vaneless passage, on the hydraulic losses was considered. Based on the numerical and experimental results, a novel formula for determination of these losses is proposed. The contribution of the studied losses to the total turbine losses is also identified.