engleski

TURBULENT FLOW SIMULATION IN KAPLAN DRAFT TUBE

This work was motivated by a need for validation of commercial CFD fluid flow solver for hydraulic turbine flow simulations. For the same reason, the ERCOFTAC draft tube has been used for many years as a base for evaluating the state-of-the-art CFD (Computational Fluid Dynamic) codes in the field of hydropower generation. Probably one of the most interesting parts, from the aspect of efficiency, is a hydraulic turbine draft tube. Its role is to increase the pressure head by converting outlet kinetic energy into static pressure and therefore impacts directly on the total efficiency of the hydropower plant. Draft tube fluid flow is difficult to predict numerically due the highly swirled, fluctuating and non-uniform flow that leaves the rotating runner and enters the draft tube. Without visualization of the fluid flow simulation results, only pure intuition existed of what the fluid flow in hydraulic turbines looks like. From the flow simulations results the fluid flow behavior inside draft tube can be understood in sufficient detail and this knowledge can be used to designe new generation of the draft tubes or revitalize old ones.

CFD; Numerical simulation; Kaplan turbine; Turbulence models; Fluent

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