Napoved izkoristka nizkotlačne cevne turbine z numerično analizo toka (Efficiency Prediction for a Low Head Bulb Turbine with Numerical Flow Analysis )

This paper presents numerical analysis of the flow in a 3-blade bulb turbine. Numerically predicted efficiency values for maximal runner blade angle are compared to the measurements. A bulb turbine, for which deviation of steady state results from the measured values was extremely large, was chosen for analysis. Transient simulation with SST turbulence model did not give satisfactory results, but with SAS SST and ZLES models the agreement between numerical and experimental results was significantly improved. The interdependence between turbulence models, flow in the draft tube and calculated efficiency values can be seen. Also the effect of grid density on results is presented.