Investigation of pitch chord ratio effect on axial hydro turbine performance

Abstract

The present study is aimed to determine the effect of pitch chord ratio on an axial turbine rotor blade design. The selected swirling flow criterion used in this study is mixed vortex. There are two models of turbine rotor that used in this study and called as Turbine 1 and Turbine 2. Both model use the same stator. Pitch chord ratio of Turbine 1 is calculated using constant diffusion factor, while turbine 2 using lift coefficient obtained from cascade analysis. Turbine design is performed through quasi 3 dimensional (Q3D) method where meridional channel from hub to tip is analyzed by actuator disc radial equilibrium method and blade to blade flow is analyzed using cascade panel method. Validation of the design is performed through computational fluid dynamic (CFD) to achieve the best performance and characteristic of each model. The result of CFD at the design point n 450 rpm showed that the Turbine 1 produces efficiency is about 85.16% while Turbine 2 is 86.82%. Turbine 1 requires greater mass flow rate than the Turbine 2. The power of Turbine 1 has increased with the increase of head, but there is decrease in efficiency when the head is increased. The power and efficiency of Turbine 2 will increase with the increasing of head, but the increasing of efficiency is smooth.