Design and Performance Analysis of Axial Hydro Turbine with Criteria of Tangential Velocity and Constant Diffusion Factor

抄録

In reality, the flow condition inside meridional channel may vary from hub to tip, therefore meridional analysis will affect to the blade geometry whether is twisted or tapered. The prediction of maximum surface velocity is not easy, but Lieblein was postulated the alternative form of diffusion factor (DF) on airfoil which can be applied for the cascade analysis. Diffusion factor on cascade is an important design parameter to avoid cavitation in turbomachinery due to the pressure distribution and velocity variation on the surface. The purpose of present study is to know the influence of tangential velocity distribution and constant DF on the blade shape and performance of the axial hydro turbine. There are four criteria of tangential velocity distribution or usually is called as swirl velocity that discussed in this paper, they are mixed vortex, free vortex, forced vortex and constant vortex. Constant DF was applied to the all tangential velocity distribution to obtain pitch chord ratio calculation. This will affect to the pitch chord ratio value and the blade shape of rotor. Performance prediction of axial turbine is performed through Computational Fluid Dynamic (CFD) to validate global parameter design. The result of numerical simulation can be used as basic consideration for manufacturing and experimental testing.