The effects of geometric shapes at different assembly gaps to achieve the optimal hydrodynamic conditions

Abstract

In turbines, kinetic energy is transferred to the shaft then converted into a rotational motion to move a generator, so having a good design in the efficiency of turbines is important. Studies show that the efficiency of turbines in the presence of shafts has not been investigated so far. Therefore, our main goal in this study is to investigate the effect of shaft presence on the final efficiency of the hydro turbine. In this paper, the flow of fluid passing through the channels around the sharp leading edge cylinders in a tunnel is simulated using Lattice Boltzmann Method (LBM). Fluid streamlines stability, flow velocity rate, and pressure coefficient in channels with different shapes at assembly gaps of 2, 1.75, and 1.5 m have been investigated. The studied channels are considered in seven Airfoil-like shapes, Reverse Airfoil-like, hyperbola, Triangle, Triple triangle, Hexa triangle, and trapezoidal. The results show that the pressure coefficient in all channels decreases by increasing assembles gaps. On the other hand, reducing the pressure coefficient in the channel leads to cavitation. Cavitation causes erosion at the tip of the hydro turbine blades and reduces the life of the turbine. Therefore, the pressure coefficient is one of the most important parameters that depend on the assembly gap. Finally, the result shows that installing Hyperbola channels with an assembly gap of 1.75 m has the best performance in simulated hydro turbines.