On the Performance of Small-Scale Horizontal Axis Tidal Current Turbines. Part 1: One Single Turbine

Abstract

The blade number of a current tidal turbine is one of the essential parameters to increase the stability, performance and efficiency for converting tidal current energy into rotational energy to generate electricity. This research attempts to investigate the effect of blade number on the performance of a small-scale horizontal tidal current turbine in the case of torque, thrust coefficient and power coefficient. Towards this end and according to the blade element momentum theory, three different turbines, i.e., two, three and four-bladed, were modeled using Solidworks software based on S-814 airfoil and then exported to the ANSYS-FLUENT for computational flow dynamics (CFD) analysis. SST-K-ω turbulence model was used to predict the turbulence behavior and several simulations were conducted at 2 ≤ tip speed ratio ≤ 7. Pressure contours, turbulence kinetic energy contours, cut-in-speed-curves, and streamlines around the blades and rotors were extracted and compared to provide an ability for a deep discussion on the turbine performance. The results show that in the case of obtainable power, the optimal value of tip speed ratio is around 5, so that the maximum power was achieved for the four-bladed turbine. Out of optimal condition, higher blade number and lower blade number turbines should be used at less than and greater than the optimal values of tip speed ratio, respectively. The results of simulations for the three-bladed turbine were validated against the experimental data with good agreement.

Analysis of a Nature-Inspired Shape for a Vertical Axis Wind Turbine

“…According to this, it is important to minimize both thickness and thrust loading. To this end, the parameter SC Pmax , Equation (10) [53], represents the superiority of the maximum C P .…”

“…Pmax Pmax F C SC %t C (10) In the equation above, %t represents the thickness of the blade as percentage of the chord length. For instance, using a 5% thickness, the results corresponding to Savonius, Fibonacci I, and Fibonacci II are shown in Table 3.…”

“…In comparison with a Darrieus turbine, the Savonius is more recommended for urban environments due to its lower starting torque, i.e., it needs lower wind velocities for starting. In offshore applications, the Savonius turbine is appropriated as a hydrokinetic turbine to generate energy from tidal currents [9][10][11][12]. Despite these advantages, the main disadvantage of the Savonius turbine is its low efficiency [13,14].…”

On the Performance of a Modified Triple Stack Blade Savonius Wind Turbine as a Function of Geometrical Parameters

“…Therefore, for thousands of years, humans have used only a tiny part of it using windmills. However, due to environmental problems and climate change issues, there is a trend of reducing dependence on fossil energy resources and increasing the use of wind [9,10].…”