Aerodynamic Simulations for Floating Darrieus-Type Wind Turbines with Three-Stage Rotors

Abstract

Growing energy demand is causing a significant decrease in the world’s hydrocarbon stock in addition to the pollution of our ecosystem. Based on this observation, the search for alternative sorts of energy to fossil fuels is being increasingly explored and exploited. Wind energy is experiencing a very important development, and it offers a very profitable opportunity for exploitation since the wind is always available and inexhaustible. Several technical solutions exist to exploit wind energy, such as floating vertical axis wind turbines (F-VAWTs), which provide an attractive and cost-effective solution for exploiting higher resources of offshore wind in deep water areas. Recently, the use of the Darrieus vertical axis wind turbine (VAWT) offshore has attracted increased interest because it offers significant advantages over horizontal axis wind turbines (HAWTs). In this context, this article presents a new concept of floating Darrieus-type straight-bladed turbine with three-stage rotors. A double-multiple stream tube (DMST) model is used for aerodynamic simulations to examine several critical parameters, including, solidity turbine, number of blades, rotor radius, aspect ratio, wind velocity, and rotor height. This study also allows to identify a low solidity turbine (σ = 0.3), offering the best aerodynamic performance, while a two-bladed design is recommended. Moreover, the results also indicate the interest of a variable radius rotor, as well as the variation of the height as a function of the wind speed on the aerodynamic efficiency.

Double-stage Savonius and Darrieus wind turbines for urban areas using fiberglass materials

“…Darrieus turbine in this study uses the NACA 0030, with variations in the pitch angle as shown in Figure 1, wherein each test of the pitch angle remains the same throughout the turbine rotation. This Darrieus turbine blade was chosen because it has the best performance based on its shape with no basin to increase the thrust [27]. Besides, based on Subramanian et al [28], who examined the Darrieus turbine using CFD simulations, obtained that the best value of Cp and TSR was NACA 0030.…”

“…The ratio between the mechanical power of the rotor and the mechanical power of the wind passing through the rotor, described as follows (27,35):…”

“…TSR is the ratio of rotor speed to wind speed. Wind speed will affect the rotational speed of the turbine rotor so that the power produced is highly dependent on the TSR, with the equation (27,35):…”

“…Numerical results obtained by the mechanics simulations determine a solidity rotary engine (σ = 0.3), providing the simplest mechanics performance. A two-blade stage is suggested to reduce the rotor weight, lowering the cutin speed [27]. The turbine radius influences Cp, where the increasing radius decreases Cp.…”

“…The turbine radius influences Cp, where the increasing radius decreases Cp. An interesting thing happens when the radius increases, the power generated increases [27]. The optimization process also considers airfoil design to improve aerodynamic and structural performance with the integrated airfoil theory method [4].…”