In an effort to reduce this gap during the design of a new SWT, the scope of the study was twofold. Over the years, these small machines have not received the same level of aerodynamic refinement of their larger counterparts, resulting in a notably lower efficiency and, therefore, a higher cost per installed kilowatt. While most wind energy comes from large utility-scale machines, small wind turbines (SWTs) can still play a role in off-grid installations or in the context of distributed production and smart energy systems. Experimental approach and measurement techniques are discussed for the design and testing of wind turbines. General design criteria for wind turbines are summarized. Effects of diffuser on produced power, airfoil types used in wind turbine blades, measures for stall delay on rotor blades and different ways of turbine operation are among topics to be considered. Since numerical solutions have large uncertainty for off-design conditions, experimental study is still dominant way of testing new turbine rotors for extreme and non-operating conditions. Advances in turbulence models have yielded successful performance prediction of wind turbine rotors. In the second part of this paper, recent experimental-numerical approaches in the aerodynamic and structural performance analysis of wind turbines are reviewed and discussed. Despite fast increase in installed wind power in recent years in Turkey, new investments should follow on this line considering that Turkey benefits only small portion of its wind potential.
China, USA and Germany are the leading countries in this respect. Installed power in wind energy has reached huge amounts in some industrialized and developing countries during recent years and total of 539 GW in the world as end of 2017. In this paper, first rapidly growing wind energy industry in Turkey and the world scale is reviewed.
Countries that do not have enough underground resources are wishing to reduce their energy deficit by renewable energy resources. On the other hand, the investment cost of renewable energy plants has decreased to competitive level against power plants working with natural gas, coal and other petroleum products. Renewable energy is getting more popular all around the World due to increasing concerns about fossil fuel effects on our home earth. The paper gives a brief knowledge about wind turbine aerodynamics, airfoil design and characteristics, blade structure and control from recent publications. In this review we tried avoid from numerical calculations, so the nontechnical audience can use this for reference purposes. During the review process, it is found that while designing airfoils there is only a few research was conducted on reducing the noise out of blades, which is a great concern for neighborhoods close to wind farms. To achieve optimal control aerodynamics and protect environmental damages of blades the morphing concepts, and electro-thermal anti-icing systems tends to be the promising solutions.
The recent publications on design structures for wind turbine blades are reviewed. The most common airfoil designs from several developers were addressed. When designing the airfoil for wind turbine, the aspects like insensitivity to roughness, high drag to lift ratio, stable stall characteristics must be considered. The geometrical shape of an airfoil, including trailing edge, leading edge, chord length, thickness, suction and pressure regions with structural and aerodynamic properties are discussed. The imaginary cross section of each region from root to tip of the blade is called airfoil. In order to generate optimum lift on blades, we need to consider the main factors such as: speed and density of the wind, surface area, lift coefficient. While the size of the wind turbine is increasing, it is important to create optimal blade designs to generate higher lift, and provide maximum torque to the generator. The performance of the aerodynamic system of wind turbine plays crucial role to get maximum torque from wind power, which is key parameter to generate power.
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