Introduction
In the world today, the need to use renewable sources of energy has risen drastically. Wind energy has been observed to be the best producer of renewable energy. A device used to trap energy from the wind is known as a wind turbine. The wind turbine has many important parts that enhance its performance, for example, the blades. Blades are the most significant piece of the wind turbine; they are the source of power that propels the generator (Paraschivoiu 57). Blades rely on the speed of the wind to move. However, the efficiency of the blades can be improved by shaping them using an airfoil design; this is important especially for areas with low wind speed.
Nature of the wind turbine blade airfoil design and related fields
The turbine intermingles with the wind through the blades. Aerodynamic effectiveness is the most significant feature of wind turbines, which depends on the shape of the airfoils making the blades. The blades apply aerodynamics to get the wind energy, which is transformed into electricity. The airfoil design of the blades affects the aerodynamic pressure on the blades. Airfoil design shows varying features from the top of the blade to the bottom while holding the structural needs of the blade. They noticeably raise the energy output of the wind turbine (Petersen 115).
In the inverse design, the airfoil exterior flow is set at particular working conditions and a shape is designed that will produce the surface conditions. This design has inadequate abilities because there is only one target pressure allocation at a single established point. However, the direct design founded on numerical optimization, has many targets for pressure distribution. Moreover, it has diverse designs where many design constraints can work at the same time.
The feature of a perfect airfoil blade relies mainly on the particular target rotor. The lift-drag fraction should be great for all angles of attack beneath maximum lift to achieve considerable energy output and for excellent off-design features. The design direction of attack should be near maximum lift for airfoils applied on the exterior of the blades to decrease blade area. The maximum lift should be great for thick airfoils applied on the inside section of the blade to decrease the blade area. The maximum lift should not be affected by edge coarseness which is a normal factor caused by dirt. On the inside blade part, the airfoils should have great rigidity, to decrease blade load and tip deflection got by rising the maximum width. The best airfoil features contain both aerodynamic and structural elements (Leishman 92).
Airfoils with appropriate features are crucial to decrease the expenses of producing energy. The airfoils that are presently used vary from NACA airfoil initially made for airplanes to devoted wind turbine airfoil. The extraction of energy from wind using a turbine relies on its effective performance and aerodynamic shape, and other standards of proficient design. The basic theory of a wind turbine is easy. The wind moves through the turbine and rotates the blades, transforming the kinetic energy of the wind into rotational energy for the turbine. The rotational energy can be exploited to create work, which is produced as electric power from a generator linked to the turbine shaft (Manwell, McGowan & Rogers 28).
Wind turbines are exposed to complex environmental conditions that are not exposed to the helicopter rotors. This comprises of ground border layer effect, atmospheric turmoil, or the impact of other wind turbines. As a result, the wind turbines work in an unfavorable, 3-D, uneven aerodynamic setting that is difficult to establish. Consequently, there have been problems in shaping wind turbines that can work consistently and efficiently for many years (Paraschivoiu 60).
A smooth airfoil is required for a wind turbine to work effectively. In theory, the blade should have a more geometric flexibility design with suitable computational expenses. The design work is described by the design constraints, working conditions, and design goals. The geometry of the blades is resolved by the ability to convert more energy from wind into electric power. Therefore, the aerodynamic structure of the wind turbine should execute the least induced loss standard (Petersen 118).
The design features of the airfoils have been restructured over the years and modified to the precise form of power control and the requirement for the off-design process. The target airfoil features can be classified into structural and aerodynamic traits. The wind turbine can be classified into the root, mid, and tip sections and is mainly established by structural features. However, the tip is established by aerodynamic conditions.
The most significant consideration for the exterior section of the blade is the maximum airfoil breadth. The breadth of the profile must handle the structure required for blade force and firmness. Based on the category of the wind turbine, specific standards for the blade are required to increase its efficiency. From the aerodynamic perspective, the most significant factor is aerodynamic efficiency. For the turbine to work effectively, the aerodynamic efficiency should be great. However, other factors should be regarded such as stall performance and the C LMAX (maximum airfoil lift coefficient). Airfoils with a high value for CLMAX and CL (airfoil lift coefficient) use a lower chord for a specific weight; this decreases weights underfilled conditions at high wind velocity (Manwell, McGowan & Rogers 35).
A smaller chord in the outboard segments also decreases the load. Moreover, a high CL number in the outboard segment decreases the height of weight change produced by wind gusts. Therefore, a high CL is required to decrease fatigue and parking weights. However, the stall can be sudden and unwanted vibrations can be provoked on the blade. Therefore, it is crucial that the change and the partition move steadily when the angle of attack raises. Another significant issue is linked to the sensation of the airfoil to the coarseness. An airfoil with a big laminar surge extension will be effective in clean setting, but very bad in case of an unclean environment (Wei 70).
Another issue connected to designing airfoils is linked to gusts. Gusts can influence the angle of attack therefore it is essential to keep good off-design operation and achieve an angle of attack varying between the design angle of attack and the one for which, noticeable separation occurs on the airfoil (Leishman 95).
Conclusion
The traditional airfoils had several limitations when used in wind turbines; stall-controlled HAWTs created much energy in high winds. As a result, the generator was destroyed. Scientists began to form designs that would improve the performance of the airfoils. Therefore, the selection of airfoils and the shape of wind turbine airfoils blades had to be modified to get effective and consistent performance (Petersen 120).
As a result, the design of airfoil-shaped blades was crucial for the ongoing advancement of wind turbines. Wind turbine airfoils should vary from previous aviation airfoils in shape, features, and structural aspects. The growth of wind turbines has been continuing since the mid-1980s and commendable work has been done by Tangler and Somers who have made many airfoil designs (Wei 79).
Works cited
Leishman, Gordon. Principles of helicopter aerodynamics. New York: Cambridge University Press, 2006.
Manwell James, McGowan Jon, Rogers Antony. Wind Energy Explained: Theory, Design and Application.UK: John Wiley & Sons Ltd, 2010.
Paraschivoiu, Ion. Wind turbine design: with emphasis on Darrieus concept. Canada: Polytechnic International Press, 2002.
Petersen, L. European Wind Energy Conference: wind energy for the next millennium. London: James & James science publishers, 1999.
Wei, Tong. Wind Power Generation and Wind Turbine Design. WIT Press, 2010.