Fan blades are the main components that receive wind energy. To obtain greater wind power, the key is to have blades that can rotate briskly. In addition to the design of the blade, it must have an efficient airfoil that accepts wind energy, a reasonable installation angle, a scientific lift-to-drag ratio, a tip speed ratio, and a blade torsion angle, but also a reasonable structure, high-quality materials and advanced craftsmanship. The blade has the ability to reliably bear wind.
The smoothness of the blade surface directly affects the frictional resistance between the blade and the air when the blade rotates. The fiber-reinforced composite material has the unparalleled superiority of other materials in terms of specific strength and specific rigidity, plus its fatigue resistance, structural stability, corrosion resistance and resistance. Excellent performance such as high temperature. Therefore, fiber-reinforced composite materials are currently the material of choice for wind turbine blades.
The relative advantages of fiber-reinforced composite fan blades
Compared with blades of other materials, composite fan blades have the following advantages:
- The strength and rigidity can be designed according to the force characteristics of the fan blades.
Fan blades are mainly subjected to longitudinal forces, namely aerodynamic bending and centrifugal force. The aerodynamic bending load is much larger than the centrifugal force, and the shear stress generated by shear and torsion is not large. Using the force theory based on fiber force, the main fiber can be arranged in the longitudinal direction of the blade, so that the mass of the blade can be reduced.
- The airfoil is easy to form and achieves maximum aerodynamic efficiency.
In order to achieve the best aerodynamic effect, the fan blades have a complicated aerodynamic shape. At different radii of the wind wheel, the chord length, thickness, torsion angle and airfoil of the blades are different. For example, it is very difficult to manufacture with metal. Especially large and medium-sized blades.
- Good vibration resistance, the natural frequency can be designed by yourself.
The composite material has large internal damping and good vibration resistance. It is an ideal material for making blades; and the natural vibration frequency of the blade can be designed and adjusted in a wide range to avoid the resonance zone.
- Higher fatigue.
The wind turbine blade uses 20a and has to withstand more than 108 fatigue cycles, so the fatigue performance of the material is better. The composite material has low notch sensitivity, and the gap expansion is restricted by intact fibers, which can improve the safety of the blade.
- Good corrosion resistance and weather resistance.
Wind turbines are installed outdoors. In recent years, offshore wind farms have been vigorously developed. Wind turbines are installed at sea. Wind turbines and blades must be affected by various climates. Select appropriate raw materials to make composite blades have good acid resistance and resistance. Alkali, seawater resistance, weather resistance and other properties.
- The maintenance is simple and easy to repair.
Composite fan blades generally do not require major maintenance except for proper maintenance (such as uniform painting) on the surface of the blade every millennia.