Actually, there are single-blade and two-blade wind turbines. But the most common number of blades in modern wind turbines is three, the result of compromises between various aspects and parameters during the design process. These aspects include, but are not limited to: aerodynamics, energy conversion efficiency, manufacturing and maintenance costs, system reliability, noise and aesthetics. From a simple analysis of technical parameters, a larger number of blades can:
(1) Increase mechanical torque;
(2) Increase power output;
(3) Reduce the maximum rotation speed;
(4) Increase manufacturing costs and make maintenance more complicated and difficult. Therefore, motors with a large number of blades are more suitable for operation in low-speed locations, such as water pumps and grain grinding motors. Wind turbines expecte the blades rotate at a relatively high speed, so the size of the generator located in the center of the blades (at the top of the tower) does not need to be large to meet the frequency requirements of the grid. Additionally, wind speeds generally increase at higher altitudes. As the wind turbine tower is very high, the blades are also very long (40m-60m*). There is a significant difference in wind speed between blades rotating to a high position and blades rotating to a low position. If the generator has only two blades, then when the blades rotate, one in the up position and one in the down position, their stress is obviously not uniform enough, so a stronger and more stable tower must be designed to maintain the generator and blades. The three-blade generator can alleviate this imbalance to some extent, allowing it to operate more smoothly. Smooth means less noise, less wear.