Why are wind turbine blades so narrow?

Lever principle: The longer the arm, the lower the force required, so the long fan blades can also be blown away by small winds. The larger the surface area of ​​the fan blades, the greater the air resistance. If the fan blade is very wide and a strong wind blows, the fan blade will be blown over by the wind. Wind turbines are used to absorb wind energy rather than block it. The three-leaf blades and small width (strength) currently used can absorb wind energy to the maximum when rotated. If the blades are wider, it will affect the airflow through the rotation plane of the blades, which is not conducive to the absorption of wind energy when the wind speed v1 in front of the rotation plane of the rotor and the wind speed v2 behind the plane are equal. in a certain ratio, the yield is the highest, which is 59.3%. Incomparison, the so-called material savings, costs and charging problems are not major problems. The key is to use this form to achieve higher absorption efficiency. If you are interested, you can search for Bates theory and Ye Su theory. Does the low-strength, few-blade wind rotor allow most of the airflow to escape? Low solidity wind turbines operate at high speeds and the linear speed of the blades is several times higher than the wind speed. They can sweep away most of the passing airflow, leaving only a small portion that does not pass through the blades. the passing airflow turns the blades and most of the wind energy is harnessed. Many experiments have been carried out at home and abroad to select the appropriate number of blades. Two, three and four blades are commonly used choices forwind turbines, three blades being the most used. Of course, the choice of three blades also depends on the structural strength, manufacturing cost, noise, appearance and other reasons of the wind turbine. The multi-blade wind rotor has high strength and a relatively low wind energy utilization rate. But multi-blade wind rotors also have advantages. The output torque of a wind rotor of the same diameter is much higher than that of a wind rotor with small blades, and it has strong starting ability at low wind speed, so it is often used. used in rural water pumping and grinding. In areas where the wind speed is stable, especially in areas with low wind speed, it is possible to achieve better wind energy utilization effects by using 4-8 blade wind turbines in operation. different uses.