Why the blades of the axial flow fan are odd and not even

First of all, many people find that the structure of the cold axial cooling fan blade is composed of odd numbers such as 5, 7, 9 and 11, but many consumers are not very familiar with it and are curious. Here is a brief share of the wonders of the axial cooling fan blade. Place.　　Because the even-numbered axial flow cooling fan blades are symmetrical, this not only makes it difficult to adjust the balance of the cooling fan, but also makes the cooling fan easy to resonate, resulting in blade or shaft fracture, so odd-numbered blades are used. Mainly due to balance considerations, it is well known that the actual heat dissipation efficiency of the radiator largely depends on the design of the blade inclination angle and the number of blades. Among them, the number of leaves plays an important role. Generally, in the design of the cooling fan, the radiator manufacturers use the method of increasing the number of blades to ensure a certain air volume and pressure.　　 Generally speaking, narrow blades have a larger blade pitch, which will cause airflow to be dispersed and weaken the cooling performance of the radiator fan. If the axial cooling fan blades are added, the spacing will be reduced and the air flow will be more concentrated, thereby improving the cooling performance of the cooling fan.　　 When other parameters remain unchanged, the more the number of axial cooling fan blades, the greater the air volume. The main reason is that because the blades divide the airflow into several parts, the pressure of the airflow on the cooling fan blades will be reduced correspondingly, and the friction between the airflow and the blades will also be reduced accordingly.　　 With the increase of the axial flow cooling fan blades, the friction between the airflow and the blades is reduced, and the corresponding noise is also reduced. However, the wind shear noise is not considered, and its increase will lead to the bottom of the wind pressure drop.