There are many factors that affect the efficiency of centrifugal fans, among which the impeller blades are more direct. Generally speaking, the diameter of the impeller and the size of the blades will directly affect the air volume of the centrifugal fan, but the actual efficiency mainly depends on the structure of the blades. What are the blade forms of centrifugal fans?
1)The blade form of the centrifugal fan
1. Forward curved blades
The centrifugal fan with forward-curved blades has an acute angle between the airflow direction and the linear velocity direction of the blades, and has the advantages of low speed, large air volume, low static pressure (relative to radial, backward-curved blades), simple molding process, and low cost. features. Excessive speed of forward-curved blades will cause motor overload, so centrifugal fans using forward-curved blades are not allowed to run without load.
2. Radial blades
The radial blade is an obtuse angle between the airflow direction and the linear velocity direction of the centrifugal fan blade, and the blade is in the form of a straight plate. It is characterized by high speed, wide speed range, small air volume, high static pressure, no overload, and high efficiency (compared with forward curved blades).
3. Back bending pressing piece
The angle between the airflow direction of the backward curved blade and the linear velocity direction of the blade is an obtuse angle, and the blade is in the form of a curved surface. The characteristics of this centrifugal fan blade are: high speed, large air volume (larger than radial blades), higher static pressure, higher efficiency, and no overload. The fan performance of the backward curved blade is very similar to that of the radial blade, but the backward curved blade has higher efficiency, more stable performance, more difficult processing technology, and is widely used in the field of high pressure fans.
2)Selection method of centrifugal fan blades
The blades of a centrifugal fan are generally composed of 6 to 64 blades. When selecting, the fan blades with corresponding performance should be selected according to different needs. The selection of each blade is as follows:
1. The size and weight of forward-curved blades are small, and the blade type is generally narrower. There are more blades, and the price is cheap and easy to manufacture. The number of blades is large, so it is easy to accumulate dust and form dirt. Because of its high wind pressure and small air volume, it is generally used on 9-19 series and 9-26 series centrifugal fans. These series of centrifugal fans are generally used in occasions with relatively high requirements. .
2. Radial blades are generally used in centrifugal fans that require high wear resistance and corrosion resistance. The structure of radial blades is relatively simple, the production cost will be reduced, and the efficiency is relatively low. Therefore, the centrifugal fan that uses it is not Not many, but because of its simple structure, it has the advantage of not being easy to scale. The centrifugal fan used in the mine environment will choose radial blades, and the outlet angle of the radial blades is β2=90°.
3. The back-curved blade is a very powerful centrifugal fan blade, because it has a large air volume, low pressure but extremely high efficiency, excellent performance in all aspects, and is not easy to accumulate dust and dirt, so it is used by many industries. Applied, but the disadvantage is that the price is higher.
