Among all kinds of fan products, the structure of centrifugal fan is relatively simple and convenient to manufacture. According to its machine number, size and purpose, its structural form is also complex and simple.
Generally, the structure of centrifugal fan below No. 6 is the simplest, and the impeller is installed on the motor shaft. Complicated is the boiler and coal mine with double suction or single suction large fan. The fan is composed of impeller, casing, transmission parts and support parts. The impeller is composed of shaft disc, rear disc, front disc and blades. The impeller and the main shaft are called rotor together. The casing is composed of volute, air inlet and air outlet. The transmission parts are composed of main shaft, bearing and pulley.
Some fans are driven by coupling link. The supporting part is composed of bearing seat and base. The air inlet, impeller, volute and air outlet are the same flow parts of the fan, even if the fan sucks and transmits gas.
Today, we will show you the characteristics of several impellers of centrifugal fans. The inlet and outlet directions of centrifugal impellers are 90 ° and ° respectively. Centrifugal impellers can be divided into forward curved impellers, backward inclined impellers and backward curved impellers.
1. Forward curved impeller: the included angle between the air flow direction and the linear speed direction of the blade is an acute angle.
Features: low speed, large air volume, low static pressure (relatively backward inclined, backward curved impeller), simple forming process and low cost. Excessive rotating speed of forward curved impeller will cause motor overload, so the fan using forward curved impeller is not allowed to operate without load.
2. Backward inclined impeller: the included angle between the air flow direction and the linear velocity direction of the blade is an obtuse angle, and the blade is in the form of straight plate.
Features: high speed, wide speed range, small air volume, high static pressure, no overload and high efficiency. (compare with forward curved impeller)
3. Backward curved impeller: the included angle between the air flow direction and the linear velocity direction of the blade is an obtuse angle, and the blade is in the form of curved surface.
Features: high speed, large air volume (larger than backward inclined impeller), higher static pressure, higher efficiency and no overload.
The fan performance of backward curved impeller is very similar to that of backward inclined impeller, but the backward curved impeller has higher efficiency, more stable performance and more difficult processing technology. It is widely used in the field of high-pressure fan.
