文章來源： 作者：羅茨機電 發布時間：2022-02-10 瀏覽次數：441
The centrifugal fan is composed of impeller, casing, air inlet, transmission group, base, etc. driven by the motor, the centrifuge rotor rotates at high speed to produce strong centrifugal force, so that the air flow inhaled from the air inlet generates centrifugal movement in the casing, and then is sent out from one side of the air outlet. It is usually used for air purification, dust removal and ventilation in industrial and mining enterprises and institutions. Due to manufacturing errors and uneven materials, when the fan is running, the air flow force on each blade and impeller is different, so the resultant force cannot be equal to zero. This produces aerodynamic interference force.
Why does Jinan centrifugal fan have aerodynamic interference force?
1. Interference force caused by blade difference
There are errors in impeller manufacturing, such as the angle and direction of each blade, and the clearance between wheel disc and wheel housing may be different. Due to different output, the sum of gas reaction forces received by each blade during operation is not equal to zero, resulting in aerodynamic interference force. The aerodynamic interference force increases with the increase of rotating speed and air volume.
2. Shaking interference between wheel disc and wheel housing
The end face runout of the wheel disc and wheel housing shall be controlled within a certain range to reduce the interference caused by vibration. The vibration of wheel disc and wheel housing will produce periodic interference force in the axial direction, and the shell will also produce vibration through air transmission.
3. Disturbing force of feedback air flow
There is a certain clearance between the impeller of the fan and the collector (air inlet). The existence of this gap will make part of the air flow return. This part of the air flow can be called feedback air flow. The stability of the feedback air flow will also affect the vibration of the fan. Therefore, during installation, the clearance between the impeller and the air inlet shall be uniform and the overlap shall be ensured. The purpose is to minimize and stabilize the feedback air flow, so as to reduce the vibration of the fan. Generally speaking, the smaller the feedback air flow, the higher the fan efficiency. On the contrary, the fan efficiency is low.
4. Pressure distribution difference in casing
When the impeller is running, the amount of air delivered is the same, but limited by the shell, the air can only move in one direction. Because the air pressure of each part of the shell is different. If Jinan centrifugal fan operates in a stable state, the pressure distribution in the fan is relatively stable and the vibration interference to the fan is relatively small. However, with the change of operating conditions, such as speed and damper opening, the pressure distribution in the fan will change, resulting in the change of vibration. This is one of the reasons why the vibration increases or decreases when changing the damper and speed. Interference exists in the change of operating state.
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