Causes of abnormal over-vibration of axial fans

When mechanical products are in use, it is difficult to avoid problems. We only need to find the cause of the problem and deal with it in time. When the axial flow fan is in use, a slight sensation is inevitable. As long as the sensation amplitude of the cooling fan does not exceed the standard rules, it can be attributed to the sensation. If the oscillation amplitude of the cooling fan increases at the original level, especially Exceeding the oscillation value permitted by the specification is abnormal oscillation. Any kind of abnormal oscillation has the potential to damage the equipment.

There are many factors for the abnormal oscillation of the axial fan, such as mechanical reasons, medium fluidity reasons, rotor thermal deformation, conflict oscillation and other reasons. The abnormal vibration of the cooling fan may be due to the mechanical reasons such as low rotor balance, unreasonable structure, poor device accuracy, excessive coupling coaxiality, and excessive closeness of the rotor speed to the critical speed, etc., which are all problems that need to be considered and eliminated.

Reasons for medium fluidity:

Because the fan blade is impacted by the unbalanced air flow, the way to avoid the air flow excitation can be to eliminate the excitation by changing the characteristics of the intake air flow of the cooling fan. The characteristic of the oscillation caused by the thermal deformation of the rotor is that the increase of the double-frequency amplitude is closely related to the rotor temperature and gas parameters. Most of them occur when the axial flow fan starts in the cold state to the load stage. At this moment, the temperature of the rotor gradually increases. The material is due to internal force. The release causes thermal deformation and causes abnormal oscillation of the axial fan.

Conflict and oscillation, because the cooling fan forms a certain conflict during the operation. For the rotor, the conflict can cause phenomena such as flutter and vortex, but the practice is that the rotor is thermally bent. The dynamic and static conflicts are caused by the different levels of conflict on the circumference. The temperature of the heavy conflict side is higher than the temperature of the light conflict side, resulting in the uneven radial temperature of the rotor and the occurrence of a new imbalance, which will cause oscillations on the rotor.