What Are the Common Causes of Cold Air Blower Noise?

Noise generated due to the rotation of blades
When the blades rotate, they will friction or impact with the air. The faster the rotation speed, the higher the frequency of contact with the air, and the sharper the noise. When the width or thickness of the blades increases, this phenomenon becomes more obvious. The frequency of the noise is composed of multiple frequencies, and these frequencies are all related to the rotation speed of the blower.
When an axial - flow fan is equipped with moving blades and static blades, the number of blades of the two is preferably different to avoid greater noise resonance. However, whether it is an axial - flow or centrifugal fan, the one with a fast wind speed and high wind pressure generates more noise.

Noise generated when vortices are produced by the blades
During the operation of the blower, vortices will be generated on the back of the moving blades. This kind of vortex not only reduces the efficiency of the blower but also generates noise. To reduce this phenomenon, the installation angle of the blades should not be too large, and the bending of the fan blades should be smooth without sudden large changes.

Noise generated due to turbulent flow
When the air is flowing, if it encounters sharp obstacles, turbulent flow is likely to occur. Although this turbulent flow is different from the situation of vortices, it will also generate noise or a high - frequency whistling sound, which will also cause an efficiency loss for the blower.

Noise generated by resonance with the duct shell
The inner - surface joints of the duct and the blower shell should be flat to avoid roughness and tearing sounds. Since the connected pipelines can generate resonance, subtle sounds will be amplified, resulting in louder noise. In the design, sometimes sound - proof materials can be covered outside the duct to reduce noise.

Noise caused by factors other than the blower
In addition to the fixed noise of the blower itself, there are many other noise sources. For example, bearings may cause abnormal noise due to insufficient precision, improper assembly, or poor maintenance.

The motor part can also generate noise. Some is caused by poor design or poor manufacturing quality control, but sometimes it is caused by the internal and external cooling fans of the motor. Gears and belts can also generate noise due to friction. The noise generated by the resonance of other structures should not be ignored, which is sometimes caused by the imbalance of the machine body.