1. Cooling fan system impedance
The range between the inlet and outlet of a cooling fan accounts for 60% to 80% of the impedance of the entire air supply system. In addition, the larger the air flow, the higher the noise. The higher the system impedance, that is, the greater the air flow requirement for heat dissipation, so if you want to reduce the noise, the impedance of the cooling fan and air duct should also be reduced to the minimum.
2. Disturbance of cooling fan airflow
Disturbance caused by obstacles encountered along the airflow path will generate noise. For example, the air inlet or air outlet should be slightly covered with fingers to reduce the noise. That is why the noise of the fan increases with the use of dust for a long time.
3. Cooling fan speed and size
Since the noise generated by the high speed fan is greater than that of the low speed fan, the low speed fan shall be selected as far as possible. A fan with large size and low speed generally has lower noise when delivering the same air volume than a fan with small size and high speed.
4. Temperature rise of cooling fan
The air volume required for cooling is inversely proportional to the allowable temperature rise within the requirement of a equipment heat dissipation parameter. If the temperature rise is allowed to increase slightly, the required delivery air volume can be reduced. Therefore, if the allowable temperature rise limit of the equipment is slightly relaxed, the required air volume will be reduced and the noise will also be reduced.
5. Cooling fan vibration
In the case of some equipment, the weight of the whole equipment is very light, as is the weight of the fan, but the equipment still needs to operate according to the original regulations. In this case, it is recommended to use soft insulating materials and buffer incoming materials to reduce vibration and thus reduce noise.
6. Cooling fan voltage variation
Voltage variation will affect the noise level. The higher the voltage applied to the fan, the higher the speed, the greater the vibration and the greater the noise.
7. Cooling fan design
The noise level will be affected by the design and material of each part that constitutes the cooling fan. The following design considerations can reduce noise: the size of winding iron core, the design of fan blades and outer frame, surface smoothness, material density, and dynamic balance treatment.
