1. System impedance

The range between the air inlet and air outlet of a shell accounts for 60% to 80% of the total system impedance. In addition, the greater the air flow, the higher the noise. The higher the system impedance, the greater the air flow required for cooling. Therefore, in order to minimize noise, the system impedance must be reduced to a minimum.

2. Airflow disturbance

Noise is generated by turbulence caused by obstacles encountered along the air flow path. Therefore, any obstruction, especially in the range of key air inlets and outlets, must be avoided to reduce noise.

3. Fan speed and size

Since high-speed fans produce more noise than low-speed fans, try and choose low-speed fans as much as possible. A fan with larger size and lower speed is usually quieter than a fan with lower size and higher speed when delivering the same air volume.

4. Temperature rise

In a system, the air volume required for cooling is inversely proportional to the allowable temperature rise. If the temperature rise is allowed to increase slightly, the required air volume can be greatly reduced. Therefore, if the restrictions imposed on the allowable temperature rise are slightly relaxed, the required air volume and noise will be reduced.

5. Vibration

In some cases, when the weight of the whole system is very light, or the system must operate in a specified way, it is particularly recommended to use soft isolation equipment to avoid the transmission of fan vibration.

6. Voltage variation

Voltage variation will affect the noise level. The higher the voltage added to the fan, the greater the vibration and noise due to the increase of rotating speed.

7. Design considerations

The design of each part constituting the fan will affect the noise level. The following design considerations can achieve noise reduction: the size of winding core, the design of fan blade and outer frame, and accurate manufacturing and balance.