Cooling fans are usually divided into three categories:

 

1. Axial flow: The direction of air outlet is the same as that of axis.

 

2. Centrifugal type: Use centrifugal force to throw the airflow out along the blade.

 

3. Mixed flow mode: having the above two air flow modes.

 

 

Speed refers to the speed of fan rotation, which is usually measured by the number of turns in one minute, namely rpm. The rotational speed is related to the number of winding turns, diameter, outer diameter and bottom diameter of fan blade impeller, blade shape and bearing used, etc. The rotational speed increases, and the air volume increases accordingly.

 

The value of rotational speed, to a certain extent, represents the size of the air volume. Under certain conditions, the greater the rotational speed, the noise and vibration will increase correspondingly. Therefore, when the air volume meets the heat dissipation requirements, the low-speed fan should be used as far as possible. General speed (taking DC axial fan as an example): 2510 fan 7000-12000rpm; 3010 fan 5000-9000rpm; 4010 fan 5000-7000rpm; 5010 fan 3500-5000rpm; 6025 fan 2600-4500rpm; 7025 fan 2400-3600rpm; 8025 fan 2000-3500rpm; 9225 fan 1600-3100m; 12025fan 1500-2500rpm; 12038fan 2000-3200rpm. Fan speed can be tested by BIOS when starting the computer, or by the monitoring software of other motherboards; it can also be tested by speed tester. Note: The first two methods must be fan which supports speed measurement function.