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Air flow:
Air flow refers to the total volume of air discharged or absorbed by the cooling fan per minute. If calculated in cubic feet, the unit of air flow is CFM.
So if you measure it in cubic meters, it's CMM.
The unit of air volume often used by cooling fans is CFM(about 0.028 m3 / min).
Air flow is the most important index to measure the cooling capacity of a cooling fan.
Obviously, the higher the air flow, the higher the cooling capacity of the fan.
That's because the heat capacity ratio of air is constant, and more air, more air per unit time, carries more heat.
Of course, the effect of the same amount of air is related to the way the air flows.
Air pressure:
Air pressure and air flow are two relative concepts.
In general, in order to design a fan with a high volume, the manufacturer has to sacrifice some air pressure in order to save costs.
If the fan can bring a lot of air flow, but the wind pressure is small, the wind is less than the bottom of the radiator (this is why some of the fan speed is high, the volume is very big, but it is the reason why the cooling effect is not good), on the contrary, the air pressure high often means that the air flow is low, there is not enough air and heat sink for heat exchange, also causes the cooling effect is not good.
Fan speed:
Fan speed refers to the number of fan blades rotating per minute in RPM.
The fan speed is determined by the number of turns of the coil in the motor, working voltage, the number of fan blades, inclination Angle, height, diameter and bearing system.
Speed and fan quality are not necessarily related.
The fan's speed can be measured by internal speed signals or by external measurements.
With the change of application condition and ambient temperature, different speed fans are sometimes needed to meet the demand.
Some manufacturers have specially designed cooling fans that can adjust the speed of the fan, both detachable and automatic.
Manual is mainly to allow users to use low speed in winter to get low noise, use high speed in summer to get a good cooling effect.
Automatic type temperature-regulating radiator with a temperature control sensor, according to the current operating temperature automatically control the fan speed, the temperature is high to increase the speed, the temperature is low to reduce the speed, in order to achieve a dynamic balance, so that the wind noise and heat dissipation effect to maintain an optimal joint point.
Fan noise:
In addition to the cooling effect, fan noise is also a common concern.
Fan noise is the volume of noise produced by a fan at work. It is affected by many factors and is measured in decibels (dB).
When measuring the noise of the fan, the noise shall be measured in an anechoic chamber with the noise less than 17dB, one meter away from the fan, and aligned with the air inlet of the fan along the direction of the fan rotating shaft, and measured by A-weighted method.
The frequency spectrum characteristic of the cooling fan noise is also very important. Therefore, it is necessary to record the frequency distribution of the fan noise with the frequency spectrum instrument. Generally, the noise of the fan should be as small as possible, and there should be no different sounds.
