ZAWARD Thermal Technology Insights
 

 
Fan Air Flow Measurement
 

 
Airflow is one of the key performance indicators when it comes to fan performance. The measuring instrument evaluates the airflow of DC fans and provides statistics for further improvements. In this issue, we will unveil from theory to functionality how measuring instrument works.
 

Ø Flowrate and static pressure

Numerous factors can affect the measurement of flow rate and static pressure; thus, precision measuring instrument is the key to getting accurate results.
Our automatic pneumatic tunnel apparatus is built per international standard of AMCA210. Its measuring range covers flow rate 3 ~ 250 CFM and static pressure 0 ~ 60 mmAq.
 

Ø Flowrate and static pressure measurement
 

 
Ø Test theory: Law of Continuity
The continuity of flow equation is one of the major tools of fluid mechanics, providing a means of calculating velocities at different points in a system. For steady flow in a stream tube, having a changeless cross-sectional area over any given cross-section, the mass of flow per unit time will be equivalent.
 
 Then: ρνS=Constant.
 
 

Suppose there are two different sections A and B in the stream tube.
At section A the cross-sectional area is S1, the velocity of flow is ν1 and its density is ρ1 At section B the cross-sectional area is S2, the velocity of flow is ν2 and its density is ρ2. Then: ρ1ν1S1 = ρ2ν2S2 = Constant
Since the flow can be considered incompressible,
so that ρ1 = ρ2, then: ν1S1 = ν2S2
 

 
 

Ø Adjust the auxiliary blower makes static pressure come to zero.

It gets the maximum flowrate point Qmax.
 

Ø Shut down the auxiliary blower makes the flow rate come to zero.

It gets the maximum static pressure point Pmax.
 

Ø Adjust different flow rate points of blower to get PQ curve.
To measure different flow rate points, the nozzle’s diameter needs to be adjusted. The pressure difference is caused between the front and rear chambers of nozzle; the pressure variation measured by the instrument is transferred to the computer. By the law of continuity, the change of pressure difference reaches equivalent air speed and flow rate (flow rate = air speed x nozzle section area)
 
 
Ø Flowrate conversion table
 

      Ø Static pressure conversion table

 
 
Zaward provides comprehensive product lines of thermal solutions. From DC/AC fan, diversified processes of heat sinks, to peripheral components such as heat pipes, fan guards, and thermal pads. We are always well prepared to solve any cooling issues with our best passion for customers worldwide.

Please kindly contact ZAWARD or visit our website for more information. Any inquiries of thermal solutions are welcome. If you have any questions, please feel free to contact us.
 

 
With best regards, 
ZAWARD CORPORATION
 

 
Carmen Chen/ Managing Director