g
Inlet Vanes
inlet vanes
| g IN |
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n |
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cwt ”t | , modulates a fan’s capacity |
by “preswirling” the air in the direction of fan rotation before it enters the fan wheel. By changing the air’s angle of entry into the fan, the modulating inlet vanes lessen the ability of the fan wheel to “bite” the air. This reduces its airflow capacity which, in turn, reduces its power consumption and its ability to generate static pressure.
Inlet Vanes
static pressure
inlet vane |
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| input power | |
position (%) |
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80% 90%
100%
airflow | g IO |
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Inlet vanes actually alter fan performance, creating a new fan performance curve with each vane position. Notice that with each increment of vane closing, the power requirement becomes less. Therefore, with inlet vanes, fan energy savings are realized any time the load drops below the design airflow.
Inlet vanes can, however, cause significant acoustical tones at part load when applied to BI, AF, and vaneaxial fans.
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