Vane axial fans are normally used when high static pressure and fan efficiency is required.
Two types of guide vanes exist
Outlet guide vanes: convert some of the turbulence created by the fan wheel or impeller to static pressure, thereby enhancing the fan's performance.
Inlet guide vanes spin the air in the opposite direction to the spin effect of the impeller. Thus when this spun air hits the impeller, the vane's spin cancels out the fan wheel's spin.
Guide vanes can be shaped as straight plate or they can have wing profiles. Outlet vanes generally do not have an airfoil profile, unless a broader efficiency range is required.
The shape of inlet vanes is more critical as they must remove any turbulence from the air before that hits the fan wheel.
Most vane axial fans have outlet guide vanes. Fans with the motor at the inlet or with inlet dampers might require an inlet guide vane to prepare the air for the impeller.
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