Fan wheels

[mike1969]

how much difference will it make if I replace the squirrel cage in an AHU where all dimensions are identical except for the number of blades.
original has 16, and my new blade will only have 10.
will there be a need to speed the fan up to move the same amount of air?

 

[Compositepro]

Number is not so important as diameter and geometry of the blades.

 

[Strong]

The blade pass pulsation frequency and harmonics will be lower (10/16) ratio to current value (depends on shaft speed). The pulsation amplitude (sound level) may go up, since the dynamic pressure per blade is higher (assumes same blade design). You may or may not have a sound or vibration issue with the wheel change depending upon installation circumstances. Fan performance difference may be minimal as Mike indicated.

Walt

 

[mike1969]

Thank you!