Vibration control of centrifugal fan

[mehdimaleki77]

hello

I want to contol vibration of a centrifugal fan

, What is the best way ?

thanks much

 

[electricpete]

some factor which may affect vibration:

mechanical unbalance
misalignment between driver and fan
base looseness
resonance
vane pass frequency
flow-related vibration

For an installed motor a typical approach is to identify the source of vib based on frequency and then attempt to remove it.

For new installation you may have options regarding base including spring-mounted fan.

Can you describe better what you are doing.

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[vanstoja]

Disregarding air-moving system noise control considerations and focusing on the centrifugal fan-only component of the system, selection of blading curvature direction and housing type, blade trailing edge cutwater clearance and blade trailing edge angular orientation are probably the most crital factors for controlling airborne noise.
Graham,J.B.,1972, "How to Estimate Fan Noise", Sound and Vibration, May, pp.24-27 shows specific sound power levels(SPL) and for Octave Bands from 63 to 8000 and "blade frequency increments" (BFI) to be added to O/B levels at Blade Passing Frequency(BPF)for centrifugal fans as below:
Blade Type 63-8000SPL BFI
Airfoil 221 3
Backward curved 221 3
Forward curved 238 2
Radial 309 5-8
Trailing edge cutwater clearance should be the maximum consistent with fan efficiency needs to control or minimize BPF peak levels above the broadband level. Blade trailing edges can be skewed about 1 blade pitch to reduce noise if cutwater clearances must be kept low for efficiency reasons. Running speed should be the lowest consistent with pressure rise and flow requirements so as to minimize airborne broadband noise levels. For structureborne noise control, shaft balancing, drivemotor stator/rotor slot combination optimization, vibration isolation mounts and structural resonance response avoidance by blade/slot number selection are ways to control transmitted structureborne noise.