2. Origin and prediction of aerodynamic noise
Aerodynamic noise from fans is the result of interaction mechanisms between the flow and the fixed and rotating parts of the fan. At this point, it should be pointed out that aerodynamic noise occurs on all three propagation paths: airborne, structure-borne and duct-borne. The level of structure-borne noise, however, is often of the second order compared with airborne and duct noise. Furthermore, the mechanisms described below do not in any way involve blade vibrations, as these hardly ever play a part in the noise generated by fans and aerial rotating machines in general.
The noise spectrum of a fan is made up of more or less pronounced lines at the blade-passing frequency FPP = BN and its harmonics (these frequencies appear if the blade spacing is constant over the circumference) and a broadband spectrum. Figure...
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Origin and prediction of aerodynamic noise
Bibliography
Standards and norms
- Fans – Airflow testing on standardized circuits. - NF EN ISO 5801 - 2017
- Industrial fans – Determination of sound power levels under standard laboratory conditions – Part 1: General presentation. - NF ISO 13347-1 - 2004
- Industrial fans – Determination of sound power levels under standard laboratory conditions – Part 2: reverberation chamber method. - NF ISO 13347-2 - 2004
- Industrial fans – Determination...
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ISO/TC 117 "Fans
CEN/TC 156 WG17 "Fans".
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