Noise reduction can generally be divided into primary and secondary measures. Primary measures have a direct effect on the generation of noise and should be given preference. Secondary measures are subsequent reductions of the previously generated noise.
Primary Measures:
- uniform speed profiles
- vortex-free inlet flow
- Avoidance of flow separation
- acoustically optimized design
Secondary measures:
- Attenuation by means of porous or fibrous absorption materials
- Obstruction of sound propagation by e.g. encapsulation
- Decoupling of vibrations via rubber or spring elements
In principle, noise quality plays an increasingly important role in the decision on the use of fans, in addition to noise reduction. A broadband noise without any outstanding tonal components is generally perceived as pleasant by humans and is therefore sought in the development of new solutions