Objectives
FAN NOISE TRACK
CONTEXT
TThe noise due to fans remains a big issue as fans are encountered in an extremely wide range of products, from the very small axial fans for cooling CPUs' in computers to the biggest ones in air-condensers of power plants, in the every-day life in domestic appliances (micro-wave, dryer), or for comfort or health purposes with the HVAC and ventilation units, at home or in transportation.
Following the success of Fan Noise 2007 and Fan 2012 & 2015 conferences, the track dedicated to fan noise will be a good opportunity to follow the progress achieved by manufacturers and institutions in the comprehension, prediction and control of the noise generation mechanisms of fans. Comparisons of predictions by numerical/analytical methods and test results will be particularly appreciated. Sound system effects associated with the fan installation in complex systems or equipment as well as the design of low-noise fans will be of great interest. The presentation of new technologies of active and passive silencers will also be in the scope of the fan noise track.
TOPICS
Aerodynamic fan noise generation mechanisms:
The noise generation mechanisms concern tonal noise at harmonics of the blade passing frequency as well as narrow-band and broadband noise (leading-edge, trailing-edge, tip clearance noise, …).
Structure-borne noise:
A fan may also radiate structure-borne noise due to the transmission of the fan/drive vibrations to the floor.
Experimental methods for noise source localization:
Experimental methods remain very important tools to assess the sound levels and get a better understanding of physical phenomena. Many techniques are available, from sound intensity or microphone array methods to correlation techniques with embedded sensors on the blades.
Design for low-noise fans:
Fan noise has to be reduced at source. Different means are investigated such as the optimization of the blade shapes, the adjunction of blade tip device for reducing tip clearance noise, etc.
Noise Prediction by analytical/numerical models:
The noise prediction is also a key issue: analytical methods and computational aeroacoustics (CAA) are more and more used.
Optimization of Fan Installation to Reduce Noise:
System effect corresponds to a coupling between the circuit and the fan, which usually results in a degradation of the aerodynamic and acoustic performances of the fan. The global optimization of the fan installation is an efficient way to reduce noise of the whole system.
Psychoacoustics:
Sometimes, the physical sound level radiated by the fans cannot be reduced but the feeling of the user can be improved by modifying some characteristics of the sound, called metrics. The sound quality is of great help for a better understanding of the relationship between the feeling of the user and the acoustic spectrum of the fan or, sometimes, the geometrical characteristics.
