Fan 2012 brought together the leading stakeholders in fan development from 27 different countries, including manufacturers, universities and government bodies. Fan noise represented a central theme at this conference. Ventac’s Laboratory Manager, Mark Simms, was pleased to present his paper on a range of innovative new fan jackets developed and manufactured at our facility in Blessington.
Ventac developed the product by measuring the sound power level of fans fitted with acoustic jackets using Sound Intensity as per ISO 9614. With this technique, noise maps could be generated showing areas radiating high levels of sound energy or ‘hot spots’.
This method identified the cooling impeller on the centrifugal fan drive motor as a key noise source for the unit. The next step was to develop a jacket which could be used over this area that would not affect the cooling air flow over the motor. The Ventac design used passive vents which forced the noise through 90° bends as it travelled with the cooling air flow. The jacket was designed to have sufficient space within it so that air could move freely.
This measure, when tested on a centrifugal fan, improved the noise reduction of break out noise from 2 decibels (LWA) to 4 decibels even without any treatment on the fan ducting.