Mark Simms, Ventac's Laboratory Manager, presented his paper on the innovative fan jackets to an audience comprised of leading fan development stake holders from 27 different countries. These groups included manufacturers, universities and government bodies.
With fan noise a central theme of the Fan 2012 conference the findings of the paper made an important contribution to understanding noise identification techniques. In their study, Ventac took fans fitted with acoustic jackets and measured their sound power levels using Sound Intensity in accordance with ISO 9614. This technique allowed Ventac to generate noise maps that revealed exactly which areas of the fans were producing the highest levels of sound energy. With these 'hot spots' located the process of finding a solution could begin.
A primary source of noise discovered by the noise mapping techniques was found to be the cooling impeller on the centrifugal fan drive motor. It was critical that the solution developed to reduce noise from this area did not impede the flow of cooling air over the motor. The design Ventac developed solved this by using passive vents which channelled the noise through 90° bends as it travelled with the cooling air flow. By designing the jacket with more internal space the air moved more freely through the bends.
Testing the noise control levels of this fan jacket on a centrifugal fan showed that noise reduction of break out noise had been improved from 2 decibels (LWA) to 4 decibels. Remarkably, these results were achieved before the fan ducting had been treated.
Established in 1972 as a purely commercial and industrial ventilation business Ventac has expanded into many areas of noise control. In 1998 Ventac built their first Acoustic Laboratory. In 2003 Ventac built a new state of the art facility where they continue to carry out a full range of acoustic and airflow testing on a large variety of products.