Proceedings of the International Conference on Noise and Vibration Engineering, ISMA 2012 pages:533-544
International Conference on Noise and Vibration Engineering, ISMA 2012 edition:2012 location:Leuven date:17-19 September 2012
A damping device combining low flow resistance with high acoustic damping has be en developed.
Such device can be applied in for example ventilation systems, turbo-engines, intake and exhaust
systems of IC-engines. The device consists of a central tube surrounded by a narrow slit. The
central tube behaves as an acoustic mass which impedance increases by frequency. This results in
an increasing acoustic flow through the slit in terms of frequency. There, its kinetic energy will be
dissipated. The properties of the device are investigated using impedance measurements using the
two microphone method on a duct setup in terms of sound pressure amplitude and an analytical
model based on an electrical equivalent circuit. The damping mechanism, consisting of viscous
damping and dissipation of flow kinetic energy behind the slit, has been analyzed analytically
including the flow distribution in the slit. This model is capable to predict the acoustic properties of
the device quite well. Acoustic absorption values of 50% are reached in this stage of the research.