Acoustic Performance of Parallel Baffled Silencers Different Configurations in HVAC Channel

Serious noise pollution is one of the most unwanted consequences of the rapid urbanization and industrialization and various studies have shown that long exposure to noise can result in different health issues. Therefore, the performance of large industrial baffled silencer is crucial for reducing the environmental noise from large industrial plants. In this particular research the acoustic parameters of several different configurations of parallel baffled silencers have been compared by using an in-situ measurement method according to the ISO-11820:1996 Standard. The geometrical parameters e.g. length, thickness and distance between baffles as well as the absorption parameters of baffles have been changed in terms of full absorption and half-absorption surface. Furthermore, their influence on the silencer performance in channel with and without flow has been measured. Transmission and insertion loss acoustic parameters in octave frequency bands from 63 Hz up to 16 kHz are determined in the in-situ measurement setup including the influence of the reflections from baffles at the inlet side and opening at the outlet side. Moreover, the analytical expression ( Piening and trapezoidal equation) for one parallel baffled silencer’s configuration has been compared with the measurement values on octave bands of interest. Additionally, the sound pressure distribution between baffles has also been measured and it can be concluded that the sound pressure level change is much larger at the beginning when compared to the value at the end of a silencer.