Investigation on Use of Absorptive Pod Silencer in Reduction Noise Air Inlet Channel Iranian Centrifugal Fan

Centrifugal fans are widely used in industrials that transfer the large volumes of air to the industrial equipment such as boilers, etc. These fans are one of the important sources of noise in industries. Therefore, in the present study, was investigated the effect of absorption silencer in reducing the low frequency sound of Iranian centrifugal fans.
In this study, the fan was selected with diameter of 55 centimeters with technical specification including fan cycle of 2980, air flow 300 cubic meters per hour. In addition, the silencer was built with galvanized iron walls and a thickness of 3 mm, the central axis with diameter of 5 cm and length of 100 cm. Iinside of silencer and around of central axis were covered with sound absorbing materials include of glass fiber .
Findings: The maximum of noise reduction was 10 dB in low frequencies. Increasing the thickness of sound absorbing materials was not significant changes in the noise reduction. However, with the increasing density from 20 to 40 kg/m3 was increased the noise reduction.
According to the results, can be used from glass fiber and flexi absorber with thickness of 10 cm and density of 40 kg/m3 to achieve the desired results of noise reduction of centrifugal fan by absorptive silencer.