Fan silencers, exhaust pipe silencers, and induced draft fan silencers are all designed in a similar form. They utilize resistive noise reduction principles that are effective for mid to high-frequency broadband characteristics, along with reactive noise reduction principles that are beneficial for low and mid-frequency as well as pulsating characteristics, incorporating micro-perforated silencers and impedance composite silencers.
Category
The silencers for fans are categorized into: centrifugal fan silencers, Roots fan silencers, blower silencers, and axial flow fan silencers. Fan silencers are primarily used to reduce aerodynamic noise at the inlets of various fans, air ducts, and enclosed machine rooms.
According to the varying structural designs of wind turbine进出口, they are categorized into circular and rectangular structures.
(1) The circular structures are designed for round air outlet connections of fans and are available in two types: A and B. Type A features flanges at both ends, which are directly connected to the pipeline (i.e., pipeline silencers). Type B has one flange and the other end is directly vented to the atmosphere (can be equipped with a rainproof wind cap). It is only suitable for installation at the end of outdoor pipelines and the air intake of enclosed machine rooms.
The impedance noise abatement panels within the circular structure are typically 100 mm or 150 mm thick, offering noise reduction of 15-30 dB. Under wind speeds of 5-12 m/s, they are suitable for air volumes ranging from 1000 to 50,000 m³/h. The structure employs two impedance noise abatement zones for high and low-frequency noise, maximizing the broadening of the noise abatement frequency range.
Structural Principles
Based on actual tests of noise sources from various industrial fans, the spectral characteristics are used to determine the required noise reduction levels for acoustic absorption materials and fluid passages. Additionally, narrow rectangular channels with extensive acoustic material linings are utilized to enhance absorption. Furthermore, the noise sources of fans often have multiple spectral values at maximum noise levels, with varying noise reduction requirements for different frequency bands. To address this, the series of ventilation pipeline silencers and exhaust fan silencers are designed as impedance type, employing resistive structures for high and medium frequency noise absorption and reactive structures for mid and low frequency noise reduction. High and low frequency acoustic absorption zones are also incorporated within the resistive channels to maximize the noise reduction frequency range, achieving excellent noise reduction and attenuation effects.
Ventilation duct silencers and blower silencers are suitable for all types of centrifugal, axial, Roots blowers, and air compressors.