Influence of Geometry of Channel on the Flow Noise Parameters

Abstract

Acoustic emission through duct walls is an important problem in engineering acoustics. This phenomenon most commonly occurs in heating, ventilating and air-conditioning (HVAC) and other gas flow ducting (large industrial silencers). Many works focus on elaboration of more exact description of the acoustic field phenomena reflecting the real conditions in which these appliances operate. As a standard, circle or rectangular ducts are used in ventilation systems. However, technical conditions during the installation of the HVAC system, due to the limitation of the assembly space, require often the use of channels with other geometries. This paper presents aeroacoustical parameters of three most common cross-sectional shapes of air-moving ductwork. The rectangular, square with roundedcorners and circular ducts were studied. The “natural” duct attenuation, which is a consequence of duct shape or noise breakout and involves a diminution of the internally propagated sound power was observed. Natural duct attenuation can be a useful way of reducing sound power levels in long runs of duct.