THE INFLUENCE OF SHAPE AND LINING CONFIGURATION ON THE NOISE REDUCTION IN BENDS OF SMALL AIR DUCTS

摘要

Application of sound absorbing material to the sides of a bend in a small air duct is notnecessary. The need for material is reduced and the overall duct dimensions can be reduced tohelp fit the duct into small machines. The 90 degree bend can be just as effective acoustically asthe 180 degree bend and due to its lesser pressure drop, permits significant increases in the heat rejection rate. Use of porous materials at the flow separation point decreases the pressure dropassociated with the separated flow region and improves low frequency sound absorption.Multiple small bends reduce pressure drop but also diminish the sound reduction and are morecomplicated to build.