A BOUNDARY-ELEMENT SCHEME FOR EVALUATION OF 4-POLE PARAMETERS OF DUCTS AND MUFFLERS WITH LOW MACH NUMBER NONUNIFORM FLOW

A boundary element scheme is proposed for evaluation of the four-pole parameters of ducts and mufflers in the presence of a low Mach number non-uniform how. A transformation of variable is used, such that the g overning sound propagation equation reduces to the Helmholtz equation in the transformed variable, which has a known fundamental solution an d is therefore amenable to BEM analysis. The validity of the results i s confirmed by comparison with those of existing one-dimensional model s of the how. The boundary element scheme has been developed as it ena bles one to determine effectively the four-pole parameters when the fl ow is non-uniform, and also high order mode behavior in ducts and muff lers of any given geometry. (C) 1995 Academic Press Limited