This paper presents a numerical study of reactive-type automotive mufflers. The main objective of the paper is to study the effects of various geometrical parameters on the muffler performance. Transmission losses (TL) are used to characterize the performance of the mufflers. Commercially available solver, ANSYS [1] is used to solve the muffler TL characteristics.
The paper also summarizes the development of a general-purpose program capable of modeling complex muffler cavities using ANSYS parametric design language (APDL). APDL is a scripting language that is used to automate common tasks and build the model in terms of parameters.
The program takes the key geometric parameters of the muffler as input variables and creates the muffler geometry, hexahedral-structured mesh, applies suitable boundary conditions, solves and then post-processes the results. The program provides good flexibility in creating complex (perforations) geometric models.
Perforated type mufflers are compared with the simple expansion type mufflers. A parametric analysis is then performed on the perforated type mufflers to study the effect of perforation density, effect of partitioning perforated mufflers using baffles, effect of baffles with holes and the effect of muffler shape. Both circular and elliptical mufflers are studied. These results are in good agreement with the available experimental results in literature.