Simulation and Validation of Transmission Loss for the Two-Inlet Muffler on Off-Highway Vehicles

Engine is one of the major sources of noise in off-highway vehicles. Muffler plays an important role in attenuating the noise emitted by engines. Mufflers are designed to provide maximum noise attenuation without significantly affecting the back pressure. Inlet and outlet arrangements of muffler are proposed based on engine exhaust system and engine compartment design. Multi-inlet and/or multi-outlet mufflers are used based on the needs.

This paper details the procedure used for evaluation of transmission loss of a muffler on off-highway vehicle which has two-radial inlets and one axial outlet. 3D simulation is used to obtain the transmission loss parameters. To validate the models, virtual analysis is carried out in two steps. In the first step, one inlet is open to source while the other is blocked and termination at the outlet is anechoic. In the second step, the open and closed inlets are swapped. Similar approach is used during physical measurement of the transmission loss and the 3D simulation model is validated. Effective transmission loss is derived using the superposition approach. This methodology can also be applied to multi-inlet and/or multi-outlet mufflers to assess the effective transmission loss.