The tail pipe noise from a commercial automotive muffler was studied experimentally and numerically
under the condition of wide open throttle acceleration in the present research. The engine was accelerated
from 1000 to 6000 rpm in 30 s at the warm up condition. The transient acoustic characteristics of its
exhaust muffler were predicted using one dimensional computational fluid dynamics. To validate the
results of the simulation, the transient acoustic characteristics of the exhaust muffler were measured
in an anechoic chamber according to the Japanese Standard (JIS D 1616). It was found that the results
of simulation are in good agreement with experimental results at the 2nd order of the engine rotational
frequency. At the high order of engine speed, differences between the computational and experimental
results exist in the high revolution range (from 5000 to 6000 rpm at the 4th order, and from 4200 to
6000 rpm at the 6th order). According to these results, the differences were caused by the flow noise
which was not considered in the simulation. Based on the theory of one dimensional CFD model, a simplified
model which can provide an acceptable accuracy and save more than 90% of execution time compared
with the standard model was proposed for the optimization design to meet the demand of time to
market.