Study on the acoustic performance of a coupled muffler for diesel engine

A new type of coupled muffler for diesel engine was proposed based on the principle of split-stream rushing and multi-unit coupling theory, and a coupling study of noise attenuation performance was carried out. The one-dimensional transfer matrix method was used to establish a transfer matrix mathematical model of the new muffler. The relative importance of the impact on the transmission loss for the coupled muffler was then able to be ranked by experimental design and MATLAB software calculation. From this, the combination of parameters with the optimal transmission loss was obtained. The transmission loss tests without airflow and the insertion loss tests with airflow between the optimal model of the coupled muffler and the original muffler supplied with the engine were verified respectively. The tests of pressure loss between the coupled muffler and the original muffler were also completed. The results show that the transmission losses of the coupled muffler in 0-2000 Hz and 0-200 Hz without airflow were 6 dB and 8 dB higher than that of the original muffler, the insertion losses of the coupled muffler in 0-2000 Hz and 0-200 Hz with airflow are 6 dB and 7 dB higher than that of the original muffler, and the noise peaks in the source spectrum are well controlled by the coupled muffler. The pressure losses of the coupled muffler are lower than that of the original muffler, which verifies that the coupling structure could reduce the airflow velocity in the muffler to improve noise attenuation performance and aerodynamic performance of the muffler at the same time. (C) 2022 Institute of Noise Control Engineering.