The split-stream rushing exhaust muffler is a design that improves acoustic attenuation performance and reduces exhaust resistance by lowering the internal airflow velocity. In the past, researchers often applied a rigid treatment to the muffler wall when studying this new muffler and neglected the acoustic–structure coupling effect. As a result, differences existed between the calculated results and practical situations. This research employed COMSOL 6.2 software to perform finite element calculations on the acoustic performance of this muffler under acoustic–structural coupling. It analyzed the causes of transmission loss discrepancies with and without the acoustic–structural coupling effect, and the findings were validated experimentally. Building upon this foundation, further optimization and refinement of the muffler’s structural parameters were conducted. The results demonstrated that the transmission loss curve under the acoustic–structure coupling effect followed a similar trend to that observed without the acoustic–structure coupling effect. However, the transmission loss curve changed owing to the influence of the acoustic–structure coupling effect on sound pressure, which resulted in a 6.24% decrease in the average transmission loss. The transmission loss curve accounting for the acoustic–structure coupling effect aligned more closely with the test results than the curve that did not account for the coupling effect. Furthermore, this study delved into the influences of the wall thickness, inner tube diameter, and inner tube length on the muffler’s acoustic performance under acoustic–structural coupling. Subsequently, the muffler was optimized based on the findings.

Diesel engines employed in non-road machinery are significant contributors to nanoparticulate matters. This paper presents a novel device based on the principle of split-stream rushing to mitigate particulate matter emissions from these engines. By organizing and intensifying the airflow movement of the jet in the rushing region, the probability of collisions between nanoparticles is enhanced. This accelerates the growth and coagulation of nanoparticles, reducing the number density of fine particulate matter. This, in turn, facilitates the capture or sedimentation of particulate matter in the diesel engine exhaust aftertreatment system. The coagulation kernel function tailored for diesel engine exhaust nanoparticles is developed. Then, the particle balance equation is solved to investigate the evolution and coagulation characteristics. Afterwards, three-dimensional numerical simulations are performed to study the flow field characteristics of the split-stream rushing device and the particle evolution within it. The results show that the device achieves a maximum coagulation efficiency of 59.73%, increasing the average particle diameter from 96 nm to 121 nm. The particle number density uniformity index exceeded 0.93 in most flow regions, highlighting the effectiveness of the device in ensuring consistent particle distribution.