Exhaust Noise Optimization of Gas Engine Aftertreatment

To address exhaust noise from gas engines in commercial vehicles without altering the existing aftertreatment system layout, two muffler optimization strategies were investigated. Scheme 1 involved adding a perforated baffle, while Scheme 2 further optimized the perforated inlet pipe based on Scheme 1. The noise reduction performance was evaluated through acoustic simulation (insertion loss) and vehicle testing (pass-by noise). Compared with Scheme 1, Scheme 2 demonstrated superior noise performance, achieving insertion loss improvements of 4.2 dB and 1.8 dB at 600 rpm and 1800 rpm, respectively. At 600 rpm, test results indicated that both schemes were insensitive to 3rd- and 9th-order noise, indicating limited effectiveness of structure-based interventions under low-speed conditions. When the operating speed increased to 650 rpm, Scheme 2 reduced 3rd-order noise by 8.00 dB through pre-control of the flow field. This study demonstrates the effectiveness of combined perforated baffle and inlet pipe optimization under fixed structural constraints and provides a technical reference for noise control in gas engine aftertreatment systems and muffler design in similar applications.