| Abstract:A rectangular pulse approach based on the CFD was proposed for simulating the acoustic performance of a muffling structure. First, the transmission loss of a single cavity perforated element was calculated neglecting airflow, and the influence of each structure parameter on the acoustic performance was researched respectively. Then, the transmission loss of a perforated intake pipe without airflow was obtained by the rectangular pulse approach and was compared with its FEM result to verify the validation. After that, the effect of mean flow on the transmission loss of the perforated intake pipe was achieved as well, revealing that reversing airflow makes the position of the peak transmission loss move slightly to the direction of low frequency with irregular change in the amplitude. Finally, a road test for an engine equipped with such perforated intake pipe was carried out. The result indicates that the intake sound pressure level (SPL) reduces apparently either at normal acceleration or emergency acceleration, especially in the frequency range of 500 to 1 600 Hz viewed in 1/3 octave spectrum, the SPL of snuffling noise reduces by almost 18 dB(A), and the overall SPL by more than 10.3 dB(A). Such perforated intake pipe has been proved to be excellent in improving the acoustic performance of an intake system. |