Effect of air flow on acoustic characteristics of an insert pipe muffler with a small length-to-diameter radio

The experimental study was carried out on the acoustic characteristics at both inside and outside of an insert pipe muffler with length-to-diameter ratio L/D of 0.60 under the inside air flow velocity from 10m/s to 100m/s.The effects of air velocity and structural parameters on the acoustic characteristics of the muffler were studied.The acoustic characteristic mechanism of the insert pipe muffler with a small length-to-diameter ratio was also analyzed according to the vortex mode in the muffler and the acoustic mode of the tail pipe.It was found that the acoustic characteristics at both inside and outside of the muffler are influenced heavily by the air velocity;the difference from the acoustic characteristics of the muffler without air flow is that the effect of the vortex mode generated by the jet flow of upstream inlet pipe in the muffler has to be taken in the study on acoustic characteristics of muffler with air flow;the acoustic characteristics of the insert pipe muffler with a small length-to-diameter ratio are closely related with the vortex mode of air regeneration noise in the muffler and the acoustic mode of the tail pipe.