Prediction of sound pressure radiated from the open end of a pipe and muffler insertion loss using a single, efficient scheme: Applications to a vacuum pump

Abstract

A single, efficient scheme developed by Sridhara and Crocker [J. Acoust. Soc. Am. 95, 2363–2370 (1994)] was used to predict the radiated sound pressure and muffler insertion loss by incorporating a simple logical statement in the computer codes. The scheme was verified through a series of experiments. A 0.06-m-diam loudspeaker and a single cylinder, reciprocating-type vacuum pump were used as sound sources during the tests. The source impedance was measured using the direct method. A 0.114-m-diam and 0.3-m-long simple expansion chamber and a 0.006-m-diam and 0.025-m-long side-branch resonator were used as mufflers. Sound-pressure level measurements for the prediction scheme were made for several source–muffler and source–straight pipe combinations. The predicted and measured sound-pressure levels were compared for all cases considered. In all cases, correlation of the experimental results and those predicted by the developed expressions was good at low frequencies. Predicted and measured values of muffler insertion loss were also compared. The agreement between the two quantities was good.