EXPERIMENTAL INVESTIGATION OF THE COMBUSTIVE SOUND SOURCE

In this paper, we describe a unique low frequency underwater sound sou rce called the combustive sound source (CSS). In this device, a combus tible gas mixture is captured in a combustion chamber and ignited with a spark, The ensuing combustion produces expanding gases which in tur n produce high intensity, low frequency acoustic pulses, With high-spe ed motion pictures of the CSS event, we relate the motion of the bubbl e to the acoustic waveform, We also compare the measured first bubble period in the CSS pressure signature with the predictions of the Rayle igh-Willis equation, including the dependence of the radiated acoustic waveform on the volume and depth of the bubble, Measurements of the f irst bubble period agree with Rayleigh-Willis theory in trend, but not in absolute value. In addition, we discuss the variation of the acous tic output with the fuel/oxygen mixture, Finally, several other factor s that effect the acoustic output of CSS are discussed. These include the shape of the CSS combustion chamber, the type of oxidizer and fuel , and the ignition source.