THE DEVELOPMENT OF VARIOUS INDUSTRIAL ACOUSTIC TECHNOLOGIES is pursued in the Signal Physics Laboratory. These projects are sponsored by private industry and government agencies in an effort to develop novel solutions to real-world problems. Ongoing projects include:
• Control of combustion emissions by application of acoustic agglomeration
• Waste heat applications of thermoacoustics

ACOUSTIC AGGLOMERATION:
ACOUSTIC AGGLOMERATION OF AEROSOLS HAS BEEN KNOWN SINCE AT LEAST 1931 when it was first observed that small particles tend to "stick" together in the presence of an intense acoustic field, thereby forming larger particles. The concept, as applied to the treatment of an exhaust stream carrying particulate (soot), is illustrated in the figure below. Without impeding the flow of particulate through an exhaust duct, a strong sound field can be applied to stimulate rapid agglomeration of smaller particles into larger ones. The larger particles can then be more effectively removed by standard particle capture methods, such as soot traps (for diesel engines) or electrostatic precipitators (for coal-fired boilers).

For questions and information regarding SPL’s industrial acoustics programs, please contact:
Email IndustrialAcoustics-SPL@arlut.utexas.edu

THERMOACOUSTICS:

THE TEMPERATURE OSCILLATIONS ASSOCIATED WITH A SOUND WAVE IN A GAS (or liquid) permit, through contact of the gas with surfaces having high heat capacity (arranged in a configuration called the “stack"), the construction of thermoacoustic engines and refrigerators. Engines convert heat to sound power, and refrigerators use sound power to move heat from a cold reservoir to a hot reservoir. The principal advantage of thermoacoustic engines is that “whereas typical engines and refrigerators have crankshaft-coupled pistons or rotating turbines, thermoacoustic engines and refrigerators have at most a single flexing moving part (as in a loudspeaker) with no sliding seals. Thermoacoustic devices may be of practical use where simplicity, reliability, or low cost is more important than the highest efficiency." [Swift, 1995] One goal of our current research is to demonstrate the use of thermoacoustic engines to convert waste heat into useful electrical energy. A schematic of one such device is shown above.