Illustration of an "acoustic compressor," designed by Timothy Lucas and his colleagues at
MacroSonix Corporation in Virginia. This device employs ultrapowerful sound
waves in place of lubricated pistons to compress gas in refrigerators and air conditioners. The sound waves
are created and sustained in a closed, horn-shaped "resonator" (cross-section shown above). Created in the large
main compartment of the resonator, the sound waves can convert low-pressure gas from the suction chamber (lower-right hand compartment) into high-pressure
gas exiting the discharge chamber on the upper right. During a single "acoustic cycle" (which lasts
2 thousandths of a second in the process shown above), the sound wave oscillates between high and low pressures
in certain regions of the main chamber. In the part of the cycle depicted above, the right end of the main chamber is a low-pressure region (blue) for the sound wave; consequently, the suction valve is pulled open and the low-pressure gas (green) is pulled
into the main chamber.
A thousandth of a second later, the right end of the main chamber becomes a high-pressure region (red) for the sound wave. This pushes open the discharge valve and allows the gas (also red) to exit in
high-pressure form.
Ordinarily, sound waves are not powerful enough to act as acoustic compressors. But using a specially desgined resonator such as the one shown above,
Lucas and his colleagues at MacroSonix have created sound waves with 1,600 times more energy
per unit volume than any previous human-made sound wave. Employing a technique which the
researchers call "resonant macrosonic synthesis," the resonator has a specially designed shape that inhibits the formation of energy-dissipating shock waves,
which typically prevent powerful
sound waves from being created. The forefront shows the solid resonator with a drive motor; the background shows a cutaway view.
These sound waves are so powerful that they can potentially carry out tasks which conventionally
require mechanical moving parts in current technologies. (Images courtesy of MacroSonix Corporation, Richmond, Virginia.)This research was reported at the 134th Meeting of the Acoustical Society of America in San Diego, December 1-5, 1997.
