Short Thermoacoustics Publications

"High-purity thermoacoustic isotope enrichment," G. W. Swift, D. A. Geller, and S. N. Backhaus, Journal of the Acoustical Society of America 136, 638-648 (2014).

"Thermoacoustic mixture separation with an axial temperature gradient," D. A. Geller and G. W. Swift, Journal of the Acoustical Society of America 125, 2937-2945 (2009).

"Continuous thermoacoustic mixture separation," G. W. Swift and D. A. Geller, Journal of the Acoustical Society of America 120, 2648-2657 (2006); erratum 124, 2421 (2008).

"Thermoacoustic enrichment of the isotopes of neon," D. A. Geller and G. W. Swift, Journal of the Acoustical Society of America 115, 2059-2070 (2004).

"Thermodynamic efficiency of thermoacoustic mixture separation," D. A. Geller and G. W. Swift, Journal of the Acoustical Society of America 112, 504-510 (2002).

"Saturation of boundary-layer thermoacoustic mixture separation," D. A. Geller and G. W. Swift, Journal of the Acoustical Society of America 111, 1675-1684 (2002).

"Thermoacoustic separation of a He-Ar mixture," P. S. Spoor and G. W. Swift, Physical Review Letters 85, 1646-1649 (2000).

"Thermal diffusion and mixture separation in the acoustic boundary layer," G. W. Swift and P. S. Spoor, Journal of the Acoustical Society of America 106, 1794-1800 (1999). Erratum 107, 2299 (2000); second erratum 109, 1261 (2001).

"Jet-Induced Phase Errors in Pulse-Tube-Refrigerator Compliance Pressure," G. W. Swift and P. S. Spoor, Proceedings of the 20th International Cryocoolers Conference (Burlington VT, June 2018).

"Why High-Frequency Pulse Tubes Can Be Tipped," G. W. Swift and S. Backhaus, Proceedings of the 16th International Cryocoolers Conference (Atlanta, May 2010), edited by S. D. Miller and R. G. Ross, Jr., pages 183-192 (ICC Press, Boulder CO, 2011).

"The pulse tube and the pendulum," G. W. Swift and S. Backhaus, Journal of the Acoustical Society of America 126, 2273-2284 (2009).

"Analytical solution for temperature profiles at the ends of thermal buffer tubes," Konstantin. I. Matveev, Gregory W. Swift, and Scott Backhaus, International Communications in Heat and Mass Transfer 50, 897-901 (2007).

"An internal streaming instability in regenerators," J. H. So, G. W. Swift, and S. Backhaus, Journal of the Acoustical Society of America 120, 1898-1909 (2006).

"Gas Diodes for Thermoacoustic Self-Circulating Heat Exchangers," Greg Swift and Scott Backhaus, submitted to the Proceedings of the 17th International Symposium on Nonlinear Acoustics, The Pennsylvania State University, 18-22 July 2005.

"Temperatures near the interface between an ideal heat exchanger and a thermal buffer tube or pulse tube," Konstantin I. Matveev, G. W. Swift, and S. Backhaus, International Journal of Heat and Mass Transfer 49, 868-878 (2006).

"Reduced-order modeling of vortex-driven excitation of acoustic modes," Konstantin I. Matveev, Acoustics Research Letters Online 6, 14-19 (2005).

Abstract: Vortex shedding that occurs in ducts with baffles in the presence of mean flow often leads to excitation of acoustic modes. Resulting flow oscillations may feed back to the process of vortex formation. A simple model is proposed for describing this complex interaction using the hypotheses for a quasi-steadiness of vortex shedding and for a short-period acoustic perturbation at the moment of vortex collision with a downstream baffle. The model is capable of predicting typical real-system phenomena, such as the lock-in of a dominant frequency of the vortex-acoustic instability in some ranges of the mean flow velocity.

"A resonant, self-pumped,circulating thermoacoustic heat exchanger," G. W. Swift and S. Backhaus, Journal of the Acoustical Society of America 116, 2923-2938 (2004).

"Power dissipation and time-averaged pressure in oscillating flow through a sudden area change," B. L. Smith and G. W. Swift, Journal of the Acoustical Society of America 113, 2455-2463 (2003).

" A comparison between synthetic jets and continuous jets," B. L. Smith and G. W. Swift, Experiments in Fluids 34 467-472 (2003). The original publication is available at Springer Link. Springer-Verlag is the copyright holder.

"An acoustic streaming instability in thermoacoustic devices utilizing jet pumps," S. Backhaus and G. W. Swift, Journal of the Acoustical Society of America 113, 1317-1324 (2003).

"Measuring second-order time-average pressure," B. L. Smith and G. W. Swift, Journal of the Acoustical Society of America 110, 717-723 (2001).

"Synthetic jets at large Reynolds number and comparison to continuous jets," B. L. Smith and G. W. Swift, AIAA 2001-3030, Proceedings of the 31st AIAA Fluid Dynamics Conference, Anaheim CA, 11-14 June 2001.

"Staging two coolers through a quarter-wave tube," G. W. Swift, D. L. Gardner, and S. Backhaus, Proceedings of the 17th International Cryocoolers Conference (Los Angeles, July 9-12, 2012), edited by S. D. Miller and R. G. Ross, Jr., pages 179-185 (ICC Press, Boulder CO, 2012).

"Quarter-wave pulse tube," G. W. Swift, D. L. Gardner, and S. Backhaus, Cryogenics 51, 575-583 (2011).

"Thermoacoustic analysis of displacer gap loss in a low temperature Stirling cryocooler," Vincent Kotsubo and Greg Swift, CP823, Advances in Cryogenic Engineering: Transactions of the Cryogenic Engineering Conference - CEC 51, edited by J. G. Weisend II (2006, American Institute of Physics, Melville NY), pages 353-360.

"The effect of gravity on heat transfer by Rayleigh streaming in pulse tubes and thermal buffer tubes," Konstantin I. Matveev, Scott Backhaus, and Gregory W. Swift, Proc. ASME 4711Xc; Heat Transfer, Volume 3:7-12, IMECE 2004, International Mechanical Engineering Conference and Expo, November 13-19, 2004, Anaheim CA.

Abstract: Thermoacoustic engines and refrigerators use the interaction between heat and sound to produce acoustic energy or to transport thermal energy. Heat leaks in thermal buffer tubes and pulse tubes, components in thermoacoustic devices that separate heat exchangers at different temperatures, reduce the efficiency of these systems. At high acoustic amplitudes, Rayleigh mass streaming can become the dominant means for undesirable heat leak. Gravity affects the streaming flow patterns and influences streaming-induced heat convection. A simplified analytical model is constructed that shows gravity can reduce the streaming heat leak dramatically.

"A cascade thermoacoustic engine," D. L. Gardner and G. W. Swift, Journal of the Acoustical Society of America 114, 1905-1919 (2003).

"Fabrication and use of parallel-plate regenerators in thermoacoustic engines," S. N. Backhaus and G. W. Swift, in the Proceedings of the 36th Intersociety Energy Conversion Engineering Conference, Savannah GA, 29 July-2 August 2001.

"A thermoacoustic-Stirling heat engine: Detailed study," S. N. Backhaus and G. W. Swift, Journal of the Acoustical Society of America 107, 3148-3166 (2000).

"A thermoacoustic-Stirling heat engine," S. N. Backhaus and G. W. Swift, Nature 399, 335-338 (1999).

"Condensation in a steady-flow thermoacoustic refrigerator," R. A. Hiller and G. W. Swift, Journal of the Acoustical Society of America 108, 1521-1527 (2000).

"Experiments with a flow-through thermoacoustic refrigerator," R. S. Reid and G. W. Swift, Journal of the Acoustical Society of America 108, 2835-2842 (2000).

"Acoustic recovery of lost power in pulse tube refrigerators," G. W. Swift, D. L. Gardner, and S. N. Backhaus, Journal of the Acoustical Society of America 105, 711-724 (1999).

"Superfluid orifice pulse tube refrigerator below 1 Kelvin," A. Watanabe, G. W. Swift, and J. G. Brisson, Advances in Cryogenic Engineering 41, 1519-1526 (1996).

"Measurements with a recuperative superfluid Stirling refrigerator," A. Watanabe, G. W. Swift, and J. G. Brisson, Advances in Cryogenic Engineering 41, 1527-1533 (1996).

"Uniform-temperature cooling power of the superfluid Stirling refrigerator," A. Watanabe, G. W. Swift, and J. G. Brisson, Journal of Low Temperature Physics 103, 273-293 (1996).

"Mode locking of acoustic resonators and its application to vibration cancellation in acoustic heat engines," P. S. Spoor and G. W. Swift, Journal of the Acoustical Society of America 106, 1353-1362 (1999).

"The Huygens entrainment phenomenon and thermoacoustic engines," P. S. Spoor and G. W. Swift, Journal of the Acoustical Society of America 108, 588-599 (2000).

"High-temperature self-circulating thermoacoustic heat exchanger," S. Backhaus, G. W. Swift, and R. S. Reid, Applied Physics Letters 87, 014102 1-3 (2005).

"A self-circulating heat exchanger for use in Stirling and thermoacoustic-Stirling engines," S. Backhaus and R. S. Reid, Space Technology and Applications International Forum (STAIF-2005). Albuquerque, NM, February, 2005, AIP Conference Proceedings 746, p. 719-726. 

Abstract: A major technical hurdle to the implementation of large Stirling engines or thermoacoustic engines is the reliability, performance, and manufacturability of the hot heat exchanger that brings high-temperature heat into the engine. Unlike power conversion devices that utilize steady flow, the oscillatory nature of the flow in Stirling and thermoacoustic engines restricts the length of a traditional hot heat exchanger to a peak-to-peak gas displacement, which is usually around 0.2 meters or less. To overcome this restriction, a new hot heat exchanger has been devised that uses a fluid diode in a looped pipe, which is resonantly driven by the oscillating gas pressure in the engine itself, to circulate the engine's working fluid around the loop. Instead of thousands of short, intricately interwoven passages that must be individually sealed, this new design consists of a few pipes that are typically 10 meters long. This revolutionary approach eliminates thousands of hermetic joints, pumps the engine's working fluid to and from a remote heat source without using moving parts, and does so without compromising on heat transfer surface area. Test data on a prototype loop integrated with a 1-kW thermoacoustic engine will be presented.

"Traveling-wave thermoacoustic electric generator," S. Backhaus, E. Tward, and M. Petach, Applied Physics Letters 85, 1085-1087 (2004).

"Design of a high efficiency power source (HEPS) based on thermoacoustic technology," M. Petach, E. Tward, and S. Backhaus, Final report, NASA contract no. NAS3-01103, CDRL 3f (2004).

"Initial tests of a thermoacoustic space power engine," S. Backhaus, Space Technology and Applications International Forum (STAIF-2003). February, 2003. Albuquerque, New Mexico. AIP Conference Proceedings 2003 654, 641-647. Edited by M. S. El Genk.

Abstract: Future NASA deep-space missions will require radioisotope-powered electric generators that are just as reliable as current-RTGs, but more efficient and of higher specific power (W/kg). Thermoacoustic engines at the similar to1kW scale have converted high-temperature heat into, acoustic, or PV, power without moving parts at 30% efficiency. Consisting of only tubes and a few heat exchangers, thermoacoustic engines are low mass and promise to be highly reliable. Coupling a thermoacoustic engine to a low mass, highly reliable and efficient linear alternator will create a heat-driven electric generator suitable for deep-space applications. Conversion efficiency data will be presented on a demonstration thermoacoustic engine designed for the 100-Watt power range.

"Thermoacoustic space power converter," E. Tward, M. Petach, and S. Backhaus, Space Technology and Applications International Forum (STAIF-2003). February, 2003. Albuquerque, New Mexico. AIP Conference Proceedings 2003 654, 656-661. Edited by M. S. El Genk.

Abstract: A thermoacoustic power converter for use in space in the conversion of radioisotope-generated heat to electricity is under development. The converter incorporates a thermoacoustic driver that converts heat to acoustic power without any moving parts. The acoustic power is used to drive a pair of flexure bearing supported pistons connected to voice coils in a vibrationally balanced pair of moving coil alternators. Initial tests of the small similar to100W thermoacoustic driver have demonstrated good efficiency. An alternator matched to the driver is now under construction. A description of the system and the results of development tests are presented.

"Thermoacoustic power systems for space applications," S. Backhaus, E. Tward, and M. Petach, Space Technology and Applications International Forum (STAIF-2002). February, 2002. Albuquerque, New Mexico. AIP Conference Proceedings 2002 608, 939-944. Edited by M. S. El Genk.

Abstract: Future NASA deep-space missions will require radioisotope-powered electric generators that are just as reliable as current RTGs, but more efficient and of higher specific power (W/kg). Thermoacoustic engines can convert high-temperature heat into acoustic, or PV, power without moving parts at 30% efficiency. Consisting of only tubes and a few heat exchangers, these engines are low mass and promise to be highly reliable. Coupling a thermoacoustic engine to a low-mass, highly reliable and efficient linear alternator will create a heat-driven electric generator suitable for deep-space applications. Data will be presented on the first tests of a demonstration thermoacoustic engine designed for the 100-Watt power range.

"Operation of thermoacoustic Stirling heat engine driven large multiple pulse tube refrigerators," Bayram Arman, John Wollan, Vince Kotsubo, Scott Backhaus, and Greg Swift, submitted to the proceedings of the 13th International Cryocooler Conference. Kluwer Academic/Plenum Publishers holds the copyright to this paper.

"Thermoacoustics for liquefaction of natural gas," G. W. Swift and J. J. Wollan, GasTIPS, Volume 8, Number 4, pages 21-26 (Fall 2002). (Erratum: page 23, column two, under the heading "How the refrigerator works": The first word of the 23rd line in that paragraph should be "falls" instead of "rises.")

"Development of a thermoacoustic natural gas liquefier," J. J. Wollan, G. W. Swift, S. N. Backhaus, and D. L. Gardner, AIChE Meeting, New Orleans LA, March 11-14, 2002.

"Thermoacoustic refrigeration --- A stirring concept for offshore associated gas liquefaction," W. C. van Wijngaarden, Monetizing Stranded Gas Reserves Conference, Houston TX, December 7-9, 1999.

"John Malone and Liquid Thermodynamics," G. W. Swift, issue 2010-3 of Stirling Machine World, edited by John Corey.

"Interactive analysis, design, and teaching for thermoacoustics using DeltaEC," W. C. Ward, G. W. Swift, and J. P. Clark, talk given at the spring 2008 meeting of the Acoustical Society of America (Paris). Abstract available at Journal of the Acoustical Society of America 123, 3546 (2008).

"Thermoacoustic energy conversion," G. W. Swift, Chapter 7 of the Springer Handbook of Acoustics, edited by Thomas Rossing (Springer, 2007).

"New varieties of thermoacoustic engines," S. N. Backhaus and G. W. Swift, Paper number 502, Proceedings of the Ninth International Congress on Sound and Vibration, Orlando FL, July 8-11 2002.

"Separation of gas mixtures by thermoacoustic waves," D. A. Geller, P. S. Spoor, and G. W. Swift, Proceedings of the 17th International Congress on Acoustics, Rome, 2-7 September 2001; Volume 1, Part A, Session "Thermoacoustics," pages 16-17.

"Thermoacoustics," G. W. Swift, McGraw-Hill Encyclopedia of Science and Technology, 9th edition, Volume 18, 353-355 (2002)

"Thermoacoustics: A unifying perspective for some engines and refrigerators," G. W. Swift, graduate-level textbook, available at ASA Books.

"The power of sound," S. L. Garrett and S. Backhaus, American Scientist 88, 516-525, (2000).

"Streaming in thermoacoustic engines and refrigerators," G. W. Swift, Nonlinear Acoustics at the Turn of the Millennium: Proceedings of the 15th International Symposium on Nonlinear Acoustics, edited by W. Lauterborn and T. Kurz, 105-114 (American Institute of Physics, Melville NY, 2000).