Thermoacoustics

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The thermoacoustic is a specialized field of acoustics and thermodynamics , which deals with thermal processes and in communication therewith acoustic waves. Thermoacoustics is based on the thermoacoustic effect , in which thermal energy is converted into vibration energy of a gaseous medium or this vibration energy is converted into thermal energy. The vibrations of the medium cause pressure changes that result in direct thermodynamic changes in state.

history

A possibly first description of the effect associated with thermoacoustics goes back to B. Higgins from 1777. He let a hydrogen flame burn in a glass tube. The inhomogeneous temperature in the glass wall is said to have stimulated clearly audible sound waves, which Higgins described as "singing flames".

In 1859, PL Rijke presented the construction of the Rijke tube named after him , in which the gas flame was exchanged for a heated wire mesh.

The first physical explanation goes back to Lord JWS Rayleigh . In 1878 and 1896, however, he only described the effect qualitatively. During this time the thermophone , a mostly electrically operated thermal-acoustic converter, was developed and investigated.

It was not until the mathematician N. Rott that the effect was also described quantitatively in a series of publications from 1969 to 1978. Rott used the elementary basic laws of physics and models of fluid dynamics and thermodynamics . The theory was verified at the ETH Zurich from 1972 to 1974 . Due to the work of Rott , thermoacoustics gained a high level of interest worldwide since around 1980. Current research and development work includes a. with chillers that work on the basis of the thermoacoustic effect.

Applications

  • Refrigeration
  • Combustion processes
  • Sensors

Individual evidence

  1. ↑ a b c d Martin Altenbokum: The phenomenon of thermoacoustics . In: KI cold-air-air conditioning . May 2007, p. 24-26 ( PDF ).
  2. ↑ Martin Altenbokum: The Thermoacoustic Phenomenon: Practical Applications Part 2/2 . In: KI cold-air-air conditioning . December 2008, p. 26-28 .
  3. ^ F. Joos: Technical combustion. Combustion technology, combustion modeling, emissions. Springer, 2006, ISBN 3-540-34333-4 .
  4. ↑ DLR: Thermoacoustics division. Investigation of combustion vibrations with phase-resolved diagnostics
  5. ↑ M. Glinka: Thermoacoustic ultrasonic power meters: modeling and experiment. Shaker Verlag , 2002, ISBN 3-8322-0830-5 .