thermoacoustics

The thermo- acoustics is a specialized field of acoustics and thermodynamics, which deals with thermal processes and in related acoustic waves. The thermal acoustics based on the thermo-acoustic effect in which thermal energy is converted into vibration energy of the gaseous medium and this vibration energy to thermal energy. Through the vibrations of the medium pressure changes occur that have a direct thermodynamic state changes result.

History

A possible initial descriptions of the related to the thermo acoustic effect goes to B. Higgins back from 1777. He let burn a hydrogen flame in a glass tube. The inhomogeneous temperature in the glass wall is said to have led to the suggestion clearly audible sound waves, which were described by Higgins as "singing flames ".

In 1859, PL Rijke presented the eponymous structure of the Rijke tube in which the gas flame was replaced with a heated wire mesh.

The first physical explanation goes Lord JWS Rayleigh back. He described the effect in 1878 and 1896, but only qualitatively. At this time was also the Thermophon a generally electrically driven thermal- acoustic transducer, developed and studied.

Only through the mathematicians N. Rott, the effect has also been described quantitatively in 1969 to 1978 in a series of publications. Rott made ​​use of this elementary basic laws of physics and models of fluid dynamics and thermodynamics. The theory has been verified in the years 1972-1974 at the ETH Zurich. Due to the work of Rott the thermoacoustics gained a worldwide high interest since about 1980. Current research and development efforts to deal, inter alia, with chillers that operate based on the thermoacoustic effect.

Applications

• Refrigeration technology

• Combustion processes

• Sensors