About 30 years ago, Ceperley proposed “a pistonless Stirling engine”, which became sufficient motivation for thermoacousticians to regard thermoacoustic phenomena as a kind of heat engine. Since then work flux, heat flux, and their mutual conversion have been suggested to be fundamental ideas for understanding thermoacoustic engines. Such new concepts can be equally applicable to some reciprocating heat engines. In this paper, based on experimental results, I discuss the working mechanism of Stirling engines from the standpoint of a thermoacoustics framework.
The fundamentals of thermoacoustics constitute understanding thermoacoustic phenomena, the proposal of new thermoacoustic devices, and the development of new experimental techniques. This paper describes a practical guide to measurements of important physical quantities in thermoacoustic systems to help beginners understand the basic techniques. The direct method, involving measurements of pressure and velocity oscillations, and the two-sensor method are introduced for the measurement of work flow. A method for the dynamic calibration of a thermocouple is also presented to make measurements of temperature fluctuation possible. Particular emphasis is given accurately determining the phasing between oscillatory quantities.