Abstract
Thermoacoustic system using thermoacoustic self-excited oscillation which is mutual conversion between heat and sound waves has been proposed as a means to effectively utilize waste heat from factories and automobiles. In thermoacoustic systems, it is important to estimate the critical temperature ratio at which self-oscillation with the desired pressure amplitude occurs for system evaluation and improvement design. Our propose is to estimate the critical temperature ratio for looped-tube traveling wave thermoacoustic systems based on steady-state oscillation control. Considering the effect of the fluctuation of pressure amplitude during self-oscillation on the estimation of the temperature ratio, the relationship between the sound source position and the estimation result was investigated in more detail using the temperature ratio near the critical temperature ratio. As a result, (i) It is possible to estimate the temperature ratio at which the desired pressure amplitude may be obtained regardless of the sound source position, (ii) It shows that the temperature ratio at which the average of the pressure amplitude becomes the desired value can be estimated with accuracy of two decimal places regardless of the location of the sound source. Furthermore, it is shown that the more the estimation is performed using a temperature ratio far from the critical temperature ratio, the more likely the estimation result differs depending on the sound source position, and that it is necessary to reproduce the amplitude ratio of the traveling wave pressure component during self-excited oscillation.
