Fundamental study on enlarge of a loop-tube-type thermoacoustic system—Measurement of onset temperature and sound field in cross-sectional area change

Abstract

We have worked to improve the output of the thermoacoustic system to expand the range of system applications. The onset temperature of a loop-tube-type thermoacoustic system was experimentally examined under changes to cross-sectional area in a loop tube. The total length of the system was not varied. This cross-sectional area, i.e., inner diameter was set to values of 24.2, 42.6, and 95.6 mm; onset temperatures at these diameters were found to be 623, 329, and 121 °C, respectively. The sound field in the system was measured to investigate the reason why the onset temperature varies depending on the inner diameter. The sound pressure distribution, particle velocity distribution, sound intensity distribution, and phase difference distribution of sound pressure and particle velocity in the system required for evaluation of the thermoacoustic system were measured. It is confirmed that the sound field is different depending on the inner diameter. It is found that the oscillation frequency is different depending on the inner diameter. The oscillation frequency of system with an inner diameter of 24.2 mm shows two-wavelength resonance. The oscillation frequencies of the other system showed one-wavelength resonance. In addition, dissipation is confirmed to increase as the inner diameter decreased.We have worked to improve the output of the thermoacoustic system to expand the range of system applications. The onset temperature of a loop-tube-type thermoacoustic system was experimentally examined under changes to cross-sectional area in a loop tube. The total length of the system was not varied. This cross-sectional area, i.e., inner diameter was set to values of 24.2, 42.6, and 95.6 mm; onset temperatures at these diameters were found to be 623, 329, and 121 °C, respectively. The sound field in the system was measured to investigate the reason why the onset temperature varies depending on the inner diameter. The sound pressure distribution, particle velocity distribution, sound intensity distribution, and phase difference distribution of sound pressure and particle velocity in the system required for evaluation of the thermoacoustic system were measured. It is confirmed that the sound field is different depending on the inner diameter. It is found that the oscillation frequency is different dependi...