Quasi-periodic bursts of acoustic oscillations were observed during the start-up process in a looped-tube thermoacoustic engine. The acoustic oscillations have a constant frequency of 111 Hz, while the bursts have “quasi-periods” in the order of 14–25 s. The quasi-periodic bursts show a new mode of amplitude growth in this thermoacoustic engine. The envelope of the acoustic oscillations has a fishbone-like shape. The nature of the observed fishbone-like instabilities suggests a strong interaction between the acoustic and temperature field.
Yu, Z., Jaworski, AJ., & Abduljalil, A. S. (2010). Fishbone-like instability in a looped-tube thermoacoustic engine. Journal of the Acoustical Society of America, 128(4), EL188-EL194. https://doi.org/10.1121/1.3486198