Control laboratory experiments in thermoacoustics using the Rijke tube

We report on experiments that investigate the dynamics, identification and control of thermoacoustic phenomena in a Rijke tube apparatus. These experiments are relatively simple to construct and conduct in a typical, well-equipped undergraduate controls laboratory, yet allow for the exploration of rich and coupled acoustic and thermal dynamics, the associated thermoacoustic instabilities, and the use of acoustic feedback control for their stabilization. We describe the apparatus construction, investigation of thermoacoustic dynamics and instabilities in both open-loop and closed-loop configurations, closed-loop identification of the underlying dynamics, as well as model validation. We also summarize a transcendental transfer function analysis that explains the underlying phenomena. These experiments are notable for the fact that rich thermoacoustic phenomena can be analyzed using introductory concepts such as the frequency response and root locus, and thus can be performed and understood by controls students with relatively little background in acoustics or heat transfer.