Self-sustained thermoacoustic oscillators with general impedance boundary: Onset and dynamic behavior determination and theoretical–experimental validation

Abstract

The self-sustained thermoacoustic oscillator, illustrating continuous operation with a static, non-uniform, and temperature-dependent heat source, offers applications in fundamental physics, materials science, fluid dynamics, acoustics, and other energy conversion technologies. Addressing the challenges of determining the onset and dynamic behaviors and improving performance remains critical for thermoacoustic oscillators. This paper presents a comprehensive framework, which attempts to find a trade-off between the advancement of theoretical guidance and the reliability of experimental verification, to analyze the onset and dynamics of a self-sustained thermoacoustic oscillator with general impedance boundaries. The theoretical analysis, rooted in the linear thermoacoustic theory, is performed using the smoothed-Fourier series and Galerkin method to satisfy the continuity of the acoustic field with general impedance boundary conditions. The accuracy of the proposed theoretical model was verified through conducting thermoacoustic instability measurement experiments. The onset and dynamic behavior of the thermoacoustic system under different geometrical and electrical parameters, such as thermoacoustic oscillator length, thermoacoustic core position, and input voltage were studied theoretically and experimentally. The analytical and experimental methodologies developed herein are valuable for designing and optimizing thermoacoustic energy harvesters and loudspeakers, as well as for controlling unstable oscillations in combustors. These advancements are set to enhance the fields of energy harvesting and flexible, wearable acoustic devices.