Predicting the Onset and Control of Thermoacoustics

Dear Colleagues,

Thermoacoustics is a highly interdisciplinary science that encompasses the fields of thermodynamics, acoustics and fluid mechanics. On the one hand, when thermoacoustic instability occurs in the propulsion systems and industrial combustors, such as in liquid/solid rocket engines, aero-engines, afterburners, land-based gas turbines and furnaces, large-amplitude pressure/heat oscillations may incur several unwanted outcomes, including structural vibrations, severe erosions, missile launch deviation from the designed trajectory, or even explosion. There are two main ways to prevent the onset of thermoacoustic instability or efficiently suppress such detrimental oscillations: passive control and active control. Passive control involves either absorbing acoustic energy by utilizing acoustic dampers, such as quarter wave tubes, acoustic liners, Helmholtz resonators, and perforated plates, or decreasing the responsiveness of the combustion process to acoustic excitation via structure modification, such as the structure asymmetry, modifying the fuel injection system and changing the position of the heat source. Active control involves using sensors, controllers and the actuators to break the positive interaction between the unsteady heat release rate and acoustic pressure. On the other hand, the interaction between acoustic waves and solid porous materials contributes to energy conversion between heat and sound, which is encouraged and lays the foundation for thermoacoustic engines and refrigerators. By integrating a thermoacoustic engine with an acoustic-to-electric transducer (such as linear alternators, piezoelectric transducers, and triboelectric nano-generators), thermoacoustics can be utilized for power generation or energy-harvesting purposes. In addition, a thermoacoustic engine can be utilized to drive a thermoacoustic refrigerator, providing a novel approach to producing cooling using heat. This Special Issue aims at the accurate prediction of its onset and effective control of large-amplitude pressure oscillations.

Dr. Xinyan Li
Dr. Chenzhen Ji
Dr. Geng Chen
Guest Editors

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• thermoacoustic oscillations
• nonlinear analysis
• prediction of its onset
• active and passive control