Robust frequency response-based active disturbance rejection control to mitigate thermoacoustic instability in the Rijke tube burner

Thermoacoustic instability challenges combustion engine operation due to acoustic wave and heat release rate coupling. Mitigating instabilities is crucial but often hindered by the complexity of the mathematical expressions involved. In this study, we propose a novel approach that leverages the easily measurable frequency response characteristics of the system, specifically the dominant oscillation frequency of the pressure pulsations, to achieve robust active disturbance rejection control for thermoacoustic instability in the Rijke tube burner. Unlike existing feedback controller designs, our model-independent active disturbance rejection control synthesis offers a general and clear design flow, enabling effective control parameter tuning and aiming to achieve optimal control performance. This design flow employs an iterative method to find an optimal set of control parameters for practical engineering applications. The simulation and experimental results confirm the effectiveness of the proposed method in suppressing oscillations across a wide frequency range (200-2000 Hz and beyond). The method achieves a rapid decrease in oscillating pressure, resulting in an approximate 99.6% reduction in amplitude. Additionally, it effectively suppresses 20% of operational fluctuations and 400% of energy fluctuations without compromising control performance. These findings demonstrate the robustness and reliability of the proposed method, as supported by both simulation and experimental data. This study contributes to the development of robust and efficient active control strategies for thermoacoustic instability, with potential benefits for enhanced engine performance and reduced emissions.