Active control of thermoacoustic oscillation based on the x-nlms algorithm

Abstract

Thermoacoustic oscillations, caused by the coupling of unsteady heat release and pressure fluctuation, can result in severe damage to the combustion chamber of gas turbines. This paper presents a novel approach to active control of thermoacoustic oscillations, which is based on a Filtered-X normalized least mean square algorithm (X-NLMS). The controller employs the pressure magnitude at a predetermined axial position preceding the flame as the control variable, which is acquired through microphones installed around the combustor periphery. Control is accomplished by modifying the output frequency and phase of a loudspeaker. The performance of the control system is evaluated through simulations on a Rijke tube, with the classical PID method used as a comparison. The experimental results showcase the efficacy of the X-NLMS algorithm in actively controlling thermoacoustic oscillations. By adaptively estimating and attenuating pressure fluctuations, the algorithm effectively suppresses the undesired acoustic disturbances associated with thermoacoustic instabilities. Comparative analysis reveals that the X-NLMS algorithm outperforms PID control in terms of oscillation suppression and system stability. Its ability to adapt to time-varying dynamics and its low computational complexity make it a promising candidate for real-time thermoacoustic control applications.