Design and experimental validation of active robust controller for the jet flame combustion oscillation

Abstract

Combustion oscillations in aircraft engines can induce significant flame and sound pressure fluctuations within the combustion chamber, leading to detrimental effects on engine performance and potential structural damage. Consequently, it is imperative to employ active control techniques to mitigate these oscillations. This study concentrates on the one-dimensional dynamic modeling of the jet flame combustion oscillation and establishes a thermoacoustic coupling model. This model accurately captures the dynamic characteristics of the combustion oscillation process by incorporating external energy excitation as the input and measuring the fluctuation in sound pressure and heat release rate as the output. Given the inherent uncertainties associated with combustion oscillation characteristics, a robust H∞ mixed sensitivity controller is designed to actively suppress combustion oscillations based on the model. Experimental validation of the active control for combustion oscillations is also conducted. The findings demonstrate that the designed H∞ robust controller surpasses the performance of the conventional phase-shift controller across various operating conditions. In the simulation of the control system, the H∞ robust controller has a suppression effect of −50dB on oscillations under the design point operating condition, and the suppression effect exceeds −20dB under other operating conditions. In the active control experiments, at the design point, the H∞ robust controller exhibits a remarkable suppression effect of over −30dB, and even within about 10 Hz range of deviation from the design point, it still achieves a suppression effect of over −10dB. These results serve to affirm the robust performance of the controller.