Thermoacoustic instabilities: modeling and control

The goal of this study was twofold. First, modeling strategies were proposed to characterize the dynamics driving the thermoacoustic instabilities in a swirl-stabilized premixed burner. Second, this model was used to synthesize controllers in order to apply active control strategies to suppress this phenomenon. An experimental combustor model based on acoustic properties of the combustion chamber was derived. This model separates the combustor into a four-block linear system. Acoustic and fuel modulations were used to obtain the frequency response of each block representing a part of the combustor test-rig. Using this linear representation H_∞ disturbance rejection and H_∞ loop-shaping controllers were computed and tested for a set of different working conditions of the chamber for the robustness of the resulting controllers. Standard phase-delay control was used as baseline control strategy to judge the performance of the proposed controllers. Experimental results show the advantages of these model-based control strategies to suppress thermoacoustic instabilities in the test-rig.