Role of actuation in combustion control

This paper presents analysis of the effect of actuation on the combustor dynamics. Two different categories of actuators are studied: flow sources, e.g., acoustic speakers, and heat sources, e.g., fuel injectors. These sources are modeled in the conservation equations and a finite dimensional model is obtained. Two methods of analysis are used to gain insight into the physics of actuation, and its stabilizing/destabilizing effect on the combustor through feedback control. The first is the energy method which is used here in a novel way to explain intricate work exchanges between the different dynamic components of the system: the acoustics, the flame, and the actuator. The energy analysis is used also to quantify the "useful" and "wasted" work generated by actuators. A more revealing method of analysis is the dynamic representation of the combustor as an oscillator, and is shown to be the basis of any optimal control analysis.