Adaptive Active Control of Combustion Instabilities

Abstract

It is shown in this article that adaptive control algorithms may be used to suppress combustion instabilities in turbulent combustors. In a typical configuration a signal delivered by a sensor monitoring the flame serves as input to a numerical adaptive filter which sends a control signal through an actuator into the combustion chamber. The controller coefficients are updated at the sampling rate using a global response signal. The controller automatically finds optimal coefficients to control the different unstable modes of oscillation. In addition it adapts to evolutions in operating conditions such as a continuous sweep of air flow rate and a shift in the global equivalence ratio. Under certain conditions a secondary mode appears when the control system is operating. While this oscillation occurs as a result of a destabilizing effect of the control loop its amplitude remains limited. The theoretical background is developed and used to explain typical implementation problems such as the filter convergence or the identification process.