Practical active control system for combustion oscillations

Abstract

A low-frequency combustion instability of a flame burning in a duct has been successfully controlled by the unsteady addition of extra fuel. A suitably phased addition of only 3% more fuel reduces the peak in the pressure spectrum due to the combustion instability by some 12 dB. The acoustic energy in the 0-400 Hz bandwidth is reduced to 18% of its uncontrolled value. Since relatively little unsteady fuel is necessary, the mechanical power requirements of the controller are modest and the system is easy to implement.