A Finite Element Method for Control of Combustion Driven Noise

Strong coupling between flame and pressure variations makes combustion driven oscillations difficult to suppress. In most cases the acoustic pressure maxima inside the combustion plant must be determined before effective remedial noise control can be implemented. A finite element method can be use to compute the pressure variation at the possible oscillation frequencies. An example is given in which a subjectively disturbing component in the one-third octave band centred on 125 Hz caused complaints from a distant resident. The noise was traced to an incinerator and the acoustic pressure variation at the oscillation frequency was calculated. By correctly positioning a small pressure release hole in the flue stack, a 24 dB reduction in sound power level at the peak frequency was achieved.