Active adaptive control of combustion

An active adaptive feedback control approach is utilized to minimize pressure fluctuations in a laboratory-scale dump combustor. The actuation mechanism is based on spanwise forcing of the inlet boundary layer. This forcing is acoustically driven and has been shown to reduce the magnitude of the pressure oscillations by altering the dynamics of the flame-vortex interaction. The control strategy is based on the adaptive filtered-x least-mean-square (LMS) algorithm. The real-time pressure signal, measured by a piezoelectric transducer, is used as feedback as well as a measure of the enter to train the adaptive algorithm. The adaptive algorithm updates the weights of a digital filter, in its efforts to minimize the pressure fluctuations, in real-time. The digital filter as well as the adaptive algorithm, reside on a digital signal processing (DSP) board. Both finite impulse response (FIR) and infinite impulse response (IIR) filter structures were investigated. It was found that the recursive direct-form filter structure is required to prevent the algorithm from driving itself towards instability.