Active Instability Control of Thermoacoustic Oscillation in Premixed Gas Turbine Combustors(<Special Issue>Advanced Fluid Information)

In this investigation, experimental results on combustion control systems to suppress the pressure oscillation and combustion noise were indicated using laboratory scale rigs of premixed gas turbine combustors. As for the way of controlling, two different control approaches were examined. One was a thermoacoustic approach using minute secondary flames. The control system had a simple time-delay algorithm and equipped a microphone as a sensor. The minute secondary flames as an actuator were formed with pulsing supply of the secondary fuel using a piezo valve. The other was a fluid mechanical approach using a secondary injection method. In that case, both fuel and air injections as the secondaryjet from the center of nozzle were examined to clarify the control factor to reduce the pressure oscillation and NOx emissions. As the results, combustion noise caused by pressure oscillation was reduced successfully with the suppression of about 10 dB by the thermoacoustic approach. Furthermore, it was found that secondary air injection was effective to suppress the NOx emissions based on thermal NO.