Experimental Investigations of the Temporal Air-Fuel Mixing Fluctuations and Cold Flow Instabilities of a Premixing Gas Turbine Burner

The advantages of premixed combustion are low NOx-emissions, but the drawbacks are possible thermoacoustic instabilities, which became the key issue of modern gas turbine combustion research. The principal mechanisms leading to combustion instabilities of modern low NOx burners are flow instabilities, caused by vortex shedding at the burner outlet, fluctuating recirculation zones and instationary fuel-air mixing. In the present study, a stationary gas turbine burner has been investigated with special emphasis on instationarities that may cause combustion instabilities. The test rig allows detailed investigations of the flow, the air-fuel mixing and the velocity field inside the combustion chamber. At the present stage of the investigations, different flame settings (pilot, non-premixed and premixed operation) were analysed at atmospheric pressure.Copyright © 2000 by ASME