Experimental Investigations of an Industrial Lean Premixed Gas Turbine Combustor With High Swirling Flow

In the interest of understanding the prospects and restrictions of fuel flexibility in a prototype industrial gas turbine combustor, an experimental study is performed. Methane is used to characterize standard gas turbine operation; in addition a non-standard fuel is explored, generic syngas (67.5 % hydrogen, 22.5 % carbon monoxide and 10 % methane). Both these gases are also investigated after dilution with Nitrogen to a Wobbe index of 15 MJ/m³. All measurements are conducted at a preheat temperature of 650 K to mimic gas turbine conditions. The pressure is atmospheric. The burner examined is a downscaled industrial 4^th generation DLE (dry low emissions) burner. This swirl-stabilized burner features three concentric sectors: the RPL (rich-pilot-lean), the Pilot and the Main. The burner is designed to be coupled with a quartz combustion liner allowing a variety of laser and optical diagnostics, including PIV (Particle Image Velocimetry) and OH-pLIF (planar Laser Induced Florescence). The mentioned techniques are used herein for identification of combustion and flow phenomena. For this study the measurement region is located at the burner recirculation zone. CFD (RANS) calculations are compared with the OH-pLIF images to identify the zones of active combustion. CFD is also used to see the effect of recirculation zone position when moving towards the lean blow out limit. Additionally, integral scales are calculated for each of the combustion cases and from these, the Kolmogorov scales are estimated. The flow field, imaged by PIV, shows that the recirculation zone location along the major flow axis is strongly dependent on the presence of combustion.