Fuel-Air Mixing and Flame Structure Measurements for Advanced, Low Emission Gas Turbine Combustors

摘要

A study of the fuel/air mixing and combustion processes downstream of a dual-annular counter-rotating swirler premixer was conducted. A brief description of the facility and results from planar laser-induced fluorescence (PLIF) OH experiments and emission measurements are included in this report. OH images show a fluctuating flame dominated by large-scale structures. The flame is anchored at the edge of the premixing duct exit in the region shown in previous mixing studies to possess fuel concentrations well above the overall equivalence ratio. The area near the center of the exit of the premixer duct is almost completely devoid of reaction. Emissions measurements of NOx, CO, and UHC were also performed. NOx emissions decrease approximately 60% as equivalence ratio is decreased from 0.7 to 0.6, attributable to decreased combustion temperatures. Though combustion temperatures increase slightly for higher pressure drop conditions, NOx emissions remain constant, likely due to decreased residence times and improved mixing for the higher pressure drops. CO emissions increase with both equivalence ratio and pressure drop. In addition to OH imaging and emission measurements, coherent anti-Stokes Raman scattering measurements have been used to quantify combustion temperature fluctuations.