Combustion Instability Interaction with Fuel-Air Mixing in a Partially-Premixed Gas Turbine Model Combustor

摘要

Fluid mechanical coupling between injected reactants and the flame-base is observed in a gas turbine model combustor. A natural combustion instability introduces oscillations in fuel and air mass flow rates which affects mixing, stabilization, instability amplitude, and anchoring. This interaction has been studied for varying fueling conditions in methane and propane flames. Redistributions of air flow rates between the individual swirlers strongly affects instability strength and shear layer mixing. Laser Doppler velocimetry (LDV) measurements of radial velocities in the various flame show velocity fluctuations which correspond to flame motion oscillations captured by high speed chemiluminescence imaging. Acetone has been introduced as a fuel tracer, for use in planar laser-induced fluorescence (PLIF) measurements. Acetone PLIF of the fuel and high speed chemiluminescence imaging reveals that coupling between the flame position and shape occurs. Flame shape has been correlated with instability strength and presence. Rayleigh indices have been compared to fuel-air distributions to understand how mixing affects instability strength.