Numerical Modeling of Oxy-Fuel Combustion in a Model Gas Turbine Combustor: Effect of Combustion Chemistry and Radiation Model

Radiation modeling and combustion chemistry are critical to accurate numerical predictions of oxy-combustion characteristics. The presence of carbon dioxide (CO₂) in oxy-fuel combustion acts as diluents and significantly changes the radiative properties of the combustion gases in comparison to air combustion. In this regard, three global reaction mechanisms: Westbrook-Dryer (3 equations), Jones-Lindstedt (5 equations) and Jones-Lindstedt (7 equations) for oxy-fuel combustion of methane were combined with different weighted sum of gray gas radiation models (WSGGM) available in literature to determine the most accurate combination for methane-oxy-fuel combustion modeling and simulation. This study was carried out in a non-premixed swirl stabilized model gas turbine combustor at a firing rate of 4MW/m³-bar. The modified Westbrook-Dryer (WD-oxy) mechanism could not predict the flame attachment to the fuel nozzle at 35% CO₂ addition. The combinations of Jones-Lindstedt (5 equations) reaction mechanism and WSGGM model proposed by Bordbar gave the closest approximation to our experimental observations and predicted the flame attachment to the fuel nozzle.