Computational Fluid Dynamics Modeling of Lean Blowout in the ARC-M1 Gas Turbine Combustor

The internal dynamics of liquid-fueled gas turbine combustors are complex due to the interaction between the combustion, spray physics, and turbulence. Computational tools help understand these processes. A Computational Fluid Dynamics (CFD) model is developed for the Army Research Combustor-Midsize, ARC-M1 to characterize the stable and lean blowout behavior of F-24 jet fuel for different operating conditions. High quality X-Ray data is used for spray model initialization. To understand the impact of the inlet air temperature and pressure drop across the combustor, the flow dynamics and fuel/air mixing are analyzed. The impact on flow features such as the recirculation zone, shear layers is investigated. Increase in the pressure drop leads to lean blow out at higher liquid flow rates. This is attributed to the reduced variation in the equivalence ratio near the nozzle that occurs due to the change in the flow features that force some of the recirculated product towards the walls instead of the central recirculation zone. With an increase in the inlet air temperature, improved vaporization by the incoming air leads to a more compact flame. As a result, downstream of the flame, most of the recirculated hot gas stays within the central recirculation zone resulting in a flame that is more resilient to lean blow out compared to lower inlet temperatures.