Large Eddy Simulation of Hydrogen Flame Stabilization in a Reheat Gas Turbine Combustor

Reheat gas turbine combustors utilizing hydrogen-dense fuel blends serve as a potentially effective low-emission alternative energy system. These combustors operate under unique conditions that lack low-cost models for accurately predicting flame stabilization. A large eddy simulation (LES) with detailed chemistry is performed on a simplified geometry of the Ansaldo GT36 sequential combustor with an elevated temperature vitiated air-hydrogen flow in a rectangular mixing duct and combustion chamber, reflective of available direct numerical simulation (DNS) results. In particular, simulation parameters are assessed for relative importance in generating accurate flame characteristics against simulation cost. Additionally, adaptive mesh refinement at the junction of the mixing duct and combust chamber is employed to resolve the high reactivity flame zones of the H₂ fuel. Detailed analyses will be performed to elucidate the importance of low-resolution inlet and outlet extensions for development of turbulent conditions and pressure dampening, respectively. Results gathered here validate the feasibility of accurate and relatively low-cost sequential combustor LES models which can complement fundamental experimental and DNS results in their application to the design process.