Combustion Computational Fluid Dynamics Simulations of a Range of Experimental Lean Hydrogen/Natural Gas Blend Flames

Abstract

Abstract Hydrogen micromix combustion is a promising technology to reduce the environmental impact of both aero and land-based gas turbines by delivering carbon-free, and potentially ultra-low-NOx, combustion with a greatly reduced risk of autoignition or flashback. A preliminary investigation of such novel injector geometries, that are capable of stabilizing premixed, partially premixed, and diffusion flames, using fuel mixtures ranging from pure methane to pure hydrogen, was performed in an Atmospheric Combustion Rig at the National Research Council Canada (NRC). High quality experimental data was collected using Particle Image Velocimetry (PIV) and both OH and acetone planar laser-induced fluorescence (PLIF). Combustion Computational Fluid Dynamics (CCFD) Methods and Tools were developed and validated against these experimental results, for multiple flame shapes, and combustion modes, resulting from fuel lean mixtures of H2/CH4 ranging from 70%/30% to 90%/10% blends, by volume. Within the current study, Large Eddy Simulations (LES) of a single injector, as well as an array of 5 injectors were investigated. A Flamelet Generated Manifold (FGM), Kinetic Rate, tabulated chemistry approach, using 1D Freely Propagating Flamelets, is used as the combustion model. LES-FGM simulations of the entire experimental injector and test section assembly were performed. Meshing and numerical methodologies were developed, resulting in good agreement for the flame shapes and positions; as well as for the measured thermoacoustic pressure fluctuation amplitude changes, over the range of simulated operating conditions. Further work is underway in applying and assessing the validity of this LES-FGM methodology for flames, with injection systems using micromix technology, at more typical engine conditions, where higher pressures and temperatures are found.