Abstract This work explores the importance of reaction mechanisms and combustion models on the flame length and emission characteristic prediction by CFD simulations of complex multi-nozzle combustor configuration, operating under CH4/H2 blend variations. For the study, both RANS and LES turbulence models are explored. Test data used for the analysis is taken from work published by KAIST University, U. Jin and K.T. Kim 1,2 on the investigation of combustion dynamics and NOx/CO emissions from lean-premixed multi-nozzle CH4/H2 blended flames. The combustion domain consists of densely distributed small-scale multi-tube injectors called Micromix nozzles. This setup provides insights into the collective behavior of small-scale multi-nozzle flames and resultant emission rates. Test data for different inlet compositions, keeping a thermal power condition of 78 kW, are considered for evaluation. Results from simulations for OH* chemiluminescence, OH concentrations, NOx, and CO emissions are compared against the test data. Reduce Model Fuel Library (MFL) mechanism with relevant NOx pathways along with Flamelet Generated Manifold (FGM) model found to predict the trend of flame length and emissions concentration with change in fuel composition reasonably well, compared to detailed chemistry combustion model as well as test data. However, for capturing impact of local non-unity Lewis number effects, detailed chemistry model found to be better for the low turbulent flow conditions, as considered in the referred experimental data
Shrivastava et al. (Thu,) studied this question.