Numerical prediction of premixed syngas/air explosion in a closed duct using a reduced combustion mechanism

A reduced combustion mechanism for syngas/air has been developed with the aim of accurately predicting premixed flame behavior during explosions. The evolution of premixed syngas/air flames in a closed duct, with hydrogen volume fractions of 50 %, 70 %, and 90 %, was investigated using detached eddy simulation and the thickened flame model. The results indicate that numerical simulations based on the reduced combustion mechanism can effectively replicate the explosion dynamics observed in experiments, e.g., flame structures and flame speeds. The key elementary reactions that significantly affect the laminar burning velocity were identified by analyzing the chemical reaction kinetics. As the hydrogen volume fraction increases, the variation of active free radicals influences the relative production rates corresponding to the primary reaction pathway. The coupling relationship between key radicals and flame structure was further elucidated by comparing and analyzing the mass fraction and reaction rate of O, H, OH, HO2 and HCO radicals.