AbstractThis study addresses the scalar structure of turbulent oxy-fuel syngas non-premixed jet flame in the context of direct numerical simulation (DNS) and detailed chemistry. The main objective is to identify the influence of the Reynolds number on oxy-fuel flame structure, and to clarify the differences of scalar structures between oxy-fuel syngas and syngas-air flames at a similar higher Reynolds number. Two oxy-syngas flames at Reynolds numbers of 3000 and 6000 and one syngas-air flame at Reynolds number of 6000 were simulated. These studies show that the existence of CO2 in the oxidant has a profound effect on scalar structure of oxy-fuel syngas flame compared to syngas-air flame