Ambient pressure effect on non-premixed turbulent combustion of CH4–H2 mixture

•Simulation of turbulent diffusion flame with the PDF approach using the flamelet model and the modified k-epsilon model.•Evaluation of the combustion model within non-premixed turbulent combustion with coaxial geometry at high pressure.•Evaluation of the effect of ambient pressure on methane enriched with hydrogen flame.•Increase ambient pressure shrinks the flame.

The present work is devoted to the study of the effect of ambient pressure on non-premixed turbulent combustion of a mixture of 20% of hydrogen and 80% of methane. The simulations were conducted using the PDF approach and modified k-ε turbulence model. The flamelet model was used with the GRI 2.11 detailed kinetic mechanism. The flame consists of two coaxial jets of air and a jet of CH4–H2 mixture with pilot flame. After validating the model used we have varied the ambient pressure from 1 to 10 atm. We observed that the increase of ambient pressure leads to a slight increase of the flame temperature and the mass fraction of NO and a decrease in the radial and axial expansions.