Numerical simulations of a turbulent lifted hydrogen flame in vitiated coflow with flamelet generated manifold approach

Numerical investigation of turbulent lifted H2/N2 jet flame in vitiated hot coflow is presented. Turbulent combustion modeling is performed by using flamelet generated manifold approach and presumed probability density function for turbulence-chemistry interaction. Sensitivity analysis of scalar dissipation modeling for mixture fraction and progress variable suggests that the combustion temperature is more sensitive to mixture fraction variance, whereas the flame lift-off height is more sensitive to progress variable variance. The present simulations provide overall good agreements with experimental measurements for mixture fraction, temperature, and chemical species, which gives further information regarding the global flame structure and reaction characteristics. Investigation on mixture fraction conditional scatter plot reveals that the evolution of lifted flame branch and flame dynamics are well captured. Two combustion modes are identified in flame zone. It indicates that non-premixed combustion dominates in core flame region, however low probability of premixed combustion is observed occurring in central fuel-rich zone.