In order to meet the EU targets on renewable energy and greenhouse gas emissions, there is an urgent need to increase the use of renewable fuels such as syngas and biogas. In the mean time, the low efficiency and emission problems associated with non-premixed combustion systems are also driving the move away from such systems towards lean premixed conditions where fuel is mixed with excess air prior to combustion. Despite substantial progress achieved in turbulent combustion, there still lacks the understanding of the following four phenomena in the context of premixed mode: (i) development of flames (ii) influence of high-pressure on turbulent burning velocities, (iii) preferential diffusion effects which are most pronounced in mixtures that contain free hydrogen, and (iv) flame quenching by very intense turbulence is still poor.The project is aimed at numerically characterizing the burning behaviour of premixed syngas and biogas combustion and developing large eddy simulation (LES) techniques to facilitate the study and design of practical combustion systems for such sustainable fuels. The main objectives are:• To carry out numerical investigations of the aforementioned three important phenomena, i.e. (1) development of syngas premixed flames; (2) influence of high-pressure on turbulent burning velocities; and (3) preferential diffusion effects.• To develop a turbulent reacting flow model that captures the underlying physical and chemical processes in flame development, the pressure and Lewis number effect; and to• To validate the numerical model with published experimental data.The project will result in a validated LES based predictive tool within the frame of open source CFD code OpenFOAM for multidimensional numerical simulations of syngas/biogas premixed flames under elevated pressures as well as a comprehensive database on the values of the time scale, computed for different mixture compositions, pressures, and temperatures.