"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 combustion 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 and is the main fundamental challenge to premixed combustion science and technology. The project is aimed at numerically characterizing the burning behaviour of premixed hydrocarbon flames diluted by the addition of H2 CO2, H2O and CO and developing high fidelity modelling techniques to facilitate the study and design of practical combustion systems involving such flames. The main objectives are: 1) To carry out numerical investigations using the large-eddy simulation techniques on the aforementioned three important phenomena, i.e. (i) development of hydrogen blended premixed flames (ii) influence of high-pressure on turbulent burning velocities, (iii) preferential diffusion effects; 2) To develop a turbulent reacting flow model accommodating above first three phenomena, 3) To validate the numerical mdoel by using: experimental data of Gökalp’s group on lean H2/CH4/air turbulent Bunsen flames at various pressures up to 9 bar, the PSI group in Switzerland on dump combustor for ultra lean stationary gas conditions for pressures up to ~14 bar and high-pressure and high-temperature flame data with CO2 and H2O as diluents."