Physical and chemical processes in turbulent combustion flows can be explained using continuity, momentum, conservation of energy, conservation of species equations, as well as the thermodynamic equation of state and expressions for calculating reaction rates and their properties. Numerical solution of these equations is almost impossible due to the variations in different quantities of turbulent flow, chemical mechanisms with a high number of species, high gradients in velocity and temperature, and the effects of unsteady flow. In this research, Large Eddy Simulation for modelling turbulent flows has been used to model some diffusion flames. In this method, large scales will be calculated and small scales will be modelled. The laminar flamelet model has been used in order to simulate the combustion part of the problem and estimate the temperature and species field. The most important objective of this investigation is studying the performance of the laminar flamelet model in turbulent combustion flows, analyzing the results, and comparing the results of the LES model to those from Algebraic Scalar Flux and Reynold stress model. In this thesis, first, to validate the Dynamic Smagorinsky subgrid model, backward facing step flow has been studied and the flow separation point and the results associated with the mean velocity were compared with available experimental results. The mean velocity results matched the experimental results, except near the wall. Then, the combustion field resulted from a bluff body was studied using turbulent Large Eddy Simulation, Dynamic Smagorinsky subgrid, and laminar flamelet combustion model. The results from time-averaged velocity field, temperature, mixture fraction, and species mass fraction were compared with the results from the RANS model and the experimental results. The results show that average field of velocity properly matches the experimental results and time averaging range needs to be increased in order to reach higher accuracy in temperature field, mixture fraction and species mass fraction. Keywords: Turbulent combustion, Large Eddy Simulation, Laminar flamelet model, Diffusion flame