Industrial flames based on the type of mixing of fuel and oxidizer divide into two type, premixed and non-premixed (diffusion). In premixed flames fuel and air mix before combustion but in diffusion flames fuel and air mix in the surface of flame. Premixed flames have more combustion efficiency and less pollutant but because of probability of explosion, in more combustion equipment non-premixed flames are in used. For use of premium of both premixed and diffusion flames , partially premixed flames can used, in a way that some of air add to fuel before combustion (primary air) and next of air add in surface of flame (secondary air). Moreover, in many industrial cases such as entrance of air in premixed flames, lifted diffusion flames, rich and lean premixed flames, local quenching of diffusion flames, autoignition in nonhomogenous distribusion of fuel and oxidizer, flames stabilized with swirl of hot gases, spray combustion, and etc partially premixed combustion happen. So use of a partially premixed model for simulation of this flames is necessary. In this thesis partially premixed models for simulation of industrial flames are used and effect of entrance of air and lift-off height are investigated. For simulation of partially premixed combustion merging of zimont combustion model (that is a premixed flamelet model based on the progress variable and flamelet or equilibrium combustion models based on the mixture fraction concept (that are diffusion combustion models), is used. For simulation of effect of air entrance, three Bunsen flames that are different in jet velocity, are modeled. In second case for simulation of lift-off height, lifted non-premixed jet flame models. Perfect premixed solution for first case and perfect diffusion solution for second case are performed. In all cases results are compared with previous experimental and numerical works. On attention the results, use of partially premixed models for above cases is necessary and perfect premixed and perfect diffusion models are not able to simulate that effects. Because of the stochiometric condition of simulated Bunsen flames, equilibrium and flamelet models are in some difference but in the case of lifted flame, difference between equilibrium and flamelet models is noticible. The used partially premixed models in the case of Bunsen flame present good results even compare level set model that is an advanced model. In the case lifted flame, that partially premixed model does not simulate stability mechanism perfectly and so predict the lift-off height lower from experiment. Key Words Partially primed flames, premixed flames, non-premixed (diffusion) flames, entrance of air, lifted flame, zimont model, diffusion flamelet model, equilibrium model.