چكيده به لاتين
Gas turbines have significant importance in the oil and gas industry and used to run the pumps and compressors in the pipeline. In the last decade more strict standards in relation to pollutants have been established. This thesis has been developed to determine the characteristics of the liquid fuel injection during the reactive flow in the combustion chamber of industrial gas turbine, in order to reduce the NOx emissions. There are complex concepts such as a reactive flow, spray, turbulent flow, multiphase flow and heat transfer by convection and radiation, as well as each of its interaction with other in the study of the liquid fueled combustion chamber. Due to the multiplicity phenomena governing and simultaneous modeling of the interactions between these phenomena, finding numerical tool according to the physics problem and available hardware equipment is very important. In order to model some of these phenomena, two models have been investigated. For modeling of turbulent flow, Realizable k-ε and LES models and the combination between them (DES) have been used. For the interaction between turbulent flow and reactive modeling, PDF and Flamelet model have been used. For the study liquid fuel injection and identify phenomena such as droplet distribution, primary and secondary breakup of droplets, droplet evaporation and the effect of speed and angle of liquid fuel injection, Euler- Lagrangian model have been used. Modeling the radiation has been done by using discrete ordinates (DO) radiation model and NOx modeling has been done separately by βPDF models in the end of numerical simulation of flow and combustion. At first, velocity distribution and flow formation has been investigated in the reactive flow with airblast injector and different turbulence approaches and the results has been compared with experimental data. This comparison is shown that the LES turbulence approach against the RANS turbulence approach is preferable in terms of quantity (Variety reports) and quality (accuracy) of results. But because of the extremely high computational cost difference between the two approaches that is more than two thousand hours, LES approach for the study of numerous parameters in combustion modeling is impossible. Combustion modeling also has been investigated from two perspectives, First flamelet and then chemical mechanisms that used in combustion flow, as the parameters of the study has been evaluated. In this way, the effect of flamelet and chemical mechanism types that is used for simulations, on the reactive flow characteristics such as velocity, temperature, turbulence, mixture fraction, scalar dissipation rate and the concentrations of species especially the pollutant concentrations has been shown.Then, by using RANS approach and to evaluate the effects of injection on NOx emissions, liquid fuel injection into the model combustor of the gas turbine with different velocities and angles have been modeled, so that the effects of each of these parameters on the temperature and droplet diameter and NOx emissions have been observed.
