Numerical Simulation Of The Lean Premixed Combustion

With the progress of technology and the improvement of the people's living standards, man begin to pay more attention to the environmental pollution which have increasingly become the common subject of various countries of the world. People begin to pay attention to the fuel combustion environmental pollution problems especially. For this purpose, the gas fuel combustion on different coefficient of air consumption has been described in this dissertation.First in this dissertation, a physical model was founded from the lean premixed combustion device in the laboratory. Then, the process of gas combustion in the combustor was simulated by FLUENT6.2 software. The influence of different air consumption coefficients on the combustion characteristic was analyzed by FLUENT6.2.Through the numerical simulation we found that: side recirculation zone and corner recirculation zone exist in the combustor. The role of side recirculation zone is to make some of high-temperature flame product back to the roots, so that the flame can be stabilized. Another role of side recirculation zone is to heat the gas that will shorten the flame length. The corner recirculation zone finally diminished with the coefficient of air consumption decreasing. After the analysis of the temperature field, it is found that when the coefficient of air consumption is less than 1, the combustion high temperature zone transformation rule is similar to that when the coefficient of air consumption is bigger than 1. The max temperature may not appear when the equivalence ratio is 1, this is related to the model chooses for simulation. Whenαis less to 1, the concentration of NO at the exit of the combustor increase asαdoes also, whileαis 0.91, the concentration of NO reaches the maximum. Whenα>1, the concentration of NO decrease withαincreasing. Because the model is coupled with the model of broadband noise source models, a local high pressure zone appears on the combustor which makes the noise field appear.Verified by the experiments, a conclusion was drawn that the numerical simulation results well agree with the experiment. This means that study on the lean premixed combustion with the numerical simulation method was satisfying.