Numerical Study Of Swirl Burner And Plasma-Assisted Combustion

With the development of science and technology as well as national economy,researchers are paying more and more attention to improving combustion efficiency and reducing pollution emissions.Swirl burner and plasma assisted combustion have become the focus of people.Swirl burner and plasma assisted combustion broad application prospects in this field.Swirl combustion and plasma assisted combustion are effective ways to improve combustion stability and reduce NOx emission,which have been used in aeroengine and gas turbine.However,the best swirl and the mechanism of plasma combustion are not clear.In this paper,the combustion process of syngas in swirl burner is studied,and the numerical calculation method is used to carry out the related research.The physical structure of three-dimensional swirling burner is constructed by Solid Works,and the grid structure of structural and non structural is established by ICEM.Through grid independence verification,a grid of 800,000 nodes is adopted for numerical calculation.Standard k-ε turbulence model is used in this paper,FGM combustion model and GRI-Mech 3.0 detailed reaction mechanism were used to study the combustion of synthetic cyclonic flow.The comparison between the simulation results and the experimental data shows that the product concentration error of swirl combustion under different equivalence ratio is within the allowable range,which verifies the accuracy of the model.Further,the UDF is programmed with C language,and Poisson equation and current continuity equation are added to solve the electric field to implement the coupling of electric field and flow field,so as to carry out the research of plasma combustion effect under different voltage conditions.The results indicate that with the increase of swirl degree,the length of flame in combustion chamber shortens,the area of recirculation zone increases,the turbulent kinetic energy of flame in swirl burner increases,the combustion becomes more sufficient,and the NO emission decreases.When the angle between the swirl plate and the horizontal axis is less than 45 degrees,the vortex structure becomes more continuous with the increase of the swirl degree.However,when the swirl is too large,there is a risk of tempering.When the swirl degree is 0.78,the combustion performance of the swirl burner is the best.The influence of different pressure on combustion shows that with the increase of initial pressure,the range of recirculation zone in combustion chamber decreases,the turbulent kinetic energy in swirl burner combustion chamber decreases,the combustion becomes more insufficient,and the temperature in combustion chamber increases,the NOx emission increases.Negative 2000 V and negative 3000 V were applied to the hydrocyclone respectively,and 4000 V and 5000 V were applied to the outer wall of the hydrocyclone respectively.Compared with no voltage condition,the promotion effect of plasma on swirl combustion was studied.The results show that the maximum temperature of flame and turbulent kinetic energy of combustion chamber will be increased when the voltage is applied to the hydrocyclone.And the maximum temperature increases with the increase of voltage.The addition of electric field leads to the reduction of NOx emission,and the negative voltage has more obvious effect on NOx emission reduction than the positive voltage.The research on the influence of different gas inlet velocity on combustion shows that when the gas inlet velocity is large,the flame propagation speed is fast,but the combustion is insufficient,and the temperature in the combustion chamber decreases.