Research On The Combustion Characteristics Of Single-head Axial Staged Combustor

In order to investigate the combustion performance,NO_x emission characteristics as well as the spacial distribution rules of single head axial staged combustor under different working conditions,the present research,on the strength of the turbulent combustion flamelet model,employs a method of combining the Steady Laminar Flamelet Model（SLFM）and Representative Interactive unsteady Eulerian Particle Flamelet Model（EPFM）to conduct a 3D numerical research of the noreacting velocity field and the combustion flow field of the single head axial staged combustor under different working conditions,analyze the spacial distribution characteristics of the NO_x in the primary combustion domain under different working conditions and discuss the impact of the inlet air temperature on the production of the NO_x.The main content of this paper includes two major parts:Firstly,the generation processes of nitrogen oxides in the gas turbine are very complex,involving a large number of the elementary reactions.Besides the time range between different elementary reactions is quite large.While the comprehensive analysis of the the NO_x production process during the combustion needs to consider detailed chemical reaction kinetics models,leading to the strongly nonlinear and rigidity problem,which will contribute to vast calculation costs.On account of this,developing a new efficient and accurate turbulent combustion model which can couple the chemical reaction mechanism is the focus of combustion numerical research.Since the Flamelet Model,which is originatesd from the Low Dimensional Manifold Method（LDM）reduces the computation costs by dimension reduction method.Therefore,on the basis of the Steady Laminar Flamelet model（SLFM）,this paper takes a numerical calculation method of combining the SLFM with the Eulerian Particle Flamelet Model（EPFM）.To verify the feasibility and reliability of the calculation method,the present research employs this method to conduct a numerical calculation on the Bluff Body Stabilized CH₄/H₂ diffusion flame of Sydney University.Meanwhile,the numerical results are compared with the experiment data and the other scholar’s simulation results which was obtained by using Large Eddy Simulation（LES）method.The comparison results show that:（1）The revised linear Reynolds Stress Model（RSM）can accurately predict the velocity field of turbulent diffusion flame;（2）The SLFM coupled with the detailed chemical kinetics model:GRI-Mech2.11 can predict the velocity and temperature fields of HM1e flame as well as the distributions of the main components like CO₂ and H₂O much better.Besides,after the coupled EPFM model conducts correction calculations on intermediate components,the NO prediction result is improved significantly,which fully verifies that this simulation method can greatly predict the turbulent combustion and the distribution of the NO_x.Secondly,based on the verified simulation methods above,the paper conduct three-dimensional calculations on the cold flow field and the combustion flow field of the single head axial staged combustor under different working conditions and inlet air temperatures.Also,the characteristics and spatial distribution of NO_x under different working conditions and inlet air temperatures are estimated.The calculation results show that:（1）With the change of working conditions,the area of high temperature zone above 1900K in the combustion chamber keeps increasing,the outlet temperature and the NO_x emission keeps increasing accordingly;（2）Thermal NO is mainly generated in the high temperature region near the flamelet.Under the action of the flow field,NO diffuses and mainly distributes in the main recirculation zone;（3）With the increase of inlet air temperature,the main recirculation zone in the combustion chamber remains virtually unchanged,the high temperature area keeps increasing,and the outlet temperature and NO emission keeps increasing accordingly.