Influence Of Structural Parameter On Combustion And NO_x Formation In Can-annular Combustion Chamber

Gas turbines and combined cycle generator sets using clean energy natural gas as fuel have very broad development prospects.The use of high-quality clean fuels can effectively adjust the energy structure to alleviate the growing problem of pollutant emissions.As an important component of gas turbines,can-annular combustion chamber are widely used in heavy-duty gas turbines.In this paper,numerical methods are used to investigate the effects of structural parameter changes on the homogeneous lean premixed turbulent combustion in a loop-type combustion chamber.The main work is as follows:First,the actual combustion chamber is hilly dimensioned and sub-area meshed using the pre-processing software GAMBIT.Local mesh encryption is performed in the entrance area of the combustion chamber,and the grid model is verified.The final grid number of 1.12 million models can correctly reflect the flow and combustion conditions in the combustion chamber.Secondly,the fluid dynamics calculation software Fluent is used to simulate the turbulent combustion of the combustion chamber.The influence of the change of the number of swirls in the main nozzle of the loop type combustion chamber on the flow,combustion and pollutant generation was investigated.Flow field characteristics include axial velocity,radial velocity,tangential velocity,and recirculation zone;temperature field parameters include overall temperature level,high temperature zone,peak temperature and outlet temperature distribution;pollutant eharacteristics include thermal NOx generation rate,NOx emission and high NOx production rate.The analysis shows that as the swirl number in the main nozzle increases,the range of the main recirculation zone increases significantly,and the reflow effect gradually increases;the overall temperature level in the combustion chamber decreases with the increase of the number of swirls,and the range of the high temperature zone also shrinks;peak value of the thermal NOx formation rate decreases,the width of the high generation rate region decreases,and the level of thermal NOx formation decreases.The trend of CO changes is opposite to NOx,and the amount of emissions increases as the number of swirls increases.When the NOx emission is guaranteed to be within a reasonable interval,the CO emission is the lowest in the scheme a2,so it is the optimal solution among the four design schemes.Finally,the influence of the change of cross-sectional area on the turbulent combustion in the combustion chamber is analyzed.The results show that reflow strength and axial velocity at the main nozzle gradually increases with the growth of cross-sectional area.The specific heat intensity of the combustion chamber decreases with the increase of the cross-sectional area,the overall temperature level decreases,and the high temperature-region of the central axis shrinks in the radial direction.As the cross-sectional area increases,the OTDF shows a downward trend,and the decline gradually decreases.As the cross-sectional area increases,both the peak temperature and the outlet NOx production level decrease;the CO emissions decrease.In program b4,both NOx emissions and CO emissions are the lowest,so option b4 is the optimal solution.