Effect Of Fuel/air Premixed Characteristics On Combustion Characteristics For Micro Gas Turbine

In recent years,gas turbine mainly pursues high efficiency and low pollution.Lean premixed combustion can greatly reduce the pollutant emissions.As for the micro gas turbine,the structure of the combustion chamber head is compact,which is not conducive to the uniform mixing of fuel and air.Therefore,the premixed characteristics of a dry low emission（DLE）micro combustor and its effect on pollutant generation characteristics were studied.Firstly,the ignition and combustion characteristics of the combustor with different components of fuel were tested.The experimental results show that the combustor has a certain fuel adaptability,and has good ignition performance under the selected fuels,and the combustion efficiency reaches more than 97%.In terms of pollutant emission,NOx emission is about 30 mg/m3,and CO emission is about 10 mg/m3 when the combustor is at full load.Then,the flow and premixed characteristics of the combustor under different structural parameters were studied by numerical simulation,and the effect of premixed characteristics on combustion characteristics was obtained.The simulated results show that the increasing of the swirl angle at the primary combustion stage swirler can increase the area of the primary recirculation zone,which can improve the premixed characteristics of fuel and air,can also reduce the temperature and the generation of NOx and CO in the combustor;The change of the number of blades at primary combustion stage has little effect on the flow field.The proper increase of the blades can promote the mixing of fuel and air;Reducing the nozzle diameter of the main combustion stage can increase the penetration depth,reduce the mixing nonuniformity in the combustor and improve the combustion characteristics of the combustor;In addition,because of the small size of the combustor head,the change of the position of fuel nozzle at the primary combustion stage has little effect on premixed characteristics.However,the increase of fuel nozzle which makes the fuel participate in the premixing at polit stage can greatly improve the premixed characteristics of fuel and air,and reduce the pollutant emissions;The premixed distance between fuel and air can be increased by properly reducing the penetration angle of fuel nozzle at primary combustion stage,and can also improve the mixing and combustion characteristics of the combustor can be improved.Finally,the combustion performance of the combustor with different fuel nozzles was compared by experiment and simulation.The error was low,which indicated that the results obtained were basically reliable,and could provide a reference for the micro gas turbine combustor design in the future.