Study On Combustion Performance Of 15kW_th Micro Gas Turbine Pressurized Combustion Chamber

Automobile energy conservation and emission reduction has always been a key issue of national concern.Under the technical conditions that traditional vehicles cannot be replaced by large scale,the optimization of power of traditional vehicles still has research value.In addition to providing power for automobiles,traditional automobile engines are also responsible for refrigeration and heating.However,a single power source cannot meet the requirements of energy saving and emission reduction under multiple conditions and multiple functions.Therefore,an automotive auxiliary power system based on a micro gas turbine is proposed.The research object in this paper is the 15kW_th combustion chamber in this system,and the maximum operating pressure is 0.3MPaA.In order to realize the pressure operation strategy of the 15kW_th micro gas turbine combustion chamber,the ignition lifting program and the recommended working points of different loads are proposed.The combustion test is used to detect the emission index,numerical simulation and flame image processing method to evaluate the ignition characteristics.The effects of pressure on the pollutant emission characteristics,flame stability and flame concentration of the combustion chamber under different thermal powers are investigated.The recommended static working points under different thermal powers are proposed.Finally,based on the evaluation results,an ignition and load-up operation strategy that can guarantee low emission of pollutants,good flame stability and concentration is designed.Firstly,the 15kW_th micro gas turbine combustor pressurization test bench was built,and the fuel injection device was partially improved according to the existing combustor structure,which was carried out under the conditions of 3.5kWth,5.8kWth,8.2kWth,10kWth,13kWth and 15kW_th.The combustion test with a combustion chamber pressure of 0-0.3MPaA measured the combustion chamber outlet temperature,CO emission concentration,NO emission concentration and O2content under different working conditions.The test found that the combustion chamber pressure has different effects on combustion emission characteristics under different thermal powers.According to the test results and literature analysis,the conclusion is that the pressure mainly affects the combustion emission characteristics by changing the degree of diesel vapor diffusion and combustion reaction rate.Then,in order to further explain the influence of combustion chamber pressure on the internal flow field of different thermal power combustion,the three-dimensional modeling and calculation of the combustion chamber watershed are carried out by numerical simulation.The test data of 3.5kWth,10kWth and15kWth with different pressure effects on combustion were selected and simulated.The effects of these three working conditions on the combustion chamber velocity field and diesel vapor concentration field were analyzed.The simulation found that under the condition of 3.5kWth,the pressure of the combustion chamber is relatively high,and the pressure has a great influence on the floating lift force.The pressure will have a great influence on the diffusion range of the diesel vapor.Under the condition of 15kWth,the effect of the lift force is not obvious due to the high flow velocity of the combustion chamber.The pressure has little effect on the diesel vapor concentration field,further verifying the conclusions obtained from the combustion experiments.Next,in order to evaluate the ignition characteristics from the viewpoint of flame stability and concentration,flame image processing at a combustion chamber pressure of 0-0.3MPaA was performed under the conditions of 3.5 kWth,5.8 kWth,8.2 kWth,10 kWth,13 kWth,and 15 kWth,respectively.The flame area and flame brightness were used to evaluate the ignition stability;the flame centroid position distribution and velocity fluctuation were used to evaluate the flame concentration;combined with the CO emission characteristics and the flame image processing results,the CO emission concentration was below 100 ppmv?15%O2?.The conclusion that the flame stability and concentration are good.Finally,according to the combustion pollutant emission measurement results and the flame image processing results,the static working points with better flame quality under different thermal powers are obtained.According to these working points,the ignition lifting load process is designed.The final design result can ensure that the outlet temperature of the combustion chamber is around 900°C,the CO emission concentration is below 100ppmv?15%O2?,the NO emission concentration is around 40ppmv?15%O2?,and the flame stability and concentration characteristics are better.