Design And Characteristic Study Of A Model Gas Turbine Combustor

Single-head direct current(DC)combustor,whose greatest strength lies in measurement,has become an important carrier for studying the turbulence and mechanism of aero-engine combustors.At present,laboratory-level combustors for high temperature and high pressure mainly focu on gaseous fuels.While experiments for liquid hydrocarbon fuels combustion are still in a traditional stage.Therefore,a single-head DC combustor has been designed for liquid kerosene in this paper,with the overall structure analysis and numerical simulation of air distribution scheme,swirler and nozzle structure scheme.The relatively optimized single-head combustor scheme is obtained and processed,and the whole test system is built.According to the laboratory gas inlet and pressure conditions,the overall scheme analysis of single-head combustor is designed.The influence of air distribution on combustion performance is studied by CRN(Chemical Reactor Network)method.At design point,the optimum air distribution is less primary air and more dilution air,and primary air should be slightly less than the air from swirler.The influence of nozzle structure parameters on atomization performance was studied through atomization experiments.With the nozzle diameter increase,the atomization angle increased and the breaking length shortened,but the flow coefficient decreased;with the column length of swirl chamber increase,the atomization angle decreased and the breaking distance becomes longer,the flow coefficient increased.The optimized nozzle is verified to have better atomization performance in a wide range of conditions by experiments and VOF model numerical simulation.When the pressure drop is above 0.5 MPa,the spray angle is more than 70 degree;the breaking distance is less than 7mm at each pressure drop;flow coefficient is about 10%higher than that of the original nozzle.The influence of structure parameters of two-stage swirler on recirculation in conbustor is studied by realizable k-? model simulation.It is concluded that the recirculation zone is closer to combustor head and the distribution of outlet flow field is more uniform when the two-stage swirler blades are in the same direction.When the swirls number in the first stage or second stage is larger,the recirculation zone in the combustor becomes shorter and wider,while the outlet velocity is more uniform.With the smaller diameter of Venturi tube throat or larger leeve throat diameter,the recirculation zone is wider and has a bigger expansion angle.Overall structure of the combustor are integrated.And the effects of inlet conditions on combustion characteristics are studied by using RANS method and PDF combustion model.The results show that the change of inlet pressure,temperature and equivalence ratio has great influence on the temperature distribution of combustion chamber:the higher inlet pressure is,the higher temperature distribution is;the higher inlet temperature is,the less obvious the mixing effect of the secondary air is;the higher the fuel-air ratio is,more completed the combustion is,the larger high temperature area is,and the worse mixing effect is.