Numerical Investigation Of Turbulence Model And Combustion Model On The Exit Flow Field Of The Burner

Fire test is the most common and effective method to show compliance for the regulation about fire,and the flow field of fire test affect the design of the fire test scheme directly,such as the arrangement of the thermocouple and heat flux meter.In order to provide reference for the design of the fire test scheme,numerical simulation is used to study the flow field of fire test,which also is the exit flow field of Nex Gen burner.But as the complex of the flow field structure,the effects of turbulence model and combustion model on the simulation results are researched to find the proper models for simulation.First,the preliminary simplified geometric model was established,and it's validition was verified by experimental data of cold flow field and combustion flow field.The preliminary simplified geometric model contains draft tube,fuel tube,stator and cone,then the stator was simplified by velocity vector distribution.And it's validition was verified by comparing the calculation results with the experimental data and the results of preliminary simplified model.Second,in order to study the effects of turbulence models on the simulated exit flow field of NexGen burner,Realizable k-? model,RNG k-? model and SST k-? model were adopted in the simulation.Then,the effects of combustion models on the calculated results were studied by calculating with the steady flamelet model,the mixture fraction PDF model and the eddy dissipation model.The results show that turbulence models have great effects on the velocity distribution,flame shape,flame length and temperature distribution of calibrated surface.And combustion models have no effects on the velocity distribution,flame shape,but have great effects on the flame length and temperature distribution of calibrated surface.In addition,both turbulence models and combustion models have no effect on the heat flux distribution of calibration surface but have great effect on heat flux value.The results show that the Realizable k-? model and mixture fraction PDF model are suitable for the numerical simulation of fire test though comparing the calculated results with the experimental results.Then the three-dimensional distribution of the flame temperature and heat flux around the calibration surface is received.In this paper,the distribution of temperature and heat flux is obtained by numerical simulation which can provide referenceand guidance for the design of fire test scheme.