Fgm Based Premixed And Partially Premixed Turbulent Combustion Model——Research And Application

Turbulent combustion model is crutial for accurately predicting pollutant emission in aero engine and gas turbine combustor. Almost all low emission combustion technology adopts premixed combustion or partially premixed combustion to reduce pollutant emissions. This is a big challenge to turbulent premixed and partially premixed combustion model. Based on FGM (Flamelet Generated Manifolds) method, turbulent premixed combustion model and partially premixed combustion model are investigated in this thesis.(1) A series of CH4and kerosene laminar premixed flame are calculated, in which the influence of equivalence ratio and pressure on laminar flame velocity, laminar flame thickness and adiabatic flame temperature et al. is analyzed. Some conclusions can be drawn from the calculation results to shed light to the FGM modeling method.(2) The calculation procedure of turbulent premixed combustion model based on FGM method is constructed and then coupled to FLUENT software. The turbulent premixed combustion model is validated by calculating F2turbulent Bunsen flame measured by CHEN Y.C. et al. in1996. The calculation results imply that velocity and main species are accurately predicted. However there are discrepancies between calculated value and measured value of temperature and minor species, although the calculation results are better than FLUENT'S.(3) The premixed combustion model is strengthened by adding mixture fraction as a coordinate variable to include the partially premix effect. After the patially premixed turbulent combustion model is established, it is coupled to the CFD solver of FLUENT and used to calculate the above mentioned turbulent Bunsen flame and Sandia D flame. The calculation results show that the present partially premixed combustion model can make correct predictions for major species, and the prediction of temperature is better than that of the premixed combustion model established in the third chapter. However, the accuracy of minor species calculation needs further improvement.(4) The FGM modeling method is used for improveing FLUENT'S partially premixed combustion model. Using the improved combustion model, a staged combustor and an aero engine combustor with dilution holes are simulated with n-decane detailed chemical mechanism. The results suggest the improved partially premixed combustion model can readily predict the flame property in staged combustor.Finally, the thesis is summarized by pointing out the drawbacks and the corresponding improvement proposal.