Reduced combustion time model for methane in gas turbine flow fields Conference Paper uri icon

abstract

  • Computational fluid dynamics modeling of the complex processes that occur within the burner of a gas turbine engine has become a critical step in the design process. However, due to computer limitations, it is very difficult to completely couple the fluid mechanics solver with the full combustion chemistry. Therefore, simplified chemistry models are required, and the topic of this research was to provide reduced chemistry models for CH4/O 2 gas turbine flow fields to be integrated into CFD codes for the simulation of flow fields of natural gas-fueled burners. The reduction procedure for the CH4/O2 model utilized a response modeling technique wherein the full mechanism was solved over a range of temperatures, pressures, and mixture ratios to establish the response of a particular variable such as chemical reaction time. The conditions covered were between 1000 and 2500K for temperature, 0.1 and 2 for equivalence ratio, and 0.1 and 50 for pressure. The kinetic times include the time to ignition, the time to equilibrium H2O formation, the time to equilibrium CO formation, and the time to equilibrium NO formation. The kinetic time models are given in Arrhenius type formulas as functions of equivalence ratio, temperature, and pressure; or fuel-to-air ratio, temperature and pressure. A single, global kinetics model was obtained for the entire range of conditions, and separate models for the low-temperature and high-temperature regions as well as for fuel-lean and rich cases were also derived. Predictions using the reduced model were verified using results from the full mechanism and empirical correlations from experiments. The models are intended for (but not limited to) use in CFD codes for flow field simulations of gas turbine combustors in which initial conditions and degree of mixedness of the fuel and air are key factors in achieving stable and robust combustion processes and acceptable emissions levels. The new model was applied to CFD simulations of a typical gas turbine burner with premixer with good results.

author list (cited authors)

  • Lamnaouer, M., Petersen, E. L., Ryder, R. C., & Brankovic, A.

publication date

  • July 2007