Modeling and simulation of premixed combustion for an industrial gas turbine

The proposed work is devoted to lean premixed combustion technology which is nowadays well established within industrial gas turbine industry in order to reduce nitric oxides emission. The engineering implementation is more difficult than previous systems of combustion. It is necessary to achieve a good preliminary mixing of fuel and air, to avoid flashback, to provide the stabilization and so on. Predictive numerical modeling of real geometry combustors at actual operation regimes is an effective time and cost saving tool. Turbulent premixed flames in industrial combustors are characterized by large turbulent Reynolds number and moderately large Damkohler number; at these conditions instantaneous reaction zones are not laminar but thickened by micro-turbulence. Instantaneous combustion takes place in thin, in comparison with integral turbulence scale, and strongly wrinkled flamelet sheets with developed small-scale structure that fundamentally cannot be unresolved by combustion model balance equations. In the presented simulations we used our TFC model, where this problem is solved in context of Kolmogorov hypothesis of statistically hydrodynamic equilibrium of the small-scale instantaneous reaction zones. It allows to express the averaged combustion rates (the source term in the equations) in terms of large-scale turbulent parameters and the characteristic chemical time. This gave the opportunity to reach a good agreement between the model and standard experimental data at turbulence level typical for gas turbines and to predict, through simulations, the dependence of the turbulent speed on turbulence and chemistry. Together with the correct prediction of the flame width and profile parameters, these are the key points for an accurate simulation of combustion in a real combustor. From the methodological point of view, the combustion model is closed to the turbulence model (both models are based on the ideas of small-scale equilibrium and are valid at intensive turbulence) and both models are consistent in spite of the counter-gradient transport phenomenon typical in premixed flames, in fact the turbulence model was only used to estimate the gradient turbulent component of the transport.

@InProceedings{ZMBM03a,
  author       = {Zimont, V. and Moreau, V. and Battaglia, V. and Modi, R.},
  title        = {Modeling and simulation of premixed combustion for an industrial gas turbine},
  booktitle    = {Combustion And Atmospheric Pollution},
  pages        = {149--155},
  year         = {2003},
  editor       = {G. D. Roy and S. M. Frolov and and A. M. Starik and Torus Press},
  address      = {Moscow},
  keywords     = {turbine, premixed combustion},
  url          = {https://publications.crs4.it/pubdocs/2003/ZMBM03a},
}