Flow Field Derived Equivalent Reactor Networks for Accurate Chemistry Simulation in Gas Turbine Combustors

A method has been developed in which the flow field predicted by Computational Fluid Dynamics (CFD) is automatically condensed into an Equivalent Reactor Network (ERN), composed of well stirred reactors, allowing rapid and accurate analysis of emissions. This paper presents the effectiveness of utilizing an ERN that is a direct abstraction of the computational flow field for combustion analysis. The CFD results are divided into reactors using various filters on flow-field variables to construct an ERN that represents the 3-D combustor flow field and flame structure. Detailed kinetics can then be used in ERN simulations to analyze effects of fuel composition and operating condition on emissions. The technique is applied to a commercial industrial gas turbine combustor fuel injector and compared against experimental emissions results. Sensitivity of emissions predictions to different parameters in the network extraction is also presented. Parameter variations in fuel flow rate are applied to the ERN to obtain relative impacts of fuel-air ratio on the emissions of NO_x without requiring new CFD solutions. This automatic approach has been found to reduce the time required to construct and analyze flow field derived ERNs with detailed chemistry by 90%. A local calculation of Damko¨hler number, important for stability analysis, is also presented. This calculation also uses abstracted information from the CFD flow field and detailed-kinetics simulations for more accurate, cost-effective analysis.