A NO{sub x} prediction scheme for lean-premixed gas turbine combustion based on detailed chemical kinetics

Journal Article · Tue Oct 01 04:00:00 EDT 1996 · Journal of Engineering for Gas Turbines and Power

DOI:https://doi.org/10.1115/1.2816992· OSTI ID:397905

Polifke, W; Doebbeling, K; Sattelmayer, T ^[1]; Nicol, D G; Malte, P C ^[2]

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1. ABB Research Center, Baden-Daettwil (Switzerland)
2. Univ. of Washington, Seattle, WA (United States). Dept. of Mechanical Engineering

The lean-premixed technique has proven very efficient in reducing the emissions of oxides of nitrogen (NO{sub x}) from gas turbine combustors. The numerical prediction of NO{sub x} levels in such combustors with multidimensional CFD codes has only met with limited success so far. This is to some extent due to the complexity of the NO{sub x} formation chemistry in lean-premixed combustion, i.e., all three known NO{sub x} formation routes (Zeldovich, nitrous, and prompt) can contribute significantly. Furthermore, NO{sub x} formation occurs almost exclusively in the flame zone, where radical concentrations significantly above equilibrium values are observed. A relatively large chemical mechanism is therefore required to predict radical concentrations and NO{sub x} formation rates under such conditions. These difficulties have prompted the development of a NO{sub x} postprocessing scheme, where rate and concentration information necessary to predict NO{sub x} formation is taken from one-dimensional combustion models with detailed chemistry and provided--via look-up tables--to the multidimensional CFD code. The look-up tables are prepared beforehand in accordance with the operating conditions and are based on CO concentrations, which are indicative of free radical chemistry. Once the reacting flow field has been computed with the main CFD code, the chemical source terms of the NO transport equation, i.e., local NO formation rates, are determined from the reacting flow field and the tabulated chemical data. Then the main code is turned on again to compute the NO concentration field. This NO{sub x} submodel has no adjustable parameters and converges very quickly. Good agreement with experiment has been observed and interesting conclusions concerning superequilibrium O-atom concentrations and fluctuations of temperature could be drawn.

• Sponsoring Organization: USDOE
• OSTI ID: 397905
• Report Number(s): CONF-950629--
• Journal Information: Journal of Engineering for Gas Turbines and Power, Journal Name: Journal of Engineering for Gas Turbines and Power Journal Issue: 4 Vol. 118; ISSN 0742-4795; ISSN JETPEZ
• Country of Publication: United States
• Language: English

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