A direct comparison of pair-exchange and IEM models in premixed combustion
- General Electric Research and Development Center, Schenectady, NY (United States)
Two pair-exchange mixing models, viz., the original Curl model and a modification thereof, are compared with the ``Interaction-by-Exchange-with-the-Mean`` (IEM) model, in the context of homogeneous combustion. The IEM model is attractive because it permits highly ``parallelizable`` computation, but the consequences of certain peculiarities--such as determinism and the shape-preserving relaxation of the initial pdf of a conserved scalar--need to be examined in the context of combustion. A numerical simulation of a partially stirred reactor (PaSR) is used to directly compare the three models, without the additional errors that contaminate comparisons made in simulations of flowfields. The fuel is 50%CO/50%H{sub 2} (by vol.). The kinetic scheme consists of 11 species and 23 reactions. The stoichiometry of the premixed inflow leads to a PSR temperature of 1,740 K, but to blowout in a PFR. The PaSR mixing frequency was varied in the range 10 Hz to 10{sup 4} Hz, by factors of the square root of 10. The pair-exchange models predict blowout earlier than does the IEM model. Means computed from the IEM model are less noisy, a consequence of the determinism inherent in the IEM model. Despite these differences, the pdfs and scatterplots of temperature, CO, OH, and O--selected because of their intrinsic importance as well as their influence on NO{sub x} emissions--are very similar between the three models. The similarity increases with the mixing frequency, which is significant given that practical (e.g., gas-turbine) combustors operate at high mass-loadings and therefore necessarily at high mixing rates.
- OSTI ID:
- 131831
- Journal Information:
- Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 3 Vol. 103; ISSN CBFMAO; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
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