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Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

A Comparative Study of Flamelet and Finite Rate Chemistry LES for a Swirl Stabilized Flame

[+] Author and Article Information
C. Fureby

 Defense Security Systems Technology, The Swedish Defense Research Agency – FOI, SE 147 25, Tumba, Stockholm, Swedenfureby@foi.se

J. Eng. Gas Turbines Power 134(4), 041503 (Jan 27, 2012) (13 pages) doi:10.1115/1.4004718 History: Received February 19, 2011; Revised July 12, 2011; Published January 27, 2012; Online January 27, 2012

Present-day demands on combustion equipment are increasing the need for improved understanding and prediction of turbulent combustion. Large eddy simulation (LES), in which the large-scale flow is resolved on the grid, leaving only the small-scale flow to be modeled, provides a natural framework for combustion simulations as the transient nature of the flow is resolved. In most situations; however, the flame is thinner than the LES grid, and subgrid modeling is required to handle the turbulence-chemistry interaction. Here we examine the predictive capabilities between LES flamelet models, such as the flamelet progress variable (LES-FPV) model, and LES finite rate chemistry models, such as the thickened flame model (LES-TFM), the eddy dissipation concept (LES-EDC) model, and the partially stirred reactor model (LES-PaSR). The different models are here used to examine a swirl-stabilized premixed flame in a laboratory gas turbine combustor, featuring the triple annular research swirler (TARS), for which high-quality experimental data is available. The comparisons include velocity and temperature profiles as well as combustor dynamics and NO formation.

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Copyright © 2012 by American Society of Mechanical Engineers
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Figures

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Figure 1

(a) Experimental test rig and (b) the triple annular research swirler (TARS) [16-20]

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Figure 2

Comparison of (a) adiabatic flame temperature Tad and (b) laminar flame-speed su over a relevant range of equivalence ratios for the combustor studied here

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Figure 3

Perspective view of the computational domain showing (a) the round combustor attached to the TARS and (b) the surface grid of the TARS

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Figure 4

Perspective and side views of the combustor showing (a) an iso-surface of the C3 H8 mass fraction together with instantaneous axial velocity contours, with a line representing zero axial velocity, (b) instantaneous axial velocity contours, (c) an iso-surface of the C3 H8 mass fraction together with instantaneous C3 H8 contours, and (d) instantaneous C3 H8 contours from the LES-PaSR model

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Figure 5

Perspective and side views of the combustor showing (a) an iso-surface of the C3 H8 mass fraction together with instantaneous temperature contours and (b) instantaneous temperature contours from the LES-PaSR model

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Figure 6

Side views of the combustor showing contours of (a) the vorticity magnitude |ω̃| and (b) the heat release Q· at the midplane from the LES-PaSR model

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Figure 7

Combustion dynamics. (a) Pressure fluctuations from the four LES models and (b) time series of volumetrically integrated pressure and heat release fluctuations. Legend: (green line) LES-FPV, (red line) three-step LES-PaSR, (blue line) three-step LES-TFM with F = 5 and (purple line) three-step LES-EDC. The pressure and heat release fluctuations are represented by solid and dashed lines, representatively.

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Figure 8

Perspective views of the combustor showing instantaneous contours of (a) YCO and (b) YNO on the midplane from the LES-PaSR model

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Figure 9

Computed and measured profiles of (a) the time-averaged axial velocity 〈ṽx〉 and (b) the corresponding rms fluctuations ṽxrms across the combustor at x/D = 0.125, 0.625, 1.000, 2.000, and 4.000. Legend: (+) experimental data [48], (green line) LES-FPV, (red line) three-step LES-PaSR, (blue line) three-step LES-TFM with F = 5, (blue dashed line) three-step LES-TFM with F = 10, and (purple line) three-step LES-EDC. The different axial locations are offset by 60 and 30 m/s, respectively, for 〈ṽx〉 and ṽxrms.

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Figure 10

Computed and measured profiles of (a) the time-averaged azimuthal velocity 〈ṽϕ〉 and (b) the corresponding rms fluctuations ṽϕrms across the combustor at x/D = 0.125, 0.625, 1.000, 2.000, and 4.000. Legend: (+) experimental data [48], (green line) LES-FPV, (red line) three-step LES-PaSR, (blue line) three-step LES-TFM with F = 5, (blue dashed line) three-step LES-TFM with F = 10, and (purple line) three-step LES-EDC. The different axial locations are offset by 30 m/s, respectively, for both 〈ṽϕ〉 and ṽϕrms.

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Figure 11

(a) Computed and measured time-averaged temperature profiles 〈T̃〉 across the combustor at x/D = 0.125, 0.625, 1.000, 2.000, and 4.000. Legend: (+) experimental data [48], (green line) LES-FPV, (red line) three-step LES-PaSR, (blue line) three-step LES-TFM with F = 5, (blue dashed line) three-step LES-TFM with F = 10, and (purple line) three-step LES-EDC. For 〈T̃〉 the different axial locations are offset by 1000 K and for 〈ỸNO〉 the different locations are offset by 0.01. (b) Computed and measured global (exit combustor area averaged) CO and NO emissions at the combustor exit.

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Figure 12

Scatter plots of (a) temperature, (b) CO mass fractions, (c) heat release, and (d) flame surface density. Legend: LES-PaSR (red circle), LES-EDC (purple circle), LES-TFM with F = 3 (blue circle), and LES FPV1 (green circle).

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