Large Eddy Simulations (LES) including Conditional Source-term Estimation (CSE) applied to two Delft-Jet-in-Hot-Coflow (DJHC) flames
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- 作者：J.W. Labahn ; C.B. Devaud ; cdevaud@uwaterloo.ca" class="auth_mail" title="E-mail the corresponding author
- 关键词：CSE ; LES ; MILD combustion ; Delft-Jet-in-Hot-Coflow ; Flame stabilization
- 刊名：Combustion and Flame
- 出版年：2016
- 出版时间：February 2016
- 年：2016
- 卷：164
- 期：Complete
- 页码：68-84
- 全文大小：2495 K
文摘
For the first time, a double conditioned CSE formulation including two mixture fractions is applied to model two Delft-Jet-in-Hot-Coflow (DJHC) flames in Large Eddy Simulation (LES). The objective is to further determine the ability of CSE to accurately predict the flame characteristics seen in the Dutch natural gas DJHC flames in the context of LES. Tabulated detailed chemistry and radiation are included. Good agreement with experimental data is found for the turbulent flow field and temperature statistics. Some discrepancies are noted near the centreline due to inaccuracies in the coflow entrainment. For both flames, the radial velocity component is shown to be more difficult to predict accurately. Possible sources of discrepancy are the sub-grid scale model and the inlet turbulence conditions. The predicted lift-off heights are lower than the experimental values. However, the trend of increasing lift-off height with increasing Reynolds number is properly captured when the same fuel composition is considered in the experiments and LES-CSE. The lift-off height predictions may be improved by adding a third conditioning variable that would reflect the effect of straining or changing the chemistry tabulation using different chemical progress variables. Qualitatively, the present simulations correctly predict flame stabilization due to the formation of ignition kernels. Further improvements may be obtained by including temperature fluctuations at the coflow inlet, a dynamic Smagorinsky model and higher order numerical schemes.