Large eddy simulations of an acoustically excited turbulent premixed flame

✍ Scribed by C. Nottin; R. Knikker; M. Boger; D. Veynante

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 415 KB
• Volume: 28
• Category: Article
• ISSN: 1540-7489
• DOI: 10.1016/s0082-0784(00)80196-4

✦ Synopsis

Large eddy simulation (LES) is a promising tool for numerical simulations of reacting flows, especially when combustion instabilities are encountered. In a first step toward prediction of such instabilities, LES of acoustically excited turbulent premixed flames is performed using a thickened flame approach, coupled to a subgrid scale model. Numerical results are carefully compared to experimental data obtained using planar laser-induced fluorescence on the OH radical. Flame surface densities, wrinkling factors, and reaction rates are extracted from images under a flamelet assumption. The large coherent motions observed in experiments are also found in simulations, but the subgrid scale model is not able to recover the right locations of maximum values of reaction rates. In fact, the subgrid scale model, implicitely based on the vorticity field, increases reaction rates in highly stretched regions, whereas according to experimental data, larger values of unresolved flame surfaces correspond to highly curved flame front regions. Therefore, a dynamic approach, where unresolved flame surfaces could be estimated from resolved flame front curvatures, appears as a promising next step.