Abstract Large eddy simulations (LES) of non reactive and reactive flows in a cavity-based scramjet combustor configuration from the U.S Air Force Research Laboratory (AFRL) are performed. These simulations feature a 22 species and 206 reactions chemical scheme for ethylene/air. The ability of LES to reproduce the main features found in the experiment is first emphasised such as the average velocity field and the stability of the combustion for the case studied. The influence of the mesh resolution and of the thermal wall condition on the simulation results is also investigated along with the soundness of the use of a laminar model for the filtered source terms. The results of the simulations with the finest grid (resolution of 100 micrometers in the flame region) are then employed to gain understanding in the flame dynamics. This reactive simulation shows the persistence of the two recirculation zones already present in the non reactive flow. The globally high temperature into the cavity helps to sustain a reactive zone located in the mixing layer above the cavity. Combustion first occurs in a diffusion dominated regime followed by the efficient burning of a well stirred mixture (rich then lean). A significant diffusion dominated burning is also found inside the cavity. The links between the residence time inside the cavity and the efficiency of the combustion are explored along with the velocity/heat release correlation.

中文翻译：

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基于空腔的超燃冲压发动机燃烧模式分析

摘要 对来自美国空军研究实验室 (AFRL) 的基于腔的超燃冲压发动机燃烧室配置中的非反应流和反应流进行了大涡模拟 (LES)。这些模拟具有 22 种物质和 206 种乙烯/空气反应化学方案。首先强调 LES 再现实验中发现的主要特征的能力，例如所研究案例的平均速度场和燃烧的稳定性。还研究了网格分辨率和热壁条件对模拟结果的影响，以及对过滤源项使用层流模型的合理性。然后采用最精细网格（火焰区域分辨率为 100 微米）的模拟结果来了解火焰动力学。该反应模拟显示了非反应流中已经存在的两个再循环区的持续性。进入空腔的全局高温有助于维持位于空腔上方混合层中的反应区。燃烧首先发生在以扩散为主的状态，然后是充分搅拌的混合物（先富后贫）的有效燃烧。在空腔内部也发现了显着的扩散主导燃烧。探讨了空腔内的停留时间与燃烧效率之间的联系以及速度/热释放的相关性。燃烧首先发生在以扩散为主的状态，然后是充分搅拌的混合物（先富后贫）的有效燃烧。在空腔内部也发现了显着的扩散主导燃烧。探讨了空腔内的停留时间与燃烧效率之间的联系以及速度/热释放的相关性。燃烧首先发生在以扩散为主的状态，然后是充分搅拌的混合物（先富后贫）的有效燃烧。在空腔内部也发现了显着的扩散主导燃烧。探讨了空腔内的停留时间与燃烧效率之间的联系以及速度/热释放的相关性。