Implicit Large Eddy Simulation of high-speed non-reacting and reacting air/H2 jets with a 5th order WENO scheme
Implicit Large Eddy Simulation of high-speed non-reacting and reacting air/H2 jets with a 5th order WENO scheme
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DOI：
10.1016/j.compfluid.2012.03.013
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发表时间：
2012-06
影响因子：
2.8
通讯作者：
M. Karaca;N. Lardjane;I. Fedioun
中科院分区：
文献类型：
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作者：
M. Karaca;N. Lardjane;I. Fedioun
这项工作报告了在多分量高速自由剪切流的特定情况下，基于耗散五阶有限差分 WENO 方案、具有显式子网格模型 (LES) 和不具有 (ILES) 的大涡模拟结果。共流空气中的跨音速非反应式和超音速反应式 H2 喷气发动机（典型的超燃冲压发动机）被选为本研究的流动原型。数值模拟的分辨率范围为32×32×128至256×256×1024。显式子网格模型是与分子扩散相关的 Smagorinsky 模型和选择性结构函数模型。通过求解纳维-斯托克斯或欧拉方程，可以在有或没有分子扩散的情况下执行隐式 LES。在无反应的情况下，Smagorinsky 模型的耗散性太大，即使常数值较低（Cs=0.1）。选择性结构函数会带来更好的结果，但与 ILES 相比并没有表现出任何优越性，无论网格分辨率如何。在反应情况下，模拟中必须进行分子粘性截断，以设置 ILES 欧拉反应区的物理宽度，从而实现网格收敛。
This work reports the results of Large Eddy Simulation based on a dissipative 5th order finite-difference WENO scheme, with explicit subgrid model (LES) and without (ILES), in the specific case of multi-component high speed free shear flows. Transonic non-reacting and supersonic reacting H2jets in coflowing air, typical of scramjet engines, are chosen to be the flow prototypes for this study. Numerical simulations are performed at resolutions ranging from 32×32×128 to 256×256×1024. Explicit subgrid models are the Smagorinsky and the Selective Structure Function models, associated to molecular diffusion. Implicit LES are performed with and without molecular diffusion, by solving either the Navier–Stokes or the Euler equations. In the non-reacting case, the Smagorinsky model is too dissipative, even with a low value of the constant, Cs=0.1. The Selective Structure Function leads to better results, but does not show any superiority compared to ILES, whatever the grid resolution. In the reacting case, a molecular viscous cut-off in the simulation is mandatory to set a physical width for the reaction zone in the ILES Euler, hence to achieve grid-convergence.