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首页> 外文期刊>Combustion theory and modelling >Large-eddy simulation of a bluff-body stabilised turbulent premixed flame using the transported flame surface density approach
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Large-eddy simulation of a bluff-body stabilised turbulent premixed flame using the transported flame surface density approach

机译：使用运输火焰表面密度接近的诈唬体稳定湍流预混火焰的大涡模拟

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摘要

A premixed propane-air flame stabilised on a triangular bluff body in a model jet-engine afterburner configuration is investigated using large-eddy simulation (LES). The reaction rate source term for turbulent premixed combustion is closed using the transported flame surface density (TFSD) model. In this approach, there is no need to assume local equilibrium between the generation and destruction of subgrid FSD, as commonly done in simple algebraic closure models. Instead, the key processes that create and destroy FSD are accounted for explicitly. This allows the model to capture large-scale unsteady flame propagation in the presence of combustion instabilities, or in situations where the flame encounters progressive wrinkling with time. In this study, comprehensive validation of the numerical method is carried out. For the non-reacting flow, good agreement for both the time-averaged and root-mean-square velocity fields are obtained, and the Karman type vortex shedding behaviour seen in the experiment is well represented. For the reacting flow, two mesh configurations are used to investigate the sensitivity of the LES results to the numerical resolution. Profiles for the velocity and temperature fields exhibit good agreement with the experimental data for both the coarse and dense mesh. This demonstrates the capability of LES coupled with the TFSD approach in representing the highly unsteady premixed combustion observed in this configuration. The instantaneous flow pattern and turbulent flame behaviour are discussed, and the differences between the non-reacting and reacting flow are described through visualisation of vortical structures and their interaction with the flame. Lastly, the generation and destruction of FSD are evaluated by examining the individual terms in the FSD transport equation. Localised regions where straining, curvature and propagation are each dominant are observed, highlighting the importance of non-equilibrium effects of FSD generation and de
机译：使用大涡模拟（LES）研究了模型喷射发动机后燃烧器配置中的三角形虚张机上稳定的预混丙烷 - 空气火焰。使用输送的火焰表面密度（TFSD）模型关闭湍流预混燃烧的反应速率源期。在这种方法中，不需要在简单的代数封闭模型中常见地完成子耕作FSD的产生和破坏之间的局部均衡。相反，创建和销毁FSD的关键进程是明确的。这允许模型在存在燃烧不稳定性的情况下捕获大规模的非定常火焰传播，或者在火焰遇到随时间逐渐皱纹的情况下。在本研究中，进行了数值方法的全面验证。对于非反应流动，获得了良好的易于平均和根均方速度场的协议，并且实验中看到的Karman型涡旋脱落行为很好地表示。对于反应流动，使用两个网格配置来研究LES结果对数值分辨率的灵敏度。速度和温度场的轮廓与粗糙和致密网格的实验数据表现出良好的一致性。这证明了LES与TFSD方法相结合的能力在代表在该配置中观察到的高度不稳定的预混合燃烧。讨论了瞬时流动模式和湍流火焰行为，通过可视化涡流结构及其与火焰的相互作用来描述非反应和反应流程之间的差异。最后，通过检查FSD传输方程中的个别术语来评估FSD的产生和破坏。观察到局部区域，其中突出，曲率和繁殖，每个主导，都突出了FSD生成和de的非平衡效应的重要性

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