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首页> 外文期刊>Combustion and Flame >Hybrid presumed pdf and flame surface density approaches for Large-Eddy Simulation of premixed turbulent combustion. Part 2: Early flame development after sparking
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Hybrid presumed pdf and flame surface density approaches for Large-Eddy Simulation of premixed turbulent combustion. Part 2: Early flame development after sparking

机译：混合假定的pdf和火焰表面密度方法，用于大涡模拟的预混湍流燃烧。第2部分：火花产生后的早期火焰发展

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摘要

This paper is the second part of a work addressing the coupling of presumed probability density function (pdf) with flame surface density (FSD) for the premixed flame modeling in a Large-Eddy Simulation (LES) framework. The main objective of this work is to propose approaches able to correctly describe local flame speed as well as detailed chemistry. Models based on the tabulation of flamelet structures, like Presumed Conditional Moments-Flame Prolongation of Intrinsic Low Dimensional Manifolds (PCM-FPI), appear as good candidates to account for complex chemistry. However, it was shown in the first part that the β-shape of the pdf provides reliable propagating velocities only in a restricted operating range. On the other hand, FSD models, like Extended Coherent Flame Model for LES (ECFM-LES), based on a transport equation for the filtered FSD, naturally enable to control the flame speed but generally rely on a simplified description of chemical kinetics. Hybrid models coupling FSD and presumed-pdf, called PCM-CFM (1 and Ⅱ), were then proposed in the previous part (Lecocq et al. [Combust. Flame 158 (6) (2011) 1201-1214]) to combine the strengths of these two approaches. In many industrial devices, such as spark-ignition engines or gas turbines, a premixed flame is initiated through the electrical discharge of a spark plug. The early flame development that follows is of major importance for the history of the flame front propagation and should then be precisely reproduced. The aim of this second paper is thus to propose modelings of spark-ignition that can be coupled to PCM-CFM models. Such a modeling is also investigated for PCM-FPI in order to understand if its operating range determined in the first part of this work can be extended to highly unsteady configurations such as flame kernel development. The sub-model AKTIM-Euler is then chosen among the models of the literature to treat spark-ignition, as it can include many physical features, notably the electrical circuit characteristics. Couplings are proposed between AKTIM-Euler and PCM-FPI as well as PCM-CFM I and II, thus providing full models accounting for detailed chemistry effects for gas composition. Canonical test cases of spherical flames expanding in a frozen turbulence are first performed to validate the functionality of these models. Notably, several strategies linking AKTIM-Euler and PCM-FPI, in terms of transition timing and Sub-Grid Scale scalar dissipation rate closure are tested, allowing to retain two different options. The experiment of Renou et al. [Combust. Flame 123 (2000) 507-521 ], for which the flame kernel was tracked at several equivalence ratios and moderate turbulent intensities, is then used for quantitative comparisons with the various models proposed. While PCM-CFM approaches coupled to AKTIM-Euler work well in all conditions, PCM-FPI does not allow the burned gases pocket transmitted by the ignition model to grow. This result can be explained by the lack of prediction capabilities of ^-presumed pdf in weakly turbulent flow with a coarse mesh resolution, as shown in the first part of this work. Consequently, synthetic tests are carried out in higher turbulent conditions, more representative of those found in industrial configurations. The PCM-FPI response looks better, close to the one brought by the hybrid models, especially when using a Bi-Modal-Ljmit closure of scalar dissipation rate. Nevertheless, close quantitative comparisons show discrepancies between this version of PCM-FPI and the PCM-CFM approaches in terms of characteristic wrinkling of the flame front.
机译：本文是研究大涡模拟（LES）框架中预混火焰建模的假定概率密度函数（pdf）与火焰表面密度（FSD）耦合的工作的第二部分。这项工作的主要目的是提出能够正确描述局部火焰速度以及详细化学过程的方法。基于小火焰结构列表的模型，例如固有的低维流形的假定条件矩-火焰延展（PCM-FPI），似乎是解决复杂化学反应的良好候选者。但是，在第一部分中显示，pdf的β形仅在有限的操作范围内提供可靠的传播速度。另一方面，FSD模型（如LES的扩展相干火焰模型（ECFM-LES））基于已过滤的FSD的传输方程，自然能够控制火焰速度，但通常依赖于化学动力学的简化描述。然后，在前一部分（Lecocq等人[Combust。Flame 158（6）（2011）1201-1214]）中，提出了将FSD和假定的pdf耦合的混合模型，称为PCM-CFM（1和Ⅱ），以结合这两种方法的优势。在许多工业设备中，例如火花点火发动机或燃气轮机，通过火花塞的放电来引发预混火焰。随后的早期火焰发展对于火焰锋面传播的历史至关重要，因此应精确复制。因此，第二篇论文的目的是提出可与PCM-CFM模型耦合的火花点火模型。还对PCM-FPI进行了这种建模研究，以了解在本工作的第一部分中确定的操作范围是否可以扩展到高度不稳定的配置，例如火焰核的发展。然后从文献模型中选择子模型AKTIM-Euler来处理火花点火，因为它可以包括许多物理特征，尤其是电路特征。提出了AKTIM-Euler与PCM-FPI以及PCM-CFM I和II之间的耦合，从而提供了完整的模型，说明了气体成分的详细化学作用。首先执行在冻结湍流中膨胀的球形火焰的规范测试案例，以验证这些模型的功能。值得注意的是，在过渡时序和子网格规模标量耗散率闭合方面，测试了连接AKTIM-Euler和PCM-FPI的几种策略，从而保留了两种不同的选择。 Renou等人的实验。 [燃烧。然后使用火焰123（2000）507-521 []跟踪了火焰核，以几个当量比和中等湍流强度进行跟踪，并与提出的各种模型进行了定量比较。虽然PCM-CFM方法与AKTIM-Euler耦合在所有情况下都能很好地工作，但PCM-FPI不允许点火模型传输的燃烧气体袋增大。如本工作的第一部分所示，该结果可以通过在粗湍流分辨率的弱湍流中缺乏^假定的pdf的预测能力来解释。因此，在更高的湍流条件下进行了合成测试，这更代表了工业配置中的测试。 PCM-FPI响应看起来更好，接近混合模型带来的响应，特别是在使用标量耗散率的双模-李密特闭合时。然而，紧密的定量比较显示，在该版本的PCM-FPI与PCM-CFM方法之间，在火焰前部起皱方面存在差异。

著录项

  • 来源
    《Combustion and Flame》 |2011年第6期|p.1215-1226|共12页
  • 作者

    Guillaume Lecocq; Stephane Richard; Olivier Colin; Luc Vervisch;

  • 作者单位

    IFP Energies nouvelles, 1-4 avenue de Bois-Preau, 92852 Rueil Malmaison, France;

    IFP Energies nouvelles, 1-4 avenue de Bois-Preau, 92852 Rueil Malmaison, France;

    IFP Energies nouvelles, 1-4 avenue de Bois-Preau, 92852 Rueil Malmaison, France;

    CORlA - CNRS ξ 1NSA de Rouen, Technopole du Madrillet, BP 8, 76801 Saint-Etienne-du-Rouvray, France;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    les; premixed flame; turbulent combustion modeling; complex chemistry; spark ignition;

    机译：les;预混火焰湍流燃烧模型复杂化学火花点火;

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