...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Combustion and Flame >Physically-derived reduced-order manifold-based modeling for multi-modal turbulent combustion
【24h】

Physically-derived reduced-order manifold-based modeling for multi-modal turbulent combustion

机译：用于多模态湍流燃烧的物理衍生的下降阶层模型

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Turbulent combustion models can be divided into two broad classes: models that make no assumption about the underlying combustion processes and models that constrain the underlying combustion processes to some a priori presumed reduced-order manifold. The former class of models, including the Transported PDF (TPDF) approach and the Linear Eddy Model (LEM), is by nature more general but comes at increased computational cost. The latter class of models, including "flamelet"-like models and Conditional Moment Closure (CMC), is computationally more efficient albeit with the need to assume something about the underlying combustion processes a priori, traditionally limiting combustion processes to a single asymptotic mode. In this work, a new turbulent combustion model is developed that breaks this inherent trade-off and enables a computationally efficient description of multi-modal combustion. The model is constructed by first postulating that all (adiabatic, isobaric, two-stream) combustion processes can be described with a two-dimensional space whose coordinates are a mixture fraction and a generalized progress variable. The governing equations for the species mass fractions and temperature are then projected onto this two-dimensional manifold through a coordinate transformation to provide the evolution equations for the thermochemical state on the manifold; this approach results in an equilibrium manifold formulation. An explicit transport equation for the generalized progress variable is derived through the choice of a (set of weighted) arbitrary reference species and the functional dependence of the reference species on the generalized progress variable. The approach can accommodate both unity Lewis numbers and differential diffusion without issue. The mode of combustion is encoded into three scalar dissipation rates (the mixture fraction dissipation rate, the generalized progress variable dissipation rate, and the cross-dissipation rate), and the asymptotic modes of combustion are recovered under appropriate limits. However, the relative ease at which the nonpremixed limit is recovered depends on the reference species. Alternatively, the evolution of the thermochemical state on the manifold can be derived by conditionally filtering (or averaging) the governing equations with respect to the manifold coordinates, resulting in a non-equilibrium manifold formulation. Simplification of the non-equilibrium manifold formulation to the equilibrium manifold formulation reveals the implicit assumptions inherent to the equilibrium manifold formulation. A new solver PDRs is developed for solving the manifold equations, and example solutions demonstrate the ability of the model to describe general multi-modal combustion phenomena as the scalar dissipation rates are varied including not only the asymptotic modes of combustion but also partially premixed and stratified premixed combustion coupled or uncoupled with autoignition. The paper concludes with a discussion of open challenges for integrating the model with Large Eddy Simulation (LES) and Reynolds-Averaged Navier-Stokes (RANS) approaches. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
机译：湍流燃烧模型可分为两种广泛的课程：没有假设底层燃烧过程和将底层燃烧过程限制为一些先验的燃烧过程的模型的模型。前一类模型，包括运输的PDF（TPDF）方法和线性涡流模型（LEM），是大自然更一般，但以增加的计算成本增加。后一类模型，包括“扑塞” - 麦克风模型和条件时刻闭合（CMC），尽管需要采用关于底层燃烧过程的事物的需要更有效，但是将传统地将燃烧过程呈现给单个渐近模式。在这项工作中，开发了一种新的湍流燃烧模型，可以破坏这种固有的折衷，并实现了多模燃燃烧的计算有效描述。该模型通过首先假设所有（绝热，异巴酸，两流）燃烧过程可以用二维空间描述，其坐标是混合分数和广义进度变量。然后通过坐标变换将物质质量分数和温度的控制方程突出到该二维歧管上，以提供歧管上的热化学状态的演化方程;这种方法导致平衡歧管配方。通过选择（一组加权）任意参考物种和参考物种在广义进度变量上的功能依赖性来导出广义进度变量的显式传输方程。该方法可以容纳统一lewis数字和差分扩散而无需问题。燃烧方式被编码成三个标量耗散速率（混合分数耗散速率，广义进度可变耗散速率和交叉耗散率），并且在适当的限度下回收燃烧的渐近模式。然而，回收非增殖限制的相对容易性取决于参考物种。或者，可以通过条件滤波（或平均）相对于歧管坐标来导出歧管上的热化学状态的演化，从而导致非平衡歧管配方。向平衡歧管配方的非平衡歧管配方的简化揭示了平衡歧管配方固有的隐含假设。开发了一种新的求解器PDR，用于求解歧管方程，并且示例性解决方案证明了模型描述一般多模燃燃烧现象的能力，因为标量耗散速率变化，包括不仅包括燃烧的渐近模式而且部分预混合和分层预混合燃烧耦合或与自燃耦合。本文讨论了与大型涡流模拟（LES）和Reynolds平均的Navier-Stokes（RAN）方法集成了开放挑战的讨论。 （c）2020燃烧研究所。由elsevier Inc.出版的所有权利保留。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号