Purpose

The purpose of this study is to present and demonstrate a numerical method for solving chemically reacting flows. These are important for energy conversion devices, which rely on chemical reactions as their operational mechanism, with heat generated from the combustion of the fuel, often gases, being converted to work.

Design/methodology/approach

The numerical study of such flows requires the set of Navier-Stokes equations to be extended to include multiple species and the chemical reactions between them. The numerical method implemented in this study also accounts for changes in the material properties because of temperature variations and the process to handle steep spatial fronts and stiff source terms without incurring any numerical instabilities. An all-speed numerical framework is used through simple low-dissipation advection upwind splitting (SLAU) convective scheme, and it has been extended in a multi-component species framework on the in-house density-based flow solver. The capability of solving turbulent combustion is also implemented using the Eddy Dissipation Concept (EDC) framework and the recent k-kl turbulence model.

Findings

The numerical implementation has been demonstrated for several stiff problems in laminar and turbulent combustion. The laminar combustion results are compared from the corresponding results from the Cantera library, and the turbulent combustion computations are found to be consistent with the experimental results.

Originality/value

This paper has extended the single gas density-based framework to handle multi-component gaseous mixtures. This paper has demonstrated the capability of the numerical framework for solving non-reacting/reacting laminar and turbulent flow problems. The all-speed SLAU convective scheme has been extended in the multi-component species framework, and the turbulent model k-kl is used for turbulent combustion, which has not been done previously. While the former method provides the capability of solving for low-speed flows using the density-based method, the later is a length-scale-based method that includes scale-adaptive simulation characteristics in the turbulence modeling. The SLAU scheme has proven to work well for unsteady flows while the k-kL model works well in non-stationary turbulent flows. As both these flow features are commonly found in industrially important reacting flows, the convection scheme and the turbulence model together will enhance the numerical predictions of such flows.

中文翻译：

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在基于密度的流动求解器中实现多组分框架以处理化学反应流

目的

本研究的目的是提出和演示求解化学反应流的数值方法。这些对于依赖化学反应作为其操作机制的能量转换装置很重要，燃料（通常是气体）燃烧产生的热量被转换为功。

设计/方法/方法

这种流动的数值研究需要扩展纳维-斯托克斯方程组以包括多种物质以及它们之间的化学反应。本研究中实施的数值方法还考虑了由于温度变化而导致的材料特性变化以及处理陡峭空间前沿和刚性源项而不引起任何数值不稳定性的过程。通过简单的低耗散平流逆风分裂 (SLAU) 对流方案使用全速数值框架，并已在内部基于密度的流动求解器的多组分物种框架中扩展。还使用涡流耗散概念 (EDC) 框架和最近的 k-kl 湍流模型实现了解决湍流燃烧的能力。

发现

数值实现已被证明用于层流和湍流燃烧中的几个刚性问题。层流燃烧结果与 Cantera 库的相应结果进行了比较，发现湍流燃烧计算与实验结果一致。

原创性/价值

本文扩展了基于单一气体密度的框架来处理多组分气体混合物。本文展示了数值框架解决非反应/反应层流和湍流问题的能力。全速SLAU对流方案在多组分物种框架中进行了扩展，湍流模型k-kl用于湍流燃烧，这是以前没有做过的。前一种方法提供了使用基于密度的方法求解低速流动的能力，而后一种方法是基于长度尺度的方法，在湍流建模中包括尺度自适应模拟特性。SLAU 方案已被证明适用于非定常流动，而 k-kL 模型适用于非平稳湍流。