Simulations and Modeling of Turbulent Combustion Using Fuel Mixtures with High Hydrogen Content

固定式燃气轮机在目前的能源供应中发挥着重要作用，其重要性将在未来的能源格局中继续增长，部分原因是其良好的负载灵活性和快速启动能力。作为目前对可再生能源和化石燃料的清洁使用的努力的结果，燃气轮机的燃料灵活操作，特别是通过氢气的燃料富集，正在成为基础研究和技术中越来越重要的课题。实例包括在整体气化联合循环（IGCC）过程中使用氢作为能量储存和合成气的燃烧。然而，富氢燃料的高氢含量导致贫油固定燃气涡轮机燃烧的燃烧特性发生显著变化。这可能导致燃烧噪音增加、回火、不必要的燃烧不稳定性，并最终导致整个机器故障。在这里，特别是热扩散不稳定性，诱导氢的差异扩散，发挥重要作用，并可能导致强烈改变和蜂窝状火焰结构表现出局部熄灭的区域。因此，本项目提案的主题是高氢混合燃料的燃烧。我们的目标是使基于计算机的模拟湍流燃烧过程中的燃烧室考虑到燃料灵活的操作中发现的影响。如今，这种模拟是燃气轮机开发和优化的重要组成部分。建模的主要科学挑战之一是火焰结构，差分扩散，热扩散不稳定性和湍流的复杂相互作用尚未得到充分理解。在本项目中，这些现象将通过直接数值模拟（DNS）进行研究。为此，DNS将进行预混湍流燃烧的甲烷/氢气混合物具有不同的氢含量。使用系统的分析工具，所得到的数据将进行分析的先验和后验，以解决一些重要的问题，例如，相对于火焰结构，燃烧速率，和热扩散不稳定性对湍流的影响。工作假设是，HHC燃料的燃烧可以用合适的多标量模型来描述。将根据DNS数据的系统分析，开发相应的未封闭项公式和模型。

Stationary gas turbines play a significant role in the present energy supply, and their importance will continue to grow in the energy landscape of the future, partly because of their good load flexibility and quick start capability. As a consequence of the present efforts for renewable energy and cleaner use of fossil fuels, fuel-flexible operation of gas turbines, and particularly fuel enrichment by hydrogen, is becoming an inceasingly important topic in fundamental research and technology. Examples include the use of hydrogen as energy storage and the combustion of syngas in the integrated gasification combined cycle (IGCC) process. However, the enrichment of fuels with high fractions of hydrogen results for lean stationary gas turbine combustion in a significant change in combustion characteristics. This can result in increased combustion noise, flashback, unwanted combustion instabilities, and eventually in complete machine failure. Here, especially thermo-diffusive instabilities, induced by differential diffusion of hydrogen, play an important role and can lead to strongly altered and cellular flame structures exhibiting locally extinguished regions. The topic of the present project proposal is therefore the combustion of fuel mixtures with high hydrogen content (HHC). The goal is to enable computer-based simulations of turbulent combustion processes in combustion chambers considering the effects found in fuel flexible operation. Such simulations nowadays are an important part of the development and optimization of gas turbines. One of the main scientific challenges for modeling is here that the complex interaction of flame structure, differential diffusion, thermo-diffusive instability, and turbulence is not yet sufficiently understood. Within this project, these phenomena shall be investigated by means of direct numerical simulations (DNS). For this, DNS will be performed for premixed turbulent combustion of methane/hydrogen mixtures with different hydrogen content. Using systematic analysis tools, the resulting data will be analyzed a priori and a posteriori to address some important questions, for example with respect to flame structure, burning rate, and the influence of thermo-diffusive instabilities on the turbulence. The working hypothesis is that the combustion of HHC fuels can be described by suitable multi-scalar models. An appropriate formulation and modeling of the resulting unclosed terms will be developed based on the systematic analysis of the DNS data.