Modeling and Simulation of Pollutant Formation in Gas Turbines

对于燃气涡轮机发动机的发展，燃烧期间的污染物形成起着重要作用。由于日益严格的排放限制，需要进一步改进和优化排放。数值模拟可以有助于降低成本和加速这一发展进程。然而，关于污染物的排放，缺乏国家的最先进的燃烧模型的预测质量往往限制了数值结果的有用性。因此，拟议的研究项目的目标是开发，验证和应用模拟模型，它可以提供可靠的预测气体涡轮机燃烧室的污染物排放。为了达到这一目标，提出了一种综合建模方法，它结合了大涡模拟（LES）与使用的燃烧和排放模型，是基于详细的化学。在与FVV项目合作伙伴的协调下，该项目被细分为两个工作包，以解决燃气涡轮机燃烧室开发过程中污染物排放的不同方面。在航空发动机中，碳烟排放是一个巨大的挑战，而在固定式燃气轮机中，部分负荷下CO排放的增加对负荷柔性系统的发展构成了限制。在该项目的头两年中，开发了层流燃烧的CO排放模型。它占部分负荷条件下的CO生产和消费过程的时间尺度的变化，并从燃烧模型的剩余部分中将这些过程分解。对于烟尘排放，重点是烟尘数密度函数的统计处理。采用一种新的基于正交矩的方法，特别是碳烟氧化，可以更准确地描述。在该项目的第二阶段，重点将是湍流和污染物形成的相互作用。为此，将对不同的配置进行直接数值模拟（DNS），这些配置代表了固定式燃气轮机和航空发动机中的燃烧过程和污染物形成。将使用最优估计方法对所得数据进行系统分析。基于所获得的关于污染物/湍流相互作用的研究结果，这两种污染物模型将在LES的背景下制定湍流燃烧。在项目结束时，项目前一阶段和下一阶段的所有模型组件都将集成到现有的多状态燃烧模型中。该集成模型将应用于模型燃烧室以及真实的航空发动机。

For the development of gas turbine engines, pollutant formation during combustion plays a significant role. Due to increasingly stringent emission limits, further improvements and optimization with respect to emissions is required. Numerical simulations can contribute to cost reduction and acceleration of this development process. However, regarding pollutant emissions, a lack in the predictive quality of state-of-the-art combustion models often limits the usefulness of numerical results. The goal of the proposed research project is therefore the development, validation, and application of simulation models, which can provide reliable predictions of pollutant emissions in gas turbine combustors. In order to reach this goal, an integrated modeling approach is proposed, which combines Large-Eddy Simulations (LES) with the use of combustion and emission models that are based on detailed chemistry. In coordination with the project partners of the FVV, the project has been subdivided into two work packages in order to address the different aspects of pollutant emissions in the development of gas turbine combustors. In aero engines, soot emissions constitute a great challenge, while in stationary gas turbines, the increase of CO emissions at part load poses limitations for the development of load-flexible systems. During the first two years of the project, an emission model for CO was developed for laminar combustion. It accounts for the change in the timescales of the CO production and consumption processes under part load conditions and decouples these processes from the remaining part of the combustion model. For soot emissions, the focus was on the statistical treatment of the soot Number Density Function. Using a novel quadrature-based moment method, especially soot oxidation could be described more accurately. In the second phase of the project, the focus will be on the interaction of turbulence and pollutant formation. To this end, Direct Numerical Simulations (DNS) will be performed for different configurations, which represent the combustion processes and pollutant formation in stationary gas turbines as well as in aero engines. The resulting data will be systematically analyzed using the Optimal Estimator method. Based on the findings obtained regarding the pollutant/turbulence interactions, both pollutant models will be formulated for turbulent combustion in the context of LES. Toward the end of the project, all model components from both the previous and the next project phases will be integrated into an existing Multi-Regime combustion model. This integrated model will be applied to a model combustor as well as a real aero engine.