Modeling and Simulation of Pollutant Formation in Gas Turbines

对于燃气轮机的发展来说，燃烧过程中污染物的形成起着重要的作用。由于排放限制越来越严格，需要在排放方面进一步改进和优化。数值模拟有助于降低成本和加快这一发展进程。然而，在污染物排放方面，最先进的燃烧模型缺乏预测质量，往往限制了数值结果的有效性。因此，拟议的研究项目的目标是开发、验证和应用模拟模型，这些模型可以为燃气轮机燃烧室的污染物排放提供可靠的预测。为了达到这一目标，提出了一种将大涡模拟(LES)与基于详细化学的燃烧和排放模型相结合的集成建模方法。在与FVV的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，开发了层流燃烧的CO排放模型。它解释了部分负荷条件下CO生产和消费过程的时间尺度的变化，并将这些过程与燃烧模型的其余部分解耦。对于碳烟排放，重点研究了碳烟数密度函数的统计处理。利用一种新的基于正交矩的方法，可以更准确地描述碳烟的氧化。在该项目的第二阶段，重点将放在湍流和污染物形成的相互作用上。为此，将对不同的构型进行直接数值模拟，这些构型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的形成。所得到的数据将使用最优估计方法进行系统分析。根据所获得的关于污染物/湍流相互作用的结果，将在大涡模拟的背景下为湍流燃烧建立两个污染物模型。在项目接近尾声时，来自前一个项目阶段和下一个项目阶段的所有模型组件将被集成到现有的多区域燃烧模型中。该集成模型将应用于模型燃烧室和实际航空发动机。

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.