SBIR Phase I: Multi-Environment Probability Density Function (PDF) Method for Modeling Turbulent Combustion Using Detailed Chemistry

这个小型企业创新研究（SBIR）第一阶段项目将研究应用多环境概率密度函数（MEPDF）方法在实际燃烧设备的综合CFD模拟中模拟具有实际化学动力学的湍流燃烧问题的适用性和优点。MEPDF保留了传输概率密度函数（PDF）方法的许多理想特性，但计算成本很小，包括精确处理化学源项的能力，以及非常精确地处理湍流和有限速率化学反应之间的非线性相互作用。MEPDF起源于化学工程界用于模拟少放热的化学过程的多环境微混合模型。最近，这种方法已经扩展到模拟气相燃烧问题，但只是非常简单的化学。本项目旨在进一步推进该方法，将其扩展到结合实际化学动力学来模拟燃烧问题，其中湍流-有限速率反应相互作用对准确预测至关重要，如污染物排放（如氮氧化物，烟尘）。这项工作最终将扩展MEPDF方法来模拟非均质燃烧问题，如煤燃烧，并提供方法来模拟在发电行业广泛使用的低NOx燃烧系统。将MEPDF方法扩展到使用复杂化学动力学模拟实际燃烧系统的活动将为科学和工程知识和理解基础奠定坚实的基础。来自不同行业的商业关注清楚地证明了改进的建模工具对复杂燃烧过程提供更可靠的预测的价值。该项目开发的先进工具为发电、化学过程、矿物过程和焚烧行业的公司提供了改进产品设计和服务的手段，最终将有利于环境、全球竞争力和国家/国土安全。对污染物形成和破坏过程的进一步了解，目前受到这些复杂过程精确建模能力的限制，将导致污染物排放的减少。减少发电厂、工艺炉和焚化炉的污染物排放将继续是一个必要的环境目标，也是一个具有挑战性的工程问题，需要尽可能最好的研究工具。

This Small Business Innovation Research (SBIR) Phase I project will investigate the applicability and merit of applying the multi-environment probability density function (MEPDF) method to model turbulent combustion problems with realistic chemical kinetics within comprehensive CFD simulations of practical combustion equipment. MEPDF retains many of the desirable properties of the transported probability density function (PDF) method but at a fraction of the computational cost, including the ability to treat the chemical source term exactly and address the nonlinear interaction between turbulence and finite rate chemical reactions with great accuracy. MEPDF originated from multi-environment micro-mixing models used in the chemical engineering community to simulate chemical processes with little heat release. Recently this method has been extended to model gas phase combustion problems, but for only very simple chemistry. This project aims to further advance this method by extending it to incorporate realistic chemical kinetics for modeling combustion problems where turbulent-finite rate reaction interaction is crucial for accurate prediction such as pollutant emission (e.g., NOx, soot). The work would eventually extend the MEPDF method to model heterogeneous combustion problems, such as coal combustion, and provide means to simulate low NOx firing systems that are widely used in the power generation industry.The activities of extending the MEPDF method to simulate practical combustion systems using complex chemical kinetics would lead to a solid foundation of the scientific and engineering knowledge and understanding base. The value of an improved modeling tool to provide more reliable predictions of complex combustion processes is clearly evidenced by commercial concerns from various industries. The development of advanced tools from this project provides means for companies in the power generation, chemical process, mineral process, and incineration industries to improve product designs and services that would ultimately benefit the environment, global competitiveness, and national/homeland security. An improved understanding of pollutant formation and destruction processes, currently limited by the ability to accurately model these complex processes, will result in reductions of pollutant emissions. Reducing pollutant emissions from power plants, process furnaces, and incinerators will continue to be both a necessary environmental objective and a challenging engineering problem requiring the best investigational tools possible.