In-situ Diagnostics and Modeling of Ammonia spray Physics and Combustion Behavior at Elevated Pressure

随着全球脱碳的趋势以及人们对可持续交通和推进的关注，了解无碳燃料在实际运行条件下的燃烧性能和排放特性变得越来越重要。氨作为一种无碳燃料和有效的氢载体，由于其相对较高的体积能量密度、低成本、易于储存和输送，以及成熟的可再生资源生产基础设施，引起了广泛的研究兴趣。尚未解决的一个主要障碍是在燃烧过程中排放一氧化氮和未燃烧的氨，这两者都与喷雾和混合过程密切相关。该提案的重点是了解高压液氨喷雾和燃烧的特性，压力高达80巴，为未来的无碳运输和推进系统提供信息。建议的工作亦会扩大学生参与研究，并把研究与教学结合起来，以加强学生的学习。这项工作不仅会影响基本的喷雾动力学和燃烧动力学，而且会对无碳运输和推进系统的发展产生革命性的影响。本研究的目的是将全面的原位激光诊断与数值模拟相结合，深入了解非汽化、汽化和反应条件下的氨喷雾。这填补了实质性的知识差距，需要在先进的激光诊断和高保真数值模拟的专业知识相结合。先进的激光诊断将包括二维拉曼、PLIF和彩虹反射仪，以获取流量、关键反应中间体和液滴大小分布。这些实验测量将提供有关高压氨燃烧作为无碳燃料的性能和排放特性的前所未有的细节。流动、温度、液滴和化学中间体分布的信息也将为使用开源CFD代码和商业软件验证模拟提供有价值的目标，以增强对未来清洁燃烧系统的建模和预测能力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the global trend of decarbonization and growing interests in sustainable transportation and propulsion, it becomes increasingly important to understand the combustion performance and emission characteristics of carbon-free fuels under practical operation conditions. Ammonia has attracted extensive research interests as a carbon-free fuel and an effective hydrogen carrier, due to its relatively high volumetric energy density, low cost, convenience to store and deliver, and mature production infrastructure from renewable resources. A major obstacle yet to be resolved is the emission of nitric oxide and unburnt ammonia during combustion, both of which are strongly coupled with the spray and mixing process. This proposal focuses on the understanding the characteristics of high-pressure liquid ammonia spray and combustion, with pressures up to 80 bar, to inform future carbon-free transportation and propulsion systems. The proposed efforts will also broaden participation in research and integrate research with teaching to enhance student learning. The proposed work will not only impact on the fundamental spray dynamics and combustion kinetics, but also be transformative for the development of carbon-free transportation and propulsion systems.The goal of this research is to combine comprehensive in-situ laser diagnostics and numerical simulation to provide in-depth understanding of ammonia sprays under non-vaporizing, vaporizing, and reacting conditions. This fills a substantial knowledge gap and requires a combination of expertise in advanced laser diagnostics and high-fidelity numerical simulations. Advanced laser diagnostics will include 2D Raman, PLIF and rainbow reflectometry to acquire flow, key reaction intermediates and droplet size distribution. These experimental measurements will provide unprecedented details about the performance and emission characteristics of high-pressure ammonia combustion as a carbon-free fuel. Information of the flow, temperature, droplet and chemical intermediate distribution will also provide valuable targets to validate simulations using both open source CFD code and commercial software to enhance modeling and prediction capability for future clean combustion systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.