This project aims to characterize the influence of hydrogen addition on the local flame structures and NOx emission formation in a premixed laminar counterflow configuration for carbon-free ammonia combustion using combined Raman/Rayleigh spectroscopy and

使用无碳燃料氨和氢作为可再生能源的化学能量储存，对于某些部门（例如海上推进）的必要脱碳非常重要。氨和氢的共燃为克服单独使用这两种燃料的困难提供了选择。氢气可以从绿色氨高效地生产。通过向氨中添加几摩尔分数的氢，与例如天然气燃烧相比，观察到火焰稳定性的显著增加，具有类似的层流燃烧速率。同时，氢气的加入改变了火焰结构和氮氧化物的局部形成。到目前为止，这些现象主要是数值研究。详细的实验研究在文献中是不可用的，但迫切需要进一步了解和验证的物理化学模型。本研究的目的是从根本上了解氢添加对氨/氢预混火焰的火焰结构、火焰稳定性和一氧化氮生成的影响。使用先进的激光诊断方法，空间分辨的热化学状态和非常不同的一氧化氮形成的反应区相比，碳氢化合物为基础的燃烧过程将进行调查。调查将进行到空气动力学熄灭极限，以分析氢气添加对火焰结构的影响以及火焰稳定性和一氧化氮形成的相互作用机制。在一个参数的变化，不同的当量比和不同的氨/氢/氮/空气混合物中的逆流配置系统地探讨。最初，氢添加引起的机制将在层流条件下进行研究，在第二个项目阶段将在湍流条件下进行研究。热化学状态（温度，物种浓度）和火焰结构将通过一维空间分辨组合拉曼/瑞利光谱测量，并随后进行分析。在此之前未知的，依赖于温度的拉曼散射截面的氨分子的准备，实验确定。还将使用激光诱导荧光定量测定一氧化氮浓度。局部拉伸率附近的反应区将被识别粒子图像测速结合同时确定的羟基自由基分布，通过激光诱导荧光。这些实验数据将被用来评估反应动力学模型，显示显着的偏差，特别是在预测一氧化氮的形成和消光极限。这些全面的调查旨在填补知识空白，以关闭的潜力，热利用的绿色氨-氢混合物。

The use of the carbon-free fuels ammonia and hydrogen as chemical energy storage for renewable energies is of great importance for the necessary decarbonization in some sectors (e.g. maritime propulsion). Co-combustion of ammonia and hydrogen opens up options to overcome the difficulties of using the two fuels individually. Hydrogen can be produced energy-efficiently from green ammonia. By adding a few mole fractions of hydrogen to ammonia, a significant increase in flame stability is observed compared to, for example, natural gas combustion, with similar laminar burning rates. At the same time, the addition of hydrogen changes the flame structure and the local formation of nitrogen oxides. So far, these phenomena have been investigated mainly numerically. Detailed experimental investigations are not available in the literature, but are urgently needed for further understanding and validation of mathematical-chemical models. The aim of this project is to fundamentally understand the influence of hydrogen addition on flame structure, flame stability and nitric oxide formation for premixed ammonia/hydrogen flames. Using advanced laser diagnostic methods, spatially resolved thermochemical states and the very different nitric oxide formation in the reaction zone compared to hydrocarbon-based combustion processes will be investigated. The investigations will be carried out up to the aerodynamic extinction limit in order to analyze the impact of hydrogen addition on the flame structure and the interacting mechanisms of flame stability and nitric oxide formation. In a parametric variation, different equivalence ratios and different ammonia/hydrogen/nitrogen/air mixtures are systematically explored in a counterflow configuration. Initially, the mechanisms caused by hydrogen addition will be investigated for laminar flow conditions, and in a second project phase for turbulent flow conditions. Thermochemical states (temperature, species concentrations) and flame structures will be measured by one-dimensional spatially resolved combined Raman/Rayleigh spectroscopy and subsequently analyzed. In preparation for this, the previously unknown, temperature-dependent Raman scattering cross sections of the ammonia molecule are determined experimentally. Nitric oxide concentration will also be quantitatively determined using laser-induced fluorescence. Local stretching rates near the reaction zone will be identified by particle image velocimetry in combination with the simultaneously determined hydroxyl radical distribution via laser-induced fluorescence. These experimental data will be used to evaluate reaction kinetic models that show significant deviations, particularly in predicting nitric oxide formation and extinction limits. These comprehensive investigations are intended to fill a knowledge gap in order to close the potentials of the thermal utilization of green ammonia-hydrogen mixtures.