Influence of atomization on particle synthesis in spray flames

前驱体溶液的雾化程度对喷雾火焰合成纳米颗粒的性能有显著影响。喷嘴附近的特征液滴和气相是火焰沿粒子轨迹形成局部合成条件的重要输入条件。因此，原子化的任何变化都会直接影响粒子的性质。在这种情况下，喷嘴的设计代表了一个基本的自由度，它可以用来更好地理解喷射火焰和颗粒形成机制的耦合，并在此基础上，能够长期有针对性地操纵颗粒特性。目前项目第一阶段的工作证明了喷嘴几何形状对喷射火焰合成的高度重要性。结果表明，不适当的雾化会导致不期望的火焰脉动。由于这种脉动阻碍了对喷雾特性对颗粒形成过程链的影响的严格研究，因此开发了一种适应的雾化器设计，可以显着减少火焰脉动。在此基础上，通过数值和实验研究，定性和定量地证明了雾化器设计对粒径分布的影响是显著的。然而，喷雾特性与颗粒特性之间是否存在直接关联以及在何种条件下存在直接关联还需要进一步的研究。此外，尚不清楚沿轨迹的喷嘴依赖的局部合成条件如何影响粒子形成的单个机制。基于这些知识，本研究项目旨在通过有针对性地改变喷雾特性和高分辨率的实验和数值方法，对局部合成条件对喷雾火焰机理的影响提供基本的认识。在这种情况下，我们将量化局部反应和合成条件的形成如何以及在多大程度上受到单个喷嘴依赖的雾化过程和随后的液滴-火焰相互作用的影响。在此基础上，将对颗粒形成机制和喷雾火焰机制的相互敏感性有一个基本的了解。新的雾化器设计将被引入和使用，它允许系统的变化相关的喷雾火焰机制的具体操作的喷雾特性。

The spray flame synthesis of nanoparticles is significantly influenced by the atomization of the precursor solutions. The characteristic droplet and gas phase in the vicinity of the nozzle is an essential input condition for the formation of local synthesis conditions in the flame along the trajectories of particles during their formation. Thus, any change of the atomization will directly affect the particle properties. In this context, the nozzle design represents an essential degree of freedom, which can be used to gain a better understanding of the coupling of spray flame and particle formation mechanisms and, on this basis, to enable a targeted manipulation of particle properties in the long term.The high importance of the nozzle geometry for spray flame synthesis was demonstrated by work in the first phase of the current project. It was revealed that an unsuitable atomization can lead to undesired flame pulsations. Since such pulsations prevent a rigorous investigation of the influence of spray characteristics on the process chain of particle formation, an adapted atomizer design was developed which significantly reduces flame pulsations. On this basis and with the help of numerical and experimental investigations, it was shown qualitatively and quantitatively that the particle size distribution can be significantly affected by the selected atomizer design. However, further research is needed to clarify whether and under which conditions a direct correlation between spray characteristics and particle properties exists. Furthermore, it is unknown how the responsible individual mechanisms of particle formation are influenced by the nozzle-dependent local synthesis conditions along the trajectory.Based on this knowledge, this research project aims to provide a fundamental understanding of the influence of local synthesis conditions on spray flame mechanisms by means of a targeted variation of spray characteristics and high-resolution experimental and numerical methods. In this context, we will quantify how and to what extent the formation of local reaction and synthesis conditions is affected by individual nozzle-dependent atomization processes and subsequent droplet-flame interactions. On this basis, a fundamental understanding of the mutual sensitivity of particle formation mechanisms and spray flame mechanisms will be achieved. New atomizer designs will be introduced and used, which allow a systematic variation of the relevant spray flame mechanisms by a specific manipulation of the spray characteristics.