Elucidation of Detailed Structure of fuel sprays by Advanced optical diagnostics and the Combustion Mechanisms

Katsuki和Akamatsu：喷雾火焰的宏观燃烧行为和光学测量为了更好地了解喷雾火焰的燃烧行为，将激光层析成像的液滴簇可视化和使用新开发的多色集成卡塞格伦接收光学系统(MICO)的局部OH化学发光和CH波段发射的同步测量应用于预混合喷雾火焰。利用Ar离子激光器和高速数码相机研究了燃烧过程中液滴团簇及其瞬变结构的时间序列平面图像。通过同时观察预混喷雾火焰中的液滴团簇和局部化学发光，证实了由于优先火焰传播，喷雾气流的一些部分很快消失，这在气态预混火焰中是常见的，而另一部分喷雾气流长期存在，形成液滴团簇，消失了…Nakajima和Ikeda：通过激光诊断和局部化学发光来阐明喷雾结构本研究的目的是研究喷雾燃烧中液滴动力学和湍流之间的相互作用。这项研究项目分三个阶段进行。首先，基于相位多普勒风速仪(PDA)在很高的数据采集率下测量的液滴速度和尺寸信息，讨论了湍流流动特性、火焰保持机理、混合气的形成和液滴的蒸发。其次，将粒子图像测速仪(PIV)应用于测量不同尺寸的瞬时空间结构、速度分布、液滴速度，提出了一种多强度层PIV。最后，通过对OH^*、CH^*、C2^*的局部化学发光测量，阐明了流体动力学与化学反应之间的关系。利用该技术可以在高的时间和空间分辨率上观察到从外部群燃烧到内部群燃烧的转变。藤本和森达：非稳态汽化喷雾中的混合气形成过程本研究的对象是非稳态和蒸发场中的自由柴油喷雾。在前人对无蒸发柴油喷雾研究成果的基础上，分析了高温高压下无蒸发喷雾的形成过程和结构。同时，提出了柴油蒸发喷雾的结构模型。在实验分析中，主要研究了喷射压力和环境气体浓度对自由喷雾结构形成过程的影响。在数值分析中，采用改进的KIVA-II程序的TAB模型分析了液滴的空间分布、燃油蒸汽浓度、液滴速度和环境气体速度。最后，我们提出了一种改进的TAB模型和DVM相结合的混合模型，用于环境气体流动和喷雾内部涡流的数值分析。较少

Katsuki and Akamatsu : Macroscopic combustion behavior of spray flames and the optical measurementIn order to better understand the combustion behavior of spray flames, simultaneous measurements of droplet cluster visualization using laser tomography and local OH chemiluminescence and CH-band emission using a newly developed optical probe system named the Multi-color Integrated Cassegrain Receiving Optics (MICRO) are applied to a premixed-spray flame. Time-series planar images of droplet clusters and their transient structures during combustion are examined using an Ar-ion laser and a high-speed digital CCD camera. By observing the droplet clusters and local chemiluminescence simultaneously in the premixed-spray flame, it is confirmed that some portions of the spray stream disappear very rapidly due to preferential flame propagation, which is often seen in gaseous premixed flames, while other portions of the spray stream survive over a long period to form droplet clusters, disappearing … More gradually from their outermost portions, which seems similar to a diffusion-flame.Nakajima and Ikeda : Elucidation of spray structure by laser diagnostics and local chemiluminescenceThe purpose of this research was to investigate interaction between the droplet dynamics and turbulent flow in spray combustion. This research project was conducted in three phases. First of all, turbulent flow characteristics, flame holding mechanism, mixture formation and Droplet evaporation were discussed based upon the droplet velocity and size information acquired by phase Doppler anemometry (PDA), which was measured at very high data acquisition rate. Secondly, particle image velocimetry (PIV) was applied to measure instantaneous spatial structure, velocity distribution, droplet velocity of different size by size discriminating PIV, as we call 'Multi-Intensity-Layer PIV', developed. Finally, local chemiluminescence measurements of OH^*, CH^*, C2^* were performed to elucidate the relation between the fluid dynamics and chemical reactions. The transition from external to internal group combustion was observed in high temporal and spatial resolution by this technique.Fujimoto and Senda : Mixture formation process in unsteady vaporizing spraysThe object of this study is free diesel spray in unsteady and evaporative field. We analyze formation process and structure for evaporating spray in high temperature and pressure field based on the previous studies on results of non-evaporating free diesel spray. Also, we propose a structural model of evaporating diesel spray. In the experimental analysis, we mainly research the effects of injection pressure and ambient gas density on the formation process of free spray structure with exciplex fluorescence method. In the numerical analysis, the spatial distributions of droplet parcels, fuel vapor concentration, parcel velocity, and ambient gas velocity are analyzed by a modified TAB model of KIVA-II code. Finally, we propose a hybrid model which consists of a modified TAB model and DVM, for numerically analyzing both ambient gas flow and inner vortex flow of spray. Less