Experiments and Model Development for the Investigation of Sooting and Radiation Effects in Microgravity Droplet Combustion
Experiments and Model Development for the Investigation of Sooting and Radiation Effects in Microgravity Droplet Combustion
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微重力液滴燃烧烟灰和辐射效应研究的实验和模型开发
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
R. Dobashi
中科院分区：
文献类型：
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作者：
Ahmet Yozgatligil;M. Choi;F. Dryer;A. Kazakov;R. Dobashi
孤立液滴的球对称燃烧是一个涉及化学反应、多相流（液体、气体、颗粒）和相变耦合的动力学问题。为此，微重力液滴燃烧作为一个理想的平台，用于推进理解通常用于内燃机和燃气轮机的液态烃燃料和添加剂的扩散火焰物理学。由于对大分子量烃液滴燃烧中的烟灰过程的复杂和不完整的理解，理论/计算公式在历史上忽略了烟灰行为。微重力试验台实验中使用液滴火焰，使用温和的煤烟燃料，正庚烷，并采用参数调整技术，以尽量减少煤烟的比较和验证的数值模型。然而，没有一种实验技术是完全成功的，炭黑仍然是液滴燃烧分析中的一个关键组成部分，与其在常规燃料燃烧中的重要性相称。如果不考察和考虑炭黑和辐射的影响，就不能对液滴燃烧行为进行彻底的解释。同时，孤立的液滴燃烧研究提供了一个机会，研究扩散火焰的动力学上的炭黑现象，并在准稳态实验，如环形射流扩散火焰中不可用的参数范围。液滴燃烧和诊断的数值模拟方法的当前状态允许考虑的瞬态性质的炭黑和辐射的细节水平，这是计算上禁止和实验棘手的多维配置。实验测量和数值模型的发展可以提供一个全面的测试，他们对燃烧速率，火焰结构，火焰熄灭，和烟尘气溶胶特性的影响。因此，这个问题是一个逻辑延伸的非炭黑液滴燃烧实验和数值模拟的努力，以前已经进行。这项研究涉及飞行实验（1.5至5毫米之间的液滴）和支持性的地面实验，同时进行数值模型的开发和验证。实验涉及两种燃料：正庚烷和乙醇。诊断测量包括
The spherically-symmetric burning of an isolated droplet is a dynamic problem that involves the coupling of chemical reactions, multi-phase flow (liquid, gas, particulate) with phase change. To this end, microgravity droplet combustion serves as an ideal platform for advancing the understanding the diffusion flame physics of liquid hydrocarbon fuels and additives that are typically used in internal combustion engines and gas turbines. Due to the complex and incomplete understanding of soot processes in the combustion of large molecular weight hydrocarbon droplets, theoretical/computational formulations have historically neglected sooting behavior. Testbed experiments in microgravity using droplet flames, used a mildly sooting fuel, n-heptane, and employed parameter adjustment techniques to minimize sooting for comparisons with and validations of numerical models. None of the experimental techniques, however, were entirely successful and sooting remains a critical component in the analysis of droplet combustion, commensurate with its importance in the burning of conventional fuels. A thorough interpretation of droplet burning behavior cannot be accomplished without examining and incorporating the influences of sooting and radiation. Concurrently, isolated droplet combustion studies offer an opportunity to investigate sooting phenomena on the dynamics of diffusion flames, and over parameter ranges not available in quasi-steady experiments such as annular jet diffusion flames. The current state of numerical modeling approaches for droplet combustion and diagnostics permits consideration of the transient nature of the sooting and radiation at a level of detail that is computationally prohibitive and experimental intractable for multi-dimensional configurations. Experimental measurements and numerical model development can provide a comprehensive test of their influence on the burning rate, flame structure, flame extinction, and soot aerosol properties. Thus, this problem is a logical extension of non-sooting droplet combustion experiments and numerical modeling efforts that have been previously conducted. This study involves flight experiments (for droplets between 1.5 to 5 mm) and supportive ground-based experiments, with concurrent numerical model development and validation. The experiments involve two fuels: n-heptane, and ethanol. The diagnostic measurements include