Research Initiation Awards: Spherically-Symmetrical Combustion of Unsupported Droplets Under Normal-Gravity Conditions

独特的落管实验装置， 球对称蒸发和燃烧的自由， 将开发和构建下落液滴。 的 该装置的设计基于以下原理 气体中的重力引起的压力梯度可以 通过适当地加速气体， 异形管 随着气体移动的液滴 浮力和强制对流会大大降低 环境，从而促进球面对称。 的 仪器将用于研究近球对称 液滴蒸发和燃烧的条件下， 迄今为止还没有实验性地实现（即，燃烧 在大气压下，初始液滴直径= 100 μ m 压力）。 实验研究将集中在1。燃烧 和碳氢化合物液滴的熄灭，2.测量 瞬态液滴和火焰直径，以及3.燃烧和 具有强烈炭黑倾向的液滴的破裂。 拟议的设施将允许许多基本和 实际的液滴燃烧和蒸发现象， 在以前未达到的条件下进行研究。 数据 将有助于检验现有的理论， 将提供有关现象的基本信息， 熄灭条件、瞬时汽化率，以及 瞬态火焰增长 这项工作的结果将是有益的 对科学界（从基本信息 获得），以及燃烧和喷雾社区， 一般，可能允许改进的实际燃烧 将开发的设备。

A unique drop-tube experimental apparatus to promote spherically-symmetric evaporation and combustion of freely- falling droplets will be developed and constructed. The design of the apparatus is based upon the principle that gravitationally-induced pressure gradients in gases may be significantly reduced by accelerating the gases with properly contoured tubes. Droplets traveling with the gases will experience greatly reduced buoyancy and forced convection environments, thereby promoting spherical symmetry. The apparatus will be used to study nearly spherically-symmetrical droplet evaporation and combustion under conditions that have heretofore not been experimentally achieved (i.e., combustion of droplets initially = 100 um in diameter at atmospheric pressure). Experimental studies will focus on 1. combustion and extinction of hydrocarbon droplets, 2. measurements of transient droplet and flame diameters, and 3. combustion and disruption of droplets with strong sooting tendencies. The proposed facility will allow many fundamental and practical droplet combustion and evaporation phenomena to be studied under conditions previously unattained. The data obtained will be useful for testing existing theories, and will provide fundamental information on phenomena such as extinction conditions, transient vaporization rates, and transient flame growth. Results from the work will be useful to the scientific community (from the fundamental information gained), and also to the combustion and spray communities in general, possibly allowing improved practical combustion devices to be developed.