STUDY OF FIREBRAND TRAJECTORIES IN A TURBULENT SWIRLING NATURAL CONVECTION PLUME
STUDY OF FIREBRAND TRAJECTORIES IN A TURBULENT SWIRLING NATURAL CONVECTION PLUME
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DOI：
10.1016/0010-2180(69)90072-8
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发表时间：
1969-01-01
影响因子：
4.4
通讯作者：
HELLMAN, JM
中科院分区：
文献类型：
--
作者：
LEE, SL;HELLMAN, JM
本文对湍流、旋流自然对流羽流中火焰的行为进行了理论和实验相结合的研究。在理论处理中，火把被理想化为密度恒定的球体，每种可燃物质的燃烧速率都是恒定的。假设燃烧剂的浓度足够低，使得流体相被认为不受颗粒相的干扰。研究结果表明，火把的轨迹取决于火把上的力的平衡。当颗粒围绕羽流的轴旋转时，在颗粒上的径向向内的拖曳力和离心力之间建立平衡，这导致颗粒朝向或远离轴移动。速度场的大小取决于羽流中粒子的高度。在实验中，将试验粒子注入羽流，观察其轨迹。决定粒子轨迹的重要参数是燃烧速率、粒子的初始尺寸和粒子的密度。在羽流中的初始位置也会影响粒子的轨迹。通过实验确定，扁平颗粒在羽流中比球形颗粒更稳定。
A combined theoretical and experimental study has been performed of the behaviour of firebrands in a turbulent, swirling natural convection plume. For the theoretical treatment, firebrands were idealized as spheres of constant density, the burning rate a constant for each type of combustible material. Concentration of firebrands was assumed low enough so that the fluid phase was considered undisturbed by the particulate phase. Results of the study showed that the trajectory of the firebrand was dependent upon a balance of forces on the firebrand. As the particle swirled about the axis of the plume, a balance was established between a radially inward drag force on the particle and the centrifugal force, which caused the particle to move either towards or away from the axis. The magnitude of the velocity field was dependent upon the altitude of the particle in the plume. Trajectories were terminated either by burnout of the particle or by grounding.Experimentally, test particles were injected into a plume, and the trajectories observed. The important parameters that determined the particles' trajectory were the burning rate, the initial size of the particle, and the density of the particle. Initial placement in the plume also affected the particles' trajectory. Experimentally it was determined that flat particles were more stable in the plume than spherical particles.