EI、Scopus 收录
中文核心期刊

液滴撞击高温球面的动力学及传热特性分析

DYNAMICS AND HEAT TRANSFER ANALYSIS OF DROPLET IMPACT ON HIGH TEMPERATURE SPHERICAL SURFACE

  • 摘要: Leidenfrost现象是液滴撞击高温壁面时产生的物理现象, 广泛存在于电子工程、机械工程、动力工程、化学工程等领域, 然而现有研究多数针对平面上的Leidenfrost现象, 针对高温曲面的研究甚少, 如高温球面. 为了探究液滴撞击高温球面的动力学特性及传热特性, 采用数值模拟方法研究了液滴撞击高温球面引起的Leidenfrost现象. 从液滴与气膜形态以及壁面热流密度与压力分布等方面, 分析了Leidenfrost现象, 探究了液滴、气膜和热壁面之间的相互作用规律, 发现气膜厚度较薄处, 壁面热流密度较高, 且液滴与壁面间的蒸汽在排出时会形成泊肃叶流, 从而影响排气速度. 随后, 进一步研究了液滴撞击速度、液滴尺寸、壁面温度等因素的影响. 研究结果表明, 撞击速度和液滴尺寸的增加都可以增强液滴的铺展从而增强传热, 但二者在气膜变化上有所不同, 撞击速度的增加会导致排气加快, 中心气膜厚度降低; 液滴尺寸的增加则会使中心气膜厚度升高. 由于液滴初始撞击动能不变, 壁面温度的改变对液滴铺展趋势的影响不大, 但壁面温度升高会加大液滴吸热量, 使得蒸发速率加快, 从而导致气膜中心厚度增加.

     

    Abstract: Leidenfrost phenomenon is a physical phenomenon caused by droplet impact on high-temperature wall surface, which is widely used in electronic engineering, mechanical engineering, power engineering, chemical engineering and other fields. However, most of the existing research focus on the Leidenfrost phenomenon on a plane, and few studies have focused on high-temperature curved surfaces, such as spheres. In order to investigate the dynamic characteristics and heat transfer characteristics of droplet impact on a high-temperature sphere, numerical simulation methods were used to study the Leidenfrost phenomenon caused by droplet impact on the hot sphere. The Leidenfrost phenomenon was analyzed from the aspects of droplet and gas film morphology, wall heat flux and pressure distribution. The interaction between droplets, gas film, and hot spherical surface was studied. It was found that the wall heat flux is higher when the gas film thickness is thinner, and the Poiseuille flow will be formed when the vapor between the droplet and the wall is discharged, thus affecting the exhaust speed. The article further studied the influence of factors such as droplet impact velocity, droplet size, wall temperature. The results indicate that both impact velocity and droplet size can enhance droplet spreading and heat transfer, but there are differences in the changes of the gas film. An increase in impact velocity leads to accelerated exhaust and a decrease in the thickness of the central gas film. The increase in droplet size will lead to an increase in the thickness of the central gas film. Because the initial droplet impact kinetic energy has no change, the change in wall temperature has little effect on the droplet spreading situation. However, the increase of the wall temperature will increase the heat absorption of the droplet and accelerate the evaporation rate, resulting in an increase in the thickness of the center gas film.

     

/

返回文章
返回