• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文会议>International Conference on Micro/Nanoscale Heat and Mass Transfer >THE SPREADING CHARACTERISTICS AND TEMPERATURE EVOLUTION OF DROPLET IMPACT ON COLD SUPERHYDROPHILIC SURFACE
【24h】

THE SPREADING CHARACTERISTICS AND TEMPERATURE EVOLUTION OF DROPLET IMPACT ON COLD SUPERHYDROPHILIC SURFACE

机译：液滴在冷超亲水表面上的扩散特性和温度演化

获取原文
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Droplet impact phenomena and thin liquid film flow are widespread in nature, industrial production and daily life. The spreading characteristics and temperature evolution of the liquid film after droplet impact are the key controlling factors in many industrial heat transfer processes. Constructing a thin micro-nano structured superhydrophilic surface on a metal surface is a promising approach to achieving heat transfer enhancement. Therefore, in this paper, we experimentally investigated the hydraulic characteristics and temperature distribution evolution of water droplet impact on cold superhydrophilic surface using high-speed imaging and infrared thermal imaging techniques. During the droplet spreading on superhydrophilic surface, there is an inertial-force-dominant rapid spreading regime followed by the friction-dominant slow spreading regime. It is observed that a precursor film forms in the radial direction. The results show that the droplet spreading diameter is positively correlated with the We number, increasing as the weber number becomes larger. The spreading diameter decreases as the wall temperature decreases, but the effect of temperature is not obvious compared with that of impact weber number. For temperature evolution, a low temperature center area forms at the impact center and a ring-shaped high temperature zone is observed first for droplet impact on cold superhydrophilic surfaces. Along spreading radial direction, the temperature distribution shows an uphill to downhill curve with its gradient inverted in sign near the high temperature zone. Then the high temperature ring disappears and the liquid film temperature shows a monotonically decreasing trend along the radial direction. The duration time of high temperature ring shortens with the increase of We number and decrease of wall temperature. Meanwhile, in order to reveal the reasons for the formation of special temperature distribution, CFD numerical simulation is adopted to analyze the mechanism of ring-shaped high temperature zone's formation. CFD numerical simulation demonstrates that the temperature evolution law is in good agreement with the experiment results. The temperature distribution of high temperature ring is caused by uneven distribution of the liquid film thickness due to the superwetting properties of superhydrophilic surface. This work is of great significance for further understanding and provides new sights of the liquid film flow on superhydrophilic surface in heat transfer process. Furthermore, it has certain reference significance for the spray and heat transfer process in engineering practice.
机译：液滴冲击现象和薄液膜流动在自然界，工业生产和日常生活中广泛存在。液滴撞击后液膜的扩展特性和温度变化是许多工业传热过程中的关键控制因素。在金属表面构造薄的微纳米结构的超亲水性表面是实现传热增强的有前途的方法。因此，在本文中，我们使用高速成像和红外热成像技术，通过实验研究了水滴撞击冷超亲水表面的水力特性和温度分布演变。在液滴在超亲水性表面上扩散的过程中，存在惯性力为主的快速扩散方式，然后是摩擦为主的慢速扩散方式。观察到在径向上形成前体膜。结果表明，液滴扩散直径与We值呈正相关，随着韦伯数的增大而增大。随着壁温的降低，铺展直径减小，但是与冲击韦伯数相比，温度的影响并不明显。为了产生温度，在冲击中心形成一个低温中心区域，首先观察到一个环形高温区，以将液滴冲击到冷的超亲水表面上。沿径向扩展，温度分布显示出从上到下的曲线，其梯度在高温区域附近呈符号反转。然后高温环消失，液膜温度沿径向显示出单调下降的趋势。随着We数的增加和壁温的降低，高温环的持续时间缩短。同时，为了揭示形成特殊温度分布的原因，采用CFD数值模拟分析了环形高温区形成的机理。 CFD数值模拟表明，温度演化规律与实验结果吻合良好。高温环的温度分布是由于超亲水性表面的超湿特性引起的液膜厚度分布不均引起的。这项工作对于进一步理解具有重要意义，并为换热过程中超亲水性表面上的液膜流动提供了新的视角。此外，它对工程实践中的喷雾传热过程具有一定的参考意义。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号