超声波影响初始霜晶生长的微观可视化研究

试验研究了超声波对平板表面结霜初始阶段霜晶生长的影响.对自然对流条件下施加20kHz频率的超声波和未施加超声波两种作用机制下平板表面结霜初始阶段冻结水珠的形态、分布以及水珠冻结后水珠表面霜晶的生长进行了微观可视化研究.对有无超声波作用的不同冷表面温度下水珠冻结粒径的大小以及水珠分布的疏密进行了对比分析.同时对有无超声波作用下水珠冻结后水珠表面霜晶的生长进行了对比观测.试验结果显示:施加超声波作用后,冻结水珠粒径显著减小,形态相对规整且接近圆形;分布相对规则且明显稀疏;水珠冻结后其表面霜晶几乎不生长.结果表明:超声波对结霜初期冻结水珠的形成以及水珠冻结后水珠表面霜晶的生长具有显著的抑制作用.

Visualization of Effects of Ultrasound on Initial Frost Crystal Growth

An experimental study concerning the effect of ultrasound on initial frost crystal growth on a cold flat surface was conducted.A microscopic visualization study on the freezing water droplets shape and distribution in the initial frost period and the frost crystal growth on the freezing water droplet surface after the water droplet freezes with\\without the effect of 20kHz ultrasound was made.The freezing water droplets size and distribution during the initial frost period were comparatively analyzed and the frost crystal growth on the freezing water droplet surface after the water droplet freezed was comparatively observed.It was found that the freezing water droplets formed on the cold surface with the effect of ultrasound were smaller and more sparse compared with those without the effect of ultrasound.Furthermore,almost no growth of the frost crystal can be seen on the freezing water droplet surface after the droplet freezes with the effect of ultrasound.The experimental results showed that the water droplets formation during the initial frost period and the frost crystal growth on the water droplets surface after the water droplets freeze on the flat surface were remarkably restrained due to the effect of ultrasound.