双疏水表面润湿和传热动力学研究

为实现润湿图案化的超疏水表面在航空电子设备散热中的应用,本文对液滴撞击双疏水表面(具有疏水性图案的超疏水基质)的润湿行为和传热特性进行了分析.通过使用高速相机和红外相机,我们获取了液滴铺展和回退阶段的动力学以及表面温度和热流量的相应空间分布.本文研究了液滴撞击超疏水、疏水和双疏水表面上的动态润湿和局部传热的差异.此外,本文还分析了表面温度和撞击高度对液滴撞击过程的影响.结果表明,所有表面在铺展阶段都具有相同的润湿特性和相似的传热行为.表面温度变化并不能对铺展阶段表面润湿特性产生较大的影响,液滴铺展时间与表面温度和撞击高度无关.在回退阶段,表面润湿特性的差异使得三个表面之间的传热特性明显不同.双疏水表面特殊润湿特性使得回退阶段液膜的接触线速度存在跳变现象,形成了许多小液滴,增加了接触面积,同时又兼具了超疏水表面的回弹特性.

Investigation of the wetting dynamic and heat transfer of bi-phobic surface

In order to realize the application of wettability-patterned superhydrophobic surfaces in avionics cooling, the dynamic wetting behavior and heat transfer characteristics of droplets impact on bi-phobic surface (superhydrophobic matrix with hydrophobic patterns) are analyzed. The dynamics of droplets spreading and receding phases, and the corresponding spatial distribution of the surface temperature and heat flux beneath the impact droplet, are acquired by using high speed camera and infrared camera, respectively. We analyze the discrepancies of dynamic wetting and local heat transfer during single droplet impingement onto superhydrophobic, hydrophobic and bi-phobic surfaces. Furthermore, the influences of surface temperature and impact height on droplet impact process are also analyzed. The results show that all surfaces have the same wetting behavior and similar heat transfer characteristics, surface temperature has little effect on the surface wetting behavior. Furthermore, the spreading time has nothing to do with surface temperature and impact height in spreading process. Due to the difference of wetting behavior, the heat transfer characteristics between the three surfaces are significantly different in receding process. The special wetting behavior of the bi-phobic surface makes the contact line velocity of the receding liquid film drastically change, produces some small droplets, increases the contact area in receding phase, and also has the resilience properties of superhydrophobic surface.