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

Abstract:

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.