Research On Dynamic Behavior Of Droplet Impacting On Cold Surface And Manipulating Directional Rebound Of Droplet

In industrial fields such as self-cleaning,enhanced heat transfer,spray cooling,microfluidics,and anti-icing,it is a very common physical phenomenon for droplet impacting a solid surface,which is affected by factors such as impact conditions,surface wettability,and surrounding environment.In a low temperature environment,when droplets impact a solid surface,icing is prone to occur.The icing phenomenon is a serious problem facing the anti-icing fields such as energy and power,transportation,power communications,and aerospace.Since the discovery of the lotus leaf effect,the superhydrophobic surface has attracted attention due to its strong water repellency.Whether the superhydrophobic surface can be used to suppress the icing of impact droplets has been a research hotspot in recent years.However,the research on the anti-icing performance of superhydrophobic surfaces mainly focuses on delaying the nucleation process of ice crystals and reducing the adhesion strength of the ice layer.There are relatively few studies on promoting the rebound of droplets from the surface before freezing,so based on the superhydrophobic surface promoting the rebound of impacted droplet,this article first conducts an experimental study on the dynamic behavior of droplet impacting on superhydrophobic cold surfaces.At the same time.the researchers found that the macrostructure could greatly reduce contact time between the droplet and the surface in the room temperature experiment.Therefore,this article also verified the anti-icing effect of the superhydrophobic surface with the macrostructure under low temperature conditions,and found that the macrostructure also has the effect of reducing the accumulation of droplets under certain impact conditions.The reduction of droplet accumulation also has important research value in the fields of anti-icing,phase change energy storage,and enhanced heat transfer.Therefore,in this paper,a wedge-shaped heterogeneous surface is designed through numerical simulation to control the directional rebound of impact droplets accurately.The main research content of this article includes three parts:(1)The effects of surface temperature and impact conditions on the dynamic behavior of droplet impacting superhydrophobic cold surface are studied.Different from the dynamics of droplet impacting superhydrophobic surface at room temperature.droplet will has various product phases such as complete adhesion,partial adhesion,partial rebound,and complete rebound on cold surface.Based on the corresponding product phases under different impact conditions and surface temperatures,a simple impact phase diagram of superhydrophobic cold surfaces is constructed;(2)A triangular ridge superhydrophobic surface with the same diameter as the droplet is designed,and the dynamic behavior and product phase of the droplet impacting the cold surface of the triangular ridge under different surface temperatures and impact conditions were studied.Compared with the kinetic process of droplet impacting a superhydrophobic horizontal surface under the same experimental conditions,it verifies the anti-icing effect of the triangular ridge super-hydrophobic surface under low temperature conditions;(3)The dynamic process of droplet impacting the wedge-shaped heterogeneous surface is studied,and the mechanical mechanism of controlling the directional rebound of the droplet is analyzed.At the same time,the influence of wedge-shaped apex angle,surface wettability and impact conditions on the directional rebound of the controlled droplet is studied.And quantitative analysis is carried out through different characteristic parameters.In summary,this paper experimentally studied the dynamic behavior of droplet impacting super-phobic horizontal surfaces and triangular ridge super-hydrophobic surfaces under low temperature conditions,and verified the anti-icing performance of superhydrophobic cold surface,which provide experimental basis and theoretical guidance for the research on suppressing the icing of impact droplets;At the same time,this paper analyzes the influence of the wedge-shaped apex angle,surface wettability and impact conditions on the precise control of the directional rebound of the droplet.Therefore,it also provides a theoretical basis and technical support for the study of using chemically non-uniform surfaces to manipulate the directional rebound of droplets.