Mechanism Of Droplets Impacting On Superhydrophobic Surfaces And Its Application In Triboelectricity

Superhydrophobic surfaces,defined as surfaces with a steady-state contact angle greater than 150°,have excellent characteristics such as self-cleaning,anti-icing,anti-corroding,etc.Therefore,research on exploring the mechanism of droplets impacting on superhydrophobic surfaces is necessary and has attract more and more attention in recent years.In this thesis,influence mechanism of roughness parameters of superhydrophobic surfaces with randomly distributed rough structures on the dynamic behaviors of droplets is studied based on the previous research.Then,according to the dynamic behaviors of droplets,a triboelectric nanogenerator composed of superhydrophobic friction materials is prepared to study the triboelectric phenomenon of superhydrophobic surfaces.Firstly,dynamic behaviors of droplets on superhydrophobic surfaces are analyzed through shooting the droplets impinging on the artificially-prepared superhydrophobic surfaces by using a high-speed camera.Then,the lattice Boltzmann simulation model is established to reconstruct superhydrophobic surfaces with different roughness and intrinsic contact angles.Parameters in the simulation model are adjusted to match the experimental results and the influence of roughness parameters on the dynamic behavior of the droplet is studied.Finally,a triboelectric nanogenerator with superhydrophobic material PTFE is prepared by using thermal evaporation and spraying.For comparation,another generator with smooth PTFE is prepared using the same methods to exploring the influence of dynamic behavior of droplets on superhydrophobic surfaces on the power generation performance of the generator.The output characteristics of the two generators are compared under the conditions of different heights and flow rates of water droplets,which is of significance for studying the application of superhydrophobic surfaces using in triboelectric nanogenerators.According to the research,the dynamic behavior of droplet after impacting the randomly distributed rough surfaces mainly includes spreading,retracting and bouncing.The maximum spreading factor,contact time and bounce ability of the droplet are affected by roughness parameters and Intrinsic contact angle.Within a certain range,the bounce ability of droplets decreases with the increase of kurtosis and skewness;the contact time of the droplet with the surface reaches the minimum when kurtosis is around 3.0 and skewness is around 0.6;the bouncing ability of the droplet performs best with kurtosis around 3.0 and skewness around 0;the increase in the intrinsic contact angle makes benefits to reduce the contact time and enhance the bouncing ability of the droplets.For the triboelectric nanogenerator,the maximum spreading factor of the droplets affects the effective friction area and the charge density of the generator,and the contact time and the bouncing ability affect the contact-separation period.Therefore,according to the conclusion drawn from the droplet impacting the superhydrophobic surface,selecting the superhydrophobic friction material within the optimal roughness range can effectively improve the power generation efficiency and increase the charge and discharge speed.The mechanism of droplets impacting on superhydrophobic surfaces with randomly distributed rough structures has been studied,providing guidance for the preparation and development of related applications of superhydrophobic surfaces.The characteristics of superhydrophobic surfaces are used applied in triboelectric nanogenerator to explore the application value of new energy resources.