Study Of The Influence Mechanism Between Interfacial Wettability And Capture Energy From Fluid-solid Friction

Capture energy from fluid-solid friction based on carbon materials is a new type of energy capture technology that has emerged in recent years.It combines many advantages such as high output energy density,low material cost,and small structural scale.The phenomenon of electric potential difference occurs at the boundary slip layer on the surface of the carbon material,which is very sensitive to the concentration,species and flow rate of the solution.Due to the fact that fluid-structure coupled energy capture refer to multiple factors and span large scale of characteristics,people have certain obstacles in their exploration of the energy capture mechanism.Interface wettability reflect two phase coupling interaction ability between liquid and solid in the boundary.Studying the interface wettability of carbon materials and its influence on nanofluid flow behavior,to understand the basic principle of micro scales solid-liquid coupling,which can become a breakthrough to discuss mechanism of fluid captive energy.Therefore,we first analyze the wetting behavior of graphene interface by establishing the wetting model.Then,the effect of lubricity on the microfluidic motion characteristics was investigated by adjusting the contact angle of the fluid channel wall.At last,the mechanism of the effect of wettability on fluid-solid coupled energy capture was analyzed from the viewpoint of boundary slip angle by preparing the energy capture structure and constructing the energy capture platform.The specific research content is as follows:?1?The droplet-graphene wetting model was constructed based on molecular dynamics,and the effects of potential trap parameters,water molecule types,water droplet size,and interface microstructure on wettability were investigated.The linear relationship between graphene contact angle and potential well parameter?_c-o is obtained.From the energy point of view,the differences in contact angles of SPC/E,TIP3P and TIP4P water droplets were analyzed.The characteristic parameters of the continuous fluid wettability are extrapolated from the extreme values of the water droplet contact angle.The influence of the spacing,height and radius of the interface carbon nanotube array on the wettability was analyzed.By concreteizing the rough factor,a rough interface wettability mathematical prediction model that can be verified with the simulation results was deduced.?2?Molecular dynamics method was used to build a microfluidic motion model with graphene and carbon tube as the channel.The effects of channel wall wettability on boundary slip,water density distribution,shear stress and viscosity were studied.The results show that the more the walls tend to be hydrophobic,the higher the degree of water slip at the boundary and the faster the slip speed.The amplitude of the oscillation distribution of the water density in the channel is affected by the wettability of the wall.The more hydrophilic the wall of the channel is,the stronger the decoupling of water molecules in the vicinity of the channel,the higher the shear stress and viscosity of the water flow.?3?With graphene as a captive energy material,the capture energy structure which has different contact angles interface was made.a capture energy test platform with NaCl and KCl as the fluid solute to form a stable laminar flow was constructed.The effects of graphene interfacial wettability,solution flow direction,velocity,and concentration on the fluid-structure coupled energy capture were investigated.Experimental results illustrate that a larger contact angle would result in a larger output voltage,and an increase from 45?to 69.5?amounts to a 66.67%increase in output voltage from 0.57 mv to 0.95 mv.The polarity of voltage is closely related to the direction of fluids and the voltage amplitude fits to a non-linear relationship with the fluidic velocity.In addition,the concentration also influences the output voltage.Aiming at the above experimental phenomena,the energy capture model for the stick-slip movement of ions at the graphene interface was proposed.Based on the simulation results of the interface wettability enhancement and boundary slippage in the previous study,the phenomenon of enhanced hydrophobic interactions on the fluid-solid coupling energy was analyzed.The macroscopic contact angle is a parameter that characterizes the binding force of the interface to water molecules,and it is also a key factor that affects the slip velocity of the solution near the interface.The enhancement effect of hydrophobicity on the stick-slip motion leads to the increase of the velocity of the interface ion-drag electrons,and consequently the output voltage amplitude increases.