Abstract:Wettability refers to the tendency of the liquid to spread on the solid surface,which can be described by the wetting angle,and is an important index for evaluating the permeability of the lubricant.In order to study the electrowetting properties of the lubricating fluid,an electrowetting wetting angle measuring device was set up to measure the wetting angle of the lubricating fluid.A negative high voltage was applied to obtain the change of the wetting angle of different lubricating fluids under different voltages.The mechanism of the wetting angle of droplets with negative voltage was analyzed by simulation method.The results show that the wetting angle of the lubricating fluid is affected by the external electric field.In a certain range,the larger the voltage,the smaller the wetting angle of the lubricating fluid.Adding nanoparticles to the lubricating fluid can improve the electrowetting performance of the lubricating fluid.Under the same voltage,compared with deionized water,deionized waterbased nanofluid,castor oil,castor oil-based nanofluid,and sunflower oil,the sunflower oil-based nanofluid has the best electrowetting performance.After the voltage is applied to the droplet of lubricant liquid,the pressure field and velocity field at each position of droplet are changed.The pressure field at the top is larger,the velocity is directed to the inside of droplet,the edge pressure field is smaller,and the velocity is directed to the outside of droplet,which causes the reduction of wetting angle