Experimental Research And Numerical Simulation Of Droplet Impact On Surface

The phenomenon of droplet impact on solid surface exists widely in the production and living, for instance, spray cooling, fuel atomization, sea water desalination, ink-jet printing. The research on the process of droplet impact on surface has a profound significance for solving the practical engineering problems theoretically, and it is also an important research content in multiphase flow field.Building static spreading mechanics model of droplet impact on solid wall is an important foundation for further study on the process of droplet collision solid wall. The article used multiple spline curve, circular curve and ellipse curve fitting for the equilibrium morphology of the droplet from vibration attenuation to stationary state after impacting on wall. It found by comparing that elliptic curve fitting is relatively accurate and operable in theory. Then the article verified the semi-ellipsoid static spreading model by experiments, and got the applicable scope of semi-ellipsoid droplet static spreading model, where this model has higher precision.The article observed the process of the droplet impact on wall in the experimental stage and extracted the photograph of a droplet image contour by using Lab VIEW programme. And then obtained the parameters of the droplet, analyzed the rules of the droplet spreading radius, height and spreading speed changing with the time and preliminary explored the changing rule of the dynamic contact angle in the droplet oscillating process. The article also used simulation method to study the distribution of velocity and dynamic contact angle in the droplet oscillating process. In order to facilitate analysis of drop oscillations and the spreading process, it would divided into the development stage and late stage according to the change speed.At last, the VOF model of Fluent software is applied in this article to simulate two-dimension infinite length liquid column impact on the rough wall with the microstructure. And then the article analysed the effects of different coarse structure (rectangular, triangular, trapezoidal) on droplet oscillation, analyzed the form and behavior characteristics of liquid column spreading and retracting on different rough structure. It got the influence law of the rough surface structure to the process of droplet spreading and the form of static balance by comparing with smooth wall. Researches show that the existence of the rough structure will change the velocity direction of liquid in internal flow process, influenced the time of droplets reaching static balance, reduce the liquid oscillation amplitude and changed the period of droplet oscillation.