Process Study Of Droplet Impacting On The Wall In Continuous Phase Medium

Droplet impact wall widely exists in daily life and engineering applications,such as inkjet printing,pesticide spraying,diesel engine combustion,oil-water separation and other industries.Oil-water separation technology is an indispensable link in petroleum exploitation and chemical industry.In the process of oil-water separation,the spreading characteristics of oil droplet impacting on the wall will directly affect the efficiency of oil-water separation.The study of the motion process and law of oil droplet hitting the wall is of great significance to the technology of oil-water separation.In this paper,a high-speed camera experimental system is built.The experimental operation method and data post-processing method are introduced.The numerical simulation method and model used in this paper are selected.The variation of droplet motion with time is compared between high-speed camera experiment and numerical simulation.The variation of spreading coefficient of experiment and numerical simulation with time is compared and analyzed.The results show that the numerical simulation results are basically consistent with the experimental results.The accuracy of the numerical simulation method and model is verified by experiments.The effects of We number,wall wettability,droplet viscosity,droplet wall tension and different inclined wall angle on the wall impact characteristics of droplet in continuous phase medium were carried out.The variation diagrams of the effects of different wall impact parameters on the motion morphology of liquid droplet were obtained.According to the different spreading degree of droplet,the spreading process of droplet can be divided into adhesive spreading type,intermittent spreading type and protruding spreading type.The whole wall impact process is divided into five stages: motion stage,spreading stage,retraction stage,oscillation stage and stable stage.The effects of wall impact parameters on dimensionless spreading coefficient and dimensionless liquid film height are summarized.The velocity vectors and pressure distribution cloud images of different spreading types are obtained by Tecplot post-processing software.The variation rules of velocity field and pressure field with time in the process of droplet impacting on the wall are obtained.The relationship between droplet shape change and velocity vector and pressure distribution is analyzed.Based on the conservation of energy,the theoretical formula of the maximum spreading coefficient in a certain range of application is established.