Experimental and theoretical investigation of the spreading behaviors of oil droplets on the surfaces with different wettabilities

Due to the oil field development enters the period of high water cut, the flow drag of oil-water two-phase flow in nonmetallic pipes requires further research. Moreover the dynamic spreading behavior of oil droplet on a pipe?s wall is of great significance to investigate the flow drag. However, the spreading behaviors of oil droplets on surfaces with different wettabilities in water system are still not clear. In this study, firstly, considering the effect of surface wettability and oil droplet diameter, the spreading behaviors of oil droplets on non-metallic and metallic substrates were observed using a high-speed imaging system. Then, according to the spreading behaviors of oil droplets on the substrates and based upon the energy balance theory, a theoretical model of the spreading behavior of oil droplets was developed for predicting the dimensionless maximum spreading diameter. The quantitative relationships among the dimensionless maximum spreading diameter, the diameter of oil droplets, the properties of oil and water, and the wettabilities of surfaces were obtained. Finally, the theoretical model was verified using experimental data with deviations generally ranging within ? 10%.