剪切流场中W/O乳状液分散相液滴破裂的临界条件

探讨剪切流场中牛顿型W/O乳状液的分散相液滴破裂机理及临界破裂条件,总结了Taylor小变形理论、De Bruijn理论和临界乳化理论3种确定临界破裂半径的方法,并尝试用其预测旋流场的液滴破碎情况,为油水分离设备内流场合理的剪切分布提供理论依据.采用Couette双圆筒装置形成薄层剪切流场,研究白油包水型和硅油包水型乳状液滴的破裂形态和临界破裂半径.实验结果表明:不同粘性比的实验介质,其分散相液滴的破裂形态和临界破裂理论的适用性不同,在实际应用时应根据流场特点和乳状液的物性特点具体分析.依据某型旋流器的流场数值模拟结果,剪切流场中的临界破裂理论可用于初步预测旋流场中给定粒径分布的乳状液能否被有效分离,但还需进一步的现场测试和分析,引入与流场的湍动强度相关的修正系数.

Critical breakage condition for dispersed droplets of W/O emulsion in shear flow

The breakage principle and critical condition for dispersed droplets of Newtonian W/O emulsion was discussed.And three theory methods of small deformation of Taylor,De Bruijn theory and critical emulsification theory were summarized to determine the critical breakage radius which was used to forecast the droplets breakage in hydrocyclone to apply the theory gist to the reasonable shear distribution in the oil-water separation device.The lamina shear flow was formed by Couette double-cylinder device to study the breakage configuration and the critical breakage condition of water-in-white oil and water-in-silicone oil emulsion.It was shown that the breakage mode and the applicability of the critical breakage theory are different to the medium with different viscosity ratio,which should be considered by the practical flow and emulsion properties.Based on the numerical simulation result of certain hydrocyclone,the critical breakage theory in shear flow can be used to primarily forecast whether the emulsion with give size distribution can be effectively separated in hydrocyclone,but it should be corrected with a factor of turbulence intensity according to a further locale test and analysis.