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为获得良好的生物柴油雾化效果,通过模型计算和实验测量研究了生物柴油雾滴在静电场中的破碎现象和机理。采用Rayleigh不稳定条件建立了生物柴油的静电破碎模型,获得了影响生物柴油静电破碎的主要因素以及不同影响因素下雾滴荷质比,并采用相位Doppler粒度分析仪(PDPA)和Faraday筒检测了生物柴油静电雾化的雾滴粒径分布与荷质比。研究表明:为了满足Rayleigh极限与Taylor极限,雾滴一方面在表面电荷(包括过剩电荷与非过剩极化电荷)的作用下克服雾滴表面张力实现Rayleigh破碎,另一方面在静电场诱导的极化力作用下产生变形,实现Taylor破碎。理论分析认为影响生物柴油雾滴破碎的关键因素包括荷电量、速度和温度,因此加热、提高射流速度以及雾滴荷质比是改善生物柴油雾化效果的有效措施。实验测量中发现生物柴油雾滴的典型荷质比约为10-9～10-8 C/g,远低于10-6 C/g的理论计算值。分析认为雾滴破碎中的静电能消耗、非过剩电荷引起的带电量增加、雾滴极化、流体力剪切破碎以及生物柴油物理特性等是造成理论分析与实验结果存在较大差距的主要原因。
In order to obtain a good biodiesel atomization effect, the phenomenon and mechanism of biodiesel droplet breakdown in an electrostatic field were studied through model calculations and experimental measurements. The electrostatic breakdown model of biodiesel was established by using Rayleigh instability conditions. The main factors influencing electrostatic breakdown of biodiesel and the droplet charge-mass ratio under different influence factors were obtained. Phase-Doppler particle size analyzer (PDPA) and Faraday tube Droplet particle size distribution and charge to mass ratio of biodiesel electrostatic atomization. The research shows that in order to satisfy the Rayleigh limit and the Taylor limit, the droplet achieves Rayleigh breakage against the surface tension of the droplet on the one hand under the effect of the surface charge (including excess charge and non-excess polarization charge) and on the other hand, Deformation under the action of force to achieve Taylor broken. Theoretical analysis shows that the key factors affecting the breakup of biodiesel droplets include charge, temperature and temperature, so heating, increasing jet velocity and droplet charge to mass ratio are effective measures to improve the atomization effect of biodiesel. The typical charge-to-mass ratio of biodiesel droplets was found to be about 10-9-10-8 C / g in experimental measurements, well below the theoretical value of 10-6 C / g. The main reason for the large gap between the theoretical analysis and the experimental results is the analysis of the static electricity consumption in the droplet breakage, the increase of the charge caused by the non-excess charge, the droplet polarization, the fluid shear force and the physical properties of biodiesel .