液液系统中荷电射流不稳定性

针对生物柴油液液静电雾化乳化过程,建立了色散方程并应用Matlab进行数值计算,分析了水射流速度、荷电电压、水与生物柴油各自的黏度、表面张力对生物柴油中水射流不稳定性的影响.研究结果表明,在水-生物柴油系统中,提高水射流的速度或荷电电压,均能使界面波最大增长率增大,对应的最优波数也随之增加.水的黏度阻碍水射流的破碎雾化,而生物柴油黏度对水射流的破碎雾化却起着促进作用.水-生物柴油的界面张力越小,对液液静电雾化乳化过程越有利.在水-生物柴油液液静电雾化乳化实际应用过程中,除提高水射流速度和荷电电压外,提高水的温度同时尽可能地降低生物柴油的温度,可以形成粒径细小均匀离散相液滴,获得优质的生物柴油乳化燃油.

Instability of charged jet in liquid-liquid system

For biodiesel emulsification process in the method of electrostatic atomization in liquid-liquid system,the dispersion equation of charged liquid jet was established. By numerical calculation with Matlab, the effect of jet velocity, charged voltage, viscosity and surface tension of water and biodiesel on the jet instability was obtained. The results show that the increasement of the velocity or the charge voltage of the water jet in water -biodiesel system can lead to the increase of the maximum growth rate of the interface wave and the corresponding optimal wave number. The viscosity of the water impedes the breakup and atomization of the water jet, while the viscosity of the biodiesel contributes to the breakup and ato-mization of the water jet. The smaller the interfacial tension of water-biodiesel, the more favorable it is to the process of electrostatic atomization in liquid-liquid system. Therefore, in the practical application of biodiesel emulsification in the method of liquid-liquid electrostatic atomization, in addition to increasing the jet velocity and the charged voltage, the temperature of water should be increased and the temperature of biodiesel should be reduced as much as possible to obtain fine grained uniform discrete droplets and to get high quality biodiesel emulsified fuel.