Linear Instability Analysis of Charged Jet in Liquid-liquid Systems

By discussing the perturbed pressure field and the perturbed electric field, the viscous dispersion equation of charged jet in water-biodiesel system was derived. Through numerical calculation, the temporal instability characteristics and the effects of parameters were discussed. The results show the effect of jet velocity and charged voltage of charged jet in liquid-liquid system on instability is same as that in liquid-gas system. with the increasing of jet velocity or charged voltage, the maximum of wave growth rate, the corresponding optimal wave number and the maximum of wave number turn bigger, and water droplet size gets smaller. Biodiesel viscosity promotes the jet breakup obviously, while water viscosity always hinders the jet breakup. The maximum growth rate and optimum wave number increase obviously with decreasing the water surface tension, while the biodiesel surface tension has the reverse effect on the maximum growth rate and optimum wave number. By comparison, the effect of water viscosity and biodiesel surface tension on instability is much less than that of biodiesel viscosity and water surface tension. Therefore, increasing jet velocity, charged voltage and biodiesel viscosity or decreasing water surface tension are good methods to obtain small water droplet in biodiesel.