交变电场作用下黏性射流的稳定性分析

Electrohydrodynamic instabilities of viscous jets under alternating electric fields

液体射流在静电或交变电场作用下的失稳和破裂问题在许多工业应用中都有涉及.与静电场作用下射流稳定性研究相比,交变电场下射流的稳定性分析研究要少得多.因此,本文采用电场力和黏性力共同修正压强的黏势流模型来描述交变电场作用下漏电介质液体射流的线性不稳定性,主要研究了交变电场、流体电学性质等参数的影响.交变电场作用下射流的毛细不稳定与静电场作用下射流不稳定特性是相似的.在足够强交变电场作用下,参数不稳定主导表面扰动的发展,从而进入共振电雾化模式.参数不稳定会被黏性耗散抑制,甚至随着频率的增加会完全消失.同时,导电电荷(主要取决于流体导电性)的作用与表面电荷是相反的,因此当电荷弛豫时间接近交变电场周期时,参数不稳定会受到强烈的抑制作用.此外,当气动作用足够强时,参数不稳定会被覆盖.

The instability and breakup of liquid jets under static or alternating electric fields are involved in numerous industrial applications.Unlike under electrostatic fields,far fewer investigations have been conducted to analyze the instability of liquid jets in alternating electric fields.Thus,the electric and viscous correction of viscous potential flow(EVCVPF)is applied here to describe the linear instability of leaky-dielectric liquid jets subjected to alternating electric fields.The effects of alternating electric fields,fluid electric properties,and other parameters are investigated.The capillary instability response is like that of the jets under electrostatic fields.Under a sufficiently strong alternating electric field,the resonance instability dominates surface disturbances,leading to the resonant atomization.Viscous damping makes the resonance weaker–even vanishing with the increasing frequency.Furthermore,the conductive charge–largely dependent on fluid conductivities–has the opposite effect of the surface charge.Thus,when the charge relaxation time approaches the imposed period,the parametric resonance is strongly inhibited.In addition,when aerodynamic effects are sufficiently strong,the resonance is covered.