针-环与针-网电极液体EHD泵静态驱动力的实验研究

Experimental Study on the Static Thrust of Liquid EHD Pump with Single Needle-ring and Needle-mesh Electrodes

为验证离子拖拽效应与异电荷层传导效应在尖端电极EHD泵中能否共存,设计了单针-环与针-网EHD泵,该结构避免尖端电极金属底座对实验产生的影响,测量了无座单级单针-环与针-网EHD泵的静态驱动力,并以更加精确的模型分析了电极间电场方向、工作液体老化程度、电极间距等因素对针-环与针-网电极EHD泵驱动力的影响,并运用Ansoft Maxwell软件对电极间电场分布进行了仿真。结果表明,离子拖拽效应与异电荷层传导效应在尖端电极EHD泵中可以共存,但两种效应并不是线性叠加的,而是相互削弱的;针-环与针-网电极液体EHD泵存在阈值电压;减小电极间距与增加环电极宽度均可提高针-环与针-网EHD泵的驱动力,而工作液体相对介电常数对其影响不大;实验还证明,尖端电极EHD泵具有明显的极性效应。

In order to verify that if ion-drag effect and conduction effect of heterocharge layer can coexist in electrohy- drodynamic （EHD） pumps equipped with point electrodes, we designed two EHD pumps with baseless needle-ring and needle-net electrodes, respectively, to measure the static pressure of the EHD pumps.The effects of the direction of elec- tric field between two electrodes, the aging degree of working liquid, electrodes span etc on the static thrust of the EHD pumps are analyzed using an accurate model, and the electric field distribution is simulated using the Ansoft Maxwell. The results prove that the ion-drag effect and conduction effect of heterocharge layer can coexist in the EHD pumps in the presence of point electrodes, but they undermine each other rather than linearly superpose.There are threshold voltages in liquid EHD pump in the presence of single needle-ring/mesh electrodes.The static thrust can be boosted by shortening electrodes span and/or broadening the ring electrode, but it barely affected by the relative dielectric constant of working liquid. Moreover, the experiments obviously prove the polarity effect in the EHD pumps.