多毛细管电雾化喷洒模式及稳定喷洒特征研究

通过采用传统的金属毛细管搭建了多喷管电雾化实验装置.初步获得了多管道电雾化喷洒的各种模式.并比较了乙醇在单、多管道条件下"锥-射流"模式喷洒的两个重要指标:稳定喷洒的起始电压和电流-流量关系.尽管结果显示由于加工/装配过程中的差异,各管道之间的喷洒状态会存在一定差异;但两种条件下的锥-射流喷洒模式服从相似规律:(1)稳定喷洒起始电压(V_C)与Taylor锥半锥角(θ)余弦的1/2次方成正比;(2)多管电雾化总电流(I)与流量(Q)的1/2次方成正比.它表明在常规尺度下,稳定电雾化喷洒射流的主要影响因素为锥-射流过渡区内液体界面上的极化电荷,而外界工作电场分布对稳定喷洒雾化效果影响较小.

EXPERIMENTAL STUDY ON ELECTROSPRAY MODES AND STEADY SPRAY CHARACTERISTICS WITH MULTIPLE METAL CAPILLARIES

Electrospray is an atomization process, in which the liquid is broken by electrical forces. It's applied widely in nano-material preparation, mass-spectrometer, et al. Coupled with MEMS fabrications, multi-emitter electrospray attracts great attention for its high output, integration and miniaturization. In this study, both single and multiple emitter electrospray apparatus are set up based on traditional metal capillaries to study the spray modes and steady spray characteristics. Two of the crucial behaviors are compared between the two setups, the onset voltage ($V_C$) of ``cone-jet' spray mode and the relationship between electrical current (I) and flow rate (Q). Though the capillary configuration influences the spray states on different needles, $V_C$ and $I$ for both setups are proportional to $ \sqrt{ \cos \theta }$ ($\theta$ is the cone degree) and $Q^{1/2}$, respectively. It implies that the resulted jet is affected mainly by rather the local electrical distribution around the cone-jet transition region, than the external global conditions. The further electrospray with micro-fabricated multi-emitter arrays can be supported by these results.