组合电极荷电雾化的实验研究

Experimental Study on Electrospray Characteristics With Combined Electrodes

为合理设计微小尺度液体燃料荷电喷雾燃烧器,开展了不同运行参数下喷雾特性的PDA(相位多普勒粒子分析仪)实验研究.实验段采用由喷嘴电极-环形电极-收集网格形成的组合电极结构,以乙醇为燃料,控制不同的喷嘴电压、环形电极电压、流量、收集网格位置等参数,测试了不同条件下的喷雾粒径、轴向速度、轴向脉动速度.在本文实验工况下发现:喷嘴电极电压的增加,粒径和速度减小.环形电极可显著减小喷雾粒径和速度。在环形电极感应荷电的作用下,粒径随着环形电极电压增加而增大。流量越小,粒径、速度越小,喷雾更稳定.增大收集网格到喷嘴出口距离,由于液滴蒸发的作用会使液滴粒径变小,在液滴粒径变小和黏滞力的双重作用下液滴轴向速度减小。

In order to rationally design a micro/small-scale electrospray combustor for liquid fuel,an experimental study on spraying characteristics under different operation parameters was carried out based on Phase Doppler Anemometer（PDA） testing. A test section with nozzle electrode-ring electrode-gathering grid was designed. Under different nozzle voltages, ring electrode voltages, flow rates of fuel, and positions of gathering grid, the experiments were performed using liquid ethanol as fuel. The droplet sizes, axial velocities and axial root mean square（RMS） velocities under different conditions all were measured by PDA. The results show droplet sizes and axial velocities decrease when increasing the nozzle electrode voltage. It is found that the ring electrode can reduce the droplet sizes and axial velocities obviously. Under the effect of induction charging from the ring electrode, droplet sizes decrease when the ring electrode increases. It is found that droplet sizes and axial velocities decrease and the spraying becomes more stable when decreasing the flow rates. If increasing the distance between nozzle outlet and gathering grid, droplet sizes decrease due to the effect of evaporation. And axial velocities also decrease as a result of both air viscous resistance and the decreasing of droplet size.