基于双电极荷电雾化的乙醇锥-射流特性

为合理设计微型荷电喷雾燃烧器,开展液体乙醇雾化试验研究。基于毛细管电极-环形电极-网格双电极燃烧器,得到稳定的锥-射流雾化工作模式。采用光学可视化方法获得雾化形态,测量锥角及电压,并与单毛细管电极的雾化结果进行了对比,讨论环形电极对锥-射流雾化模式的影响。理论分析荷电雾化锥-射流模式产生的液锥面受力情况,在液锥垂直面上基于受力平衡建立力学模型,并根据双曲线模型,求解液锥的半锥角。研究表明:在电压达到一定值时,流体会形成具有固定锥角的锥-射流,该临界锥角远小于Taylor半锥角49.3°,更加接近理论计算值34.72°。在相同雾化模式下,双电极形成的锥-射流锥角小于单电极形成的锥角。采用双电极雾化装置,选择合适电压的环形电极,可以显著降低毛细管电压,促进稳定的锥-射流雾化的形成。

Cone-jet Characteristics of Ethanol by Electrospraying Using Double Electrodes

In order to design a micro-scale electrospraying combustor reasonably, some experiments of electrospraying are carried out using liquid ethanol as fuel. A stable cone-jet mode is obtained based on the new combustor mainly consisting of a capillary, a ring electrode and a stainless steel grid. The electrospraying mode is visualized, cone angle and voltage are measured. The comparison is performed between with those of single capillary electrode combustor. The effect of ring electrode on cone-jet mode is discussed. The stress distribution on the cone surface is analyzed in the electrospraying cone-jet mode. Based on the force equilibrium on the vertical surface of cone, the mechanical model is established. According to hyperboloidal model, the semi-cone angle is calculated theoretically. The results show that the fluid acquires a stable shape when the voltage reached a certain value, the critical semi-cone angle is far less than the Taylor angle of 49.3o, closer to the theoretically calculated value of 34.72o. Under the same spraying mode, the cone formed using double electrodes combustor is less than that formed using single electrode combustor. The capillary electrode voltage can be significantly reduced when adopting the double electrodes combustor and choosing an appropriate ring electrode voltage, which can enhance the formation of stable cone-jet.