イオン液体静電噴霧における液滴形成過程および噴霧特性の数値シミュレーション

抄録

Ionic liquid is a molten salt composed of only anion and cation. The melting point of ionic liquid can be decreased to around room temperature by the combination of anion and cation. Because of the unique properties of ionic liquid such as high ionic conductivity, very low vapor pressure, electrochemical and thermal stability, solubility and absorbability, ionic liquid is applied to various energy and environmental technologies. In this study, the droplet formation process and spray characteristics in ionic liquid electrospray have been investigated by axisymmetric two dimensional multi-phase numerical simulation using surface tracking method. The formation of Taylor cone and droplet ejection resulting from electrostatic force acting on the interface with applied voltage was successfully demonstrated by numerical simulation. The spray mode transition with discontinuous decrease of droplet diameter occurs between 400 and 500 V in this operation conditions. After transition, the break-up location becomes almost independent of applied voltage and the droplet ejection frequency increases. It was found that the relationship between Bond number, Bo and Weber number, We with elongation velocity of liquid thread as representative velocity shows that spray is initiated at Bo ~ 0.7 and We ~ 50, and the spray mode transition occurs at around Bo~4 regardless of supply flow rate.