NUMERICAL INVESTIGATIONS OF THE JET BREAKUP REGIME OF ELECTROSPRAY IONIZATION USING A CARBON FIBER EMITTER

摘要

This paper presents numerical investigations of jet breakup in electrospray ionization using a carbon fiber emitter. The emitter has a pointed carbon fiber located coaxial with a fused silica capillary of 360μm OD and 75μm ID, with its tip extending 30 micron beyond the capillary exit. The model employs leaky-dielectric formulations to solve electrodynamics and volume-of-fluid technique for tracking the interface. The existing leaky-dielectric model is modified to consider presence of free charges both in the bulk of the liquid as well as on the interface. A velocity perturbation is used at the capillary inlet to emulate the naturally occurring disturbance necessary for the jet breakup. The model is first validated by comparing the model predictions with experimental results for a conventional emitter. Then, it is used to simulate electrospray performance of the carbon fiber emitter, including the Taylor cone and jet breakup processes. The influence of emitter geometry and operating conditions are thoroughly investigated. The droplet diameter and velocity are correlated with flow rate and the correlation results are compared with that reported in literature.