Phenomenology of AC-driven bio-alcohol electrosprays

  • Hamda Ahmed Alkaabi

Student thesis: Master's Thesis


A low-frequency alternating current electrospray ionization source has been investigated experimentally at flow rates ranging from 5 to 25 ml/hr, and applied root mean square (RMS) voltages ranging from 3 to 6 kV, and frequency ranging between 0.1 to 10 kHz. The AC electrospray source provided pulsing spray and hopping modes. The spray phenomenology consisted of five dominant modes, namely dripping, cone-jet, multi-jet, ramified-jet, and spindle dripping. Mode maps were generated that showed the prevailing mode for varying voltage, frequency, and flowrate. The morphology of the sprays that were manipulated by AC demonstrated cyclic variation. The cycle frequency was measured with the use of a high-speed camera. At 0.1 kHz frequency cone-jet mode cycle frequency not effected by flowrate, and transition from multi-jet to ramified-jet produced the highest cycle frequency. Measurements of the dispersion angle of the spray showed that the maximum angle occurred the cone-jet mode of low cycle frequency and high voltage. In general, the dispersion angle reduced with increasing frequency. The pertaining electrohydrodynamic equations were reviewed and characteristic timescales of the AC electrospray were calculated, which showed that the ionic injection time, space charge relaxation time, and ohmic charge relaxation time coupled with the applied AC frequency.
Date of AwardOct 2019
Original languageAmerican English
SupervisorDimitrios Kyritsis (Supervisor)


  • electrospray
  • fuel atomization
  • AC-driven
  • electrohydrodynamic (EHD)
  • bio-alcohol
  • electrospray modes
  • cycle frequency
  • and ESI.

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