Experimental Study on Size and Velocity of Charged Droplets

Abstract

A kind of twin-fluid sprayer with annular and needle combined electrode is developed and droplets are generated out of the chamber, where gas and liquid mixing together and finish the energy exchanging. Much important geometrical and physical information are obtained in this paper. Droplets diameter and velocity distribution in electrostatic spray flow field are measured by PDPA. The spray characteristics including droplets size and velocity under different electrostatic voltages are investigated systemically and analyzed. The experimental results demonstrate that the droplets diameter and velocity distribution are affected apparently by electrical field. The droplets would produce secondary atomization in spray plume due to maintaining droplets stable conditions which are called as Rayleigh and Taylor instability respectively. In addition, droplets movement is dominated by gas in twin-fluid spray, while the electrostatic force is crucial to the droplets movement in the case of that droplets diameter is very small. Droplets velocity in uncharged spray is as similar as in charged spray with different voltages. Meanwhile, droplets turbulent pulsating intensity is obtained by analyzing the data. Turbulent pulsating intensity is dominated by fluid force, and the electrostatic force could assuredly affect the movement characteristics for small size droplets.