Drop formation from a vibrating orifice generator driven by modulated electrical signals

Abstract

The recently introduced technique of amplitude-modulated (AM) excitation of laminar liquid jets to produce drops by controlled Rayleigh-type jet disintegration is extended to frequency modulation (FM) and investigated in detail to quantify the available ranges of excitation wavenumbers and modulation depths for various jet velocities and liquids. The AM and FM techniques are compared regarding the achievable ratios of carrier and modulation frequencies. The modulated excitation is applied to a vibrating orifice drop generator (TSI Inc.). Four different drop formation processes are observed for different wavenumber domains. Experiments with three different Newtonian liquids and a dimensional analysis yield a generalized representation of the parameter windows of the technique in terms of excitation wavenumber and jet velocity for a wide range of liquid viscosity and surface tension.