Micro-Gravity Study on Instability of Near-Critical Mixing Surface Jet (Mechanisms of Rayleigh-Taylor Instability Excitation at Nozzle Exit and Short Spacing Disintegration)

Abstract

Atomization of a round liquid jet is initiated by the excitation of Taylor instability immediately downstream of the nozzle exit. A self-sustaining mechanism of this process is theoretically explored on the basis of observation of the instability behaviors of a SF₆ liquid issued into an otherwise stationary nitrogen gas at pressures exceed the critical pressure of SF₆, which has the thermodynamic surface state close to the critical mixing condition. In micro-gravity condition, the vanishing surface tension allows us to use a liquid jet which is issued from a nozzle in laminar flow form at a low speed in order to realize an equivalent condition to a high speed jet at low pressures. The mechanism for the disintegration of the liquid jet at short wavelength, which is characteristic to the near-critical mixing surface jet, is also proposed on the basis of the experimental observation and theoretical consideration.