Explosive boiling-up in a swirl jet of superheated ethanol

•Explosive boiling-up is one of the conditions for the complete jet breakup of a superheated liquid.•The effect of a low-speed swirl of a hot ethanol jet on spraying is insignificant.•A high intensity swirl is a dominant factor in the dispersion of a boiling liquid and the jet shape evolution.•1/f fluctuations have been revealed in a precessing jet of boiling-up ethanol. Based on the knowledge of the kinetics of liquid vaporization under conditions of high and attainable superheats, experimental data on the atomization of a jet of boiling ethanol at various speeds of a flow swirl are discussed. It has been stated that under conditions of low superheats and boiling-up on solitary non-interacting heterogeneous sites, the rotation of the flow is considered to be the decisive factor in the atomization process. At high superheats and the realization of the mechanism of intense heterogeneous vaporization, the effect of boiling-up on the jet disintegration becomes dominant. When establishing conditions for explosive boiling-up (homogeneous nucleation) under attainable superheats, a complete jet breakup was observed both without a swirl and at low swirl speeds. With an increase in the swirl speed, the temperature range of the breakup narrowed. With a strong swirl the breakup disappeared completely. In the initial states of ethanol close to the thermodynamic critical point, the jet shape was similar to a gas one with or without a swirl. The 1/f fluctuations revealed were caused by oscillations (nutation) of the precessional motion of the jet. They indicate a possibility of large-scale outbursts in the jet.