Towards a unified treatment of fully flashing sprays

This paper presents a systematic study on flashing atomisation, which includes both standards and retrograde fluids. A novel data reduction method is proposed in terms of the controlling parameters for (bubble) nucleation. The analysis indicates that bubble nucleation is the rate-controlling process for both the transition to fully flashing and for the spray lateral spreading. Specifically, the onset condition coincides with the surmount of the energy barrier to nucleation. The spray lateral spreading, instead, is directly linked to the population of bubble clusters: the larger the population the wider the spray angle. Theoretical aspects of bubble nucleation theory are also reviewed. An interesting conclusion of the analysis is that the experimental trends observed in fully flashing jets are compliant with recent advances in nucleation theory. At very high initial superheat, a complex shock wave structure appears around the flashing jets. The novel aspect of this work is that such shock-systems are observed consistently in both standard and retrograde substances. This similarity indirectly confirms that, far from the critical temperature, the phase transition mechanism is the same for all substances, independently from their degree of retrogradicity. (C) 2013 Elsevier Ltd. All rights reserved.