REVIEW ARTICLE Interaction of a polydisperse spray with vortices C. Lacour • D. Durox • S. Ducruix • M. Massot Received: 23 April 2010 / Revised: 19 December 2010 / Accepted: 28 January 2011 / Published online: 17 February 2011 Ó Springer-Verlag 2011 Abstract The objective of the present work is to provide, through the association of optical diagnostics on a well- chosen experimental configuration, new insights into the coupling of a vortical gaseous flow with a polydisperse evaporating spray representative of practical injections. A cloud of droplets is injected in an inert laminar round jet, axisymmetric and pulsated, enabling the study of the interaction of strong-vorticity structures with a polydis- perse spray. The experiment is a laboratory-scale repre- sentation of realistic injection configurations such as in engine combustion chambers or industrial burners. The chosen set-up leads to a well-controlled configuration and allows the coupling of two optical diagnostics, particle imaging velocimetry (PIV) and interferometric particle imaging (IPI), which leads to the study of both the flow dynamic and the droplet size distribution. The behaviour of droplets is analysed regarding their relaxing and evapo- rating properties. Size-conditioned preferential concentra- tion of both weakly evaporating and strongly evaporating sprays is investigated. Droplet trajectories are also analysed by means of high-rate tomographic visualizations. The time history between their ejection from the nozzle and their interaction with the vortex is strongly related to the droplet preferential concentration and the observed heterogeneous repartition in the gas flow. 1 Introduction Sprays are present in numerous applications such as industrial or military combustion chambers, in internal combustion, gas turbine, liquid-fuelled rocket engines, as well as liquid-fuelled industrial burners. Generally, gaseous flows are turbulent, inducing vortical structures of various sizes, from the smallest dissipative scales to sizes compa- rable to the combustion chamber dimensions. These large vortices are, for example, encountered in car engines where swirl and tumble sizes are imposed by the geometry of the cylinder and the piston. The phenomena involved in two- phase flows are particularly complex, and multiple pro- cesses are implied: (1) the turbulence of the flow, (2) the polydispersity of sprays, (3) the droplet evaporation, gen- erating mixture heterogeneity, (4) the possibility of droplet coalescence (5) and finally, the presence of reactive fronts in the case of combustion applications. Recent studies intend to improve spray combustion and related phenom- ena understanding by focusing on the simulation of evap- orating sprays in turbulent flows and on the droplet ejection from vortical structures (Laurent and Massot 2001; Re ´ve- illon and Vervisch 2005; Massot 2007; Massot et al. 2007; Kah et al. 2010; Fre ´ret et al. 2010; Vie ´ et al. 2010). The validation of these recently developed models requires a rigorous comparison with experimental works reproducing the interactions between evaporating sprays and vortical structures at a laboratory scale. However, there are only few experimental studies dealing with these phenomena. Experimental works are essentially focused on the dynamics of non-evaporating sprays or on the dynamics of particles laden in turbulent or pulsated gas flows. Crowe et al. (1985) showed that the particles preferential disper- sion is due to organized gas structures. The works of Chein and Chung (1987) and Lazaro and Lasheras (1989) allowed C. Lacour  D. Durox (&)  S. Ducruix  M. Massot Laboratoire EM2C. CNRS et E ´ cole Centrale Paris, Grande Voie des Vignes, 92295 Cha ˆtenay-Malabry, France e-mail: daniel.durox@em2c.ecp.fr Present Address: C. Lacour CORIA CNRS UMR6614 Site Universitaire du Madrillet, 76801, St Etienne du Rouvray Cedex, France 123 Exp Fluids (2011) 51:295–311 DOI 10.1007/s00348-011-1050-1