Improving droplet breakup and vaporization models by including high pressure and turbulence effects

This article reviews recant experimental work conducted at the Laboratoire de Combustion et Systemes Reactifs (LCSR), Orleans, France, on single dropl et breakup and vaporization. Emphasis is essentially put on high pressure a nd turbulence effects. The experimental facilities developed and the diagno stics used are first presented. Droplet breakup studies are conducted with cryogenic and noncryogenic droplets subjected to aerodynamic shear forces u nder high-pressure conditions. The transition criteria between droplet brea kup regimes, characteristic breakup times, and secondary droplet distributi ons are obtained for uniquely low values of the density ratio between liqui d and gas phases and systematically varied vales of droplet Weber and Reyno lds numbers. Combined effects of high pressure and temperature oil droplet vaporization are also systematically explored. The variation patterns of av erage vaporization rates with reduced pressure and temperature are conclusi vely established and compared to estimates from the quasi-steady model. The influence of turbulence on droplet vaporization rates is explored in detai l. It is demonstrated that droplet vaporization rates increase significantl y with turbulent Reynolds number, even when the droplet size is smaller tha n the turbulence integral length scalp. Comprehensive correlations are esta blished to take into account these various effects. Suggestions are made fo r ways of including these correlations as submodels into spray combustion n umerical prediction codes and for future work to further improve them.