progress variable approach is presented for the numerical simulation of a turbulent dilute ethanol/air spray flame.The standard spray flamelet formulation is revised in order to account for pre-vaporization effects and partially premixed regimes in the turbulent spray flame.For this purpose,a reaction progress variable is introduced.The full description of the dilute fuel spray flame is achieved with a Eulerian-Lagrangian formulation.The Monte-Carlo Lagrangian particle method is used to solve the joint PDF transport equation for the mixture fraction,reaction progress variable,and gas enthalpy,and a Eulerian finite-volume algorithm is employed to determine the turbulent time scales and the mean velocity field.The molecular mixing is described with the extended interactionby-exchange-with-the-mean(IEM)model,where additional terms account for spray evaporation.Following the discrete parcel method,the dynamics of the dilute ethanol spray is described in Lagrangian coordinates,which includes the Lagrangian equations for the droplet evaporation,heating,and motion.The computed results are compared with experimental data.Generally,good agreement is achieved for the gas temperature,droplet size as well as mean and fluctuating droplet velocities.Moreover,the local flame structure is analyzed in terms of the scatter data of the gas temperature versus the mixture fraction of the gas phase,and both regimes of non-premixed and premixed combustion are identified.