A comparative study of numerical models for Eulerian–Lagrangian simulations of turbulent evaporating sprays D.I. Kolaitis, M.A. Founti * Heterogeneous Mixtures and Combustion Systems, Thermal Engineering Department, School of Mechanical Engineering, National Technical University of Athens, Heroon Polytechniou 9, Polytechnioupoli Zografou, 15780 Athens, Greece Received 3 August 2004; received in revised form 8 November 2005; accepted 13 January 2006 Available online 9 March 2006 Abstract The paper comparatively assesses the computational performance of a selected number of theoretical and semi-empirical liquid drop- let evaporation models that focus on thermodynamic non-equilibrium effects, physical property estimation methods and convective and blowing effect corrections for the calculation of the heat and mass transfer rates. Three different test cases are examined in order to estab- lish the most appropriate model, in terms of both physical accuracy and numerical efficiency for implementation in two-phase CFD spray simulations. The considered cases span from a single, isolated droplet, evaporating in a convective environment, to a fully turbulent, evaporating, hollow cone spray; for the latter case, an in-house Eulerian–Lagrangian CFD code is used. Predictions are validated against experimental data for all test cases and the most promising model is established on the basis of accuracy and CPU time requirements. As a result, the ‘‘infinite conductivity’’ equilibrium droplet evaporation model, combined with an analytic expression for the convective and blowing effect correction can be proposed as most appropriate for CFD spray applications. Ó 2006 Elsevier Inc. All rights reserved. Keywords: Spray modelling; Droplet evaporation; Heat and mass transfer; Two-phase CFD 1. Introduction Liquid droplets, in a form of a spray, are employed in a wide spectrum of industrial applications. Oil fired furnaces and boilers, internal combustion engines and gas turbines utilize liquid fuel sprays in order to accelerate the rates of evaporation and combustion by increasing the free fuel sur- face area. The fuel is usually injected into the combustion chamber through an atomizing nozzle, resulting in the pro- duction of a spray comprising a large number of droplets, typically the order of 10–100 lm in diameter. Spray com- bustion involves a variety of complex phenomena, such as simultaneous momentum, mass and energy transfer as well as oxidative chemical reactions, which usually take place in a fully turbulent environment. Numerical simulation of droplet dynamics and heat and mass transfer processes in a turbulent, two-phase flow is a particularly challenging problem. Phenomena such as primary and secondary atomization, droplet evaporation, turbulent dispersion, droplet collisions and splashing must be modelled in order to accurately describe the two-phase flowfield. Momentum, mass and energy interchange bet- ween the gas and liquid phases are crucial for the accurate prediction of the interacting droplet evaporation phenom- ena that are addressed in a number of review papers (Law, 1982; Faeth, 1983; Aggarwal et al., 1984; Sirignano, 1993; Miller et al., 1998). Experimental investigations (Ranz and Marshall, 1952; Kulmala et al., 1995) and sin- gle-droplet computational fluid dynamics (CFD) simula- tions (Renksizbulut and Haywood, 1988; Abramzon and Sirignano, 1989; Haywood et al., 1989; Chiang et al., 1992) have yielded correlations that can be used for numer- ical modelling of turbulent sprays. 0142-727X/$ - see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.ijheatfluidflow.2006.01.002 * Corresponding author. Tel.: +30 210 7723605; fax: +30 210 7723527. E-mail address: mfou@central.ntua.gr (M.A. Founti). www.elsevier.com/locate/ijhff International Journal of Heat and Fluid Flow 27 (2006) 424–435