Transported PDF Modeling of Ethanol Spray in Hot-Diluted Coflow Flame
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This paper presents a numerical modeling study of one ethanol spray flame from the Delft Spray-in-Hot-Coflow (DSHC) database, which has been used to study Moderate or Intense Low-oxygen Dilution (MILD) combustion of liquid fuels (Correia Rodrigues et al. Combust. Flame 162(3), 759–773, 2015). A “Lagrangian-Lagrangian” approach is adopted where both the joint velocity-scalar Probability Density Function (PDF) for the continuous phase and the joint PDF of droplet properties are modeled and solved. The evolution of the gas phase composition is described by a Flamelet Generated Manifold (FGM) and the interaction by exchange with the mean (IEM) micro-mixing model. Effects of finite conductivity on droplet heating and evaporation are accounted for. The inlet boundary conditions starting in the dilute spray region are obtained from the available experimental data together with the results of a calculation of the spray including the dense region using ANSYS Fluent 15. A method is developed to determine a good estimation for the initial droplet temperature. The inclusion of the “1/3” rule for droplet evaporation and dispersion models is shown to be very important. The current modeling approach is capable of accurately predicting main properties, including mean velocity, droplet mean diameter and number density. The gas temperature is under-predicted in the region where the enthalpy loss due to droplet evaporation is important. The flame structure analysis reveals the existence of two heat release regions, respectively having the characteristics of a premixed and a diffusion flame. The experimental and modeled temperature PDFs are compared, highlighting the capabilities and limitations of the proposed model.
KeywordsSpray FGM Transported PDF MILD combustion Evaporation
- 4.Beishuizen, N.A.: PDF modelling and particle-turbulence interaction of turbulent spray flames. Ph.D. thesis, Delft University of Technology (2008)Google Scholar
- 7.CHEM1D: A one-dimensional laminar flame code, Eindhoven University of Technology. URL < http://www.combustion.tue.nl/chem1d/ >
- 13.de Meester, R.: Analysis of scalar mixing in hybrid RANS-PDF calculations of turbulent gas and spray Flames. Ph.D. thesis, University Gent (2012)Google Scholar
- 25.Hollmann, C., Gutheil, E.: Modeling of turbulent spray flames including detailed chemistry. In: 26th Symposium (International) on Combustion, pp. 1731–1738 (1996)Google Scholar
- 32.Ma, L., Zhu, S., Tummers, M.J., van der Meer, T.H., Roekaerts, D.: Numerical investigation of ethanol spray-in-hot-coflow flame using steady flamelet model. In: Eighth Mediterranean Combustion Symposium (2013)Google Scholar
- 36.Naud, B.: PDF modeling of turbulent sprays and flames using a particle stochastic approach. Ph.D. thesis, Delft University of Technology (2003)Google Scholar
- 37.Naud, B.: Particle dispersion modelling based on the Generalised Langevin Model for the seen velocity. Turbul. Heat Mass Transf. 7, 1 (2012)Google Scholar
- 40.Naud, B., Novella, R., Pastor, J.M., Winklinger, J.F.: RANS modelling of a lifted H2/N2 flame using an unsteady flamelet progress variable approach with presumed PDF. Combust. Flame, in press. doi: 10.1016/j.combustflame.2014.09.014(2015)
- 41.van Oijen, J.A.: Flamelet-generated manifolds: development and application to premixed laminar flames. Ph.D. thesis, Eindhoven University of Technology (2002)Google Scholar
- 51.Sirignano, W.A.: Advances in droplet array combustion theory and modeling. Prog. Energy Combust. Sci., 1–33 (2014)Google Scholar
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