Context

Crucial issues when designing a gas turbine combustor for liquid fuel are the understanding of flame ignition and extinction and the prediction of pollutant formation. An accurate modeling of these phenomena requires taking into account turbulence, heat transfers, spray evaporation and detailed chemistry effects.

Combustion chemistry is highly complex and despite the rapid advance in computational power, it remains unfeasible to make turbulent simulations of industrial configurations including detail chemistry. In order to reduce the computational cost, various strategies have been proposed to tabulate chemistry from elementary flame configurations (FPI, diffusion flamelets models, etc… ).

Tabulated chemistry techniques have been widely studied at the EM2C laboratory [1-2]. Such techniques have been developed for laminar and turbulent (in both RANS [3] and LES [4] context) gaseous flame simulations. To our knowledge, applications of these modeling strategies have never been done for multi-phase combustion.

Objectives

The main objective of this work is to introduce detailed chemistry effects in spray combustion at a reduced CPU cost. Key parameters that describe chemical subspaces accessed in multi-phase reacting flows will be identified in order to generate a low dimensional chemical database. A tabulated chemistry model will be developed and coupled to a LES turbulent spray combustion model.

The PhD student will first investigate the chemical structure of spray laminar flames. He will implement a polydisperse spray model [5] in a 1D detailed dimensional counterflow flame complex chemistry code developed by the EM2C laboratory. A parametric study will be conducted in order to understand the chemistry of multi-phase combustion. In particular, the effect of the polydisperse character of the spray on the chemical flame structure will be investigated. The objectives are to identify a reduced chemical subspace in order to propose a tabulated chemistry technique dedicated to mutli-phase combustion.

Finally the PhD student will focus on modeling the interactions between combustion and turbulence in a two phase flow context. A turbulent combustion model will be developed and implemented into the flow solver AVBP, developed at CERFACS. Large Eddy Simulations of a turbulent spray flame will be conducted to validate the proposed methodology.

[1]      Gicquel O, Darabiha N and Thevenin D 2000 Proc. Combust. Inst. 28 1901–8

[2]      B. Fiorina, R. Baron, O. Gicquel, D. Thevenin, S. Carpentier,  N. Darabiha. Modelling non-adiabatic partially premixed flames using flame prolongation of ILDM. Comb. Theory and Modelling. 7 (2003) 449-470.

[3]     B. Fiorina, O. Gicquel, L. Vervisch, S. Carpentier, N. Darabiha. Premixed turbulent combustion modeling using tabulated chemistry and PDF. Proc. Combust. Inst. Vol 30(1) pp 867-874 (2005)

[4]     R. Vicquelin, B. Fiorina, N. Darabiha, V. Moureau, L. Vervisch and D. Veynante. Coupling Tabulated Chemistry with Large Eddy Simulation of Turbulent Reactive Flows. Proceeding of the Summer Program, 2008. Center for Turbulence Research, Stanford University.

[5]     M. Massot, M. Kumar, M.D. Smooke and A. Gomez. Proc. Combust. Inst. 27 1975–1983

Location:

Laboratoire EM2C

CNRS et Ecole Centrale Paris

92295 Châtenay-Malabry

France

www.em2c.ecp.fr

Châtenay-Malabry is located in the south suburb of Paris (about 10 km from Paris center).


PhD advisors:

Benoît FIORINA (Assistant professor at Ecole Centrale Paris)

Nasser DARABIHA (Professor at Ecole Centrale Paris)

To apply: Send your application and a vitae to Benoît Fiorina at: benoit.fiorina@em2c.ecp.fr