Analysis of local extinction of a n-heptane spray flame using large-eddy simulation with tabulated chemistry

• DOI: 10.1016/j.combustflame.2021.111730
• Publication Date: 2021-09-18T12:12:54Z
• Authors: J. Benajes; J.M. García-Oliver; J.M. Pastor; I. Olmeda; A. Both; D. Mira
• Keywords: Large eddy simulation; Extinction; Flamelet generated manifolds; 7. Clean energy; 01 natural sciences; Àrees temàtiques de la UPC::Informàtica::Aplicacions de la informàtica::Aplicacions informàtiques a la física i l‘enginyeria; :Informàtica::Aplicacions de la informàtica::Aplicacions informàtiques a la física i l‘enginyeria [Àrees temàtiques de la UPC]; Spray combustion; 13. Climate action; Propulsion systems; MAQUINAS Y MOTORES TERMICOS; 0103 physical sciences; Combustion--Mathematical models; Simulacio per ordinador

This work is focused on the study of flame stabilization and local extinction of a spray flame in an atmospheric non-swirled test rig referred to as the CORIA Rouen Spray Burner. This burner shows a double reaction front structure, with an outer laminar diffusion flame and an inner wrinkled partially-premixed flame undertaking local extinction. This unsteady phenomenon is investigated here using large-eddy simulations with a tabulated chemistry method based on steady and unsteady diffusion flamelets with heat loss. A validation of the numerical simulations is conducted first for the carrier and dispersed phase and good agreement with the experimental data is found for mean and fluctuating quantities. The present results were able to predict relevant parameters of the flame like the lift-off length and flame shape. Numerical results evidence some intermittency on the OH concentration with the presence of high values of formaldehyde indicating the existence of localized extinction in the leading edge of the flame. A detailed analysis showed the impact of droplets on the reacting layer and the existence of rich pockets quenching the flame front. Further downstream, it was shown that when the scalar dissipation rate reaches high values near the reaction zone, the flame front becomes thinner and wrinkled until it eventually quenches. The numerical results evidence that the applied tabulated chemistry method is capable of capturing the local extinction and re-ignition events occurring in the inner layer. This work was partially funded by the Spanish Ministerio de Econom´ıa y Competitividad within the frame of the CHEST (TRA2017-89139-C2-1-R) project. BSC also acknowledges the funding from the CoEC project through the European Union’s Horizon 2020 research and innovation programme under grant agreement No 952181. Authors acknowledge the computer resources at Marenostrum and the technical support provided by Barcelona Supercomputing Center (BSC) (IM-2019-3-0025, IM-2020-1-0017, IM-2020-2-0026). Authors also thank the access to the CRSB database kindly provided by Prof. B. Renou. Peer Reviewed