Skip to main content Accessibility help

Two-stage autoignition and edge flames in a high pressure turbulent jet

  • Alex Krisman (a1) (a2), Evatt R. Hawkes (a1) (a3) and Jacqueline H. Chen (a2)


A three-dimensional direct numerical simulation is conducted for a temporally evolving planar jet of n-heptane at a pressure of 40 atmospheres and in a coflow of air at 1100 K. At these conditions, n-heptane exhibits a two-stage ignition due to low- and high-temperature chemistry, which is reproduced by the global chemical model used in this study. The results show that ignition occurs in several overlapping stages and multiple modes of combustion are present. Low-temperature chemistry precedes the formation of multiple spatially localised high-temperature chemistry autoignition events, referred to as ‘kernels’. These kernels form within the shear layer and core of the jet at compositions with short homogeneous ignition delay times and in locations experiencing low scalar dissipation rates. An analysis of the kernel histories shows that the ignition delay time is correlated with the mixing rate history and that the ignition kernels tend to form in vortically dominated regions of the domain, as corroborated by an analysis of the topology of the velocity gradient tensor. Once ignited, the kernels grow rapidly and establish edge flames where they envelop the stoichiometric isosurface. A combination of kernel formation (autoignition) and the growth of existing burning surface (via edge-flame propagation) contributes to the overall ignition process. An analysis of propagation speeds evaluated on the burning surface suggests that although the edge-flame speed is promoted by the autoignitive conditions due to an increase in the local laminar flame speed, edge-flame propagation of existing burning surfaces (triggered initially by isolated autoignition kernels) is the dominant ignition mode in the present configuration.


Corresponding author

Email address for correspondence:


Hide All
Al-Noman, S. M., Choi, S. K. & Chung, S. H. 2015 Autoignition characteristics of laminar lifted jet flames of pre-vaporized iso-octane in heated coflow air. Fuel 162, 171178.
Arndt, C. M., Papageorge, M. J., Fuest, F., Sutton, J. A., Meier, W. & Aigner, M. 2016 The role of temperature, mixture fraction, and scalar dissipation rate on transient methane injection and auto-ignition in a jet in hot coflow burner. Combust. Flame 167, 6071.
Borghesi, G., Mastorakos, E. & Cant, R. S. 2013 Complex chemistry DNS of n-heptane spray autoignition at high pressure and intermediate temperature conditions. Combust. Flame 160 (7), 12541275.
Buckmaster, J. 2002 Edge-flames. Prog. Energy Combust. Sci. 28 (5), 435475.
Cao, S. & Echekki, T. 2007 Autoignition in nonhomogeneous mixtures: conditional statistics and implications for modeling. Combust. Flame 151, 120141.
Chakraborty, N. & Mastorakos, E. 2008 Direct numerical simulations of localised forced ignition in turbulent mixing layers: the effects of mixture fraction and its gradient. Flow Turbul. Combust. 80 (2), 155186.
Chatakonda, O., Hawkes, E. R., Aspden, A. J., Kerstein, A. R., Kolla, H. & Chen, J. H. 2013 On the fractal characteristics of low Damköhler number flames. Combust. Flame 160 (11), 24222433.
Chen, J. H., Choudhary, A., de Supinski, B., DeVries, M., Hawkes, E. R., Klasky, S., Liao, W. K., Ma, K. L., Mellor-Crummey, J., Podhorszki, N. et al. 2009 Terascale direct numerical simulations of turbulent combustion using S3D. Comput. Sci. Disc. 2 (1), 015001.
Choi, S. K. & Chung, S. H. 2013 Autoignited and non-autoignited lifted flames of pre-vaporized n-heptane in coflow jets at elevated temperatures. Combust. Flame 160 (9), 17171724.
Chong, M. S., Perry, A. E. & Cantwell, B. J. 1990 A general classification of three dimensional flow fields. Phys. Fluids A 2 (5), 765777.
Cifuentes, L., Dopazo, C., M., J. & Jimenez, C. 2014 Local flow topologies and scalar structures in a turbulent premixed flame. Phys. Fluids 26 (6), 065108.
Dahms, R. N., Paczko, G. A., Skeen, S. A. & Pickett, L. M. 2017 Understanding the ignition mechanism of high-pressure spray flames. Proc. Combust. Inst. 36 (2), 26152623.
Dec, J. E.1997 A conceptual model of DI diesel combustion based on laser-sheet imaging. SAE Paper 1997-97-0873.
Deng, S., Zhao, P., Mueller, M. E. & Law, C. K. 2015a Autoignition-affected stabilization of laminar nonpremixed DME/air coflow flames. Combust. Flame 162 (9), 34373445.
Deng, S., Zhao, P., Mueller, M. E. & Law, C. K. 2015b Stabilization of laminar nonpremixed DME/air coflow flames at elevated temperatures and pressures. Combust. Flame 162 (12), 44714478.
Domingo, P. & Vervisch, L. 1996 Triple flames and partially premixed combustion in autoignition of non-premixed turbulent mixtures. Proc. Combust. Inst. 26 (1), 233240.
Echekki, T. & Chen, J. H. 1998 Structure and propagation of methanol-air triple flames. Combust. Flame 114, 231245.
Echekki, T. & Chen, J. H. 2002 High-temperature combustion in autoigniting non-homogeneous hydrogen/air mixtures. Proc. Combust. Inst. 29 (2), 20612068.
Fieweger, K., Blumenthal, R. & Adomeit, G. 1997 Self-ignition of s.i. engine model fuels: a shock tube investigation at high pressure. Combust. Flame 109 (4), 599619.
Fleck, J. M., Griebel, P., Steinberg, A. M., Arndt, C. M. & Aigner, M. 2013a Auto-ignition and flame stabilization of hydrogen/natural gas/nitrogen jets in a vitiated cross-flow at elevated pressure. Int. J. Hydr. Energ. 38 (36), 1644116452.
Fleck, J. M., Griebel, P., Steinberg, A. M., Arndt, C. M., Naumann, C. & Aigner, M. 2013b Autoignition of hydrogen/nitrogen jets in vitiated air crossflows at different pressures. Proc. Combust. Inst. 34 (2), 31853192.
Fu, X. & Aggarwal, S. K. 2015 Two-stage ignition and NTC phenomenon in diesel engines. Fuel 144, 188196.
Gong, C., Jangi, M. & Bai, X. S. 2014 Large eddy simulation of n-dodecane spray combustion in a high pressure combustion vessel. App. Energ 136, 373381.
Grout, R. W., Gruber, A., Yoo, C. S. & Chen, J. H. 2011 Direct numerical simulation of flame stabilization downstream of a transverse fuel jet in cross-flow. Proc. Combust. Inst. 33 (1), 16291637.
Hawkes, E. R., Sankaran, R. & Chen, J. H. 2008 Extinction and reignition in direct numerical simulations of CO/H2 temporal plane jet flames. In Proceedings of the Australian Combustion Symposium, Newcastle, Australia, 2008, pp. 12711274. Combustion Institute, Australia and New Zealand Section.
Hawkes, E. R., Sankaran, R., Sutherland, J. C. & Chen, J. H. 2007 Scalar mixing in direct numerical simulations of temporally evolving plane jet flames with skeletal CO/H2 kinetics. Proc. Combust. Inst. 31 (1), 16331640.
Hinze, J. O. 1975 Turbulence. McGraw-Hill.
Idicheria, C. A. & Pickett, L. M.2006 Formaldehyde visualization near lift-off location in a diesel jet. SAE Paper 2006-01-3434.
Im, H. G. & Chen, J. H. 1999 Structure and propagation of triple flames in partially premixed hydrogen-air mixtures. Combust. Flame 119 (4), 436454.
Im, H. G., Chen, J. H. & Law, C. K. 1998 Ignition of hydrogen-air mixing layer in turbulent flows. Symp. (Int.) Combust. 27 (1), 10471056.
Karami, S., Hawkes, E. R., Talei, M. & Chen, J. H. 2015 Mechanisms of flame stabilisation at low lifted height in a turbulent lifted slot-jet flame. J. Fluid Mech. 777, 633689.
Karami, S., Hawkes, E. R., Talei, M. & Chen, J. H. 2016 Edge flame structure in a turbulent lifted flame: a direct numerical simulation study. Combust. Flame 169, 110128.
Karami, S., Talei, M., Hawkes, E. R. & Chen, J. H. 2017 Local extinction and reignition mechanism in a turbulent lifted flame: a direct numerical simulation study. Proc. Combust. Inst. 36 (2), 16851692.
Kennedy, C. A. & Carpenter, M. H. 1994 Several new numerical methods for compressible shear-layer simulations. Appl. Numer. Maths 14 (4), 397433.
Kerkemeier, S. G., Markides, C. N., Frouzakis, C. E. & Boulouchos, K. 2013 Direct numerical simulation of the autoignition of a hydrogen plume in a turbulent coflow of hot air. J. Fluid Mech. 720, 424456.
Krisman, A., Hawkes, E. R., Talei, M., Bhagatwala, A. & Chen, J. H. 2015 Polybrachial structures in dimethyl ether edge-flames at negative temperature coefficient conditions. Proc. Combust. Inst. 35 (1), 9991006.
Krisman, A., Hawkes, E. R., Talei, M., Bhagatwala, A. & Chen, J. H. 2016 Characterisation of two-stage ignition in diesel engine-relevant thermochemical conditions using direct numerical simulation. Combust. Flame 172, 326341.
Krisman, A., Hawkes, E. R., Talei, M., Bhagatwala, A. & Chen, J. H. 2017 A direct numerical simulation of cool-flame affected autoignition in diesel engine-relevant conditions. Proc. Combust. Inst. 36 (3), 35673575.
Lignell, D. O., Chen, J. H. & Smith, P. J. 2008 Three-dimensional direct numerical simulation of soot formation and transport in a temporally evolving nonpremixed ethylene jet flame. Combust. Flame 155 (12), 316333.
Liu, S., Hewson, J. C., Chen, J. H. & Pitsch, H. 2004 Effects of strain rate on high-pressure nonpremixed n-heptane autoignition in counterflow. Combust. Flame 137 (3), 320339.
Lu, T. F., Yoo, C. S., Chen, J. H. & Law, C. K. 2010 Three-dimensional direct numerical simulation of a turbulent lifted hydrogen jet flame in heated coflow: a chemical explosive mode analysis. J. Fluid Mech. 652, 4564.
Lyra, S., Wilde, B., Kolla, H., Seitzman, J. M., Lieuwen, T. C. & Chen, J. H. 2015 Structure of hydrogen-rich transverse jets in a vitiated turbulent flow. Combust. Flame 162 (4), 12341248.
Maes, N., Meijer, M., Dam, N., Somers, B., Toda, H. B., Bruneaux, G., Skeen, S. A., Pickett, L. M. & Manin, J. 2016 Characterization of spray a flame structure for parametric variations in ecn constant-volume vessels using chemiluminescence and laser-induced fluorescence. Combust. Flame 174, 138151.
Markides, C. N., De Paola, G. & Mastorakos, E. 2007 Measurements and simulations of mixing and autoignition of an n-heptane plume in a turbulent flow of heated air. Exp. Therm. Fluid Sci. 31 (5), 393401.
Markides, C. N. & Mastorakos, E. 2005 An experimental study of hydrogen autoignition in a turbulent co-flow of heated air. Proc. Combust. Inst. 30 (1), 883891.
Markides, C. N. & Mastorakos, E. 2011 Experimental investigation of the effects of turbulence and mixing on autoignition chemistry. Flow Turbul. Combust. 86 (3–4), 585608.
Mastorakos, E. 2009 Ignition of turbulent non-premixed flames. Prog. Energy Combust. Sci. 35 (1), 5797.
Mastorakos, E., Baritaud, T. A. & Poinsot, T. J. 1997 Numerical simulations of autoignition in turbulent mixing flows. Combust. Flame 109, 198223.
Micka, D. J. & Driscoll, J. F. 2012 Stratified jet flames in a heated (1390 k) air cross-flow with autoignition. Combust. Flame 159 (3), 12051214.
Minamoto, Y. & Chen, J. H. 2016 DNS of a turbulent lifted DME jet flame. Combust. Flame 169, 3850.
Mukhopadhyay, S. & Abraham, J. 2012a Influence of heat release and turbulence on scalar dissipation rate in autoigniting n-heptane/air mixtures. Combust. Flame 159 (9), 28832895.
Mukhopadhyay, S. & Abraham, J. 2012b Influence of turbulence on autoignition in stratified mixtures under compression ignition engine conditions. Proc. Inst. Mech. Engrs 227 (5), 748760.
Müller, C. M., Breitbach, H. & Peters, N. 1994 Partially premixed turbulent flame propagation in jet flames. Proc. Combust. Inst. 25 (1), 10991106.
Müller, C. M. & Peters, N. 1992 Global kinetics for n-heptane ignition at high pressures. Proc. Combust. Inst. 20, 777784.
Musculus, M. P. B., Miles, P. C. & Pickett, L. M. 2013 Conceptual models for partially premixed low-temperature diesel combustion. Prog. Energy Combust. Sci. 39, 246283.
Pantano, C. 2004 Direct simulation of non-premixed flame extinction in a methane-air jet with reduced chemistry. J. Fluid Mech. 514, 231270.
Papageorge, M. J., Arndt, C., Fuest, F., Meier, W. & Sutton, J. A. 2014 High-speed mixture fraction and temperature imaging of pulsed, turbulent fuel jets auto-igniting in high-temperature, vitiated co-flows. Exp. Fluids 55 (7), 1763.
Pei, Y., Hawkes, E. R., Bolla, M., Kook, S., Goldin, G. M., Yang, Y., Pope, S. B. & Som, S. 2016 An analysis of the structure of an n-dodecane spray flame using TPDF modelling. Combust. Flame 168, 420435.
Peters, N. 2001 Turbulent Combustion, vol. 12. Cambridge University Press.
Pickett, L. M., Kook, S. & Williams, T. C.2009 Visualization of diesel spray penetration, cool-flame, ignition, high- temperature combustion, and soot formation using high-speed imaging. SAE paper 2009-01-0658.
Pickett, L. M., Siebers, D. L. & Idicheria, C. A.2005 Relationship between ignition processes and the lift-off length of diesel fuel jets. SAE Paper 2005-01-3843.
Poinsot, T. J. 1992 Boundary conditions for direct simulations of compressible viscous flows. J. Comput. Phys. 99 (2), 352.
Pope, S. B. 2000 Turbulent Flows. Cambridge University Press.
Ruetsch, G. R., Vervisch, L. & Liñán, A. 1995 Effects of heat release on triple flames. Phys. Fluids 7 (6), 14471454.
Sankaran, R., Hawkes, E. R., Chen, J. H., Lu, T. & Law, C. K. 2007 Structure of a spatially developing turbulent lean methane–air bunsen flame. Proc. Combust. Inst. 31 (1), 12911298.
Sankaran, R., Hawkes, E. R., Yoo, C. S. & Chen, J. H. 2015 Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames. Combust. Flame 162 (9), 32943306.
Siebers, D. L. & Higgins, B.2001 Flame lift-off on direct-injection diesel sprays under quiescent conditions. SAE Paper 2001-01-0530.
Siebers, D. L., Higgins, B. & Pickett, L.2002 Flame lift-off on direct-injection diesel fuel jets: oxygen concentration effects. SAE Paper 2002-01-0890.
Sreedhara, S. & Lakshmisha, K. N. 2000 Direct numerical simulation of autoignition in a non-premixed, turbulent medium. Proc. Combust. Inst. 28 (1), 2533.
Sreedhara, S. & Lakshmisha, K. N. 2002 Autoignition in a non-premixed medium: DNS studies on the effects of three-dimensional turbulence. Proc. Combust. Inst. 29 (2), 20512059.
Sripakagorn, P., Mitarai, S., Kosály, G. & Pitsch, H. 2004 Extinction and reignition in a diffusion flame: a direct numerical simulation study. J. Fluid Mech. 518, 231259.
Sullivan, R., Wilde, B., Noble, D. R., Seitzman, J. M. & Lieuwen, T. C. 2014 Time-averaged characteristics of a reacting fuel jet in vitiated cross-flow. Combust. Flame 161 (7), 17921803.
Thévenin, D. & Candel, S. 1995 Ignition dynamics of a diffusion flame rolled up in a vortex. Phys. Fluids 7 (2), 434445.
Vanquickenborne, L. & van Tiggelen, A. 1966 The stabilization mechanism of lifted diffusion flames. Combust. Flame 10 (1), 5969.
Viggiano, A. 2004 A 2-D investigation of n-heptane autoignition by means of direct numerical simulation. Combust. Flame 137 (4), 432443.
Viggiano, A. 2010 Exploring the effect of fluid dynamics and kinetic mechanisms on n-heptane autoignition in transient jets. Combust. Flame 157 (2), 328340.
Wang, Y. & Rutland, C. J. 2007 Direct numerical simulation of ignition in turbulent n -heptane liquid-fuel spray jets. Combust. Flame 149 (4), 353365.
Yoo, C. S., Richardson, E. S., Sankaran, R. & Chen, J. H. 2011 A DNS study on the stabilization mechanism of a turbulent lifted ethylene jet flame in highly-heated coflow. Proc. Combust. Inst. 33 (1), 16191627.
Yoo, C. S., Sankaran, R. & Chen, J. H. 2009 Three-dimensional direct numerical simulation of a turbulent lifted hydrogen jet flame in heated coflow: flame stabilization and structure. J. Fluid Mech. 640, 453481.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
  • URL: /core/journals/journal-of-fluid-mechanics
Please enter your name
Please enter a valid email address
Who would you like to send this to? *

JFM classification


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed