Challenges for turbulent combustion

Assaad R. Masri

Research output: Chapter in Book/Report/Conference proceedingConference contribution

48 Scopus citations


Turbulent combustion will remain central to the next generation of combustion devices that are likely to employ blends of renewable and fossil fuels, transitioning eventually to electrofuels (also referred to as e-fuels, powerfuels, power-to-x, or synthetics). This paper starts by projecting that the decarbonization process is likely to be very slow as guided by history and by the sheer extent of the current network for fossil fuels, and the cost of its replacement. This transition to renewables will be moderated by the advent of cleaner engines that operate on increasingly cleaner fuel blends. A brief outline of recent developments in combustion modes, such as gasoline compression ignition for reciprocating engines and sequential combustion for gas turbines, is presented. The next two sections of the paper identify two essential areas of development for advancing knowledge of turbulent combustion, namely multi-mode or mixed-mode combustion and soot formation. Multi-mode combustion is common in practical devices and spans the entire range of processes from transient ignition to stable combustion and the formation of pollutants. A range of burners developed to study highly turbulent premixed flames and mixed-mode flames, is presented along with samples of data and an outline of outstanding research issues. Soot formation relevant to electrofuels, such as blends of diesel-oxymethylene ethers, hydrogen-methane or ethylene-ammonia, is also discussed. Mechanisms of soot formation, while significantly improved, remain lacking particularly for heavy fuels and their blends. Other important areas of research, such as spray atomization, turbulent dense spray flames, turbulent fires, and the effects of high pressure, are briefly mentioned. The paper concludes by highlighting the continued need for research in these areas of turbulent combustion to bring predictive capabilities to a level of comprehensive fidelity that enables them to become standard reliable tools for the design and monitoring of future combustors.
Original languageEnglish (US)
Title of host publicationProceedings of the Combustion Institute
PublisherElsevier BV
Number of pages35
StatePublished - Apr 10 2021
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2022-07-01
Acknowledgements: The author would like to thank Professors Timothy Lieuwen and Fei Qi as Program Co-Chairs of the 38th International Combustion Symposium for inviting me to present this Plenary Lecture. I am eternally grateful to the Australian Research Council for the continued and generous support it has provided for my research through a series of grants, the most recent being: DP200103609, DP180104190, LE180100203, DP160105023, DP130104904, DP110105535, DP1097125, and DP0772408. I am also funded by Qatar National Research Fund Project NPRP-7-036-2-018. Support and encouragement within the University of Sydney and in particular, my School of Aerospace, Mechanical and Mechatronic Engineering has provided me with a continued incentive to advance my research and grow my team and network of collaborators who are largely responsible for the work presented here. I am blessed to have colleagues of the calibre of Prof. John Kent, A/Prof. Matthew Cleary, Dr Matthew Dunn and Dr Agisilaos Kourmatzis who, together with our students and Postdoctoral Fellows, provide a stimulating, enjoyable and productive environment for research. Advances in many projects discussed here would not have been possible without the help of my long term collaborators, namely Dr Robert Barlow, then at Sandia National Laboratories, Livermore, USA, Professor William Roberts at King Abdullah University of Science and Technology, KAUST in Saudi Arabia, Professor Andrea D'Anna and Dr Mariano Sirignano at the University of Naples Federico II, Italy, Professor Epaminondas Mastorakos at the University of Cambridge, UK, Professor Steve Pope at Cornell University, USA, Professor Mohy Mansour at the American University of Cairo, Dr Salah Ibrahim at Loughborough University, UK and Professor Fei Qi from Shanghai Jiao Tong University in China. I am indebted to the following colleagues (listed in alphabetical order) who have provided thoughtful comments on the manuscript and subsequent stimulating discussions which have helped bring the manuscript to its current stage: Dr Robert Barlow, A/Prof. Matthew Cleary, Dr Matthew Dunn, Prof. Evatt Hawkes, Dr Gautam Kalghatgi, Dr Agisilaos Kourmatzis, Professor Prof. Heinz Pitsch and Professor Epaminondas Mastorakos . I am grateful to Dr Wesley Boyette, Dr Thibault Guiberti, Dr Mrinal Juddoo for helping with various figures. The able assistance of Dr Gajendra Singh in various tasks of editing and refining the figures is very much appreciated. Last, but not least, the constructive feedback of the anonymous reviewers is also acknowledged. This paper is dedicated to my family, who continue to put up with my erratic hours, to the souls of my parents and, my mentor, the late Professor R.W. Bilger who introduced me to this wonderful field of combustion.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.

ASJC Scopus subject areas

  • General Chemical Engineering
  • Mechanical Engineering
  • Physical and Theoretical Chemistry


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