Five kHz thermometry in turbulent spray flames using chirped-probe-pulse femtosecond CARS, part II: Structure of reaction zones

Albyn Lowe, Levi M. Thomas, Aman Satija, Robert P. Lucht, Assaad R. Masri

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Temperature was measured in turbulent spray flames of ethanol and acetone stabilized on the piloted Sydney Needle Spray Burner (SYNSBURNTM) using single-laser-shot, chirped-probe-pulse femtosecond coherent anti-Stokes Raman spectroscopy (CPP-fs-CARS) with a repetition rate of 5 kHz. The burner features air-blast atomization of liquid injected from a needle that can be translated by a length Lr within a co-flowing air stream so that piloted spray flames ranging from dilute to dense can be studied. Part I of these investigations has reported on the CPP-fs-CARS technique and extensive details of data processing methodology. Part II is concerned with the structure of the reaction zones at different spray loadings and for different departures from blow-off. While not performed simultaneously, measurements of the size distribution of liquid fragments are also reported and discussed in conjunction with the measured temperature. Measured probability density functions of temperature show that for flames with the same liquid loading but different recess lengths, Lr, the near-field spray structure that forms upstream of x/D = 10 affects flame structure and stability further downstream. As the spray exiting the burner becomes denser, with a higher proportion of ligaments and ‘irregular’ shaped objects, the entrainment of hot pilot gases into the spray envelope is affected, hence changing the rates of vaporization and subsequent combustion. The reported results will also form a useful platform for validating sub-models of atomization and combustion in turbulent, dilute to dense spray flames.
Original languageEnglish (US)
Pages (from-to)417-432
Number of pages16
JournalCombustion and Flame
Volume200
DOIs
StatePublished - Jan 22 2019
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2022-06-07
Acknowledged KAUST grant number(s): 1975-01
Acknowledgements: The University of Sydney Combustion Group is supported by the Australian Research Council. The Department of Mechanical Engineering at Purdue University was supported by a fellowship from the Purdue Military Research Initiative. Funding was provided by the U.S. Department of Energy, Division of Chemical Sciences, Geosciences and Biosciences, Grant No. (DE-FG02-03ER15391) and by the King Abdullah University of Science and Technology, CCF subaward (No. 1975-01).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.

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