eprintid: 10068827
rev_number: 18
eprint_status: archive
userid: 608
dir: disk0/10/06/88/27
datestamp: 2019-02-25 10:24:13
lastmod: 2021-10-10 23:02:50
status_changed: 2019-02-25 10:24:13
type: article
metadata_visibility: show
creators_name: Wang, X
creators_name: Jin, T
creators_name: Luo, KH
title: Response of heat release to equivalence ratio variations in high Karlovitz premixed H2/air flames at 20 atm
ispublished: pub
divisions: UCL
divisions: B04
divisions: C05
divisions: F45
keywords: Science & Technology, Physical Sciences, Technology, Chemistry, Physical, Electrochemistry, Energy & Fuels, Chemistry, Direct numerical simulation, Lean premixed flame, Heat release rate, Equivalence ratio, DIRECT NUMERICAL-SIMULATION, THERMAL UNIMOLECULAR REACTIONS, HYDROGEN JET FLAME, FALL-OFF RANGE, LEWIS NUMBER, PRESSURE, COMBUSTION, LAMINAR, SPEED, MIXTURES
note: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
abstract: This paper presents three-dimensional direct numerical simulations of lean premixed H2/air flames with equivalence ratios 0.4, 0.5 and 0.6, respectively. The initial Karlovitz number is around 2335 and the pressure is 20 atm, which is relevant to gas turbine conditions. The heat release in reaction zones under different equivalence ratios is examined statistically with the aim to extend our understanding of lean combustion under high-pressure conditions. With increasing equivalence ratio, the relative thickness of reaction zone (δf/δL) is increasing for both laminar and turbulent flames, but the extent of increase is reduced under high equivalence ratio. By examining the local structures of flame fronts, it is found that trenches and plateaus of local equivalence ratio are located on separate sides of the reaction zone edge. Due to the decreased Lewis number under high equivalence ratio, the trench ‘depth’ and plateau ‘height’ are reduced. For the flame under ultra-lean conditions, there are some spots with temperatures above adiabatic temperature. This is attributed to the high-fraction of radicals in these regions, which will promote heat release. Furthermore, the heat release rates of elementary reactions are investigated with the analysis of radical fractions and rate constants. When the mixture equivalence ratio varies, the local heat release is changed in different temperature windows due to the combined effects of radical fractions and reaction rate constants.
date: 2019-01-28
date_type: published
publisher: PERGAMON-ELSEVIER SCIENCE LTD
official_url: https://doi.org/10.1016/j.ijhydene.2018.12.027
oa_status: green
full_text_type: other
language: eng
primo: open
primo_central: open_green
article_type_text: Article
verified: verified_manual
elements_id: 1621479
doi: 10.1016/j.ijhydene.2018.12.027
lyricists_name: Luo, Kai
lyricists_id: KLUOX54
actors_name: Stacey, Thomas
actors_id: TSSTA20
actors_role: owner
full_text_status: public
publication: International Journal of Hydrogen Energy
volume: 44
number: 5
pagerange: 3195-3207
pages: 13
issn: 1879-3487
citation:        Wang, X;    Jin, T;    Luo, KH;      (2019)    Response of heat release to equivalence ratio variations in high Karlovitz premixed H2/air flames at 20 atm.                   International Journal of Hydrogen Energy , 44  (5)   pp. 3195-3207.    10.1016/j.ijhydene.2018.12.027 <https://doi.org/10.1016/j.ijhydene.2018.12.027>.       Green open access   
 
document_url: https://discovery.ucl.ac.uk/id/eprint/10068827/1/Luo%202019%20IJHE%20accepted.pdf