Strain distribution on material surfaces during combustion regime transitions
File(s)
Accepted version
Author(s)
Hampp, F
Lindstedt, RP
Type
Journal Article
Abstract
A multi-fluid state approach is used to analyse the underlying conditions for burning mode transitions from close to the corrugated flamelet regime to distributed reactions. Turbulent (Ret ≃ 380) premixed DME/air flames were aerodynamically stabilised in a back-to-burnt opposed jet configuration with the Damköhler number varied through the mixture stoichiometry. Simultaneous Mie scattering, OH-PLIF and PIV allowed the delineation of five separate fluid states (reactants, combustion products, mixing fluid, mildly and strongly reacting fluids) with associated material surfaces. The analysis shows self-sustained flames in low strain regions with a collocated flow acceleration for higher Damköhler numbers. By contrast, in highly strained regions (e.g. beyond the twin flame extinction point) the burning mode is governed by the counter-flowing hot combustion products resulting in increased levels of vorticity and an absence of a preferential dilatation direction. The current analysis provides novel insights into combustion regime transitions by means of (i) strain rate statistics conditioned upon material surfaces and (ii) the evolution of fluid state interface probabilities as a function of the Damköhler number. The work further shows (iii) that the combustion mode influences scalar transport and that increased levels of turbulence retards the transition to non-gradient transport.
Date Issued
2016-07-21
Date Acceptance
2016-07-06
Citation
Proceedings of the Combustion Institute, 2016, 36 (2), pp.1911-1918
ISSN
1540-7489
Publisher
Elsevier
Start Page
1911
End Page
1918
Journal / Book Title
Proceedings of the Combustion Institute
Volume
36
Issue
2
Copyright Statement
© 2016 Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Subjects
Science & Technology
Physical Sciences
Technology
Thermodynamics
Energy & Fuels
Engineering, Chemical
Engineering, Mechanical
Engineering
Strain rate
Combustion regime transition
Premixed DME flames
Multi-fluid statistics
Fractal grid generated turbulence
TURBULENT PREMIXED FLAMES
OPPOSED-JET FLAMES
FLOW
STATISTICS
VELOCITY
SCALE
TEMPERATURE
EXTINCTION
RESOLUTION
TRANSPORT
0902 Automotive Engineering
0904 Chemical Engineering
0913 Mechanical Engineering
Publication Status
Published