The structure of premixed and stratified low turbulence flames

• Published in: Combustion and flame Vol. 158; no. 5; pp. 935 - 948
• Main Authors: Sweeney, M.S., Hochgreb, S., Barlow, R.S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01-05-2011; Elsevier
• Subjects: Applied sciences; Combustion; Combustion. Flame; Cross-planar OH-PLIF; Curvature; Density; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Laminar flames; Laser diagnostics; Lean stratified combustion; Low turbulence; Mathematical analysis; Scalars; Theoretical studies. Data and constants. Metering; Turbulence; V-flame; Combustion; Lean stratified combustion; Cross-planar OH-PLIF; V-flame; Laser diagnostics; Turbulent flame; Laminar flame; Turbulence; Premixed flame; Flame propagation; Temperature measurement; Laser; Flame structure; Curvature
• ISSN: 0010-2180; 1556-2921
• DOI: 10.1016/j.combustflame.2011.02.007

Practical combustion systems typically operate in stratified regimes to leverage the advantages of a spatially varying mixture fraction field. Although these benefits are well known in industry, the fundamental physics underpinning these effects are currently an area of active research. In this paper simultaneous Rayleigh–Raman–LIF measurements of temperature and major species concentrations along a line are used to investigate the structure of a weakly turbulent stratified flame. Concurrent cross-planar OH-PLIF enables the extraction of flame orientation relative to the measurement line, as well as flame front curvature. The behavior of major species concentrations with respect to temperature is found to agree well with laminar flames at the local mixture fraction, even in stratified flows. However, measurements of the surface density function, ∣∇
c∣, and scalar dissipation,
χ
c
, suggest that both premixed and stratified flames are spatially thicker at the microscale than corresponding laminar flames.