TY - JOUR
T1 - Edge flames in mixing layers
T2 - Effects of heat recirculation through thermally active splitter plates
AU - Lu, Zhanbin
AU - Matalon, Moshe
N1 - Funding Information:
The work of Zhanbin Lu was supported by the National Science Foundation of China , under grant Nos. 51776136 and U1738117 . We are grateful to Mr. Shikhar Mohan from the University of Illinois at Urbana-Champaign for his help in carrying out some of the numerical calculations.
Publisher Copyright:
© 2020 The Combustion Institute
PY - 2020/7
Y1 - 2020/7
N2 - A numerical study is carried out to investigate the stabilization and dynamic properties of the edge flame formed in the wake of two merging streams, one containing fuel and the other oxidizer, separated by a splitter plate. Several plates are considered to illustrate the effects of their thermo-physical properties on the edge flame for low- and high-Lewis-number mixtures. The objective is to provide a comprehensive understanding of the effects of the heat recirculation cycle, from the edge flame through the splitter plate and back to the fresh reactants, on the edge flame. A diffusive-thermal model is adopted, with the flow field determined by solving the incompressible Navier–Stokes equations in the vicinity of the plate trailing edge, and the combustion field determined by solving the transport equations with a constant density. Two distinct modes of flame stabilization are identified and examined: a stationary mode, where the edge flame is held stationary at a well-defined distance, whether attached to or lifted from the tip of the plate, and an oscillatory mode where the edge flame undergoes sustained oscillations relative to an (unstable) equilibrium position. To characterize the heat recirculation effect under varying flow/mixture conditions, we introduce the thermal sensing distance, as a heuristic parameter that determines whether substantial thermal interaction between the edge flame and the plate occurs, and the average output heat flux, as a universal measure characterizing the efficiency of the heat recirculation cycle.
AB - A numerical study is carried out to investigate the stabilization and dynamic properties of the edge flame formed in the wake of two merging streams, one containing fuel and the other oxidizer, separated by a splitter plate. Several plates are considered to illustrate the effects of their thermo-physical properties on the edge flame for low- and high-Lewis-number mixtures. The objective is to provide a comprehensive understanding of the effects of the heat recirculation cycle, from the edge flame through the splitter plate and back to the fresh reactants, on the edge flame. A diffusive-thermal model is adopted, with the flow field determined by solving the incompressible Navier–Stokes equations in the vicinity of the plate trailing edge, and the combustion field determined by solving the transport equations with a constant density. Two distinct modes of flame stabilization are identified and examined: a stationary mode, where the edge flame is held stationary at a well-defined distance, whether attached to or lifted from the tip of the plate, and an oscillatory mode where the edge flame undergoes sustained oscillations relative to an (unstable) equilibrium position. To characterize the heat recirculation effect under varying flow/mixture conditions, we introduce the thermal sensing distance, as a heuristic parameter that determines whether substantial thermal interaction between the edge flame and the plate occurs, and the average output heat flux, as a universal measure characterizing the efficiency of the heat recirculation cycle.
KW - Diffusion flame
KW - Edge flame
KW - Flame oscillation
KW - Heat recirculation
KW - Mixing layer
UR - http://www.scopus.com/inward/record.url?scp=85083891528&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85083891528&partnerID=8YFLogxK
U2 - 10.1016/j.combustflame.2020.04.010
DO - 10.1016/j.combustflame.2020.04.010
M3 - Article
AN - SCOPUS:85083891528
SN - 0010-2180
VL - 217
SP - 262
EP - 273
JO - Combustion and Flame
JF - Combustion and Flame
ER -