Combustion in a turbulent mixing layer formed at a rearward-facing step

Journal Article · Tue Nov 01 04:00:00 EST 1983 · AIAA J.; (United States)

DOI:https://doi.org/10.2514/3.8290· OSTI ID:6738853

Pitz, R W; Daily, J W

A premixed propane/air flame was stabilized in a turbulent mixing layer formed at a rearward-facing step. The mean and rms averages of the turbulent velocity flowfield were determined by laser velocimetry for both reacting (phi 0.57) and nonreacting flows (Re 15,000-37,000 based on step height). The reacting-flow was visualized by high-speed schlieren photography. Large-scale structures dominate the reacting mixing layer. The growth of the large-scale structures was tied to the propagation of the flame. The linear growth rate of the reacting mixing layer defined by the mean velocity profiles was unchanged by combustion but the virtual origin moves downstream. The reacting mixing layer boundaries based on the mean velocity profiles were shifted toward the recirculation zone and reattachment lengths were shortened by 30 percent. The edge of the flame controlled by the large-scale structure development propagated faster into the incoming reactants than the boundary of the mixing layer given by the mean velocity flowfield. Thus, the region of high velocity gradient did not coincide with the region of high reaction and heat transfer.

• Research Organization: California Univ., Berkeley
• OSTI ID: 6738853
• Journal Information: AIAA J.; (United States), Journal Name: AIAA J.; (United States) Vol. 21; ISSN AIAJA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
CHEMICAL REACTIONS
COMBUSTION
ENERGY TRANSFER
ENTRAINMENT
FLAME PROPAGATION
FLAMES
HEAT TRANSFER
MIXING
OXIDATION
PHOTOGRAPHY
SCHLIEREN METHOD
THERMOCHEMICAL PROCESSES
VELOCITY