Secondary effects in combustion instabilities leading to flashback

Conference · Fri Jan 01 04:00:00 EST 1982 · AIAA Pap.; (United States)

OSTI ID:5507499

Vaneveld, L; Hom, K; Oppenheim, A K

The secondary effects in turbulent combustion instabilities leading to flashback are investigated, including those due to buoyancy and contraction at the combustor outlet. Experiments were conducted in an oblong, rectangular cross-section combustion tunnel, where the effects of a bluff-body flames holder were generated by a rear-facing step behind a streamlined inlet nozzle. The results of experiments leading to flashback with the step mounted at the bottom of the combustion chamber were compared to those of experiments in which it was located at the top. Irrespective of the flow obstructions introduced downstream, the critical equivalence ratio for flashback was consistently lower with the step at the bottom, indicating that buoyancy was enhancing the growth of the recirculation zone that pushed the flame upstream and caused flashback. The contraction at the end of the combustion chamber had a promoting influence on the process of vortex pairing, re-enforcing the influence of the trailing vortices over that of the recirculation vortex system, and thereby curbing the tendency to flashback. Provided that the flow velocity was low, however, the characteristic features of combustion instabilities leading to flashback in the absence of contraction could still be established in its presence.

• Research Organization: Univ. of California, Berkeley
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5507499
• Report Number(s): CONF-820106-
• Conference Information: Journal Name: AIAA Pap.; (United States) Journal Volume: 82-0037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
BOUNDARY LAYERS
CHEMICAL REACTIONS
COMBUSTION
COMBUSTION CHAMBERS
COMBUSTION INSTABILITY
FLAME PROPAGATION
FLASHBACK
FLUID FLOW
INSTABILITY
LAYERS
NOZZLES
OXIDATION
THERMOCHEMICAL PROCESSES
TURBULENT FLOW
VELOCITY
VORTICES