Transition to detonation in a flame jet

Journal Article · Tue Feb 28 23:00:00 EST 1989 · Combust. Flame; (United States)

DOI:https://doi.org/10.1016/0010-2180(89)90045-X· OSTI ID:6262312

Moen, I O; Bjerketvedt, D; Engebretsen, T; Jenssen, A; Hjertager, B H; Bakke, J R

The results of an experimental and numerical investigation of flame-jet ignition of an acetylene-air cloud contained in a 2 m diameter plastic bag, 8 m long, are reported. The flame jet is produced by an acetylene-air flame in a 0.66 m diameter tube, 11 m long. The composition of the mixture was varied to obtain the critical composition for initiation of detonation in the cloud, with and without obstacles at the end of the tube. Numerical calculations were used to characterize the flame jet. Transition to detonation in the flame jet from an open tube was observed for acetylene-air mixtures with more than 7.9% C/sub 2/H/sub 2/. The mechanism of transition observed on the high-speed film records is analogous to that seen in similar laboratory experiments, with a localized explosion somewhere in the turbulent flame jet leading to the onset of detonation. Transition was facilitated by placing various obstacles at the exit of the tube. With an orifice plate with 50 mm diameter holes, initiation of detonation in a 7.0% C/sub 2/H/sub 2/ mixture occurs uniformly across the flame jet a short distance downstream of the plate. With a circular central obstacle in the tube exit, transition to detonation was observed in a 5.6and C/sub 2/H/sub 2/ mixture. From the results of this investigation, it is concluded that the phenomena of hot gas jet initiation of detonation seen in laboratory experiments with fuel-oxygen mixtures also occur in fuel-air mixtures provided the jet is large enough.

• Research Organization: Defence Research Establishment Suffield, Ralston, Alberta, T0J 2N0 (CA); Research Center, Norsk Hydro, Porsgrunn (NO); Trondheim (NO); Norwegian Defence Construction Service, Akershus, Oslo (NO); The Chr. Michelsen Institute, Bergen (NO)
• OSTI ID: 6262312
• Journal Information: Combust. Flame; (United States), Journal Name: Combust. Flame; (United States) Vol. 75:3; ISSN CBFMA
• Country of Publication: United States
• Language: English

Related Subjects

090110 -- Hydrocarbon Fuels-- Properties-- (1979-1989)
10 SYNTHETIC FUELS
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
42 ENGINEERING
420400 -- Engineering-- Heat Transfer & Fluid Flow
ACETYLENE
AIR
ALKYNES
CHEMICAL COMPOSITION
DATA
DETONATIONS
DISPERSIONS
EXPERIMENTAL DATA
FLAMES
FLUID FLOW
FLUIDS
FUELS
GASES
HYDROCARBONS
IGNITION
INFORMATION
JET ENGINE FUELS
MIXTURES
NUMERICAL DATA
NUMERICAL SOLUTION
ORGANIC COMPOUNDS
TUBES
TURBULENT FLOW