Extinction of nonpremixed flames with halogenated fire suppressants

Hamins, Anthony P.; Trees, D.; Seshadri, K.; Chelliah, Harsha K.

doi:10.1016/0010-2180(94)90125-2

Cited by 89 publications

(50 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Buoyancy always accelerates hot combustion gases relative to the cold oxidizer with the result that the flame surface will be subject to a nonzero perpendicular strain rate. The results of Hamins et al [76] and the current findings suggest this minimum strain rate is on the order of a few tens of inverse seconds.…”

Section: Effects Of Nitrogen Addition On Diffusion Flame Extinctiosupporting

confidence: 53%

“…An important question is: what strain rate is appropriate to use when determining the minimum value of an added thermal agent required to extinguish buoyancy-dominated diffusion flames at normal gravity? The only discussion of this point of which we are aware was presented by Hamins et al [76] These authors compared cup burner measurements (heptane fuel) of extinguishing concentrations for a variety of agents with corresponding measurements made in a counterflow flame. The counterflow measurements were made over a range of flow velocities which were characterized in terms of a global strain rate appropriate for the oxidizer flow impinging on a liquid surface.…”

Section: Effects Of Nitrogen Addition On Diffusion Flame Extinctiomentioning

confidence: 99%

“…[52,53,54,55] Very recently, inhibited flames studies have been extended to laminar opposed flow diffusion flames. [55,56,57,58,59] Despite the large number of detailed kinetic modeling studies dealing with inhibition and extinction of flames by various agents, we have identified only one study which systematically considered the effects of inert thermal agents on a combustion system. Tuovinen calculated the structure of methane/air premixed flames in a well-stirred reactor with added C0 2 , H 2 0, N 2 , and He.…”

Section: Screening Of Thermophysical Properties Databases For Supmentioning

confidence: 99%

See 2 more Smart Citations

Characterization and identification of super-effective thermal fire extinguishing agents :

Pitts¹,

Yang²,

Bryant³

et al. 2006

View full text Add to dashboard Cite

Section: Effects Of Nitrogen Addition On Diffusion Flame Extinctiosupporting

confidence: 53%

Section: Effects Of Nitrogen Addition On Diffusion Flame Extinctiomentioning

confidence: 99%

Section: Screening Of Thermophysical Properties Databases For Supmentioning

confidence: 99%

See 1 more Smart Citation

Characterization and identification of super-effective thermal fire extinguishing agents :

Pitts¹,

Yang²,

Bryant³

et al. 2006

View full text Add to dashboard Cite

“…The value determined previously [15] is X c =.0.025 and applies to all step heights. This agent concentration threshold must be a property of the type of fuel and is roughly consistent with the minimum agent concentration of ~3 % obtained using a cup burner and counterflow diffusion flames at a low strain rate (50 s" 1 ) [7,8]. Furthermore, there existed a minimum injection period, below which the flame could not be extinguished even at high agent concentrations: At ~ 0.05 s for h s = 32 mm, At ~ 0.1 s for h s = 64 mm [15], and At ~ 0.15 s for /; s = 96 mm.…”

Section: Resultssupporting

confidence: 75%

Suppression of bluff-body stabilized pool flames

Takahashi

Schmoll

Belovich³

1999

37th Aerospace Sciences Meeting and Exhibit

View full text Add to dashboard Cite

Public reposing burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate SUPPLEMENTARY NOTESNo copyright is asserted in the United States under Title 17, U.S. code. The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for Government purposes. All other rights are reserved by the copyright owner. 12a. DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release: distribution is unlimited. 12b. DISTRIBUTION CODEA ABSTRACT (Maximum 200 Words)The suppression mechanisms of a nonpremixed flame stabilized behind a backward-facing step in a wind tunnel have been studied using a gaseous fire-extinguishing agent (Halon 1301, bromotrifluoromethane) into the aireflow. Methane or JP-8 jet fuel was used to simulate a pool fire behind a clutter in the aircraft engine nacelle. The characteristic mixing time in the recirculation zone in the wake was measured by impulsively injecting salt water mist into the airflow and by determining a time constant for the exponential decay of the sodium D-line emission at high temperatures. For both methane and JP-8 fuels under relatively high air velocities, the dependence of the critical agent mole fraction at extinction on the injection period is predictable using the characteristic mixing time and the minimum agent mole fraction, which is a fuel property measurable by a steady-state cup-burner method. SUBJECT TERMS ABSTRACTThe suppression mechanisms of a nonpremixed flame stabilized behind a backward-facing step in a wind tunnel have been studied using a gaseous fireextinguishing agent (Halon 1301, bromotrifluoromethane) into the airflow. Methane or JP-8 jet fuel was used to simulate a pool fire behind a clutter in the aircraft engine nacelle. The characteristic mixing time (r exp ) in the recirculation zone in the wake was measured by impulsively injecting salt water mist into the airflow and by determining a time constant for the exponential decay of the sodium D-line emission at high temperatures. For three different step heights (/; s ) and various mean inlet air velocities (U a0 ), T ap linearly depended on /z s /U a o-For both methane and JP-8 fuels under relatively high air velocities, the dependence of the critical agent mole fraction at extinction on the injection period is predictable using the characteristic mixing time and the minimum agent mole fraction, which is a fuel property measurable by a steady-state cup-burner method. INTRODUCTIONA recirculation zone formed behind a clutter in the aircraft engine nacelle, which encases the engine compressor, combustors and turbine, can stabilize fires under over-ventilated con...

show abstract

“…Buoyancy always accelerates hot combustion gases relative to the cold oxidizer, with the result that flame surfaces are subject to nonzero strain rates. The results of Hamins et al [25] and Saso et al [26], along with the current findings, suggest this strain rate limit is on the order of a few tens of inverse seconds.…”

Section: Detailed Chemical Kinetic Model and Mechanismsupporting

confidence: 50%

An Investigation of Extinguishment by Thermal Agents Using Detailed Chemical Modeling of Opposed Jet Diffusion Flames

Pitts¹,

Yang²,

Bryant³

et al. 2008

Fire Saf. Sci.

View full text Add to dashboard Cite

Detailed chemical kinetic modeling of methane planar opposed-jet laminar diffusion flames burning in air mixed with a variety of thermal agents is used to characterize their effects on maximum flame temperature and extinction behavior. The identification of a well-defined limit temperature allows extinguishing concentrations for buoyancy-dominated methane flames to be predicted. Predicted extinguishing volume fractions are shown to be in good agreement with experimental results for opposed flow methane flames. It is further demonstrated that the calculations provide reliable estimates of relative thermal agent extinguishing effectiveness for both methane coflow flames and liquid-fueled heptane flames burning in a surrounding coflow, even though the required volume fractions of a given agent can differ substantially from those predicted for the opposed flow methane flames. This is the case despite the fact that the extinction mechanisms for the opposed-flow (global flame extinction due to flame cooling) and coflow (blow off of an edge flame stabilized in the local flow field by a reaction kernel) flames are believed to be different. The results of the calculations demonstrate the dependence of extinguishment mechanism on the local flow fields at the flame and the need for thermal agents to lower the temperature of the flame zone to a well defined limit temperature.

show abstract

Extinction of nonpremixed flames with halogenated fire suppressants

Cited by 89 publications

References 7 publications

Characterization and identification of super-effective thermal fire extinguishing agents :

Characterization and identification of super-effective thermal fire extinguishing agents :

Suppression of bluff-body stabilized pool flames

An Investigation of Extinguishment by Thermal Agents Using Detailed Chemical Modeling of Opposed Jet Diffusion Flames

Contact Info

Product

Resources

About