Extinction of stretched spray flames with nonunity Lewis numbers in a stagnation-point flow

Shuhn Shyurng Hou, Ta-Hui Lin

Research output: Contribution to journalConference article

17 Citations (Scopus)

Abstract

The extinction of stretched premixed flames under the influence of dilute fuel sprays is studied using activation energy asymptotics. A completely prevaporized mode and a partially prevaporized mode of flame propagation are identified. Three parameters for flame extinction in the analysis consist of the mass fraction of liquid fuel and the initial droplet size of the spray, indicating the internal heat loss and heat gain for rich and lean sprays, respectively, and the flow stretch coupled with Lewis number (Le) that intensifies and weakens the burning strength of the Le< 1 and Le > 1 flame, respectively. The study presents sample calculations on lean ethanol-spray flames (Le > 1), rich ethanol-spray flames (Le > 1), and rich methanolspray flames (Le < 1). Results show that the burning intensity of a spray flame with Le > 1 is weakened by the flow stretch; however, it is enhanced (further reduced) when the lean (rich) spray has a larger amount of liquid fuel loading or a smaller initial droplet size. It is generally found that the external heat loss associated with the flow stretch dominates the trend for flame extinction. The coupling effects of flow stretch and internal heat gain result in that there exists flame flashback instead of flame extinction for rich methanol-spray flames (Le < 1).

Original languageEnglish
Pages (from-to)2009-2015
Number of pages7
JournalSymposium (International) on Combustion
Volume27
Issue number2
DOIs
Publication statusPublished - 1998 Jan 1
Event27th International Symposium on Combustion - Boulder, CO, United States
Duration: 1998 Aug 21998 Aug 7

Fingerprint

Lewis numbers
stagnation point
Liquid fuels
Heat losses
sprayers
flames
extinction
Ethanol
Methanol
Activation energy
liquid fuels
flashback
ethyl alcohol
fuel sprays
Hot Temperature
heat
heating
premixed flames
flame propagation
methyl alcohol

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Mechanical Engineering
  • Physical and Theoretical Chemistry
  • Fluid Flow and Transfer Processes

Cite this

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title = "Extinction of stretched spray flames with nonunity Lewis numbers in a stagnation-point flow",
abstract = "The extinction of stretched premixed flames under the influence of dilute fuel sprays is studied using activation energy asymptotics. A completely prevaporized mode and a partially prevaporized mode of flame propagation are identified. Three parameters for flame extinction in the analysis consist of the mass fraction of liquid fuel and the initial droplet size of the spray, indicating the internal heat loss and heat gain for rich and lean sprays, respectively, and the flow stretch coupled with Lewis number (Le) that intensifies and weakens the burning strength of the Le< 1 and Le > 1 flame, respectively. The study presents sample calculations on lean ethanol-spray flames (Le > 1), rich ethanol-spray flames (Le > 1), and rich methanolspray flames (Le < 1). Results show that the burning intensity of a spray flame with Le > 1 is weakened by the flow stretch; however, it is enhanced (further reduced) when the lean (rich) spray has a larger amount of liquid fuel loading or a smaller initial droplet size. It is generally found that the external heat loss associated with the flow stretch dominates the trend for flame extinction. The coupling effects of flow stretch and internal heat gain result in that there exists flame flashback instead of flame extinction for rich methanol-spray flames (Le < 1).",
author = "Hou, {Shuhn Shyurng} and Ta-Hui Lin",
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Extinction of stretched spray flames with nonunity Lewis numbers in a stagnation-point flow. / Hou, Shuhn Shyurng; Lin, Ta-Hui.

In: Symposium (International) on Combustion, Vol. 27, No. 2, 01.01.1998, p. 2009-2015.

Research output: Contribution to journalConference article

TY - JOUR

T1 - Extinction of stretched spray flames with nonunity Lewis numbers in a stagnation-point flow

AU - Hou, Shuhn Shyurng

AU - Lin, Ta-Hui

PY - 1998/1/1

Y1 - 1998/1/1

N2 - The extinction of stretched premixed flames under the influence of dilute fuel sprays is studied using activation energy asymptotics. A completely prevaporized mode and a partially prevaporized mode of flame propagation are identified. Three parameters for flame extinction in the analysis consist of the mass fraction of liquid fuel and the initial droplet size of the spray, indicating the internal heat loss and heat gain for rich and lean sprays, respectively, and the flow stretch coupled with Lewis number (Le) that intensifies and weakens the burning strength of the Le< 1 and Le > 1 flame, respectively. The study presents sample calculations on lean ethanol-spray flames (Le > 1), rich ethanol-spray flames (Le > 1), and rich methanolspray flames (Le < 1). Results show that the burning intensity of a spray flame with Le > 1 is weakened by the flow stretch; however, it is enhanced (further reduced) when the lean (rich) spray has a larger amount of liquid fuel loading or a smaller initial droplet size. It is generally found that the external heat loss associated with the flow stretch dominates the trend for flame extinction. The coupling effects of flow stretch and internal heat gain result in that there exists flame flashback instead of flame extinction for rich methanol-spray flames (Le < 1).

AB - The extinction of stretched premixed flames under the influence of dilute fuel sprays is studied using activation energy asymptotics. A completely prevaporized mode and a partially prevaporized mode of flame propagation are identified. Three parameters for flame extinction in the analysis consist of the mass fraction of liquid fuel and the initial droplet size of the spray, indicating the internal heat loss and heat gain for rich and lean sprays, respectively, and the flow stretch coupled with Lewis number (Le) that intensifies and weakens the burning strength of the Le< 1 and Le > 1 flame, respectively. The study presents sample calculations on lean ethanol-spray flames (Le > 1), rich ethanol-spray flames (Le > 1), and rich methanolspray flames (Le < 1). Results show that the burning intensity of a spray flame with Le > 1 is weakened by the flow stretch; however, it is enhanced (further reduced) when the lean (rich) spray has a larger amount of liquid fuel loading or a smaller initial droplet size. It is generally found that the external heat loss associated with the flow stretch dominates the trend for flame extinction. The coupling effects of flow stretch and internal heat gain result in that there exists flame flashback instead of flame extinction for rich methanol-spray flames (Le < 1).

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