Effects of radiation losses on very lean methane/air flames propagating upward in a vertical tube

Higuera Antón, Francisco and Muntean, Victor (2014). Effects of radiation losses on very lean methane/air flames propagating upward in a vertical tube. "Combustion and Flame", v. 161 (n. 9); pp. 2340-2347. ISSN 0010-2180. https://doi.org/10.1016/j.combustflame.2014.02.013.

Description

Title: Effects of radiation losses on very lean methane/air flames propagating upward in a vertical tube
Author/s:
  • Higuera Antón, Francisco
  • Muntean, Victor
Item Type: Article
Título de Revista/Publicación: Combustion and Flame
Date: 2014
Volume: 161
Subjects:
Faculty: E.T.S.I. Aeronáuticos (UPM)
Department: Motopropulsión y Termofluidodinámica [hasta 2014]
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

The stationary upward propagation of a very lean methane/air flame in a long vertical tube open at the bottom and closed at the top is simulated numerically using a single overall chemical reaction to model combustion and assuming an optically thin gas and a transparent or non-reflecting tube wall to approximately account for radiation losses from CO2CO2 and H2OH2O. Buoyancy plays a dominant role in the propagation of these flames and causes a large region of low velocity of the burnt gas relative to the flame to appear below the flame front when the equivalence ratio is decreased. The size of this region scales with the radius of the tube, and its presence enhances the effect of radiation losses, which would be otherwise negligible for a standard flammability tube, given the small concentration of radiating species. Heat conduction is found to be important in the low velocity region and to lead to a conduction flux from the flame to the burnt gas that causes extinction at the flame tip for a value of the equivalence ratio near the flammability limit experimentally measured in the standard tube. The effect of radiation losses decreases with the radius of the tube. Numerical results and order-of-magnitude estimates show that, in the absence of radiation, a very lean flame front fails to propagate only after recirculation of the burnt gas extends to its reaction region and drastically changes its structure. This condition is not realized for the standard flammability tube, but it seems to account for the flammability limit measured in a tube of about half the radius of the standard tube.

Funding Projects

TypeCodeAcronymLeaderTitle
Madrid Regional GovernmentS2009/ENE-1957UnspecifiedUnspecifiedUnspecified
Government of SpainS2009/ENE-1957UnspecifiedUnspecifiedUnspecified
Government of SpainDPI-2045-C03-01UnspecifiedUnspecifiedUnspecified

More information

Item ID: 35181
DC Identifier: http://oa.upm.es/35181/
OAI Identifier: oai:oa.upm.es:35181
DOI: 10.1016/j.combustflame.2014.02.013
Official URL: http://www.sciencedirect.com/science/article/pii/S0010218014000728
Deposited by: Memoria Investigacion
Deposited on: 17 Nov 2015 11:21
Last Modified: 06 May 2019 11:31
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