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Title: Autoignited laminar lifted flames of propane in coflow jets with tribrachial edge and mild combustion

Abstract

Characteristics of laminar lifted flames have been investigated experimentally by varying the initial temperature of coflow air over 800 K in the non-premixed jets of propane diluted with nitrogen. The result showed that the lifted flame with the initial temperature below 860 K maintained the typical tribrachial structure at the leading edge, which was stabilized by the balance mechanism between the propagation speed of tribrachial flame and the local flow velocity. For the temperature above 860 K, the flame was autoignited without having any external ignition source. The autoignited lifted flames were categorized in two regimes. In the case with tribrachial edge structure, the liftoff height increased nonlinearly with jet velocity. Especially, for the critical condition near blowout, the lifted flame showed a repetitive behavior of extinction and reignition. In such a case, the autoignition was controlled by the non-adiabatic ignition delay time considering heat loss such that the autoignition height was correlated with the square of the adiabatic ignition delay time. In the case with mild combustion regime at excessively diluted conditions, the liftoff height increased linearly with jet velocity and was correlated well with the square of the adiabatic ignition delay time. (author)

Authors:
; ;  [1]
  1. School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744 (Korea)
Publication Date:
OSTI Identifier:
21137924
Resource Type:
Journal Article
Journal Name:
Combustion and Flame
Additional Journal Information:
Journal Volume: 156; Journal Issue: 2; Other Information: Elsevier Ltd. All rights reserved; Journal ID: ISSN 0010-2180
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; AUTOIGNITION; COMBUSTION; PROPANE; HEIGHT; LAMINAR FLAMES; JETS; VELOCITY; HEAT LOSSES; TIME DELAY; AIR; FLAME PROPAGATION; NITROGEN; CORRELATIONS; TEMPERATURE RANGE 0400-1000 K; NONLINEAR PROBLEMS; TEMPERATURE DEPENDENCE; Liftoff height; Tribrachial flames; Mild combustion; Ignition delay

Citation Formats

Choi, B C, Kim, K N, and Chung, S H. Autoignited laminar lifted flames of propane in coflow jets with tribrachial edge and mild combustion. United States: N. p., 2009. Web. doi:10.1016/J.COMBUSTFLAME.2008.10.020.
Choi, B C, Kim, K N, & Chung, S H. Autoignited laminar lifted flames of propane in coflow jets with tribrachial edge and mild combustion. United States. https://doi.org/10.1016/J.COMBUSTFLAME.2008.10.020
Choi, B C, Kim, K N, and Chung, S H. 2009. "Autoignited laminar lifted flames of propane in coflow jets with tribrachial edge and mild combustion". United States. https://doi.org/10.1016/J.COMBUSTFLAME.2008.10.020.
@article{osti_21137924,
title = {Autoignited laminar lifted flames of propane in coflow jets with tribrachial edge and mild combustion},
author = {Choi, B C and Kim, K N and Chung, S H},
abstractNote = {Characteristics of laminar lifted flames have been investigated experimentally by varying the initial temperature of coflow air over 800 K in the non-premixed jets of propane diluted with nitrogen. The result showed that the lifted flame with the initial temperature below 860 K maintained the typical tribrachial structure at the leading edge, which was stabilized by the balance mechanism between the propagation speed of tribrachial flame and the local flow velocity. For the temperature above 860 K, the flame was autoignited without having any external ignition source. The autoignited lifted flames were categorized in two regimes. In the case with tribrachial edge structure, the liftoff height increased nonlinearly with jet velocity. Especially, for the critical condition near blowout, the lifted flame showed a repetitive behavior of extinction and reignition. In such a case, the autoignition was controlled by the non-adiabatic ignition delay time considering heat loss such that the autoignition height was correlated with the square of the adiabatic ignition delay time. In the case with mild combustion regime at excessively diluted conditions, the liftoff height increased linearly with jet velocity and was correlated well with the square of the adiabatic ignition delay time. (author)},
doi = {10.1016/J.COMBUSTFLAME.2008.10.020},
url = {https://www.osti.gov/biblio/21137924}, journal = {Combustion and Flame},
issn = {0010-2180},
number = 2,
volume = 156,
place = {United States},
year = {Sun Feb 15 00:00:00 EST 2009},
month = {Sun Feb 15 00:00:00 EST 2009}
}