Autoignited laminar lifted flames of methane, ethylene, ethane, and n-butane jets in coflow air with elevated temperature

Journal Article · Wed Dec 15 00:00:00 EST 2010 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2010.06.011· OSTI ID:21390738

Choi, B C; Chung, S H ^[1]

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1. Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

The autoignition characteristics of laminar lifted flames of methane, ethylene, ethane, and n-butane fuels have been investigated experimentally in coflow air with elevated temperature over 800 K. The lifted flames were categorized into three regimes depending on the initial temperature and fuel mole fraction: (1) non-autoignited lifted flame, (2) autoignited lifted flame with tribrachial (or triple) edge, and (3) autoignited lifted flame with mild combustion. For the non-autoignited lifted flames at relatively low temperature, the existence of lifted flame depended on the Schmidt number of fuel, such that only the fuels with Sc > 1 exhibited stationary lifted flames. The balance mechanism between the propagation speed of tribrachial flame and local flow velocity stabilized the lifted flames. At relatively high initial temperatures, either autoignited lifted flames having tribrachial edge or autoignited lifted flames with mild combustion existed regardless of the Schmidt number of fuel. The adiabatic ignition delay time played a crucial role for the stabilization of autoignited flames. Especially, heat loss during the ignition process should be accounted for, such that the characteristic convection time, defined by the autoignition height divided by jet velocity was correlated well with the square of the adiabatic ignition delay time for the critical autoignition conditions. The liftoff height was also correlated well with the square of the adiabatic ignition delay time. (author)

• OSTI ID: 21390738
• Journal Information: Combustion and Flame, Vol. 157, Issue 12; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AUTOIGNITION
BUTANE
ETHANE
ETHYLENE
METHANE
LAMINAR FLAMES
AIR
COMBUSTION
HEIGHT
HEAT LOSSES
TIME DELAY
TEMPERATURE RANGE 0400-1000 K
FLAME PROPAGATION
CONVECTION
JETS
VELOCITY
STABILIZATION
CORRELATIONS
ADIABATIC PROCESSES
TEMPERATURE DEPENDENCE
Liftoff height
Tribrachial flames
Mild combustion
Ignition delay
Schmidt number