TY - JOUR
T1 - Effect of hydrogen addition on autoignited methane lifted flames
AU - Choin, Byung Chul
AU - Chung, Suk Ho
N1 - KAUST Repository Item: Exported on 2020-10-01
PY - 2012/1/1
Y1 - 2012/1/1
N2 - Autoignited lifted flames in laminar jets with hydrogen-enriched methane fuels have been investigated experimentally in heated coflow air. The results showed that the autoignited lifted flame of the methane/hydrogen mixture, which had an initial temperature over 920 K, the threshold temperature for autoignition in methane jets, exhibited features typical of either a tribrachial edge or mild combustion depending on fuel mole fraction and the liftoff height increased with jet velocity. The liftoff height in the hydrogen-assisted autoignition regime was dependent on the square of the adiabatic ignition delay time for the addition of small amounts of hydrogen, as was the case for pure methane jets. When the initial temperature was below 920 K, where the methane fuel did not show autoignition behavior, the flame was autoignited by the addition of hydrogen, which is an ignition improver. The liftoff height demonstrated a unique feature in that it decreased nonlinearly as the jet velocity increased. The differential diffusion of hydrogen is expected to play a crucial role in the decrease in the liftoff height with increasing jet velocity.
AB - Autoignited lifted flames in laminar jets with hydrogen-enriched methane fuels have been investigated experimentally in heated coflow air. The results showed that the autoignited lifted flame of the methane/hydrogen mixture, which had an initial temperature over 920 K, the threshold temperature for autoignition in methane jets, exhibited features typical of either a tribrachial edge or mild combustion depending on fuel mole fraction and the liftoff height increased with jet velocity. The liftoff height in the hydrogen-assisted autoignition regime was dependent on the square of the adiabatic ignition delay time for the addition of small amounts of hydrogen, as was the case for pure methane jets. When the initial temperature was below 920 K, where the methane fuel did not show autoignition behavior, the flame was autoignited by the addition of hydrogen, which is an ignition improver. The liftoff height demonstrated a unique feature in that it decreased nonlinearly as the jet velocity increased. The differential diffusion of hydrogen is expected to play a crucial role in the decrease in the liftoff height with increasing jet velocity.
UR - http://hdl.handle.net/10754/562050
UR - http://www.dbpia.co.kr/Journal/ArticleDetail/NODE01757227
U2 - 10.3795/ksme-b.2012.36.1.075
DO - 10.3795/ksme-b.2012.36.1.075
M3 - Article
SN - 1226-4881
VL - 36
SP - 75
EP - 81
JO - Transactions of the Korean Society of Mechanical Engineers B
JF - Transactions of the Korean Society of Mechanical Engineers B
IS - 1
ER -