Comparative Investigation of N-Heptane Droplet Ignition in High Temperature Convective Environments

2007 ◽  
Author(s):  
J. Chen ◽  
X. F. Peng ◽  
Y. G. Ju ◽  
B. X. Wang
Keyword(s):  
High Temperature ◽  
Ignition Delay ◽  
Comparative Investigation ◽  
Elementary Reactions ◽  
Fuel Droplets ◽  
Ignition Delay Times ◽  
Delay Times ◽  
One Step ◽  
Flame Behavior ◽  
Skeletal Mechanism

A 2-D numerical model was proposed to investigate the ignition of liquid fuel droplets in convective environments at high temperature. This model employed a skeletal mechanism consisting of 34 reactive species and 56 elementary reactions, rather than one-step overall reaction as in normal 2-D droplet ignition models, because the skeletal mechanism for n-heptane reproduces ignition delay times at various temperatures and pressures reasonably well. In present investigation an emphasis was addressed on the comparative analysis of suitability of the model, particularly numerical simulations were compared with experiments available in the literature, or for N-heptane droplets ignition in the convective air at temperature in a range of 1100K∼1400K and velocity of 2m/s. The ignition delay time and ignition position were obtained using an ignition criterion based on OH radical mass fraction. The flame behavior after ignition was also studied comparatively. The agreement between numerical simulation and experiments is reasonably good.

Reaction Mechanisms for Methane Ignition

2000 ◽  
Author(s):  
S. C. Li ◽  
F. A. Williams
Keyword(s):  
Temperature Sensitivity ◽  
Reaction Mechanisms ◽  
Ignition Delay ◽  
Low Temperatures ◽  
Gas Turbines ◽  
Elementary Reactions ◽  
Detailed Mechanism ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Flame Chemistry

To help understand how methane ignition occurs in gas turbines, dual-fuel diesel engines and other combustion devices, the present study addresses reaction mechanisms with the objective of predicting autoignition times for temperatures between 1000 K and 2000 K, pressures between 1 bar and 150 bar and equivalence ratio between 0.4 and 3. It extends our previous methane flame chemistry and refines earlier methane ignition work. In addition to a detailed mechanism, short mechanisms are presented that retain essential features of the detailed mechanism. The detailed mechanism consists of 127 elementary reactions among 31 species and results in 9 intermediate species being most important in autoignition, namely, CH3, OH, HO2, H2O2, CH2O, CHO, CH3O, H, O. Below 1300 K the last 3 of these are unimportant, but above 1400 K all are significant. To further simplify the computation, systematically reduced chemistry is developed, and an analytical solution for ignition delay times is obtained in the low-temperature range. For most fuels, a single Arrhenius fit for the ignition delay is adequate, but for hydrogen the temperature sensitivity becomes stronger at low temperatures. The present study predicts that, contrary to hydrogen, for methane the temperature sensitivity of the autoignition delay becomes stronger at high temperatures, above 1400 K, and weaker at low temperatures, below 1300 K. Predictions are in good agreement with shock-tube experiments. The results may be employed to estimate ignition delay times in practical combustors.

Measurements of the High Temperature Ignition Delay Times and Kinetic Modeling Study on Oxidation of Nitromethane

2019 ◽  
Vol 192 (2) ◽  
pp. 313-334 ◽  
Author(s):  
Zhongquan Gao ◽  
Meng Yang ◽  
Chenglong Tang ◽  
Feiyu Yang ◽  
Ke Yang ◽  
...  
Keyword(s):  
High Temperature ◽  
Kinetic Modeling ◽  
Ignition Delay ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Modeling Study

scholarly journals A skeletal mechanism for prediction of ignition delay times and laminar premixed flame velocities of hydrogen-methane mixtures under gas turbine conditions

2019 ◽  
Vol 44 (33) ◽  
pp. 18573-18585 ◽  
Author(s):  
Yuanjie Jiang ◽  
Gonzalo del Alamo ◽  
Andrea Gruber ◽  
Mirko R. Bothien ◽  
Kalyanasundaram Seshadri ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Ignition Delay ◽  
Premixed Flame ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Skeletal Mechanism

The Shock Tube Autoignition of Biodiesels and Biodiesel Components

2013 ◽  
Author(s):  
Weijing Wang ◽  
Matthew A. Oehlschlaeger
Keyword(s):  
High Temperature ◽  
Methyl Ester ◽  
Shock Tube ◽  
Ignition Delay ◽  
Methyl Esters ◽  
Acid Methyl Ester ◽  
Oh Radicals ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times

The autoignition of fatty-acid methyl ester biodiesels and methyl ester biodiesel components was studied in gas-phase shock tube experiments. Ignition delay times for two reference methyl ester biodiesel fuels, derived from methanol-based transesterification of soybean oil and animal fats, and four primary constituents of all methyl ester biodiesels, methyl palmitate, methyl stearate, methyl oleate, and methyl linoleate, were measured behind reflected shock waves for fuel/air mixtures at temperatures ranging from 900 to 1350 K and at pressures around 10 and 20 atm. Ignition delay times were determined by monitoring pressure and chemiluminescence from electronically-excited OH radicals around 310 nm. The results show similarity in ignition delay times for all methyl ester fuels considered, irrespective of the variations in organic structure, at the high-temperature conditions studied and also similarity in high-temperature ignition delay times for methyl esters and n-alkanes.

Reaction Mechanisms for Methane Ignition

2002 ◽  
Vol 124 (3) ◽  
pp. 471-480 ◽  
Author(s):  
S. C. Li ◽  
F. A. Williams
Keyword(s):  
Temperature Sensitivity ◽  
Reaction Mechanisms ◽  
Ignition Delay ◽  
Low Temperatures ◽  
Gas Turbines ◽  
Elementary Reactions ◽  
Detailed Mechanism ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Flame Chemistry

To help understand how methane ignition occurs in gas turbines, dual-fuel diesel engines, and other combustion devices, the present study addresses reaction mechanisms with the objective of predicting autoignition times for temperatures between 1000 K and 2000 K, pressures between 1 bar and 150 bar, and equivalence ratio between 0.4 and 3. It extends our previous methane flame chemistry and refines earlier methane ignition work. In addition to a detailed mechanism, short mechanisms are presented that retain essential features of the detailed mechanism. The detailed mechanism consists of 127 elementary reactions among 31 species and results in nine intermediate species being most important in autoignition, namely, CH3, OH, HO2,H2O2,CH2O,CHO, CH3O, H, O. Below 1300 K the last three of these are unimportant, but above 1400 K all are significant. To further simplify the computation, systematically reduced chemistry is developed, and an analytical solution for ignition delay times is obtained in the low-temperature range. For most fuels, a single Arrhenius fit for the ignition delay is adequate, but for hydrogen the temperature sensitivity becomes stronger at low temperatures. The present study predicts that, contrary to hydrogen, for methane the temperature sensitivity of the autoignition delay becomes stronger at high temperatures, above 1400 K, and weaker at low temperatures, below 1300 K. Predictions are in good agreement with shock-tube experiments. The results may be employed to estimate ignition delay times in practical combustors.

High-Temperature Ignition Delay Times and Kinetic Study of Furan

2012 ◽  
Vol 26 (4) ◽  
pp. 2075-2081 ◽  
Author(s):  
Liangjie Wei ◽  
Chenglong Tang ◽  
Xingjia Man ◽  
Xue Jiang ◽  
Zuohua Huang
Keyword(s):  
High Temperature ◽  
Kinetic Study ◽  
Ignition Delay ◽  
Ignition Delay Times ◽  
Delay Times
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