Time-Resolved Measurements of Intermediate Concentrations in Fuel-Rich n-Heptane Oxidation Behind Reflected Shock Waves

2017 ◽  
Author(s):  
Zachary E. Loparo ◽  
Joseph G. Lopez ◽  
Sneha Neupane ◽  
Subith S. Vasu ◽  
William P. Partridge ◽  
...  
Keyword(s):  
Shock Waves ◽  
Shock Tube ◽  
Chemical Kinetics ◽  
Continuous Wave ◽  
Time Resolved ◽  
Ethylene Concentration ◽  
Reflected Shock ◽  
Concentration Time ◽  
Time Histories ◽  
Kinetics Of

The chemical kinetics of the oxidation of n-heptane (C7H16) — an important reference compound for real fuels — are well studied at stoichiometric and lean conditions. However, there is only limited information on the chemical kinetics of fuel-rich combustion. In order to improve the accuracy of chemical kinetic models at these conditions, the oxidation of rich n-heptane mixtures has been investigated. Combustion of n-C7H16/O2/Ar mixtures at equivalence ratios, ϕ, of 2.0 behind reflected shock waves has been studied at temperatures ranging from 1075 to 1418K and at pressures ranging from 1.6 to 1.9atm. Reaction progress was monitored by recording ethylene (C2H4) concentration time-histories and initial n-heptane decay rates at a location 2cm from the endwall of a 13.4m long, 14cm inner diameter shock tube. Ethylene and n-heptane concentration time-histories were measured using absorption spectroscopy at 10.532μm from a tunable CO2 laser and at around 3.4μm from a continuous wave distributed feedback interband cascade laser (ICL), respectively. The measured concentration time-histories were compared with modeled predictions from the Lawrence Livermore National Lab (LLNL) detailed n-heptane reaction mechanism. To the best of our knowledge, the current data are the first time-resolved n-heptane and ethylene concentration measurements conducted in a shock tube at these conditions.

CH Kinetics Measurements and Their Importance for Modeling Prompt NOx Formation in Gas Turbines

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Sean P. Cooper ◽  
Clayton R. Mulvihill ◽  
Olivier Mathieu ◽  
Eric L. Petersen ◽  
Mark W. Crofton ◽  
...  
Keyword(s):  
Shock Tube ◽  
Chemical Kinetics ◽  
Gas Turbines ◽  
Near Infrared ◽  
Elevated Temperatures ◽  
Frequency Doubling ◽  
Tunable Laser ◽  
Detailed Chemical Kinetics ◽  
Reflected Shock ◽  
Time Histories

Abstract Recent work by the authors and others has uncovered the need for further chemical kinetic-related modeling and experiments, specifically for NOx kinetics at engine conditions. In particular, data on CH formation at realistic combustion conditions are needed for further refinement of the prompt-NOx kinetics. To this end, a series of shock-tube experiments to obtain CH concentration time histories at elevated temperatures was performed behind reflected shock waves at the Aerospace Corporation using a tunable laser. This Ti-Sapphire laser was operated in the near infrared at about 854 nm; blue light at 426.9 nm was obtained using an external, frequency-doubling crystal. The resulting light was used in a differential absorption setup with common-mode rejection to measure CH time histories. New measurements in CH4–C2H6–O2 mixtures highly diluted in argon were performed at temperatures between 1890 K and 2719 K. These new data are compared to several modern, detailed chemical kinetics mechanisms with updated NOx submechanisms. Sensitivity and rate of production analyses at the shock-tube conditions along with a gas turbine model are used to elucidate the current state of affairs in CH prediction by the literature models and its effect on NOx production, particularly through the prompt mechanism. A brief discussion of the chemical kinetics for an important reaction in the production of CH is also presented to emphasize the need for further study and refinement of reactions leading to CH production.

scholarly journals Ignition and chemical kinetics of acrolein–oxygen–argon mixtures behind reflected shock waves

Fuel ◽  
2014 ◽  
Vol 135 ◽  
pp. 498-508 ◽  
Author(s):  
K. Chatelain ◽  
R. Mével ◽  
S. Menon ◽  
G. Blanquart ◽  
J.E. Shepherd
Keyword(s):  
Shock Waves ◽  
Chemical Kinetics ◽  
Reflected Shock ◽  
Kinetics Of

CH Kinetics Measurements and Their Importance for Modeling Prompt NOx Formation in Gas Turbines

2019 ◽  
Author(s):  
Sean P. Cooper ◽  
Clayton R. Mulvihill ◽  
Olivier Mathieu ◽  
Eric L. Petersen ◽  
Mark W. Crofton ◽  
...  
Keyword(s):  
Shock Tube ◽  
Chemical Kinetics ◽  
Gas Turbines ◽  
Near Infrared ◽  
Elevated Temperatures ◽  
Frequency Doubling ◽  
Chemical Kinetic ◽  
Detailed Chemical Kinetics ◽  
Reflected Shock ◽  
Time Histories

Abstract Recent work by the authors and others has uncovered the need for further chemical kinetic-related modeling and experiments, specifically for NOx kinetics at engine conditions. In particular, data on CH formation at realistic combustion conditions are needed for further refinement of the prompt-NOx kinetics. To this end, a series of shock-tube experiments to obtain CH concentration time histories at elevated temperatures was performed behind reflected shock waves at The Aerospace Corporation using a tuneable laser. This Ti-Sapphire laser was operated in the near infrared at about 854 nm; blue light at 426.9 nm was obtained using an external, frequency-doubling crystal. The resulting light was used in a differential absorption setup with common-mode rejection to measure CH time histories. New measurements in CH4-C2H6-O2 mixtures highly diluted in argon were performed at temperatures between 1890 K and 2719 K. These new data are compared to several modern, detailed chemical kinetics mechanisms with updated NOx submechanisms. Sensitivity and rate of production analyses at the shock-tube conditions along with a gas turbine model are used to elucidate the current state of affairs in CH prediction by the literature models and its effect on NOx production, particularly through the prompt mechanism. A brief discussion of the chemical kinetics for an important reaction in the production of CH is also presented to emphasize the need for further study and refinement of reactions leading to CH production.

Shock Tube Study on the Reaction of Si Atoms with CH3 with Respect to SiC Formation

2001 ◽  
Vol 215 (6) ◽  
Author(s):  
A. Kunz ◽  
K.A. Bhaskaran ◽  
R. Roth
Keyword(s):  
Shock Waves ◽  
Shock Tube ◽  
Reaction Kinetics ◽  
Ground State ◽  
Reflected Shock ◽  
Kinetics Of ◽  
Tube Study

The reaction kinetics of ground state Si atoms was studied behind reflected shock waves in the presence of excess CHSi+CH↔ SiCHwith

Shock-initiated exothermic reactions. VI. The oxidation of ethylene oxide and cyclopropane

1969 ◽  
Vol 22 (7) ◽  
pp. 1355 ◽  
Author(s):  
LJ Drummond ◽  
J Kikkert
Keyword(s):  
Shock Waves ◽  
Ethylene Oxide ◽  
Shock Tube ◽  
Induction Period ◽  
Ignition Delay ◽  
Exothermic Reactions ◽  
Induction Periods ◽  
Reflected Shock ◽  
Formaldehyde Oxidation ◽  
Temperature Dependences

Mixtures of ethylene oxide or cyclopropane with oxygen and argon were ignited with reflected shock waves In a shock tube. The temperature dependences of the ignition delay and the growth of light emitted during the induction period to explosion of C2H4O-O2 mixtures indicate that the rate-controlling reaction is that of formaldehyde oxidation. The temperature dependence of induction periods for C3H6-O2 mixtures suggests that a complicated but undetermined mechanism controls the delay to ignition.

Shock tube measurements of branched alkane ignition times and OH concentration time histories

2003 ◽  
Vol 36 (2) ◽  
pp. 67-78 ◽  
Author(s):  
M. A. Oehlschlaeger ◽  
D. F. Davidson ◽  
J. T. Herbon ◽  
R. K. Hanson
Keyword(s):  
Shock Tube ◽  
Concentration Time ◽  
Time Histories ◽  
Ignition Times
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