Advances and challenges in laminar flame experiments and implications for combustion chemistry

Laminar flow between parallel plates with injection of a reactant at high reynolds number

Counterflow diffusion flames

A comprehensive experimental and numerical study on ethanol oxidation kinetics has been conducted. The laminar flame speeds of ethanol/air mixtures were determined by using the counterflow twin-flame technique at 1 atm pressure and for initial mixture temperatures between 363 and 453 K. A detailed kinetic scheme was subsequently compiled by grafting the latest information on ethanol kinetics onto a previously developed methanol scheme, and was found to be self-consistent in that it closely predicts not only the experimental laminar flame speeds of ethanol, but also those of methane, methanol, and all the C2-hydrocarbons. Further recognizing that prediction of the laminar flame speeds is not sufficient for the satisfactory validation of a kinetic mechanism, the present scheme has also been tested against experimental data in the literature on the species and temperature profiles in flow reactors and on the ignition delay times in shock tubes. Such studies demonstrate the importance of the CH3 and HO2 radical chemistry, and the present results suggest that the rate of CH3+HO2→ CH3O+OH may be slower while that of CH3+HO2→CH4+O2 may be faster than values frequently used in recent literature.

A study on ethanol oxidation kinetics in laminar premixed flames, flow reactors, and shock tubes

Structural response of counterflow diffusion flames to strain rate variations

The opposed jet assembly has been adapted for stabilizing a counter flow diffusion flame of ethanol. Data on the thermo-aerodynamic structure of the flame, obtained with the help of interferometric and particle track techniques, have been presented and analysed to yield the heat release rate. The maximum flame temperature is found to be close to adiabatic and the net heat release is in agreement with the theoretically expected value. The luminous flame is accompanied by endothermic zones on both the fuel and oxygen sides. Mass spectromctric analysis of the flame gases is found to confirm the presence of ethanol pyrolysis on the fuel side and to point out the possibility of significant chemical reactions on the oxygen side. The observations thus tend to strengthen the earlier findings (of endothermic zones) on gaseous diffusion flames.

Structure of Counterflow Diffusion Flame of Ethanol

A ethod for stabilizing diffusion flames of liquid fuels has been described. Results are presented for the thermal structure of such a flame (of ethyl alcohol) as determined by an interferometric study.

T. P. Pandya

Papers

Structure of Counterflow Diffusion Flame of Ethanol

Technical Note OUNTERFLOW DIFFUSION FLAME OF ETHYL ALCOHOL