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CO2‐laser‐induced deflagration of fuel/oxygen mixtures

 

作者: Wayne M. Trott,  

 

期刊: Journal of Applied Physics  (AIP Available online 1983)
卷期: Volume 54, issue 1  

页码: 118-130

 

ISSN:0021-8979

 

年代: 1983

 

DOI:10.1063/1.331737

 

出版商: AIP

 

数据来源: AIP

 

摘要:

Weakly focused pulsed‐CO2‐laser radiation has been examined as an ignition source for low‐pressure (85–100 Torr), near‐stoichiometric fuel/oxygen mixtures containing the following fuels: ethylene, methyl fluoride, methanol, ethanol, dimethyl ether,p‐dioxane,n‐propyl nitrate, and iso‐propyl nitrate. The data analysis includes characterization of the spatially dependent ir absorption in the test cell, calculation of appropriate medium temperatures from the absorbed laser energy, and correlation of observed ignition delay timestigwith the calculated temperatures. Effects of hydrodynamic motion on the pressure, density, and temperature profiles of the irradiated samples were modeled using a computer code for two‐dimensional wave propagation. Code predictions are in accordance with experimental pressure‐time histories obtained using a piezoelectric transducer. Minimum ignition temperatures ranged from 590 K for the iso‐propyl nitrate/O2system to 1645 K for CH3F/O2. The observed functional relationship betweentigand temperatureTwas generally of the form ln tig=A/T+B, whereAandBare constants. This relationship follows the form predicted by thermal and degenerate chain ignition theories, viz., ln tig=Eact/RT+constant, whereEactcorresponds to an overall activation energy. Using this relation, derived activation energies are 86, 57, 42, 47, ∼40, 13, and 12 kcal/mole for the CH3F/O2, CH3OCH3/O2, CH3OH/O2, C2H5OH/O2, C4H8O2/O2,n‐propyl nitrate/O2, and iso‐propyl nitrate/O2mixtures, respectively. These results are in reasonable agreement with available data from shock‐tube and hot air stream injection techniques. In contrast, an anomalous, threshold‐like effect was observed for laser ignition of C2H4/O2. The applicability of ignition schemes of this type to time‐resolved kinetic spectroscopic studies is briefly discussed.

 

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