CARS and Fluorescent study of ignition of H2/O2 mixtures upon photodissociation of O2 molecular

Vitaly Kobtsev,Konstantin Vereshchagin,Valery Smirnov,Sergey Kostritsa,Sergey Volkov,Alexey Pelevkin,Sergey Torokhov,Natalia Titova,Dmitrii Kozlov,A Mebel,V Azyazov

doi:10.1051/matecconf/201820900010

Abstract

The research is devoted to gas mixtures ignition by UV laser radiation. The dissociation of O2 molecules by a pulse of excimer ArF laser radiation at 193-nm wavelength with formation of the chemically active oxygen atoms initiating chain reactions which cause ignition of H2/O2 mixture was employed. The experimental test bench was created with CARS and fluorescent techniques for experimental investigation of some peculiarities of mixture ignition and combustion caused by such photo-dissociation, at conditions typical for combustion chamber. Two-dimensional numerical modeling of combustion process in model combustion chamber, based on kinetic mechanism of H2 oxidation including atom O(1P) and radicals OH(A2Σ+), was performed.

Highlights

Among different methods of gas mixture ignition, the considerable attention is paid to the burning initiation by laser radiation
In the first column (t=0 s) are shown the images, which were registered at the moment of the UV laser radiation pulse and represent the luminescence of laser-excited O2(B3Σu-) molecules within the Schumann-Runge band in the focal area
It is evident that a total time needed for complete combustion of the mixture will be smaller in the case b) than that in the case a). It means that using the excimer laser radiation, one can ignite simultaneously a large volume of a flammable mixture

Summary

Introduction

Among different methods of gas mixture ignition, the considerable attention is paid to the burning initiation by laser radiation. In the overviews [1,2], the methods of resonant and non-resonant impact on the molecules of combustible gas mixture leading to heating, optical breakdown, photo-ionization or photo-dissociation are discussed. This work is devoted to the experimental and numerical study of temporal and space behavior of such important parameters of combustion development as temperature and concentration of radicals OH at the initial stage of ignition and combustion (~5–50 s) of H2-O2 mixture upon the photo dissociation of O2 molecules by the focused resonance laser radiation with a wavelength of 193 nm

Methods

Results

Conclusion