Chemiluminescence emissions of OH measured at different positions during flame propagation of H2/CH4 mixtures explosion

Abstract

In view of the shortcomings of the research on the chemiluminescence intensity of OH in the flame propagation process of H₂/CH₄ mixtures explosion, especially the emission of OH at different positions during the flame propagation process of H₂/CH₄ explosion. A 20 L horizontal duct was used, combined with a high-speed camera and a transient spectrum test system, to study the characteristics of chemiluminescence emissions of OH measured at different positions during flame propagation H₂/CH₄ mixtures explosion under different volume fraction of H₂(α) and different equivalence ratios(φ), and the relationship between chemiluminescence emissions and flame propagation. The experimental results show that the main wavelength of chemiluminescence emissions of OH is 308.9 nm, and its intensity is the largest and is most affected by the increase of α and φ. The large amount of afterglow emission during the convective motion of the flame flow field is an important reason why the emissions intensity at the second position is higher than at other positions. With the increase of α, the maximum emissions intensity of OH increases continuously and begins to increase abruptly at α = 0.6. When α changes, the maximum explosion pressure is closely related to the maximum emissions intensity of OH. The oscillation phenomenon increases the emissions intensity of OH at the 4th position when the explosion pressure decreases at the 2nd position, and when the explosion pressure at the 4th position decreases, the emissions intensity of OH at the 2nd position increases. The emissions of distorted 'Tulip' flame radicals mainly come from the flame front and afterglow emission, while the emissions of typical 'Tulip' flame radicals are more from afterglow emission. The research results can provide an experimental basis for the study of chemiluminescence emissions, and provide a theoretical basis for the development of targeted spraying inhibitors.