Numerical Study of Formation of a Detonation Wave in a Supersonic Flow over a Wedge by an H2-O2 Mixture with Nonequilibrium Excitation of Molecular Vibrations of Reagents

Abstract

Specific features of formation of an oblique detonation wave in a supersonic hydrogenoxygen mixture flow over a plane wedge are analyzed. Preliminary excitation of molecular vibrations of H 2 is shown to lead to a noticeable (severalfold) decrease in the induction-zone length and the distance at which the detonation wave is formed. These effects are manifested even if H 2 molecules are excited in a narrow region in the vicinity of the flow centerline. The reason for these effects is intensification of chain reactions in the H 2 -O 2 (air) mixture owing to the presence of vibrationally excited hydrogen molecules in the flow.

Plasma-assisted ignition and combustion

“…Work [Light& Matsumoto, 1978] gives an experimental estimation for ratio of the rate constants of processes OH + H 2 (v=0)  H 2 O + H and OH + H 2 (v=1)  H 2 O + H: k v=1 /k v=0 ≤ 1000 at T=298 K, which is in good agreement with the estimation by model [Zatsepin et al, 2001] shows the oxidation rate increase in H 2 -air mixture at T = 300K in 3-5 times. As an example of possible applications of vibrational excitation of the flow we will mention the paper [Bezgin et al, 2006]. Peculiarities of an oblique detonation wave formation in a supersonic hydrogen-oxygen mixture flow over a plane wedge were numerically analyzed.…”

“…It was demonstrated that the reason for these effects was an intensification of chain reactions in the H 2 -O 2 (air) mixture owing to the presence of vibrationally excited hydrogen molecules in the flow [Bezgin et al, 2006].…”

On the role of excited species in hydrogen combustion

“…It will hardly survive between ozone generator and combustion zone, yet pertinent reactions are included in the model for completeness since it can also be formed in reactions of non-excited radicals. Specifically, reaction between hydrogen atoms and hydroperoxyl radicals has several channels H + HO 2 = OH + OH (12) H + HO 2 = H 2 + O 2 (-14) H + HO 2 = H 2 + O 2 (1 ) (-31) H + HO 2 = H 2 O + O (-13) H + HO 2 = H 2 O + O(1D) (39) Theoretical studies of Karkach and Osherov [62], of Mousavipour and Saheb [74] and of Burke et al [54] revealed that atomic oxygen can be formed in a ground state (reaction (-13)) or in excited state via reaction (39). These channels, however, are minor and their role is still disputable.…”

Plasma-assisted ignition and deflagration-to-detonation transition

“…Preliminary excitation of molecular vibrations of H 2 was shown to lead to a noticeable decrease in the induction-zone length and the distance at which the detonation wave was formed. It was demonstrated that the reason for these effects was an intensification of chain reactions in the H 2 -O 2 (air) mixture, owing to the presence of vibrationally excited hydrogen molecules in the flow [28].…”