Investigation initiation, transition and extinction of detonation instability

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I investigated initiation, transition and extinction of detonation instability.One of the studies aimed at revealing the unsteadiness of one-dimensional unsteady detonation wave front and the explosion nature behind the shock wave. Based on the results of numerical study of one-dimensional unsteady detonation. I investigated an analogy between one-dimensional piston-supported unsteady detonations and two-dimensional wedge-induced steady oblique detonations, and the analogy was applied to a prediction of the wave structure of the wedge-induced steady oblique detonation. The detailed features of one-dimensional detonation were indicated. A one-step chemical reaction obeying an Arrhenius rate expression and 19 forward and backward chemical reactions for hydrogen-oxygen combustion mechanism were used. The unsteadiness of the detonation wave front and the features of the explosion behind the shock were investigated using each reaction model. When the detailed chemical reaction model was used, the induction region can be reproduced regardless of gas conditions. Furthermore, the features related to the second explosion limit appeared in the flow field because the detailed chemical reaction model can reproduce the production and deactivation of OH radical.The other of the studies revealed the characteristics of longitudinal oscillations due to the interaction between the shock front and the reaction front. One- and two-dimensional detonation simulations were performed with a simplified reaction mechanism to compare their oscillations. I have treated two-dimensional detonations with a detailed reaction mechanism to clarify the characteristics of transverse oscillations that play a prominent rule in detonation propagation. According to the results, transverse wave intensity was newly proposed for a guide to understand the mixture properties. It gave us the insight into control of detonation in safety engineering, and application in aerospace engineering.