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Proposes an effective nondimensional parameter, referred to as the first Damkohler parameter, to quantitatively classify the unsteady flow regime of shock-induced combustion around a hypervelocity spherical projectile. Development of a prediction method; Computational study for validation; Results of the study.

Studies the flow features of an unsteady shock-induced combustion around projectiles using a series of simulations of an oxygen-hydrogen reaction mechanism. Mechanism of the unsteady combustion around hypersonic projectiles; Characterization of the combustion; Mechanism of the wave interaction on the stagnation streamline; Mechanisms for the large-disturbance regime.

Gas dynamics in a simplified pulse detonation engine (PDE) was theoretically analyzed. A PDE was simplified as a straight tube with a fixed cross section. One end of the tube was closed, namely, this end was the thrust wall, and the other end was open. A detonation wave was initiated at the closed end and simultaneously started to propagate toward the open end. When the detonation wave broke out from the open end, a rarefaction wave started to propagate from the open end toward the closed end. This rarefaction wave was reflected by the closed end. By considering this rarefaction wave to be self-similar in the analysis of the interference between this rarefaction wave and its reflection from the closed end, we analytically formulated the decay portion of the pressure history at the closed end (thrust wall) without any empirical parameters. By integrating the obtained pressure history at the thrust wall with respect to time, important performance parameters of a PDE were also formulated. The obtained formulas were compared with numerical and experimental results and agreed with them very well. [ABSTRACT FROM AUTHOR]