TY - JOUR

T1 - Criticality for stabilized oblique detonation waves around spherical bodies in acetylene/oxygen/krypton mixtures

AU - Kasahara, Jiro

AU - Arai, Takakage

AU - Chiba, Shingo

AU - Takazawa, Kouki

AU - Tanahashi, Yu

AU - Matsuo, Akiko

PY - 2002

Y1 - 2002

N2 - We have experimentally studied self-sustained oblique detonation waves around projectiles as part of a fundamental investigation of the application of an oblique detonation wave engine and a high-efficiency detonation wave combustor as a power generator. In previous papers we used optical observation to clarify the fluid-dynamic structure of self-sustained oblique detonations stabilized around cone-nosed projectiles. In this study we investigated the criticality for detonation waves. The first expression of the criticality was a mean-curvature coefficient, a rate between a detonation cell width and a mean-curvature radius in which the normal velocity component was the Chapman-Jouguet (C-J) velocity, of 5.03. The mean-curvature coefficient was constant and did not depend on the type of fuel mixture (H2/O2/Ar or C2H2/O2/Ar), initial mixture pressure, projectile diameter, projectile velocity, or diluent mole fraction. We obtained a more accurate mean-curvature coefficient for stabilized oblique detonation around symmetric spherical bodies in highly krypton-diluted acetylene/oxygen mixtures that have extremely low C-J velocities. The mean-curvature coefficient of 7.8 was determined to be the most important value for stabilizing the self-sustained oblique detonation waves around multidimensional bodies. Based on experimental results obtained athigh- and low-projectile-velocity ranges, it may be concluded that a lower-velocity projectile can stabilize a self-sustained oblique detonation wave more effectively than can a higher-velocity one. In the high-projectile-velocity region, the experimental critical condition is inconsistent with Lee's detonation initiation theory. We propose a semiempirical criticality equation for the stabilization, which was the secondary expression of the criticality and identical with present and past experimental results.

AB - We have experimentally studied self-sustained oblique detonation waves around projectiles as part of a fundamental investigation of the application of an oblique detonation wave engine and a high-efficiency detonation wave combustor as a power generator. In previous papers we used optical observation to clarify the fluid-dynamic structure of self-sustained oblique detonations stabilized around cone-nosed projectiles. In this study we investigated the criticality for detonation waves. The first expression of the criticality was a mean-curvature coefficient, a rate between a detonation cell width and a mean-curvature radius in which the normal velocity component was the Chapman-Jouguet (C-J) velocity, of 5.03. The mean-curvature coefficient was constant and did not depend on the type of fuel mixture (H2/O2/Ar or C2H2/O2/Ar), initial mixture pressure, projectile diameter, projectile velocity, or diluent mole fraction. We obtained a more accurate mean-curvature coefficient for stabilized oblique detonation around symmetric spherical bodies in highly krypton-diluted acetylene/oxygen mixtures that have extremely low C-J velocities. The mean-curvature coefficient of 7.8 was determined to be the most important value for stabilizing the self-sustained oblique detonation waves around multidimensional bodies. Based on experimental results obtained athigh- and low-projectile-velocity ranges, it may be concluded that a lower-velocity projectile can stabilize a self-sustained oblique detonation wave more effectively than can a higher-velocity one. In the high-projectile-velocity region, the experimental critical condition is inconsistent with Lee's detonation initiation theory. We propose a semiempirical criticality equation for the stabilization, which was the secondary expression of the criticality and identical with present and past experimental results.

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U2 - 10.1016/S1540-7489(02)80344-3

DO - 10.1016/S1540-7489(02)80344-3

M3 - Conference article

AN - SCOPUS:0038156293

SN - 1540-7489

VL - 29

SP - 2817

EP - 2824

JO - Proceedings of the Combustion Institute

JF - Proceedings of the Combustion Institute

IS - 2

T2 - 30th International Symposium on Combustion

Y2 - 25 July 2004 through 30 July 2004

ER -