Propagation of near-limit gaseous detonations in small diameter tubes

Abstract

In this study, detonation limits in very small diameter tubes are investigated to further the understanding of the near-limit detonation phenomenon. Three small diameter circular tubes of 1.8 mm, 6.3 mm, and 9.5 mm inner diameters, of 3m length, were used to permit the near-limit detonations to be observed over long distances of 300 to 1500 tube diameters. Mixtures with high argon dilution (stable) and without dilution (unstable) are used for the experiments. For stable mixtures highly diluted with argon for which instabilities are not important and where failure is due to losses only, the limit obtained experimentally is in good agreement in comparison to that computed by the quasi-steady ZND theory with flow divergence or curvature term modeling the boundary layer effects. For unstable detonations suppression of the instabilities of the cellular detonation due to boundary conditions is responsible for the failure of the detonation wave. Different near-limit propagation regimes are also observed, including the spinning and galloping mode. Based on the present experimental results, an attempt is made to study an operational criterion for the propagation limits of stable and unstable detonations.

Dynamics of hydrogen–oxygen–argon cellular detonations with a constant mean lateral strain rate

“…where µ and ρ 0 are the post-shock state viscosity and the initial density, respectively. This turbulent boundary layer displacement thickness relation has then been applied in a large number of subsequent works investigating detonation velocity deficts [5,6,9,[11][12][13][14][15]. In the present study, this relation is also adopted as one approach for evaluating the boundary layer induced mass divergence rate.…”

“…These non-ideal factors include lateral mass divergence, unsteadiness, and momentum and heat losses [1]. Extensive efforts have been made to quantitatively compare the experimentally measured velocity deficits and propagation limits with the theoretical predictions made by relatively simple models, which build up on the classical one-dimensional (1D) Zeldovich-von Neumann-Doering (ZND) model [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The multi-dimensional transient cellular structures, consisting of an intricate ensemble of interacting triple points, shear layers, and transverse waves, of the real gaseous detonations, however, greatly complicate these attempts.…”

Detonation in hydrogen–nitrous oxide–diluent mixtures: An experimental and numerical study

“…It is composed of 11 reversible chemical reactions and [50,56]. These effects can be taken into account within the framework of a steady one dimensional model by including heat transfer and friction coefficients [57,58] or a curvature term [59]. For multi-dimensional simulations, detailed consideration of boundary layer and confinement effects have to be accounted for using a highly-resolved viscous model.…”

Experimental characterization of galloping detonations in unstable mixtures

“…As the detonation limits are approached, large longitudinal fluctuations of the detonation velocity are often observed [1][2][3][4][5]. Of particular interest is the phenomenon of ''galloping detonations'' where the detonation decays from an overdriven state to a low-velocity regime, and then re-accelerates back to the overdriven state for the next cycle.…”