On the propagation mechanism of a detonation wave in a round tube with orifice plates

Abstract

This study deals with the investigation of the detonation propagation mechanism in a circular tube with orifice plates. Experiments were performed with hydrogen air in a 10-cm-inner-diameter tube with the second half of the tube filled with equally spaced orifice plates. A self-sustained Chapman-Jouguet (CJ) detonation wave was initiated in the smooth first half of the tube and transmitted into the orifice-plate-laden second half of the tube. The details of the propagation were obtained using the soot-foil technique. Two types of foils were used between obstacles, a wall-foil placed on the tube wall, and a flat-foil (sooted on both sides) placed horizontally across the diameter of the tube. When placed after the first orifice plate, the flat foil shows symmetric detonation wave diffraction and failure, while the wall foil shows re-initiation via multiple local hot spots created when the decoupled shock wave interacts with the tube wall. At the end of the tube, where the detonation propagated at an average velocity much lower than the theoretical CJ value, the detonation propagation is much more asymmetric with only a few hot spots on the tube wall leading to local detonation initiation. Consecutive foils also show that the detonation structure changes after each obstacle interaction. For a mixture near the detonation propagation limit, detonation re-initiation occurs at a single wall hot spot producing a patch of small detonation cells. The local overdriven detonation wave is short lived, but is sufficient to keep the global explosion front propagating. Results associated with the effect of orifice plate blockage Communicated by and spacing on the detonation propagation mechanism are also presented.

Flame quenching by crimped ribbon flame arrestor: A brief review

“…The simulations showed that hot spots are generated in obstructed tubes (both straight and bent), which is in accordance with the works reported in Ref. 59,62. More recently, Li et al [48] conducted experiments to study the incident waves for DDT in ethylene-air mixtures in an S-shaped tube.…”

“…Experimental, theoretical, and numerical studies focused on flame acceleration and DDT in smooth tubes and obstructed tubes have been performed in some previous literature [51,[53][54][55][56][57][58][59]63]. As suggested by Silvestrini et al [53], the relation between the flame velocity and position in smooth tubes follows an exponent function:…”

DDT limits of ethanol–air in an obstacles-filled tube

“…In this study, experiments were performed in a tube filled with orifice plates to obtain the DDT composition limit of ethanol-air mixtures. The tests were carried out in the same 10-cm diameter tube and 0.44 BR orifice plates used in the Ciccarelli and Cross (2016) experiment that confirmed the applicability of the DDT criterion d/λ = 1 for gaseous fuels. Using the DDT composition limits measured in this study for ethanol-air, and the DDT criterion of d/λ = 1, it is possible to determine which cell size data reported by Diakow et al (2015), i.e., small or large, should be used to predict DDT for ethanol-air mixtures.…”

“…Detonation initiation typically occurs as the result of the interaction of the lead shock wave with the obstacle face, or the tube wall (Rainsford and Ciccarelli, 2017). Ciccarelli and Cross (2016) studied the influence of the orifice blockage ratio (BR) on the DDT limit (i.e., minimum mixture composition resulting in DDT). The BR is defined as the ratio between the cross-sectional area of the tube blocked by the obstacle and the cross-sectional area of the tube; for a tube with diameter D, the BR is BR ¼ 1 À d=D ð Þ 2 .…”

Visualization of detonation propagation in a round tube equipped with repeating orifice plates

“…In this set-up, detonation propagation has been primarily classified according to average combustion front velocity derived from time-of-arrival measurements taken at regular intervals along the combustion channel [5]. More recently, sooted foils, which provide information on detonation structure, have been used inside the combustion channel between obstacles to better understand detonation propagation [6].…”