Detonation Initiation in a Tube via Imploding Toroidal Shock Waves

Abstract

The effectiveness of imploding waves at detonation initiation of stoichiometric ethylene-and propane-oxygennitrogen mixtures in a tube was investigated. Implosions were driven by twice-shocked gas located at the end of a shock tube, and wave strength was varied to determine the critical conditions necessary for initiation as a function of diluent concentration for each fuel. Hydrocarbon-air mixtures were not detonated due to facility limitations, however, detonations were achieved with nitrogen dilutions as large as 60 and 40% in ethylene and propane mixtures, respectively. The critical-energy input required for detonation of each dilution was then estimated using the unsteady energy equation. Blast-wave initiation theory was reviewed and the effect of tube wall proximity to the blast-wave source was considered. Estimated critical energies were found to scale better with the planar initiation energy than the spherical initiation energy, suggesting that detonation initiation was influenced by wave reflection from the tube walls.

Numerical Investigation on Detonation Control Using a Pulse Hot Jet in Supersonic Combustible Mixture

“…Ishii et al (Ishii et al, 2009) investigated experimentally detonation initiation and propagation using a hot jet in high-speed combustible flows where the Mach numbers are 0.9 and 1.2. Han et al (Han et al, 2012;Han et al, 2013) conducted experiments of detonation initiation and deflagration to detonation transition (DDT) using a hot jet in supersonic combustible mixtures with the Mach number above 4.0, and detonations A c c e p t e d M a n u s c r i p t 3 were initiated exactly through shocks or shock reflections (Gamezo et al, 2008;Jackson and Shepherd, 2008;Gavilanes et al, 2011;Gavilanes et al, 2013;Chaumeix et al, 2014;Liu et al, 2015).…”

Adaptive simulations of cavity-based detonation in supersonic hydrogen–oxygen mixture

“…Han et al [14] [15] studied detonation initiation and DDT process using a hot jet experimentally in supersonic hydrogen-air mixtures with Mach numbers 3 and 4, where detonations were initiated through shocks or shock reflections [16][17][18][19][20] on the walls induced by the hot jet. A series of simulations on detonation combustion in straight channels with a hot jet initiation in supersonic hydrogen-oxygen mixtures were conducted by Cai et al [21][22][23][24][25] and Liang et al [26] , where the SAMR (Structured Adaptive Mesh Refinement) framework [27] based open-source program AMROC [28][29][30][31][32] (Adaptive Mesh Refinement Object-oriented C++) is utilized.…”

Influence of Channel Width on Cylindrical Detonation Wave Propagation

“…Typical methods involve the use of shock-reflection and shock-focusing devices. [14][15][16] or a cone-shaped exit with a gradual area change that reduces lateral expansion. [17][18][19][20] To enhance the transmission efficiency of the pre-detonator, a combination method using a "reflector" and "overfilling" of the driver gas was proposed in references 21) and 22), as shown in Fig.…”