Numerical investigation on detonation initiation using toroidal shock wave focusing

Shock wave focusing was considered to be a potential alternative method to initiate detonation wave in detonation-based propulsion system. A two-dimensional numerical investigation was carried out for hydrogen-air mixtures. Toroidal shock wave formation and detonation initiation by shock wave focusing were analyzed. Besides, considering the flame accelerating zone width and length are potential geometric factors affecting detonation initiation. Effects of different structural parameters on jet intensity and shock wave focusing detonation initiation process were compared. The numerical results indicated that flame acceleration is the critical factor determining toroidal shock wave formation. One possible mechanism of rapid detonation initiation is that shock waves produced by two explosions can compress premixed gas rapidly, and accelerate the deflagration to detonation transition. In addition, with the increase of flame acceleration zone width, two explosion pressures decrease, as a result, the detonation initiation time and distance increase. When the flame accelerating zone width is 1 mm, the time and distance are 380 mu s and 28.85 mm, which are the shortest. With the increase of flame acceleration zone length, two explosion pressures increase, the detonation initiation time and distance decrease. When the flame acceleration zone length is 140 mm, the shortest initiation time and distance are 30 mm and 382 mu s respectively. (C) 2019 Elsevier Masson SAS. All rights reserved.