ID#: 215
Abstract Title: The Stability of High Speed Turbulent Deflagrations in Fuel-Air Mixtures in an Obstacle Field
Session Title: Premixed Turbulent Flames III
Session Date: 7/31/01
Session Start Time: 8:30 AM
Contributing Author: Chao, J.C.
Organization: McGill University
Country: Canada
Authors: Jenny Chao, John H.S. Lee
Short Abstract: In previous studies on the propagation of high speed turbulent deflagrations in obstacle fields in circular tubes, terminal flame speeds are averaged over a few tube diameters. Local velocities taken over a tube diameter are not as meaningful and fluctuate greatly since flames can jet through successive orifices at once. In the present experiment, a 30 cm x 30 cm square cross section tube with a staggered obstacle array of cylindrical rods is used to investigate the fluctuations in the local velocities of high speed turbulent deflagrations, thereby gaining more insight into the propagation mechanisms. For quasi-detonations, it is found that the fluctuations are a result of auto-explosions of quenched pockets of unreacted mixture which are formed from the failure of diffracted detonations. In less sensitive mixtures with large characteristic cell sizes, turbulence and transverse waves that are generated by the obstacles promote auto-ignition in the reaction zone.