Vented deflagrations for near lean flammability limit hydrogen-air mixtures in large scale inter-connected volumes

This paper presents vented combustion data gathered in a 120 m3 large scale vented combustion test facility at the Canadian Nuclear Laboratories. Experiments were performed with single volumes (57 or 120 m3), or two (60 and 57 m3 each) and three (25, 28 and 57 m3 each) interconnected volumes using lean H2-air mixtures (6-10 vol.% H2) under the initially quiescent or turbulent conditions. The effects of scaled vent area (Av/V2/3), number of connected volumes, initial turbulence and hydrogen concentration on dynamics of vented combustion are examined. The test results show that combustion in an interconnected multi-compartment geometry could produce significant flame acceleration and local pressure build-up for mixtures containing 8 vol.% or higher H2 in air due to flame jet ignition and flame interaction between compartments, resulting in much higher overpressures than in a single volume.