Pressure Wave and Flame Front Positions Originating from Methane-Air Explosions in a 1m~3 Vessel with Circular Duct

摘要

Mitigation of an explosion propagating in a duct requires accurate pressure wave and flame velocity data to actuate a safety device preventing flame and pressure travel through a duct system. This study examines the rate of pressure rise along a duct system and provides correlations between pressure wave and flame front velocities with methane-air concentrations within the flammable range ignited by a 1 kJ pyrotechnic chemical ignitor under initially turbulent conditions. The experimental study was conducted in a 1 m~3 spherical explosion vessel with a high pressure injection chamber and 9.8 m 146 mm ID duct connected with a check valve. Piezoelectric pressure transducers and 200-1100 nm photodiodes were utilised to characterise the deflagration explosion pressure profiles and flame (by emitted light) velocities. High turbulence scenarios were investigated by using high pressure gas injection system moments before ignition. The maximum rate of pressure rise was higher inside the duct (194 bar.s~(-1) at 4.0 m from the ignition source) than inside the vessel (173 bar.s~(-1)) for 9.5% methane.