The experimental of methane-air flame propagation in the tube with quadrate cross section

摘要

The flame propagation of methane-air mixture with various methane concen-trations was experimentally investigated at venting flame acceleration tube with quad-rate cross section under different obstacles presented. The flame shape and propaga-tion speed was observed by high-speed color video camera. The explosion pressure was determined by piezoelectricity pressure transducers. The results are: The flame propagates in the shape of a hemisphere before the flame reaches the first baffle and flame propagation speed is not more than 15 m/s. When the flame propagates across the baffle, the flame begins to accelerate due to turbulence induced by obstacle. Blockage ratio has relatively greater effect on the flame propagation speed than re-peated baffle number does. The flame propagation speed and the pressure at different location along the tube are maximum when methane-air mixture is near the chemical stoichoimetric ratio. The pressure increases with the distance from ignition end at first and the maximum pressure was obtained at the middle of tube, but the pressure de-creases and again increases at venting end.