The Effect Of Porous Structure On Flame Velocity And Pressure In Pipes

Research on the propagation of premixed gas flame in pipeline can provide new methods and experimental basis for the suppression of combustion and explosion of gas in pipeline and the design and application of flame arresters. In this paper, experimental investigation into flame velocity, pressure, impulse and destroy ranking in pipeline with porous materials lining was conducted in order to study the propagation mechanism and restrain conditions. It is important for the design and application of flame arresters and deflagration suppression of gas in pipeline or unconfined space. The main work and conclusions in this paper are as follow:1) Experimental system of pipeline combustion and explosion was improved. The system matched with high frequency data acquisition system can get the flame propagation velocity and pressure of five points at the same time. The premixed gas distribution system was established and the tightness and the production method of supporting skeleton of porous materials were improved. Set the porous materials region in pipeline without changing of cross sectional area by changing the diameter of part pipeline.2) The propagation and suppression of propane/air premixed gas in pipeline was experimentally investigated with 5.5% volume fraction of propane, latm of initial pressure of the premixed gas in pipeline and end opening ignittion to research the suppression effect of the porous material with different geometric structures.3) The effects of obstacle and porous material on flame velocity and pressure in pipes were compared in order to illustrate the turbulent disturbance action of variable cross-section, the role of absorbing waves and the effect of the cold wall. Along with the increase of porous materials length, the suppression effect is enhanced.4) In the case that useing porous materials to replace a part of rigid wall, investigation into the propagation of the premixed flame without turbulent disturbance action was conducted. Along with the increase of porous materials length, the outletting flame propagation velocity decreases. The pressure drop along the direction of flame propagation drops when the length is more than 600mm,5) According to the pressure-impulse criterion, the effect of porous materials on the abilities of impact and destroy of pressure wave was researched, evaluating the suppression ability of porous materials. When there is nothing in the pipeline, the destroy ranking of outlet pressure wave is level 2; after adding obstacles, the destroy ranking is up to level 3 or level 4; when adding the lined porous region, the destroy ranking declines; when using porous materials to replace a part of rigid wall, the destroy ranking decreases faster; when the length of porous region is larger than 600mm, the specific impulse of outlet pressure wave become less than the static parameters, causing almost no damage.