Study On Fire Resistance Characteristics Of Perforated Plate For Hydrogen-Air Flame In A Channel

As a kind of clean energy,hydrogen energy has the characteristics of inexhaustible and it is a hot topic in the field of energy technology.However,due to its danger,there are some safety problems to be solved in the production,storage,transportation and utilization of hydrogen energy.In the hydrogen pipeline,if the combustible gas is ignited and explodes,the flame may spread in the whole pipe network.Therefore,to avoid this danger,flame arrester is often used in the pipeline to suppress flame propagation by its characteristics.In this paper,one of the fire-resistance materials,perforated plate,is used to study its fire-resistance characteristics at the early stage of the development of hydrogen-air flame.The influence of the parameter changes of the perforated plate on the fire-resistance effect and quenching law is studied to guide the development of the key technologies of the fire-resistance of the perforated plate.To obtain the dynamic combustion process of hydrogen-air mixed gas,a quenching experimental platform was established to explore the influence of the initial pressure of mixed gas,the thickness of the perforated plate,porosity of the perforated plate and hydrogen equivalent ratio on fire resistance characteristics.The flame image was collected by the schlieren system and high-speed camera,and the pressure dynamic change in the pipeline was recorded by the pressure data acquisition system,and the flame image and pressure data were analyzed.Three modes of flame development can be observed as the hydrogen-air mixture burns to form a laminar flame and passes through the perforated plate: "Pass","Quench" and "Near limit".In the "Pass" mode,flame development goes through three stages: laminar flame,jet flame and turbulent flame.However,only laminar flames can be observed in the "Quench" mode.With the increase of initial pressure,laminar flame propagation velocity increases.If the flame passes through the perforated plate,the flame velocity increases greatly and develops into a turbulent flame.In the "Pass" mode,three pressure peaks were found in the upstream region of the perforated plate,among which P1 was caused by the slow combustion of the mixed gas,P2 was caused by the overpressure in the downstream of the perforated plate,and P3 was caused by the pressure waves reaching the end wall and reflecting the upstream region of the perforated plate.The pressure increases significantly in the downstream region,and there are only two pressure peaks,the first of which is caused by the accelerated impact of the flame,and the second pressure peak may be caused by the reflection of the pressure wave on the bottom wall surface downstream of the perforated plate.In the "Quench" mode,the pressure is almost undetectable.The peak pressure and the maximum pressure rising rate increase with the increase of the initial pressure,and the time to peak earlier.By changing the hydrogen equivalent ratio,it can be found that the flame propagation speed increases with the increase of the hydrogen equivalent ratio.In the "Pass" mode and the "Quench" mode,the pressure peak of PT1 increases with the increase of the hydrogen equivalent ratio,and the peak occurs earlier,and the maximum pressure rising rate increases.PT2 pressure peak and maximum pressure rising rate first increases then decreases,the maximum ? = 1.25.By changing the thickness of the perforated plate,it has no effect on the laminar flame propagation process in the upstream region,but in the downstream region,the increase in the thickness of the perforated plate leads to a severe rate decrease until quenching occurs.In the "Pass" mode,the pressure peak and the maximum pressure rising rate increase with the increase of the thickness of the perforated plate.By changing the porosity of the perforated plate,it can be found that the flame propagation velocity decreases with the increase of porosity.In both the "Pass" mode and the "Quench" mode,the pressure peak decreases with the increase of porosity and the amplitude of oscillation increases.After analyzing the quenching critical pressure data of different variables,it is found that when the hydrogen equivalent ratio is near 1.0,the reaction is intense,and it is not easy to be quenched.Both lean hydrogen and rich hydrogen are beneficial to quenching.The larger the thickness of the perforated plate and the smaller the porosity,the more likely it is to be quenched.