Study Of Hydrogen Detonation Suppression Mechanism By Inner Boundary Of Channel

Due to the energy depletion and environmental issues of fossil fuels,finding alternative clean energy is a task which brooks no delay.Hydrogen energy has increasingly attracted wide attention because of its high utilization rate,high combustion heat and zero-emission of greenhouse gases.However,due to the special characteristics of hydrogen,such as wide explosion limit,fast flame speed,low ignition energy and density,it is extremely easy to induce the deflagration and detonation with extremely high temperature and overpressure if hydrogen leakage accident occurs or air enters a hydrogen pipeline or hydrogen storage tank.Therefore,study on the suppression of deflagration and detonation is very necessary from the perspective of the safe utilization of hydrogen energy.At present,the study on the suppression of the low-speed deflagration is relatively thorough.The study on the suppression of high-speed detonation is less,and the suppression mechanism is not clear,especially for the complex boundary conditions.The detonation wave is a complicated phenomenon happening not only in the accident but also in the nature such as supernova explosions.Besides,the detonation also appears in the industrial process and propulsion system such as rotating and pulse detonation engines.The paper focuses on the detonation suppression with different inner boundaries of the channel:the suppression mechanism of the Mach reflection on the rough wedge surface,the suppression and re-initiation mechanism behind the perforated plate with high blockage rate,and the suppression mechanism of the donation on the sound absorption walls.The suppression mechanism of the hydrogen detonation has been systematically analyzed.The smoked track and schlieren technology were used to analyze the suppression mechanism of the detonation Mach reflection on the rough wedge with step-like surface.The effects of the wedge angle,the step number and the initial pressure on the Mach reflection of the detonation wave were considered,and simulation software(COM3D)was used to verify,two formation mechanisms of the Mach reflection on the rough surface of the step were presented.The Mach stem on the rough surface is weaker and the triple-point is easily deflected.The initial pressure has a more significant effect on the Mach reflection on the rough surface.Due to the horizontal step surface,the Mach stem on the rough surface is not perpendicular to the wedge surface.The three-shock theory of the smooth surface can also be used to predict the triple-point trajectory angle of Mach reflection on the rough.However,for the rough wedge,the wedge angle of the regular reflection to Mach reflection transition is dependent on the step number.The smoked track and schlieren technology were also used to analyze the suppression and re-initiation mechanism behind the perforated plate with the high blockage rate.The Chapman-Jouguet(CJ)detonation and overdriven detonation were used to collide with the perforated plate.The effects of thickness and the hole size on the cell size and downstream flow field were considered.For the CJ detonation,both the thickness and hole size have a significant effect on the critical pressure for the detonation re-initiation success(within 10D)and failure.The ratios of the hole hydraulic diameter and the critical cell size(d _H/?~*)are less than 1.The ratios increase with the thickness and the hole size except 1cm-thickness case.For the overdriven detonation,the detonation can be re-initiated quickly,and the re-initiation distances are all less than twice the tube hydraulic diameter.The re-initiation distance increases with the hole size while the thickness has little effect on the re-initiation distance.The critical condition of detonation propagation can be quantified as d _H/?~*>3.37 and 3.77 for the 3 mm-hole and 2 mm-hole perforated plates,respectivelyThe suppression mechanism of the detonation on the different sound absorption walls is focused.The different thickness of the flexible sponge materials and rigid wire brush materials were uesd to the sound absorption walls in the present paper.The conclusions show that the the detonation propagation limits on each damping wall with the various thickness are relatively uniform.The average limit values D_H/?_c are 6.12 and8.64 on the sponge and wire brush walls,respectively.The failure limit on the sponge wall appears to be dictated by the balance between the rate of transverse wave attenuation at the wall and regeneration of new transverse waves from local perturbations in the reaction zone.The failure mechanism on the wire brush wall observed experimentally is consistent with the global mass divergence mechanism leading to a curved shock front.