Experimental Study On The Influence Of Perforated Plate On Supersonic Combustion Wave Propagation Characteristics In The Tube

As traditional energy consumption intensifies,the search for alternative energy has increasingly become the only way to develop.Hydrogen energy has the characteristics of multiple production methods,clean combustion products,and no pollution.It has been widely concerned by the international community.However,the low ignition energy and wide ignition limit of hydrogen also bring huge hidden dangers.Hydrogen leakage may cause serious explosion accidents,so hydrogen safety issue becomes the key to the large-scale application of hydrogen energy.Pipeline transportation is one of the ways hydrogen is transported.Once ignited,the gas flame may spread throughout the pipe network.Therefore,a flame arrester is used in a pipeline to avoid the risk of explosion,and a perforated plate is a commonly used flame arrester structure.Previous studies have shown that the flame arrester has a noticeable suppression effect on lower flame speed,but whether it is adequate to suppress supersonic flame propagation still needs further verification.In particular,there are few studies about the influence of perforated plate parameters on the suppression of supersonic flame and the change of flame propagation patterns in the upstream and downstream perforated plate.In this paper,the supersonic combustion wave is subdivided into fast flame and detonation.The influence of perforated plates on fast flame and detonation propagation characteristics is investigated.This paper establishes an experimental platform for supersonic combustion wave damping by a perforated plate.The geometric parameters of the perforated plate and the type of combustible gas are considered in the experimental study.Soot foils were employed to record the triple-point trajectory of a detonation through the perforated plate.Pressure transducers were used to measure the shock time-of-arrival,based on which average velocity was derived.Five modes of propagation were observed: fast flame to fast flame,fast flame to detonation,overdriven detonation to detonation,detonation to fast flame,and detonation to re-initiate detonation.When there is a steady fast flame upstream of the perforated plate,the perforated plate can inhibit and promote fast flame,which is up to the geometric parameters of the perforated plate and the gas reactivity.The perforated plate can inhibit fast flame for the combustible gas with low reactivity(low initial pressure).That is the downstream velocity of the perforated plate decreases.The inhibition effect is strengthened with the increase of perforated plate thickness and blockage ratio.However,the perforated plate disturbs the fast flame to increase the reaction rate and form detonation at a certain distance downstream for the combustible gas with high reactivity.The onset of detonation is affected by the perforated plate parameters.The larger the hole diameter,the smaller the critical initial pressure.When premixed gas formed detonation upstream of the perforated plate,the perforated plate had an inhibition effect on detonation.When the stable detonation passes through the perforated plate,the detonation wave front is killed,resulting in the decoupling of the leading shock and the reaction zone,a fast flame.However,experiments observe that fast flame initiates again after a specific distance induction.This process is affected by the coupling of the initial gas pressure and the geometric parameters of the perforated plate.Generally,the stronger the decoupled leading shock is,the more likely it is to reignite.Therefore,once the initial pressure is reduced and the thickness and blockage ratio of the perforated plate increases,the leading shock is weaker,and the reignite is more complicated.The re-initiate detonation distance also confirmed the mechanism;with the rise of initial pressure and holes diameter and the thickness decrease,then re-initiate detonation distance decreases.At the same time,another phenomenon is observed.While deflagration is to transit into detonation just close to the upstream wall of the perforated plate,it passes through the perforated plate in an overdriven state.The overdriven detonation can pass through the perforated plate without decoupling once the holes diameter is larger than a critical value.By analyzing the statistical data of hole diameter and overdriven detonation cell,it is found that the crucial criterion in overdriven detonation successfully through the perforated plate is d/λ>2.29,slightly greater than Peraldi’s criterion(d/λ>1).To prove the applicability of the criterion,by increasing the initial pressure(decreasing λ),the stable detonation formed in the perforated plate upstream reaches d/λ=2.However,steady detonation still decouples in the perforated plate downstream.Therefore,no decoupling occurs when detonation passes through the perforated plate,requiring the detonation to be overdriven and d/λ>2.29.