Overpressure Peak Value Research Articles

The changing law of underwater explosion shock wave parameters with hydrostatic pressure

The effects of hydrostatic pressure on shock wave parameters were analyzed by using a combination of experiments and numerical simulations in this paper. The functional relationship between the overpressure peak and hydrostatic pressure was established, and the functional expression between the slope of the linear change and the specific distance was obtained. Underwater explosion experimental data were obtained for 0.3 g Pentaerythritol Tetranitrate (PETN) under four working conditions with initial pressures of 0.1, 0.25, 0.5, and 1 MPa. The underwater explosion of 0.3 g PETN was simulated under 11 working conditions with initial pressures ranging from 0.1 to 30 MPa using ANSYS software. In the simulation, the effects of water depth on the density of the water medium and the speed of sound were considered. The accuracy of the simulation was verified in comparison with the experimental data. According to the simulation results, the overpressure peak of the shock wave (the difference between the positive shock wave pressure and hydrostatic pressure), the decay characteristic time θ, the propagation speed, the impulse, and the specific shock energy with the change rule of hydrostatic pressure can be obtained. The results show that the decay characteristic time θ, the impulse, and the specific shock energy decreased with increasing hydrostatic pressure, and the decay amount increased with increasing distance. The overpressure peak of the shock wave and propagation speed linearly change with increasing hydrostatic pressure, and as the distance increases, the increase in the overpressure peak value decreases.

A novel method for investigating the underwater explosion loads and bubble evolution

This paper presents an innovative experimental method for studying the evolution and energy output characteristics of underwater explosion bubbles. We independently constructed an experimental testing system for underwater electrical wire explosions (UEWE), in which electrodes connected to a metal wire serve as the load, and underwater explosions are initiated through instantaneous high-voltage discharge. By varying the diameter of the metal wire and configuring parallel wire arrays, we analyzed and discussed the explosion characteristic parameters and the current–voltage (I–V) signals under different conditions. The maximum bubble radius of the underwater metal wire explosion was compared with the corresponding equivalent explosive simulation results, and a numerical model for underwater metal wire explosion equivalent to explosive detonation was established. Subsequently, we discussed the characteristics of bubble generation and evolution under various conditions, clarifying the similarities and differences between wire explosions and explosive detonations. On this basis, we explored the propagation laws of shock waves and secondary pulsation waves (SPW) under different conditions. We also calculated and analyzed energy output characteristic parameters, such as shock wave energy and bubble energy. The results indicate that there are significant differences between copper wire and aluminum wire loads in UEWE. For copper wires with a diameter greater than 0.4 mm, the shock wave overpressure peak value significantly decreases, while for aluminum wires with a diameter greater than 0.5 mm, it slightly decreases. Both metals exhibit similar trends in parallel wire arrays, with the shock wave overpressure peak value initially increasing and then decreasing as the number of wires increases. Unlike underwater explosive detonations, the SPW peak value in UEWE may exceed that of the shock wave. For single wires, the SPW peak value of copper wires is generally higher than that of aluminum wires, but in wire arrays, the trend is reversed. The multi-wire parallel connection can improve the energy conversion efficiency of the shock waves. However, for bubble energy, under all conditions, a single aluminum wire with a diameter of 0.5 mm produced the maximum bubble energy, reaching 1023.1 J. These findings provide new insights into the energy features of UEWE.

Research on shock wave driving technology of methane explosion

In order to improve the driving ability of the explosion wave simulation equipment, reduce the erosion effect of condensed explosives on the explosion wave simulation equipment, improve the safety of the test process, and make better use of the meteorological detonation driving method, it is necessary to optimize the source of the shock wave load in the driving section. Based on the finite volume method of FLACS, a methane detonation driving model corresponding to the test is established to explore the feasibility of using methane as an explosion source to test the structure against explosion shock wave. A methane detonation drive test was carried out to verify the accuracy of the numerical model. Finally, an engineering model for attenuation of shock wave overpressure peak value in pipeline is established by dimensional analysis, and the model coefficient is determined by numerical simulation and test data. The results show that the blast pressure is the highest when the methane volume ratio reaches 9.5 vol% in the methane-air mixture. Simply increasing oxygen content has little effect on the peak overpressure and positive pressure duration of shock wave. In the pure oxygen environment, the detonation effect can be achieved when the volume ratio of methane to oxygen is 1:2, and the incident pressure of the shock wave is proportional to the volume of the gas cloud. When the gas cloud volume is constant, a reasonable selection of methane-oxygen mixture ratio can achieve a better detonation effect, which can effectively increase the peak overpressure of the shock wave in the test section. The research results can provide technical reference for the development of new explosion wave simulation equipment.

Experimental study on characteristics of flame propagation and pressure development evolution during methane-air explosion in different pipeline structures

A gas explosion experimental system based on a piece of 15 m-long and φ180 semi-closed wide open steel pipe was constructed. An explosion experimental study on straight pipelines and pipeline structures with different angles (45°, 90°, and 135°) was conducted. Research results demonstrated that before the turn, flame propagation speed and flame sustaining time in different pipeline structures were consistent. With the increase of the distance away from the ignition source, the flame propagation velocity increases and the flame sustaining time decreases; at the turning point, the flame velocity suddenly decreases and the flame duration increases obviously. Meanwhile, the peak value of overpressure on the lateral wall of the turning corner is greater than that on the inner wall. Among the three different angles, the peak value of overpressure on the lateral wall of 135° bend is the highest. Different pipeline structures have great influence on gas explosion overpressure and flame propagation speed. These research conclusions provide theoretical references for gas explosion resistance in coal mines.

Flame evolution and pressure dynamics of premixed stoichiometric ammonia/hydrogen/air in a closed duct

Ammonia is regarded as a promising energy carrier due to its zero-carbon emissions and its suitability for long-distance, large-scale storage, and transportation. Ammonia/hydrogen mixed combustion is an important way to solve the problem of high ignition temperature and low flame speed in the process of ammonia combustion. This study systematically investigates the evolution of flames and pressure dynamics in a closed duct for ammonia/hydrogen/air mixtures with varying hydrogen blending ratio (0–100 %). Simultaneously, the study assesses the impact of flame instability and heat release on the evolution of ammonia/hydrogen/air flames and pressure dynamics. The results show that the flame tip speed and overpressure increase with the increase of hydrogen blending ratio and initial pressure, and when the hydrogen blending ratio is more than 25 %, the growth range of flame tip speed peak and overpressure peak value increases significantly. At the same time, the flame thickness decreases after hydrogen blending, the hydrodynamic instability increases, and the degree of wrinkles on the flame surface increases, which promotes flame acceleration. The Froude number increases significantly, the influence of buoyancy instability gradually weakens, and the flame core does not undergo significant displacement. In the later stage of flame propagation, both the flame front propagation velocity and pressure show significant pulsation phenomena. The heat release calculation results show that hydrogen blending significantly increases the adiabatic flame temperature. Consistent with the evolution law of overpressure, when the hydrogen blending ratio is greater than 25 %, the net heat release increases significantly. The elementary reaction with the highest heat release rate changes from the chain termination reaction R41 to the chain termination reaction R3. The research results can provide theoretical basis and experimental data support for the formulation of safety standards during the regulation and utilization of the combustion structure of ammonia/hydrogen/air mixtures.

Effects of an Explosion-Proof Wall on Shock Wave Parameters and Safe Area Prediction

To study the influences of an explosion-proof wall on shock wave parameters, an air explosion protection experiment was performed, the time history of shock wave pressure at different positions before and after the explosion-proof wall was established, and the characteristics of shock wave impulse and dynamic pressure were analyzed. The explosion-proof working conditions of five different diffraction angles were simulated and analyzed using Autodyn software(2019R3). Results indicated the following findings. The explosion-proof wall exerted an evident attenuation effect on the explosion shock wave, but considerable pressure still existed at the top of the explosion-proof wall. Overpressure behind the wall initially increased and then decreased. The larger the diffraction angle, the faster the attenuation speed of the diffraction overpressure of the shock wave in the air behind the wall. The history curve of shock wave pressure exhibited an evident bimodal structure. The shock wave diffraction of the wall made the shock wave bimodal structure behind the wall more prominent. The characteristics of the bimodal structure behind the wall (the interval time of overpressure peak Δt was less than the normal phase time of the diffracted shock wave T+) caused the shock wave impulse to stack rapidly, significantly improving its damage capability. The peak value of dynamic pressure on the oncoming surface was approximately two times the peak value of overpressure, and the inertia of air molecules resulted in a longer positive duration of dynamic pressure than overpressure. The maximum overpressure on the ground behind the explosion-proof wall appeared at approximately two times the height of the explosion-proof wall, while the maximum overpressure in the air behind the explosion-proof wall appeared at approximately one times the height of the explosion-proof wall. The relatively safe areas on the ground and in the air behind the wall were approximately 4–4.5 times and 3.5–4 times the height of the explosion-proof wall, respectively.

Difference Analysis of Different Explosion Load Simulation Methods Based on LS-DYNA

LS-DYNA provides a variety of different explosion load simulation methods, which are widely used in the field of explosion shock. Compared with the direct application of explosion load on the structural surface, the simulation method of establishing the air domain is more complex, but it can reproduce the evolution process of the explosion flow field and consider the interaction between the shock wave and the structure. The simulation results are more consistent with the actual situation. In this paper, the four commonly used explosion load simulation methods in LS-DYNA software are compared and analyzed, and the sensitivity analysis of grid size is carried out. The differences in the results of the four explosion load simulation methods under typical explosion conditions are compared and analyzed from the aspects of explosion shock wave waveform, arrival time, overpressure peak and specific impulse. The analysis results show that the proportional detonation distance of 0.8 m/kg1/3 is the boundary point of grid sensitivity ; under the same grid size, different explosion load simulation methods have little effect on shock wave arrival time, but have obvious influence on overpressure peak value and specific impulse. It is critical to reasonably select the termination time of the low-dimensional model when using the mapping method ; method 1 and method 2 are preferred for simulation without considering the computational cost or small model size. When the model is large, method 3 and method 4 should be preferred to improve the computational efficiency.

Experimental study on pressure wave-induced explosion of different types of deposited coal dust

When the gas explosion occurs in a coal mine, the pressure wave will induce coal dust (CD) to participate in the explosion reaction, which will further expand the accident and eventually cause more serious casualties. Based on this hazard, experiments were performed on three representative types of CD with the aid of a self-built experimental pipeline for gas/CD explosion. The explosion characteristics under the condition that pressure waves entrain different CD to participate in the explosion were studied. Furthermore, the influence of volatile content in CD on the compound explosion was analyzed from a microscopic perspective. The following beneficial conclusions were obtained: The overpressure peak value and the flame propagation velocity in the compound explosion are positively correlated with the volatile content in CD. Under those three conditions, the maximum overpressure is obtained at P2 position, and obvious stratification occurs in the process of flame propagation. However, compared with the other two working conditions, the average flame propagation speed of the composite explosion system with anthracite decreased by 51.2% and 52.6%, respectively, and flame surface breaks and becomes discontinuous earlier. After the explosion, the volatile content of three kinds of CD is significantly reduced, and the volatile content of lignite, bituminous coal and anthracite is 75.6%, 75.7% and 44.7% of the industrial analysis value of raw coal, respectively. With reference to the analysis on the microscopic test results, the amount of volatile gas decomposed from volatiles determines the intensity of the homogeneous reaction in the whole combustion process, while the coke formed after the reaction determines the intensity of the non-homogeneous reaction. Therefore, the volatile content in CD is a key factor affecting CD explosion. The research results provide an important scientific and theoretical basis for the prevention, control and reduction of CD explosion disasters.

Analysis of flow field in a blast simulator combined-driven by explosive charge and compressed gas

The flow field characteristics of blast simulators with the explosive-driven method and compression-driven method have been extensively investigated; however, limited effort has been made to the flow field in blast simulators combined-driven by explosive charge and compressed gas. In this paper, the finite volume method governed by the Navier–Stokes equation based on an explosive detonation and k-omega SST turbulence equation was used to analyze the flow field characteristics of blast simulators with three kinds of drive methods, namely, explosive-driven method, compression-driven method, and combined-driven method. The results show that the numerical method could simulate the flow field characteristics of the blast simulators with the explosive-driven method and compression-driven method accurately by comparing to the experimental data. Also, the influence of air turbulence on the explosion flow field cannot be neglected in the case of long running time. It is obtained that the combined-driven method could increase the pressure peak value of shock waves and extends positive pressure duration effectively, owing to the interaction of the shock waves generated from the explosive detonation and the rarefaction wave formed by rupturing the diaphragm. The first overpressure peak value, the second overpressure peak value, and the positive pressure duration obtained by the combined-driven method of 5 kg TNT and 0.3 MPa compressed gas were 1.669 times, 2.172 times, and 2.308 times more than those obtained by the explosive-driven method of 5 kg TNT, respectively. The maximum overpressure and positive pressure duration obtained by the combined-driven method of 5 kg TNT and 0.3 MPa compressed gas were 2.56 times and 1.162 times more than those obtained by the compression-driven method of 0.3 MPa compressed gas, respectively. Moreover, various shock wave environments could be simulated by controlling the charge mass of explosive charge and the initial pressure of compressed gas.

Influence of Ground Impedance on Explosive Shock Wave Test Accuracy

Different propagation media have different effects on explosion shock wave attenuation during the propagation process. Studying the attenuation effect of dielectric impedance on shock wave pressure is of great significance to accurately measure shock wave pressure and evaluate the ammunition damage power. This study analyzes the measured shock wave overpressure peak data of TNT bare charge (60 kg) on soil, sand soil, and concrete grounds. Dimensional analysis was used to establish the medium impedance expressed by material densityρ, burst center distancer, equivalent TNT quality ω, and impedance coefficient η. Based on this, the mapping relationship between the propagation medium impedance coefficientηand the shock wave overpressure peak value was established. The test data were analyzed, and the results showed that in the same explosive environment, different ground propagation media had different impedance effects on the shock wave pressure, which is specifically expressed as ηsoil>ηsandsoil>ηconcrete; the modified calculation model of shock wave pressure established using material impedance coefficient has a fitting accuracy of 93.39% to the measured data, which can well represent the attenuation law between different ground propagation media and shock wave overpressure peak. This provides a theoretical basis and method for obtaining shock wave pressure data in explosion field and verifying validity of the test data.

Study on the Influence of Vent Shape and Blockage Ratio on the Premixed Gas Explosion in the Chamber with a Small Aspect Ratio.

Given the current situation of deflagration caused by gas leakage for domestic use and the study of the single shape of the vent, the differential change law of vent parameters on the small aspect ratio of the chamber explosion flame evolution and explosion overpressure and other effects were experimentally investigated. Based on the theory of geometric similarity, the experimental platform of a small length–diameter ratio explosion chamber was designed and built, and the premixed gas explosion experiment was carried out by changing the shape (square and rectangle) and blockage ratio (0.1, 0.3, 0.5, 0.7, and 0.9). The explosion flame structure, flame front position, flame propagation speed, explosion pressure waveform, overpressure peak value, and so on were tested and analyzed. The results showed that the blockage ratio had the most significant effect on flame propagation and explosion flame evolution. With the increase of blockage ratio, the stretching degree of the flame became more and more obvious, the flame front became sharper and sharper, and the sharp flame changed from the lower part to the upper part. The position of the flame front increased rapidly, and the steepness and peak value of explosion overpressure became larger. The oscillation of the flame propagation velocity was more violent after the turn, and the speed of propagation to the outside of the chamber gradually accelerated. In the same blockage ratio, there was a difference in the time point at which the flame propagation velocity turned under the rectangular and square shape of the vent. In blockage ratios of 0.1, 0.3, 0.5, and 0.9, the peak overpressure reduction under the shape of the blast square relative to the rectangle was 41.3, 47.9, 1.03, and 27.6%. This indicated that the explosion relief effect of the square was better than that of a rectangle. The research results can provide a reference and basis for the reasonable deployment of explosion venting and explosion decompression work.

Combustion and flame characteristics of fuel cloud induced by flow ignition

It is a typical domino phenomenon in explosion accidents that high temperature fragments from disasters fly to form a flow ignition source and penetrate into the fuel cloud to form an explosion. It is a new challenge to the field of explosion safety to reveal the ignition mechanism of gas-liquid two-phase fuel. In this study of the explosion propagation law of gas-liquid two-phase fuel in the open space, the ignition mode of flow ignition is considered. The physical process of fuel cloud transient flow and its coupling effect of explosion waves of space and time are analyzed. The influence of flow ignition velocity and fuel concentration on the premixed zone on explosion propagation is revealed. The explosion overpressure of the fuel cloud decays rapidly when it propagates outside the premixed region. The higher the ignition velocity is, the closer the overpressure peak value is to the premixed boundary. When the flow ignition velocity is 1500 m/s, the peak value of explosion overpressure can reach up to 0.88 MPa.

Study on explosion resistance process simulation and blast fracture failure of Ti[sbnd]6Al[sbnd]4V titanium alloy sheet

The application of high-strength and high-toughness titanium alloy in armour protection is increasing with its excellent properties. However, there is little research on titanium alloy in explosion protection, especially the dynamic response process under localised explosion load and finite element simulation of the explosion resistance process of titanium alloy sheet. In this paper, the deformation and fracture failure features of the 1.6 mm thick Ti6Al4V titanium alloy sheet during the blast loading process were studied by combining LS-DYNA finite element simulation and air explosion experiments. The error of the overpressure peak value of explosion shock wave between the value obtained by improved theoretical empirical formula calculation of cylindrical charge and the value obtained by numerical simulation is only 0.2%. By studying the influence of explosive shape and air domain mesh size on the overpressure value in the process of detonation wave propagation, the Structured Arbitrary Lagrangian-Eulerian (S-ALE) algorithm was selected for finite element simulation. When the air domain mesh size is 1 mm, the tensile failure criterion was introduced into the finite element simulation process. The results show that the numerical simulation results of the full-scale model and the test results were consistent. The destruction morphology of the target showed severe asymmetry. Under 50 g TNT blast load, the 1.6 mm thick Ti6Al4V titanium alloy target was damaged seriously, and the central area of the target was completely torn. The failure features were mainly petal-shaped warping tearing cracks and localised plastic deformation. The tensile stress is the main stress mode of the target failure. Therefore, dynamic tensile strength should be used as one of the selection criteria for explosion-resistant titanium alloy sheets. The target failure mode is dominated by adiabatic shear fracture.

Dynamic Multiprojectile Attack and Killing Effects of Detonation Warheads

Dynamic spatial distribution and killing characteristics of warhead fragments are important topics in the field of weapon effectiveness and protection. However, there is little research on the fragment distribution formed by continuous dynamic attacks of multiple projectiles that explode above the ground. This study analyzes spatial distributions of warhead fragments using witness boards in a rectangular target test. The results show that the fragment distribution of multiple projectiles in continuous dynamic attacks demonstrates a spatial superposition characteristic. The superimposed distribution is the sum of the distributions of two independent fragment distributions. The distribution characteristics are consistent with fragment scattering behavior. Therefore, they can be used to analyze the killing effects of multiple projectiles conveniently. The effects of falling speed, falling angle, and explosion height on the damage range of fragments were explored by a fragment spatial distribution model obtained from experiments. Analysis indicates that the prefabricated fragment distribution conformed to a spatial superposition relationship under dynamic multiprojectile continuous attacks, and the superposition obeyed fragment scattering characteristics. As the projectile falling angle increased at the explosion center, or as the falling height decreased, the positive pressure duration increased gradually. The falling speed had the greatest impact on the specific impulse of overpressure. The falling angle had the greatest impact on the peak value of overpressure. Both the falling angle and the explosion height had the greatest impact on the positive pressure acting time.

Simulation Study of Gas Explosion Propagation Law in Coal Mining Face With Different Ventilation Modes

In ventilation working face, different ventilation way is one of the important factors affecting the propagation of gas explosion shock wave. In order to study the gas explosion shock wave propagation laws in coal mining faces with different ventilation methods, using Fluent simulation software, combined with pipeline gas explosion experiments and the actual situation of gas accumulation area explosion in the corner of 415 coal face in Chenjiashan coal mine, Shaanxi Province, and on the basis of building a three-dimensional mathematical and physical model, the gas explosion simulations under Y-type and W-type ventilation methods were carried out, respectively. The results are described as follows: (1) The attenuation trend of overpressure peak value of inlet roadway 1 and working face with Y-type ventilation conforms to the power function form. Intake airway 2 and return airway have the same peak overpressure attenuation trend, but the peak value of overpressure in return airway is generally 10.6% higher than that in intake airway 2, and its attenuation rate is a process from low to high and then to low. (2) The peak attenuation trend of overpressure in intake airways 1 and 2 with W-type ventilation conforms to the form of power function, and the peak attenuation trend of overpressure in return airway conforms to the form of exponential function. The peak value of overpressure decreases with the increase in the distance from the explosion source, and its attenuation rate decreases gradually. The research results have important theoretical significance for improving the prevention of gas explosion in coal mining face with different ventilation modes.

Experimental analysis of overpressure characteristics of gasoline–air mixture explosion in multi-branch tubes

Taking the multi-branch structure pipelines common in the field of energy and chemical industry as the research object, the combined experimental pipeline was used to control the constant total length of the pipeline, and the experimental analysis was carried out on the characteristics of oil and gas explosion overpressure under different distribution forms, distribution locations, length and number of branch tubes. The results showed that: Compared with straight pipelines, multi-branch pipelines have great influence on the peak value and rise rate of overpressure. Under the relative arrangement, the maximum overpressure and the maximum overpressure rise rate are less than those of the one-line arrangement and staggered arrangement, and the time to reach the maximum overpressure and the maximum overpressure rise rate is also delayed. The relationship of the maximum explosion overpressure rising rate at different branches of the tube is as follows: far from the ignition end > near the ignition end > evenly distributed along the main tube. With the increase of branch pipe length, both the peak value of overpressure and the rise rate of the maximum overpressure show a trend of decreasing first and then increasing. When the branch length is 1.5 m, the peak value of overpressure and the rise rate are smaller than the straight pipe condition. The increase in the number of branches does not lead to a continuous increase in the peak and maximum rate of overpressure rise. When the number of branches is less than 3, the peak value and the rate of rise of the maximum overpressure increase with the increase of the number of branches, while when the number of branches is more than 3, both the peak value and the rate of rise of the maximum overpressure decrease.

Estimation of explosion overpressure associated with background leakage in natural gas pipelines

Gathered natural gas (NG) clouds caused by background leakage from buried municipal gas pipelines or those used by gas stations pose potential threats to humans and the environment. If the leaked gas cloud (GC) ignited, significant injury caused by the explosion could occur. Therefore, the influences of the outside overpressure on the outside and inside of the building should be predicted to evaluate the damage level. Moreover, when the generated explosion overpressure is calculated, it is generally assumed that the entire GC is ignited, and its shape is hemispheric, which need further study and confirmation for background leakages. In this work, the actual explosion volume of a cubic leaked NG cloud is determined by establishing a generation model for the overpressure peak value with the help of numerical simulations and experiments, and the overpressure distribution outside and inside the building is evaluated by establishing a propagation model, using numerical simulations. The results show that for a cubic NG cloud, the actual explosion volume is 0.07 times the total volume of the leaked GC, by which the peak generation can be accurately predicted with errors smaller than 15%. Considering the influences of the building on the peak, the positive and negative peak outside and inside of the building can also be evaluated with small errors, which helps to identify safe places for people facing a VCE explosion.

Performance of utility tunnels under gas explosion loads

Gas explosion accidents could lead to great losses of lives and property. Reliable prediction of structural responses under gas explosion loads is essential for developing effective technologies to mitigate the potential hazards of gas explosions. In the present study, numerical studies are conducted to investigate the performance of utility tunnels under gas explosion loads. Numerical models were developed by using LS-DYNA and the accuracy of numerical models in predicting the responses of reinforced concrete (RC) structures subjected to gas explosions was verified by comparing with the testing data. Based on the verified numerical method, the numerical models of utility tunnels under gas explosion loads were established and the effects of load intensity, concrete strength, reinforcement strength and section type on the performance of utility tunnels were analyzed and discussed. It is found that the gas explosion loads with high overpressure peak value can bring about severe damage of tunnels and the failure of inner diaphragms. The influence of concrete strength is limited. Improving reinforcement strength and the confinement of slab-slab joints of the gas compartment can enhance the performance of utility tunnels under gas explosion loads effectively.

Experimental study on methane explosion characteristics with different types of porous media

Porous media has a significant effect on flame and overpressure of methane explosion. In this paper, the pore diameter and thickness of porous media are studied. Nine experimental combinations of different pore diameter and thickness on the propagation of flame and overpressure of methane explosion in a tube are analyzed. The results show that the porous media not only can suppress the explosive flame propagation, but the porous media with large pore diameter can cause deflagration and accelerate the transition of flame from laminar to turbulent. The pore diameter of the porous media mainly determines the quenching of the flame. Simply increasing the thickness of porous media may cause the flame to temporarily stop propagating, but the flame is not completely extinguished for larger pore diameter. However, the deflagration propagation speed of flame is affected by the thickness. The attenuation of overpressure by porous media is mainly reflected in reducing the duration of overpressure and the peak value of overpressure. The smaller the pore diameter, the greater the thickness, and the more remarkable the reduction in overpressure duration and peak value. Suitable pore diameter and thickness of porous media can effectively suppress flame propagation and reduce the maximum value and duration of overpressure.

Dynamic Compensation of Piezoresistive Pressure Sensor Based on Sparse Domain

In the process of transient test, due to the insufficient bandwidth of the pressure sensor, the test data is inaccurate. Firstly, based on the projection of the shock tube test signal in the sparse domain, the feature expression of the signal sample is obtained. Secondly, the problem of insufficient bandwidth is solved by inverse modeling of sensor dynamic compensation system based on swarm intelligence algorithm. In this paper, the method is used to compensate the shock tube test signals of the 85XX series pressure sensors made by the Endevco company of the United States, the working bandwidth of the sensor is widened obviously, the rise time of the pressure signal can be compensated to 12.5 μs, and the overshoot can be reduced to 8.96%. The repeatability of dynamic compensation is verified for the actual gun muzzle shock wave test data, the results show that the dynamic compensation can effectively recover the important indexes such as overpressure peak value and positive pressure action time, and the original shock wave signal is recovered from the high resonance data.