Overpressure Values Research Articles

Experimental validation study of equivalent bare charge calculation model for two shelled warheads

After the explosion of the warhead shell fragments will consume a portion of the charge release energy, a method of calculating the shockwave overpressure value of the explosion of the warhead is to calculate the shockwave overpressure value by firstly converting the actual charge C of the warhead into the charge CEB of the bare charge, and then converting CEB into TNT equivalent. Experimental results were used to compare the calculation error size of the two models for calculating the equivalent bare charge of the warhead, and the results show that the calculation results of Chi Jiachun's modified model are in better conformity with the experimental results; by analyzing the influence of the empirical constant in Chi Jiachun's modified model on the calculation results, the value of the empirical constant is given as a suggestion.

Experimental investigation on the development characteristics of high-pressure hydrogen jet flame under different ignition conditions

With the rapid development and application of hydrogen in the chemical and energy industry, the safety of hydrogen industrial facilities has been widely concerned. In this study, the safety of hydrogen accidently released from a high-pressure tube storage system (tube diameter:10 mm, storage tank volume:4 L) was explored experimentally. The combustion behavior of the transient hydrogen jet and explosion overpressure under self-ignition and electric spark induction were investigated. Besides, the explosion overpressure and jet flame evolution laws of the hydrogen cloud induced by the release of unsteady turbulent hydrogen jets into the open environment were analyzed. The results revealed that the peak value of hydrogen self-ignition explosion overpressure was higher than that of electric spark ignition overpressure. Compared with spark ignition, hydrogen self-ignition flame structures can be maintained for longer time. However, spark ignition at low release pressures was more likely to cause hydrogen ignition and explosion compared to self-ignition. Finally, the combustion behavior and potential hazards of the ignited free transient hydrogen jet under different ignition modes were analyzed. This study can provide a reference for the prevention and control of hydrogen explosion accidents in practice.

Fuelling the Future with Safe Hydrogen Transportation Through Natural Gas Pipelines: A Quantitative Risk Assessment Approach

The global transition to clean and sustainable energy sources has sparked interest in hydrogen as a potential solution to reduce greenhouse gas emissions. Efficient and safe transportation of hydrogen is crucial for its integration into the energy network. One approach is utilizing existing natural gas infrastructure, but it introduces unique challenges. Hydrogen has distinct characteristics that pose potential hazards, requiring careful consideration for safe transportation through natural gas pipelines. Moreover, the absence of field data on component failure rates adds to the existing uncertainty in Quantitative Risk Assessment (QRA) for hydrogen transportation. QRA plays a vital role in enabling the safe deployment of hydrogen transportation through existing pipelines and is increasingly integrated into the permitting process. The lack of data impedes the comprehensive understanding of risks associated with hydrogen transportation. This paper aims not only to analyse the effects of hydrogen blending ratios on gas dispersion, release rates, jet fires, and explosions in natural gas pipelines, but also highlight the disparities in leak frequencies currently used for hydrogen or blended hydrogen. A QRA for hydrogen blending in natural gas pipelines is novel and timely because the behaviour of hydrogen in natural gas pipelines, a novel process with potential hazards, is not fully understood. Conducting a thorough QRA on hydrogen blending in gas pipelines, our study reveals innovative insights: higher blending ratios reduce release rates, impact safe distances, and maintain stable flame lengths. Despite an elevated explosion risk, scenarios remained below lethal overpressure values. This paper offers unique contributions to safety considerations in hydrogen transportation, guiding stakeholders toward informed decisions for a secure and sustainable energy future.

Evaluating evidence supporting the relevancy of 4 psi as a blast overpressure value associated with brain health and performance outcomes following low-level blast overpressure exposure

Evaluating evidence supporting the relevancy of 4 psi as a blast overpressure value associated with brain health and performance outcomes following low-level blast overpressure exposure

Dyke to sill deflection in the shallow heterogeneous crust during glacier retreat: part II

Changes from dyke to sill propagation in the shallow crust are often caused by dissimilar layer properties. However, most previous studies have not considered the influence of glacial loading and unloading on dyke and sill deflection processes. Here, we attempt to collectively explore mechanical (layer stiffness) and geometrical (dyke dip, layer thickness) realistic parameters subject to two different magma overpressure values (namely 5 MPa and 10 MPa) that promote dyke-sill transitions in both non-glacial and glacial settings. To do this, we use as a field example, the Stardalur laccolith: a multiple stacked-sill intrusion located in SW Iceland. The laccolith lies near the retreating Langjökull glacier and was emplaced at the contact between a stiff lava layer and a soft hyaloclastite layer. We initially model two different stratigraphic crustal segments (stratigraphy a and b) and perform sensitivity analyses to investigate the likely contact opening due to the Cook-Gordon debonding and delamination mechanism under different loading conditions: magma overpressure, regional horizontal extension, glacial vertical load and a thin elastic layer at the stratigraphic contact. Our results show that contact opening (delamination) occurs in both non-glacial and glacial settings when the dissimilar mechanical contact is weak (low shear and tensile stress, zero tensile strength). In non-glacial settings, stiff layers (e.g., lavas) concentrate more tensile stress than soft layers (e.g., hyaloclastites/breccia) but accommodate less total (x–y) displacement than the surrounding host rock (e.g., soft hyaloclastites) in the vicinity of a dyke tip. Yet, a thicker hyaloclastite layer in the stratigraphy, subject to higher magma overpressure (Po = 10 MPa), may encourage dyke-sill transitions. Instead, in glacial domains, the stress conditions imposed by the variable vertical pressure of the ice cap result in higher tensile stress accumulation and displacement in stiff layers which they primarily control sill emplacement.

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.

Overpressure Estimation Based on Velocity Data Analysis in The Subduction Zone of Hyuga-nada at Western Nankai Trough, Japan

Subduction zone is one of the areas which has great potential of earthquake. Nankai trough in Japan is such an area with subduction zone where earthquake records are well archived, despite its complexity. Also, slow earthquakes have been detected in this zone over the past 20 years, so that there are many opportunities to understand the dynamics and deformation in such an active setting. To expand the knowledge about slow earthquake which might occur and trigger a bigger earthquake, this study wants to infer the relationship between overpressure, one of the states and properties of seismogenic zone, and tremors. To carry out this research, 4 velocity models of seismicity line taken in Hyuga-nada are used. And the recorded tremor data placed around the lines came from Yamashita. In correlating the overpressure and tremors, this research is started by converting the Vp model to porosity model using Wyllie equation to predict the pore pressure conditions in the area. Then, the model will be used for fitting the actual data. Assuming there is an exact location following the normal compaction curve as a function of effective stress, it can be used for estimating the overpressure. Overpressure is economized by comparing the observed porosity and the reference curve at the same depth below seafloor. Potential overpressure occurred may be associated with areas of low Vp. The estimated overpressure is in the range of 1.2 to 12 MPa in the depth range of 700 to 4000mbsf. This study also concludes that the overpressure zone overlaps with the tremor location, although the overpressure value estimated is also still uncertain due to the uncertainty of the density value used.

Numerical Evaluation of Harmful Consequences after Accidental Explosion at a Hydrogen Filling Station

Abstract This study aims to present computational technology that can be used to evaluate numerically the harmful environmental consequences caused by an accidental hydrogen release from failed high-pressure dispensing cylinders and its explosion at a vehicle hydrogen filling station. A coupled problem of a hydrogen explosion products expansion in the atmospheric ground layer and a harmful explosion pressure wave shock impact on service personnel and infrastructure buildings at an accident site is solved by means of computer experiment simulation series. A spatial time-dependent model of compressible hydrogen-air mixture flow is used to obtain pressure history in calculation area in order to assess maximum overpressure in control points of human possible locations and on building surfaces exposed to hydrogen blast wave impact. A deterministic impact consequences model is based on comparing maximum overpressure values extracted from the mathematical model with threshold ranges corresponding to certain degrees of human damage and infrastructure destruction. The presented computer technology allows safety experts to identify potentially dangerous zones by means of mathematical modelling and recommend effective protection measures to mitigate negative consequences of explosions.

Numerical analysis of the effect of ventilation door on the propagation characteristics of gas explosion shock waves

Ventilation door are commonly found in tunnels and other underground engineering ventilation structures, disaster periods using its explosion isolation, explosion relief, wind regulation characteristics for disaster prevention and mitigation is of great significance. This paper numerically simulates the propagation characteristics of the gas explosion shock wave in the nearby tunnel when the ventilation door are opened at different degrees, and analyzes the influence mechanism of the opening degree on the change law of the shock wave overpressure distribution in the nearby tunnel. The results show that the shock wave forms a strong turbulence area (high pressure area) on both sides in front of the ventilation door, and the area range and the overpressure value decrease with the increase of the opening degree; the ventilation door reduce the intensity of the shock wave, so that the overpressure behind the ventilation door decreases, and the smaller the opening degree, the lower the overpressure behind the ventilation door. The secondary explosion formed shock wave and the ventilation door reflected shock wave meet to form a stronger shock wave, which leads to different opening degrees of ventilation door, its before, after the roadway and after the bifurcation of the main roadway in the measured points of the overpressure change curve is different, the main difference is that the peak overpressure for the first wave or the second wave peak. The peak overpressure in the tunnel before and after the ventilation door decreases and increases respectively with the increase of the opening length, and the overall decay of the peak overpressure at 5 m and 10 m before the ventilation door is 49.56% and 4.04% respectively and only has an effect on the peak overpressure in main tunnel within 20 m from the bifurcation.

Large-scale transient simulation for consequence analysis of hydrogen-doped natural gas leakage and explosion accidents

Transporting blended hydrogen natural gas through existing natural gas pipeline networks is an important strategy for meeting the growing demand for hydrogen energy. However, gas leakage poses a serious safety concern. This study conducts a large-scale simulation of gas leakage and explosion accidents in a hydrogen-doped natural gas station and aims to evaluate the impact of pipeline pressure and leakage direction on the accident consequences. Simulation results indicated that the high pipeline pressure led to more accumulated flammable gas, which caused severer explosion disasters. Within the 100s simulation period, the cumulative volume of the flammable gas cloud reached 2329.80 m3 under 4 MPa pipeline pressure, and the peak explosion overpressure increased by 69.64% compared with the 1 MPa case. Leakage directions also significantly affect the evolution of accidents. Suppose the leakage direction is towards living areas, flammable gas is more likely to accumulate in confined spaces up to 2363.20 m3. The gas explosion will severely damage the building structure with a 17 kPa explosion overpressure and 7 kPa shock wave intensity. Interaction with wind and the disturbance of obstacles also contributed to the flammable gas cloud accumulation, which increased peak values of explosive overpressure.

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.

Mechanism Analysis of Airbag Explosion Suppression and Energy Absorption in a Flexible Explosion Suppression System

The unfixed flame propagation velocity of a gas explosion and the fixed response time of explosion suppression devices are the important reasons for the poor protective effect of active explosion suppression. A flexible explosion suppression method based on buffer energy absorption is detailed in this study. The explosion suppression system consists of an explosive characteristic monitoring system, an explosion suppression agent system, and an explosion suppression airbag. An empty pipe experiment and an explosion suppression experiment with a flexible-airbag gas-explosion suppression device were conducted in a 20.5 m-long pipe with an inner diameter of 180 mm. The flame propagation velocity and maximum overpressure values were compared between the two groups of experiments. The experimental results show that the flame wave propagation can be completely suppressed by the explosion suppression device under certain pressure. The occurrence time of maximum overpressure at each pressure measuring point is also analyzed. P3 is generally later than P4, which verifies the existence of energy absorption and explosion suppression effect of airbag. Finally, the energy absorption effect of the airbag is analyzed theoretically. The shock wave overpressure calculated in the sealing limit state of the airbag is 0.3432 MPa, and the maximum error is 7.8%, which provides reliable guidance and prediction for the experimental process in the future.

Effects of H2 addition on the instability characteristics of CO/air and CH4/air in a horizontal narrow channel

ABSTRACT This paper investigates the instability characteristics of CO/H2/air and CH4/H2/air mixtures in a narrow channel under standard temperature and pressure conditions. The CO/H2 mixture exhibits a greater overpressure growth rate and maximum explosion overpressure as compared to the CH4/H2 mixture at the same hydrogen content. As the hydrogen content increases, the maximum explosion overpressure (P max) value increases, while the corresponding time (θ) value gradually decreases. The maximum explosion overpressure of CH4/H2 and CO/H2 mixtures is 28.27 kPa and 25.09 kPa, respectively. The flame wrinkles to form cells due to the Darius-Landau instability, and the interaction between the vortex tube and premixed flame affects the structure of turbulent premixed combustion. The oscillation frequency of the overpressure increases with increasing hydrogen content, and the oscillation belongs to the Helmholtz oscillation. The CO/H2 mixtures exhibit greater flame thickness than CH4/H2 mixtures, resulting in lower Peclet numbers and therefore greater relative importance of heat losses. As the hydrogen content increases, the sensitivity coefficient of R99 (OH + CO <=> H + CO2) in the CO/H2 mixture gradually decreases, while the sensitivity coefficients of R38 (H + O2 <=> O + OH) and R84 (OH + H2 <=> H + H2O) increase. The elementary reaction R38 plays a leading role in increasing the laminar burning velocity of the CH4/H2 mixture. The trend of R38 variation in the two mixtures is opposite with increasing hydrogen content.

Hydraulic Conditions in Foul Water Stacks

Foul water stacks are a separate chapter in the design of sanitary installations, especially in high-rise buildings. The problematic part is the complicated hydraulic conditions in the stacks, which lead to high values of negative pressure and overpressure. Exceeding the maximum negative pressure values leads to the extraction of water from the traps, which causes the spread of annoying smells in the interior. Another problematic part is the high hydraulic jumps caused by a sudden change in the velocity of water in the stack, especially above the change in the direction of stacks. Such sudden changes in velocity cause excessive vibrations and noise that spread from stacks to the building structures and surrounding areas. The contribution deals with the issue of hydraulic conditions in the flow of foul water in stacks, assessment of the maximum values of negative pressure and overpressure, technical solutions that ensure optimal water flow in the drainage systems of buildings. Based on measurements that were performed in companies abroad, the authors prepared graphs of pressure fluctuations in stacks for selected boundary conditions.

The TNO multi-energy method combined to mathematical programming and computational fluid dynamics for optimisation of gas detectors

Gas leakage is a matter of concern for several industries such as oil and gas, mining, food, and healthcare. When the industry considers gas detectors, the main questions are: How many gas detectors are required? Where is the best location to install them? To answer these questions Computational Fluid Dynamics (CFD) simulations and optimisation procedures are employed to calculate the plume location and plume volume to better position the gas detectors. We investigated how the optimisation cell size for the set covering problem can be calculated based on a given explosion overpressure threshold. Resorted by the multi-energy explosion model, we calculate the flammable cloud volume associated with a pre-defined overpressure value. The cloud volume is applied in the solution of the set covering problem and an optimal set for the gas detectors is obtained. The final gas detector network (number and location of the devices) is validated against CFD simulations for small releases. The results provide evidence that the optimal gas detector networks is able to detect gas leaks within a feasible time.

Устройство для создания защитного водоплёночного экрана от теплового излучения пожара

Introduction. A device for creating a water-film protective screen designed to protect the fireman in case of fire by significantly reducing the density of the radiant heat flux was studied by the author in this work. The proposed device, unlike analogues, does not have additional metal structures, for example, shields, while being able to create a stable liquid shield necessary to protect the fireman from the thermal radiation of a fire. By mathematical transformations, dependences are obtained for determining the thickness of the water film screen and the required value of the internal overpressure of the liquid in the device. In the course of mathematical transformations, an expression is obtained for determining the fluid pressure required for the expiration of a stable liquid film of a given thickness. Purposes and tasks. To learn how the device works. To create an experimental device to study the process of a water-film screen forming. To develop a methodology of experiments. To carry out an experiment to determine the device operating modes, depending on the fluid flow parameters. To determine experimentally the maximum value of the diameter of a continuous and stable water-film screen. To get a mathematical relationship to determine the thickness of the water-film protective screen and the value of the required overpressure of the liquid inside the device to obtain a continuous and stable screen. Methods. Natural experiment. Observation. Measurement. Description. Finding dependencies based on mathematical processing of experimental data. Results and discussion. A natural experiment was conducted. The results of research on the creation of a water-film protective screen have been obtained. The most optimal parameters of the device operation have been determined. It is established that the value of the diameter of the water film screen is 10 times greater than the value of the diameter of the channel of the device for the outflow of liquid. The use of known means of protection against the effects of radiant heat exposure contributes to a significant reduction in the distance from the point of use of fire extinguishing means to the point of fire occurrence. However, the devices used are made of heat-conducting materials, which makes it difficult to operate them as a means of protection against radiation from a thermal source of ignition at a small distance between them. In addition, the presence of metal structures reduces the possibility of using these devices when using additional fire extinguishing means. The basis for the regular operation of the proposed device for the formation and issuance of a protective liquid screen for fireman is to create a film curtain of liquid, the thickness and diameter of which is determined and regulated by the hydrodynamic operating mode and design characteristics. Conclusions. The proposed device works without additional metal structures (shields and nets), which makes it possible to use it at facilities with difficult access to an ignition source. Keywords: fire; thermal radiation; water curtain; water film; protective screen.

Monitoring of Blasting Operations Techniques and Assessment of their Impacts on Groundwater in the Context of Underground Mining: Case of ROXGOLD SANU, Burkina Faso

This study focused to study the blasting operations and to evaluate their impacts on Groundwater at the ROXGOLD SANU underground mine in Burkina Faso. ROXGOLD SANU is a mining and exploration company, under Burkinabe law and the State is a non-contributing shareholder up to 10%. The seismic vibration values measured on the ground are between 0.075 and 8.45 mm/s. These values are therefore all below the limit value of 10 mm/s defined by the Burkinabe law for mining operations carried out in quarries and mines and in compliance with the IFC standard. The values of acoustic overpressure were also all below 122 dB, i.e. below the limit value of 125 dB allowed for blasting in quarries and solid rock mines. The analysis of groundwater levels recorded since 2014 showed that the different water tables on the site do not communicate with each other. The impact of mining activities on groundwater levels is limited mainly to one piezometer. ROXGOLD SANU has therefore implemented good blasting practices, as the average values of the data collected during blasting are well below the recommended thresholds. Nitrate values measured in mine water in 2016 ranged from 7.1 mg/l to 1054 mg/l. However, in 2018 an average concentration of 484 mg/l was measured. Nitrite values ranged from 0.015 mg/l to 51.5 mg/l in 2016. In 2018, a concentration of 1.9 mg/l of nitrite was observed in the study area. As for ammonium, its concentrations measured in the field in 2016 vary from 0.08 to 145 mg/l. Thus, it emerges that the concentration values of Nitrites, Ammoniums and Nitrates measured in the field are higher than the limit of the regulations in force. These high values of Nitrites (NO3-), Ammoniums (NH4+) and Nitrates (NO2-) observed in mine water of the study area could be directly linked to the blasting operations which release nitrogen into the environment. The mine water of the study area is not dumped on the ground. It is carefully managed and controlled, in case of flooding it is sent to the TSF and does not flow into nature. Nevertheless, It is therefore important to set up a mechanism for complaints and requests from the local population to study the effects of blasting in depth.

The Pressure Resistance of Odor Traps for Sanitary Appliances and their Impact on the Hygiene of an Indoor Environment

Abstract The biggest problem with sanitary technology in high-rise buildings is the design of foul water stacks in which high negative pressure and overpressure values must not occur. When pressure exceeds maximum values, water from the trap is ejected, sucked out, or left bubbling in the trap. Measurements by other researchers have shown that when traps lose their function, in addition to the spreading of unpleasant odors, there is also the spreading of various viruses from the sewer and drainage systems. The paper deals with the mathematical analysis and simulation of the pressure resistance of different traps under various boundary conditions, considering the quality of the internal environment. The effect of water evaporation on pressure resistance was also simulated and assessed. The results of the work are clear tables of pressure resistances with a description of their effect on the water level in the trap.

Dyke-induced graben formation in a heterogeneous succession on Mt. Etna: Insights from field observations and FEM numerical models

The most common way of magma transfer towards the surface is through dyking. Dykes can generate stresses at their tips and the surrounding host rock, initiating surficial deformation, seismic activity, and graben formation. Although scientists can study active deformation and seismicity via volcano monitoring, the conditions under which dykes induce grabens during their emplacement in the shallow crust are still enigmatic. Here, we explore through FEM numerical modelling the conditions that could have been associated with dyke-induced graben formation during the 1928 fissure eruption on Mt. Etna (Italy). We use stratigraphic data of the shallow host rock successions along the western and eastern sections of the fissure that became the basis for several suites of numerical models and sensitivity tests. The layers had dissimilar mechanical properties, which allowed us to investigate the studied processes more realistically. We investigated the boundary conditions using a dyke overpressure range of 1–10 MPa and a local extensional stress field of 0.5–2 MPa. We studied the effect of field-related geometrical parameters by employing a layer thickness range of 0.1–55 m and a variable layer sequence at the existing stratigraphy. We also tested how more compliant pyroclastics, such as scoria, (if present) could have affected the accumulation of stresses around the dyke. Also, we explored how inclined sheets and vertical dykes can generate grabens at the surface. We propose that the mechanical heterogeneity of the flank succession and the local extensional stress field can largely control both the dyke path and dyke-induced graben formation regardless of the tested dyke overpressure values. Similarly, soft materials in the stratigraphy can greatly suppress the shear stresses in the vicinity of a propagating dyke, encouraging narrow grabens at the surface if only the fracturing condition is satisfied, while inclined sheets tend to form semigrabens, respectively. Finally, we provide some insights related to the structural evolution of the 1928 lateral dyking event. All the latter can be theoretically applied in similar case studies worldwide.

Study on the dynamic process of premixed hydrogen-air deflagration flame propagating in a closed space with obstacles

This paper investigates the kinetic behavior of premixed hydrogen-air deflagration flame propagation in a closed tube with different obstacle arrangements with the Large Eddy Simulation (LES) technique. Comparing the computational accuracy of four different types of turbulent flame wrinkling models, it finds that the prediction results of the dynamic wrinkling model have a high match with the experimental and theoretical values in quantitative and qualitative terms. Numerical results show that the deflagration flame propagation process in the closed barrier tube has undergone a spherical flame, finger flame, jet flame, vortex flame, and tulip-like flame, five forms of the evolution process. The obstacle center arrangement and all-around arrangement induced the maximum and minimum values of flame propagation speed and deflagration overpressure, respectively; the ratio of the first speed peak, the second speed peak, and the growth rate of overpressure were 1.46, 1.51, and 1.9 times for the two arrangements, respectively. The flame propagation process is mainly influenced by the coupling of Rayleigh-Taylor (R-T) and Kelvin-Helmholtz (K-H) instability mechanisms. Furthermore, a simplified analytical model of hydrodynamic instability is developed, and it is found that instability plays a crucial role in the deformation and acceleration of the flame front.