Flame Propagation Behavior Research Articles

Research on Gas Explosion Pressure and Flame Propagation Characteristics in Turning Pipelines.

In order to investigate the overpressure and flame propagation characteristics of gas explosions in turning pipelines, this study designed a transparent organic glass pipeline test system with different turning angles (30°, 60°, 90°, 120°, and 150°) and conducted a series of experimental studies to analyze the explosion shock wave overpressure and flame propagation behavior. The experimental results show that with the increase of the turning angle of the pipeline, the overpressure of the explosion shock wave significantly increases. In terms of flame propagation characteristics, when the turning angle is small, the flame can adhere to the outer wall of the pipeline corner and gradually fill the entire pipeline section. When the turning angle increases, the flame forms a blank area near the outer wall of the corner, and the blank area expands with the increase in the corner. In addition, the increase in the turning angle promotes the increase in the velocity of the explosion flame front. The research results of this review are of great significance for a deeper understanding of the mechanism of gas explosions in turning pipelines and evaluating their potential hazards.

Effect of airflow velocity in vessel-pipelines on dust explosion during pneumatic conveying

In order to investigate the flame propagation and pressure characteristics of dust particles during airflow transportation, a dust explosion experimental apparatus simulating dust handling processes was designed. The system is supplied with a stable airflow by a high-pressure fan, capable of continuously transferring dust from the vessel to the pipeline at a controllable speed. Dust explosion experiments were meticulously executed by applying 1 kJ of ignition energy to the transported dust particles at airflow velocities of 5, 10, and 15 m/s. This study examines the effects of airflow velocity, pipe diameter, and ignition position on explosion characteristics and delves into the mechanisms of these effects through a detailed analysis of experimental results. For the maximum explosion pressure, an increase in airflow velocity causes the maximum explosion pressure to rise. As the pipe diameter increases, the maximum explosion pressure first rises and then falls. The maximum explosion pressure occurs in the case of bottom ignition. The range of maximum explosion pressure values is expected to provide a reference for explosion detection and explosion venting. For flame propagation, the flame undergoes five processes within the vessel, including ignition of dust particles, spherical flame development, flame stretching towards the mouth of the pipe, complete combustion of particles, and near exhaustion of particle combustion. The higher the airflow velocity and the larger the pipe diameter, the more pronounced the flame stretching and development towards the pipe opening become. Within the pipe, two distinct flame propagation behaviors were observed under conditions of high and low airflow velocities. Compared with the experimental results of high-pressure pneumatic powder spraying forming a dust cloud within a vessel-pipeline, this study measures the maximum explosion pressure at specific turbulence levels and establishes a quantitative relationship between airflow velocity and explosion characteristics. Utilizing this correlation can provide a reference for predicting industrial-grade dust explosion characteristics at different airflow velocity levels, thereby offering a more optimized design basis for the design and safety protection of industrial equipment.

Construction and combustion behavior of horizontal two-dimension combustion networks of boron-metal oxides

In order to break through the top-down combustion mode brought by the traditional pillars, it is explored to explore the exploration of delay composition array construction in two-dimensional dimensions. In this study, B-CuO, B-Bi2O3, B-Fe2O3 sticks and combustion networks with good forming properties were prepared with the help of a micro-pen direct ink writing device by dispersing the above materials in DMF with boron and metal oxides as the main body of the charge and F2602 as the binder. The sticks were thermally ignited using a nichrome wire, and the flame propagation behaviors of the sticks with different formulations, spacings and heights were tracked with a high-speed camera, and a series of combustion networks were designed on the premise of not leaping into flames. Results show that the B-CuO stick has the fastest ignition speed level (19.71–29.02 mm ·s−1) at equivalence ratios of 1.0–4.0, followed by B-Bi2O3 (5.99–16.01 mm ·s−1) and B-Fe2O3 is the slowest (1.91–4.94 mm ·s−1). The sticks burned best at an equivalence ratio of 1.0–1.5. A variety of combustion networks were constructed on 50 × 50 mm glass slides by selecting B-CuO, B-Bi2O3, and B-Fe2O3 at the equivalence ratios of 1.0, 1.5, and 1.5, respectively, among which B-CuO had the shortest combustion time (5.17 s), the shortest total combustion network length (252 mm), and 400 mm network could be realized for B-Bi2O3. Construction and 19.85 s, and B-Fe2O3 can realize 608 mm network length and 130.7 s combustion time. Through these studies, the two-dimensional combustion network construction of boron-metal oxides was realized, which provides a new idea for the delay action in small size.

Experimental Study on Explosion Characteristics and Consequences for Homogeneous and Inhomogeneous Methane-Air Mixtures within a Kitchen

ABSTRACT Owing to the effect of a non-uniform concentration distribution, natural gas leakage explosion accidents usually cause different degrees of damage inside residential kitchens. According to the similarity principle, a reduced-scale experiment setup of a kitchen was established. Uniform and non-uniform explosion experiments for methane-air mixtures with concentrations of 7.7%, 9.5%, and 11.2% were performed. The flame propagation behavior and pressure evolution characteristics were analyzed for homogeneous and inhomogeneous methane-air mixtures. In addition, two dimensionless coefficients, namely macroscopic and directional non-uniformity coefficients, were introduced to quantify the uneven distribution of gas concentration within the kitchen. Furthermore, the flame development process and pressure evolvement characteristics were compared between homogeneous and inhomogeneous methane-air mixtures in a fuel-lean, chemical equivalence concentration and fuel-rich state. The results show that the macroscopic non-uniformity coefficients are 0.0998, 0.0653, and 0.0571 on the fuel-lean, chemical equivalence concentration and fuel-rich conditions, respectively. It indicates that the greatest non-uniformity of methane concentration distribution within the kitchen is represented on the fuel-lean condition. The concentration gradient could obviously reduce the explosion overpressure in the fuel-lean condition, whereas it would not significantly decrease the explosion overpressure in the chemical equivalence concentration or fuel-rich condition. It means that the greater the non-uniformity coefficient is, the more significant the effect on the overpressure peak is.

Flame propagation mechanism of methanol fuel spray explosion in a square closed vessel

Methanol, as an important chemical raw material and clean energy source, easily forms explosive droplet clouds during its production, processing, and usage. Therefore, understanding the evolution and propagation mechanisms of methanol spray explosion flames is crucial for its widespread use and the design of safety measures. This paper studies the flame propagation behavior of methanol spray explosions using a 16.2-L visualized enclosed vessel. The results indicate that the flame structure of methanol spray explosions is similar to that of premixed gas explosions but significantly differs from traditional fossil fuels. It demonstrates homogeneous combustion characteristics primarily governed by the kinetics-controlled regime. As the methanol spray concentration increases, both the maximum flame propagation speed and the maximum explosion pressure initially increase and then decrease, reaching their peak at a concentration of 224.68 g/m3, with values of 9.96 m/s and 0.72 MPa, respectively. The heat losses during combustion exhibit a trend opposite to that of explosion pressure. Numerical simulation results indicate that the concentrations of key radicals such as O, H, and OH vary significantly between lean and rich combustion states. The increase in H radical concentration enhances the elementary reactions that suppress flame temperature and promotes chain-terminating reactions.

Effect of mass ratio on flame propagation behaviors and thermal radiation performance of Al–AlH3 composite dust

Aluminum (Al) is a high-energy density fuel additive commonly used in solid composite propellants. However, Al dust will form a dense oxide layer, which will reduce activity. Aluminum hydride (AlH3) can release hydrogen, destroying the oxide film structure and releasing more energy. In this paper, the flame and thermal radiation characteristics of Al–AlH3 composite dust explosion with different mass ratios were studied experimentally. The results indicate that under the same mass ratio, the propagation height, velocity, and flame surface temperature of the composite system show a trend of first increasing and then decreasing. With the decrease of Al, the propagation height, velocity, and flame surface temperature increase gradually, with maximum values of 420 mm, 17.9 m⋅s−1, and 2033 °C, respectively. With the increase of AlH3 content, the composite system releases more H2, which lead to the enhancement of reaction intensity. Based on experimental and semi-empirical static models, the heat radiation flux is calculated. Compared with the quasi-static process on the tube side, the experimental value of vertical heat flux is greater than the calculated value. Therefore, the model is modified by introducing λ. It provides a theoretical basis for the flame and thermal radiation of dust explosions confined by vertical tubes.

Flame stabilization and pollutant emissions of turbulent ammonia and blended ammonia flames: A review of the recent experimental and numerical advances

Compared to traditional hydrocarbon fuels, ammonia presents significant challenges as a fuel, including high ignition energy, low reactivity, slow flame propagation, and high NOx emissions, which hinder its use as a renewable fuel. Blending ammonia with fossil fuels like natural gas improves its combustion reactivity and helps mitigate CO2 emissions. However, there is still much to understand about the complex dynamics of ammonia and its blends with hydrocarbons. Key areas such as reaction kinetics mechanisms, ignition properties, flame propagation behaviors, and methods for controlling combustion performance under various conditions require further elucidation. This paper reviews recent advancements in experiments and numerical simulations aimed at developing stable, and low-emission combustors for ammonia-fired power generation. Recent burner and flame configurations, including non-swirling jets, single-stage swirl burners, two-stage burners, and newly developed double-swirl burners are analyzed for their flame stability and pollutant emission potential when firing ammonia and ammonia blends. Chemical kinetic modeling of ammonia and its blends plays a crucial role in understanding combustion behavior and pollutant emissions, particularly for NOx. However, there are challenges in predicting NOx emissions accurately, with significant disparities among different models. High-fidelity numerical simulations using detailed and skeletal mechanisms, direct numerical simulation, and large eddy simulation, have helped uncover crucial operational conditions affecting combustion and pollutant emissions, such as combustor pressure, air dilution, wall cooling, fuel/air mixing, and fuel blending. Nonetheless, the accuracy of chemical kinetic models and their integration into turbulent flow simulations remain critical limitations for numerical simulations of ammonia combustion.

Gravitational effects on large-scale premixed flame dynamics: From linear to nonlinear evolution

Gravitational effects on premixed flame propagation, coupled with Darrieus–Landau instability, are investigated through direct numerical simulations under both thermal-diffusive (TD) stable and unstable situations. During the early stage of propagation, the dispersion relation between the linear growth rate σ and wavenumber k of perturbations exhibits good symmetry, allowing it to be well-fitted by the polynomial σ=c+ak−bk2. The modified Clavin–Garcia relation derived from asymptotic analysis aligns with numerical results only in the low-wavenumber region, since the significant error in the second-order coefficient bg renders it inapplicable for the high-wavenumber region. In the nonlinear regime, three morphological effects of gravity on the flame propagation have been identified: flattening the flame front, suppressing the cusp fusion rate, and promoting the new cusp generation (front splitting). The first two effects slow down the flame propagation, respectively, by reducing the overall flame front length and delaying the appearance of velocity peaks. Nevertheless, the promotion of front splitting accelerates the flame by facilitating more frequent velocity peaks arising from both cusp generation and fusion events. These various morphological effects, along with their distinct impacts on either accelerating or decelerating the flame propagation, result in significant variations in the behavior of large-scale flame propagation under different gravitational levels, despite gravity being a large-scale stabilizing effect.

Flame propagation behavior inside a closed duct upstream of a flame arrester housing

A possible way to introduce hydrogen into the energy matrix would be to enrich traditional fuels like natural gas and propane with hydrogen. Therefore, the study of the flame propagation behavior of these hydrogen enriched fuels becomes important to future industrial applications. In the present work the aim was to experimentally study the effect of hydrogen enrichment of propane and natural gas. However, in order to achieve more generality, the studied mixtures were characterized through the Lewis (Le), Zeldovich (Ze) and the reaction Damköler (Da°) numbers. A total of six mixtures were considered, in which the Ze varied from 4.94 to 8.45, the Le varied from 0.71 to 1.36 and the Da° varied from 14.56 to 36.11. In addition, the obtained results were compared to previous work to assess the effect of the experimental boundary conditions on the flame propagation velocity. The experimental results show that, for mixtures with similar Le numbers, the lower the Ze number the higher the flame propagation velocity. The maximum propagation velocities obtained in the first propagation section of the module are between 18.60 m/s and 57.11 m/s. Therefore, these flames can be considered as weakly accelerating flames. Moreover, the maximum flame propagation velocities showed a good correlation with the product Le × Ze. Regarding the presence of the flame arrester housing without an arrester element, it was observed that it causes an increase in flame propagation velocity. However, when compared to a previous work in which a flame arrester element was inside the housing, the velocity was higher for the present work.

Effects of methane concentration on flame propagation mechanisms and dynamic characteristics of methane/coal dust explosions

The study explores the flame propagation and explosion dynamic behavior of gas/powder two-phase compound explosions, taking methane and coal dust mixture as the research object. The influence of different methane concentrations on the compound explosion characteristics was researched. The vertical pipeline, high-speed camera, ion current probe, and pressure sensor be used to test the propagation behaviors, microstructure characteristics, and explosion dynamics of compound explosion flames. The function of methane concentration on the propagation behaviors, combustion reaction zone thickness, flame temperature, propagation velocity, and explosion pressure of compound flame was revealed, and the propagation mechanisms of gas/powder compound explosion flames were explained. The experimental research discovered that the compound flame of methane/coal dust explosion presents a white luminous zone with uniform distribution and appears to have an approximate homogeneous combustion state. The explosion dynamics parameters all showed a trend of first increased and then decreased as the methane concentration increased, but the reaction zone thickness of the combustion first reduced and then increased. In addition, the dominant position of homogeneous or heterogeneous combustion in the combustion reaction zone will also switch with the change in methane concentration. The compound flame is similar to premixed gas combustion under optimal methane concentration, the combustion zone thickness (δ) and preheating zone thickness (β) are the smallest, and the compound explosion shows powerful performance. In addition, the flame propagation mechanisms of methane/coal dust compound explosion were elucidated based on the theory of heat.

Characteristic Behavior of Methane/Hydrogen Premixed Flame in Ultrafine Water Mist with Potassium Additives

ABSTRACT In order to improve the suppression effect of methane/hydrogen deflagration, it is essential to understand the effects of the addition of ultrafine water mist on their explosion characteristics. An experimental study on the flame propagation behavior of methane/hydrogen premix flames influenced by ultrafine water mist with K2C2O4·H2O additives was carried out in a 10 mm × 10 mm × 100 mm tube. The results confirmed that potassium additives can improve the inhibition effect of ultrafine water mist, but the inhibition effect shows an inverted “V” shape with the increase of mass concentration. Inhibitory effects from high to low are: 15% K2C2O4·H2O >3% K2C2O4·H2O >0% K2C2O4·H2O >9% K2C2O4·H2O The addition of ultrafine water mist has both an inhibiting and an enhancing effect on flame propagation. Physical inhibition includes energy absorption by droplet fragmentation, heat absorption by evaporation and dilution of combustible gas components with CO2 to reduce the rate of combustion. Chemical inhibition occurs when small molecule alkali metals reduce the concentration of free radicals such as •O, •H and •OH. In addition, the unevaporated droplets and CO from pyrolysis have an enhanced effect on deflagration.

Experimental Observation of Flame Propagation Behavior of Hydrogen Enriched Flames Upstream of a Flame Arrester Housing with Parallel Plates as the Arrester Element

ABSTRACT The phenomenon of flame propagation in closed and semi-open ducts that have no obstacles is of interest due to the need to include alternative fuels into the energetic matrix. Tulip flames can develop under these configurations. Therefore, the behavior of flame propagation upstream of a flame arrester housing is relevant to assess the challenges of flame quenching under this configuration. The objective of this article is to investigate the effect of the effective Lewis (Leeff ) number, Zeldovich (Ze) number and initial pressure (p i ) on the flame propagation behavior upstream of a flame arrester housing with parallel plates as the flame arrester element. The Leeff and Ze numbers were varied between 0.60 and 1.36 and between 4.19 and 8.77 respectively. In addition, the initial pressure was varied from 40 kPa to 80 kPa. The mixtures considered involved natural gas, hydrogen, helium and air, which were stoichiometric in all cases. It was observed that the tulip flame developed in all cases, but with different positions of the tulip flame formation. This is important for the development and testing of flame arresters as the inlet velocity and pressure are influenced by this phenomenon. The maximum flame propagation velocities (V max ) and the maximum pressure ratios (p max /p i ) were also determined. It was found that V max decreased for higher values of the product Leeff ⨯Ze for all mixtures and initial pressures. Similarly, p max /p i decreased with increasing Le eff ⨯Ze for the initial pressures of 40 kPa and 60 kPa. A slightly different behavior was observed for pmax/pi at 80 kPa, which did not decrease significantly with higher Leeff ⨯Ze. Therefore, the flames were characterized by weak acceleration and moderate pressure ratios.

Cellular instabilities of outwardly propagating spherical hydrogen-oxygen flames using a soap bubble method

Explosion hazards associated with hydrogen-oxygen mixtures remain a significant challenge for the energy industry, despite hydrogen garnering attention as a carbon emissions-free alternative energy source. While several studies have been conducted on hydrogen-air explosions, research on hydrogen-oxygen explosions has been limited. In the current study, we employed a spherical soap bubble method to experimentally investigate the flame propagation behavior of an unconfined hydrogen-oxygen explosion. The experimental values of the laminar burning velocity were in agreement with its calculated values and were notably higher than those observed hydrogen-air mixtures. In the case of hydrogen-oxygen mixtures, a spherical expanding flame is accelerated due to the presence of Darrieus-Landau and diffusive-thermal instabilities. Furthermore, we compared the correlation between the critical Pѐclet number and the critical Karlovitz number with the Markstein number for hydrogen-oxygen mixtures to results obtained with propane-oxygen and methane-oxygen mixtures.

Energy release behavior of Zr/B/KNO3 dual-fuel energetic composites: Powders and sticks

To enhance the reactivity of B/KNO3 (BPN) energetic composites and study the energy release behavior of energetic sticks, Zr/KNO3 (ZPN) was added to the BPN energetic system, and the energetic sticks with different ZPN/BPN ratios and different thicknesses were prepared by direct ink writing (DIW). In addition, the pore-size distribution, thermal decomposition characteristics, combustion characteristics, and pressure release characteristics of the different energetic sticks were studied. Considering this, the flame propagation behavior of the energetic powders and sticks was examined. The results demonstrate that energetic sticks with different ZPN/BPN ratios and thicknesses exhibit a consistent pore-size distribution. With increasing ZPN content, the peak temperature of the condensed phase reaction of the composite decreased from 479.9 °C to 362.1 °C, the reaction enthalpy increased from 879.5 to 3200.4 J·g−1, and the burning rate of the energetic sticks increased from 62.1 to 136.8 mm·s−1, indicating that the addition of ZPN improved the reaction characteristics of the composite. In addition, the reactivity of the energetic sticks can be regulated by adjusting their thickness With the increase of layers, the burning rate of energetic sticks increases from 58.6 mm·s−1 to 113 mm·s−1. The burning rate–time curves of all energetic sticks show different numbers and ranges of platforms. In comparison to energetic powder, energetic sticks exhibit lower pressure release and pressurization rates but a longer reaction time. This study provides valuable insights into the microscale reactivity regulation of BPN energetic composites and their application in microenergy devices.

Deflagration evolution of premixed H2/CH4/air mixture undergoing a sudden expansion near the ignition source in a half-open duct

Experiments were carried out in a half-open duct to investigate the deflagration evolution of premixed CH4/H2/air mixtures undergoing a sudden expansion. Obstacles were located over and under the ignition source to simulate a long and narrow flat gap, and when the flame shot through the gap into the main body of the explosion duct, it would undergo a process of sudden expansion. By adjusting the spacings (S) and widths (W) of the gap, a series of sudden expansion conditions were considered, and the flame propagation behaviors and explosion characteristics were investigated. The results showed that different extent of flame front inversion was observed under different size of gap conditions, including inclined flat flame, vertical flat flame and tulip flame. Besides, results indicated that the vortex pairs near the obstacles play an essential role in the flame front inversion phenomenon. In addition, it was also found that the maximum overpressure in the sudden expansion duct was much lower than that in the smooth duct or with obstacles in the middle of duct. In addition, the maximum pressure (Pmax) exhibits a concave function with the increase of W, and the minimum value of Pmax was obtained at W = 150 mm, S = 30 mm, which was closely related to the combined effect of venting and combustion expansion.

Experimental investigation on the explosion characteristics and flame propagation behavior of aluminum hydride dust

Aluminum hydride (AlH3) dust is a high-capacity hydrogen storage material but is prone to explosion. In this paper, explosion characteristics and flame propagation behavior of AlH3 dust are investigated. The results indicate that the exposure of bare aluminum and the increase of specific surface area lead to the maximum explosion pressure of AlH3 dust being 4 times higher than that of Al dust. The enhancement of heat transfer by hydrogen combustion causes a higher combustion rate, leading to a higher maximum explosion pressure rise rate and flame propagation velocity of AlH3 dust. The thermo-diffusive instabilities and the evolution of hydrogen result in a pulsation flame propagation velocity of AlH3 dust. Combining the explosion temperature calculated by NASA CEA with the explosion residues analysis, the explosion mechanism of AlH3 dust is further revealed. The break of the oxide film and the combustion of hydrogen result in a different explosion mechanism.

Experimental and numerical study on suppressing coal dust deflagration flame with NaHCO3 and MPP

In this paper, the flame propagation behavior and free radical reaction mechanism of two powder explosive suppressants, sodium bicarbonate (NaHCO3) and polyphosphate melamine (MPP), at different additions were investigated using Hartmann experimental system and CHEMKIN-PRO numerical simulation. The results showed that NaHCO3 and MPP showed different inhibitory advantages. MPP mainly suppressed the propagation of flame during the development and rapid rise stages, while NaHCO3 had a better suppression effect at the preliminary stage of explosion. The gas phase kinetic analysis also proved that the NaHCO3 reaction was rapid, and it could decompose and endothermy at the beginning of the explosion, and generate gaseous H2O and CO2 to dilute the concentration of volatile components. Meanwhile, NaOH, NaO, and NaO2 produced by decomposition consumed free radicals and reduced the initial reaction rate of the explosion. In the process of gas phase reaction, MPP continuously reduced the amount of flame free radicals through a inhibition cycle of HPO3 ⇔ PO2, and generated a large number of inert products for inerting fixed carbon, exhibiting better long-term effectiveness. This study can provide a reference for the selection and design of explosion suppressants.

Explosion mechanism of nano-sized dust cloud in interconnected vessels

The effect of pipe diameter and volume ratio on overpressure characteristics and flame propagation behavior of nano-sized PMMA dust in interconnected vessels is investigated in this study. To reveal the explosion mechanism of nano-sized dust clouds in interconnected vessels, a model to predict the pre-compression level of turbulence and choking flow is established. The results show that the dust explosions in interconnected vessels go through three stages: the forward flow of the medium, the violent combustion of the pre-compressed dust cloud, and pressure oscillations. Due to changes in the geometry of the pipe inlet, the flame front is stretched and accelerated propagates. The loss of kinetic energy and the suspended acceleration of the flame front depend heavily on the diameter of the pipe. The increase in volume ratio significantly enhances the explosion intensity in the second vessel. Particularly, for a pipe diameter of 40 mm, the maximum explosion overpressure with a volume ratio of 6 is 2.6 times that of a 1/6 volume ratio, and the maximum pressure rise rate is 10.14 times higher. The prediction model accurately predicts the pre-compression in the second vessel, which supports the safety design of interconnected vessels in industrial processes.

Effects of Al powder on the reaction process and reactivity of B/KNO3 energetic sticks

Boron/potassium nitrate (B/KNO3) is a type of critical energetic composite material (ECM). However, the inert oxide layer on the B surface of B/KNO3 hinders the contact between pure fuel and oxidant, thus limiting energy release This limitation could be eliminated by adding highly reactive Al powder. To discern the effects of Al powder size on the reaction process and reactivity of B/KNO3, this study prepared Al/B/KNO3/polyvinylidene fluoride (PVDF) energetic sticks using the direct ink writing (DIW) technology. This study characterized the macroscopic morphology and structure of the energetic sticks using a laser scanning microscope and a scanning electron microscope, examined the reaction process of the composites using a differential scanning calorimeter and a thermogravimetric analyzer, and observed the flame propagation behavior of energetic sticks and energetic architectures using a high-speed camera. Furthermore, it tested the pressure output characteristics of the energetic composites using a closed volume tank. The results show that adding Al powder can improve the combustion efficiency of B/Al composite fuels and reduce the agglomeration of the combustion products. The Al powder with various particle sizes affects various reaction stages of the composite. The combustion and pressure output tests suggest that adding Al powder with a particle size of 1 μm yielded high reactivity and that flame jump propagation appeared in energetic architectures when the channel spacing was below 10 mm. These findings provide a guide for modifying the B/KNO3 energetic composites and regulating the reactivity of energetic sticks.

Study on Gasoline–Air Mixture Explosion Overpressure Characteristics and Flame Propagation Behaviors in an Annular Cylindrical Confined Space with a Circular Arch

Gasoline–air mixture explosions mostly occur in buried tank rooms, which are annular cylindrical confined spaces with circular arches. In this paper, explosion experiments at different gasoline–air mixture volume fractions are carried out in an annular cylindrical steel bench with a circular arch curvature radius of 900 mm and an annular half-perimeter to radial width ratio of 12π. The results show that the development process of explosion overpressure is clearly divided into four stages after first-order differentiation treatment. Compared with other types of confined spaces, 1.70% is still the most dangerous gasoline–air mixture volume fraction. However, this type of confined space has a larger inner surface area in the same volume condition, which will inevitably increase the heat absorption rate, reduce the chemical reaction rate, and slow down the flame propagation speed. Meanwhile, this spatial structure will inevitably make the explosion flames collide, which will promote positive feedback coupling between explosion flames and pressure waves, making the explosion more violent and dangerous. These results can provide theoretical and technical support for the explosion prevention design of buried tank rooms.