Due to the presence of nitro groups, the dust generated during the production and utilization of energetic materials may potentially lead to dust explosion even under low-oxygen or anaerobic conditions.Considering the...Due to the presence of nitro groups, the dust generated during the production and utilization of energetic materials may potentially lead to dust explosion even under low-oxygen or anaerobic conditions.Considering the high energy density of energetic materials, dust explosion can cause serious production safety accidents. Therefore, it is necessary to understand the dust explosion characteristics of energetic materials and the mechanism of dust explosion. According to the literature review, among various influencing factors, the physical and chemical properties of dust are the decisive factors affecting the explosion characteristics of dust. In addition to experimental studies, numerical simulation is another important tool. However, it is subjected to certain limitations. Moreover, it is essential but challenging to fully understand the underlying mechanism. In addition, given the safety hazards posed by dust explosion, explosion suppression has attracted extensive attention for research. Depending on the medium used, there are different forms of suppression, including powder explosion suppression, water spray explosion suppression, inert gas explosion suppression, porous material explosion suppression, and vacuum chamber explosion suppression. As for the selection of explosion suppression agent, consideration must be given to the characteristics of the material. Furthermore, the above research has laid a foundation for discussing the future progress in studying dust explosion of energetic materials, with nano dust and the constraints of existing technology as the focal point.展开更多
In this study, we focused on the effect of the underwater explosion parameters of multi-point array explosion. The shock wave and bubble parameters of aggregate charge, two charges, and four charges were measured thro...In this study, we focused on the effect of the underwater explosion parameters of multi-point array explosion. The shock wave and bubble parameters of aggregate charge, two charges, and four charges were measured through an underwater explosion test, and their influence on the explosion power field of charge quantity and array distance was analyzed. Results show that the multi-shock wave collision of array explosion can be approximated to a linear superposition, and the interaction of delayed shock wave can be deemed as the increase of the shock wave baseline. Shock wave focusing and delayed superposition increase the shock wave peak pressure. Compared with the aggregate charge, the greater the number of array explosion points is, the higher the impulse and the gain of the bubble peak pressure are. At the same array distance, the smaller the charge quantity is, the higher the bubble impulse will be. At the same charge quantity, the smaller the array distance is, the higher the bubble impulse will be. The bubble period decreases gradually with the increase of the charge quantity, but the test orientation has little effect on the bubble period.展开更多
Measuring the dust explosion characteristics of aluminum-based activated fuels was a prerequisite for developing effective prevention and control measures.In this paper,ignition sensitivity,flame propagation behaviors...Measuring the dust explosion characteristics of aluminum-based activated fuels was a prerequisite for developing effective prevention and control measures.In this paper,ignition sensitivity,flame propagation behaviors and explosion severity of aluminum/polytetrafluoroethylene(Al/PTFE)compositions including 2 PT(2.80 wt.%F),4 PT(7.18 wt.%F)and 8 PT(11.90 wt.%F)were studied.When the content of F increased from 2.80 wt.%to 11.90 wt.%,the minimum explosive concentration MEC decreased from380 g/m^(3)to 140 g/m^(3),due to the dual effects of increased internal active aluminum and enhanced reactivity.The average flame propagation velocities increased as the percentage of F increased.The maximum explosion pressure Pmof 500 g/m3aluminum-based activated fuels increased from 247 k Pa to299 kPa.Scanning electron microscopy demonstrated that with the increase of PTFE content,the reaction was more complete.On this basis,the explosion mechanism of aluminum-based activated fuels was revealed.展开更多
An infrared colorimetric radiation thermometrical system was established based on the theory of optical radiation. The dynamic temperature history of fuel air explosive (FAE) was measured to obtain the temperature res...An infrared colorimetric radiation thermometrical system was established based on the theory of optical radiation. The dynamic temperature history of fuel air explosive (FAE) was measured to obtain the temperature responses of primary initiation FAE and secondary initiation FAE in real time. And the characteristics of their temperature history curves were compared and analyzed. The results show that the primary initiation FAE has higher explosion temperature and longer duration compared to the secondary initiation FAE.展开更多
With different structural forms of ventilation pipes have various attenuation effects on incident shock waves while meeting ventilation requirements.The attenuation mechanism and the propagation law of shock waves in ...With different structural forms of ventilation pipes have various attenuation effects on incident shock waves while meeting ventilation requirements.The attenuation mechanism and the propagation law of shock waves in ventilation pipes of different structures are investigated by experiments and numerical simulations.Furthermore,for the same structure,the effects of peak pressure and positive pressure time on the attenuation rate are discussed.It is found that the attenuation rate increases with the incident shock wave pressure,and the shock wave attenuation rate tends to reach its limiting value k for the same structure and reasonably short positive pressure time.Under the same conditions,the attenuation rate is calculated using the pressure of the shock wave as follows:diffusion chamber pipe,branch pipe and selfconsumption pipe;the attenuation rate per unit volume is calculated as follows:self-consumption pipe,branch pipe and diffusion chamber pipe.In addition,an easy method is provided to calculate the attenuation rate of the shock wave in single and multi-stage ventilation pipes.Corresponding parameters are provided for various structures,and the margin of error between the formulae and experimental results is within 10%,which is significant for engineering applications.展开更多
The method of two-dimensional viscous space-time conservation element and solution element (CE/SE) can be used to calculate the gas-liquid two-phase interior flow field in pulse detonation engine (PDE). In this paper,...The method of two-dimensional viscous space-time conservation element and solution element (CE/SE) can be used to calculate the gas-liquid two-phase interior flow field in pulse detonation engine (PDE). In this paper, the evolution of the detonation wave and the distribution of its physical parameters were analyzed. The numerical results show that the change of axial velocity of gas is the same as that of detonation pressure. The larger the liquid droplet radius is, the longer the time to get stable detonation wave is. The calculated results coincide with the experimented results better.展开更多
To further explore the damage characteristics and impact response of the shaped charge to the solid rocket engine(SRE) in storage or transportation, protective armor was designed and the shelled charges model(SCM)/SRE...To further explore the damage characteristics and impact response of the shaped charge to the solid rocket engine(SRE) in storage or transportation, protective armor was designed and the shelled charges model(SCM)/SRE with protective armor impacting by shaped charge tests were conducted. Air overpressures at 5 locations and axial acceleration caused by the explosion were measured, and the experimental results were compared with two air overpressure curves of propellant detonation obtained by related scholars. Afterwards, the finite element software AUTODYN was used to simulate the SCM impacted process and SRE detonation results. The penetration process and the formation cause of damage were analyzed. The detonation performance of TNT, reference propellant, and the propellant used in this experiment was compared. The axial acceleration caused by the explosion was also analyzed.By comprehensive comparison, the energy released by the detonation of this propellant is larger, and the HMX or Al particles contained in this propellant are more than the reference propellant, with a TNT equivalent of 1.168-1.196. Finally, advanced protection armor suggestions were proposed based on the theory of woven fabric rubber composite armor(WFRCA).展开更多
In order to study and apply the penetration performance of jetting penetrator charge at long stand-off distance, three jetting penetrator charges(JPC), including spherical cone liner, truncated wide-angle liner and sp...In order to study and apply the penetration performance of jetting penetrator charge at long stand-off distance, three jetting penetrator charges(JPC), including spherical cone liner, truncated wide-angle liner and spherical segment liner, are designed. The numerical simulation analysis of the formation, elongation and penetration processes of rod-like jet is conducted by using LS-DYNA software. And the penetrating test is carried out at long stand-off distance. The test results show that the rod-like jet formed by the optimized spherical segment liner can pierce through a 90mm thick 45# steel target at 20 charge diameters(CD) stand-off distance when the charge detonation mode is a central point initiation, and the penetration depth can be up to 1.6CD. It is concluded that, at 20 CD stand-off distance, the penetration performance of JPC with spherical segment liner is the best, that of truncated wide-angle liner takes second place, and that of spherical cone liner is the worst.展开更多
With respect to the problems of that the shaped charge warhead currently uses a cover method to improve the penetration power, a method using an explosive network technology as the detonation mode of shaped charge war...With respect to the problems of that the shaped charge warhead currently uses a cover method to improve the penetration power, a method using an explosive network technology as the detonation mode of shaped charge warhead is proposed. In the context of some shaped charge warhead, a synchronous explosive network prototype is designed according to some charge structure parameters, such as the liner and main grain. From the performance comparison test, it can be known that the explosive network not only stably detonates, but also largely improves the penetration power and stability. Experimental results show that explosive network technology is an effective method for improving the penetration power. The results lay a solid foundation for the engineering application of the technology in the shaped charge warhead.展开更多
In this study, 40 Cr Mn Si B steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A midexplosi...In this study, 40 Cr Mn Si B steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A midexplosion recovery experiment for the metal cylinder under internal explosive loading was designed, and the wreckage of the casings at the intermediate phase was obtained. The effects of different tempering temperatures on the macroscopic and microscopic fracture characteristics of 40 Cr Mn Si B steel were studied. The influence of tempering temperatures on the fracture characteristic parameters of the recovered wreckage were measured and analyzed, including the circumferential divide size, the thickness and the number of the circumferential divisions. The results show that as the tempering temperature was increased from 350 to 600 ℃, at first, the degree of fragmentation and the fracture characteristic parameters of the recovered wreckage changed significantly and then became essentially consistent. Scanning electron microscopy analysis revealed flow-like structure characteristics caused by adiabatic shear on different fracture surfaces. At the detonation initiation end of the casing, fracturing was formed by tearing along the crack, which existed a distance from the initiation end and propagated along the axis direction. In contrast, the fracturing near the middle position consists of a plurality of radial shear fracture units. The amount of alloy carbide that was precipitated during the tempering process increased continuously with tempering temperature, leading to an increasing number of spherical carbide particles scattered around the fracture surface.展开更多
To study a new shaped charge of perforator, the jet formation and penetration processes in concrete targets are simulated numerically by using LS-DYNA finite element analysis software. The results show that the cylind...To study a new shaped charge of perforator, the jet formation and penetration processes in concrete targets are simulated numerically by using LS-DYNA finite element analysis software. The results show that the cylindrical liner can form jet and most materials on top of liner form the tip of jet, while the others form the tail of jet. The jet has a better continuity, and the ratio of cumulative jet length to the liner diameter can reach to 7.56. Furthermore, the ratio of bore diameter to the liner diameter is from 0.36 and 1, and the ratio of penetration depth to the liner diameter can be up to 5.5.展开更多
The expansion process of ablation plasma jet in liquid was experimentally investigated by using high speed digital camera. The sequential pictures show that, in the initial stage of the jet, the Taylor cavity expands ...The expansion process of ablation plasma jet in liquid was experimentally investigated by using high speed digital camera. The sequential pictures show that, in the initial stage of the jet, the Taylor cavity expands in the axial and radial directions simultaneously, and then, is subjected to the constraint of chamber wall, in axial direction mainly. The maximum axial speed of the cavity's head ranges from 240m/s to 280m/s. Some strong heat conduction and mass transmission effects can be found in the surface of Taylor cavity, where the plasma cools down and condenses as solid particles while the liquid vaporizes as gas. Compared the expansion processes of the cavities among the different discharge energies and the nozzle diameters, it can be seen that the expansion speed of the cavity is directly proportional to the discharge energy and inversely to the nozzle diameter, and the effect of the discharge energy is stronger than that of the nozzle diameter. A set of equations describing the expansion process of ablation plasma jet was derived under the assumption of momentum conservation. The calculated results by use of the equations coincide with the experimented results better.展开更多
The mechanical performance of ultra-high molecular weight polyethylene fiber (UHMWPE) and its composites were proposed. Penetrated properties of different thicknesses UHMWPE FRP laminates (URP) impacted by 3.3g cubic ...The mechanical performance of ultra-high molecular weight polyethylene fiber (UHMWPE) and its composites were proposed. Penetrated properties of different thicknesses UHMWPE FRP laminates (URP) impacted by 3.3g cubic high velocity fragments were studied. According to the ballistic experimental results and theoretical analysis, the linear relation between ballistic limit vBL and area density AD was confirmed. The relative parameters of showing experientially residual velocity vr were expressed by the function of AD. In the end, versatile experiential expression between vr and AD was found. Prediction of vr and vBL using obtained expressions under the above stated condition of impacting URP was consistent with the experimentaled results. Consequently, the two experiential relations can be used to predict the residual velocity and ballistic limit of cubic high velocity fragments impacting URP. The residual characteristic of high-velocity steel fragments penetrating UHMWPE FRP laminates can be more exactly forecasted by the two derived experiential formulas.展开更多
基金the financial support of the Shanxi Fire & Explosion-Proofing Safety Engineering and Technology Research Center, North University of China。
文摘Due to the presence of nitro groups, the dust generated during the production and utilization of energetic materials may potentially lead to dust explosion even under low-oxygen or anaerobic conditions.Considering the high energy density of energetic materials, dust explosion can cause serious production safety accidents. Therefore, it is necessary to understand the dust explosion characteristics of energetic materials and the mechanism of dust explosion. According to the literature review, among various influencing factors, the physical and chemical properties of dust are the decisive factors affecting the explosion characteristics of dust. In addition to experimental studies, numerical simulation is another important tool. However, it is subjected to certain limitations. Moreover, it is essential but challenging to fully understand the underlying mechanism. In addition, given the safety hazards posed by dust explosion, explosion suppression has attracted extensive attention for research. Depending on the medium used, there are different forms of suppression, including powder explosion suppression, water spray explosion suppression, inert gas explosion suppression, porous material explosion suppression, and vacuum chamber explosion suppression. As for the selection of explosion suppression agent, consideration must be given to the characteristics of the material. Furthermore, the above research has laid a foundation for discussing the future progress in studying dust explosion of energetic materials, with nano dust and the constraints of existing technology as the focal point.
文摘In this study, we focused on the effect of the underwater explosion parameters of multi-point array explosion. The shock wave and bubble parameters of aggregate charge, two charges, and four charges were measured through an underwater explosion test, and their influence on the explosion power field of charge quantity and array distance was analyzed. Results show that the multi-shock wave collision of array explosion can be approximated to a linear superposition, and the interaction of delayed shock wave can be deemed as the increase of the shock wave baseline. Shock wave focusing and delayed superposition increase the shock wave peak pressure. Compared with the aggregate charge, the greater the number of array explosion points is, the higher the impulse and the gain of the bubble peak pressure are. At the same array distance, the smaller the charge quantity is, the higher the bubble impulse will be. At the same charge quantity, the smaller the array distance is, the higher the bubble impulse will be. The bubble period decreases gradually with the increase of the charge quantity, but the test orientation has little effect on the bubble period.
基金financially supported by National Natural Science Foundation of China(No.51922025 and No.51874066)China Postdoctoral Science Foundation(No.2020M670759)the Fundamental Research Funds for the Central Universities(No.DUT20GJ201)。
文摘Measuring the dust explosion characteristics of aluminum-based activated fuels was a prerequisite for developing effective prevention and control measures.In this paper,ignition sensitivity,flame propagation behaviors and explosion severity of aluminum/polytetrafluoroethylene(Al/PTFE)compositions including 2 PT(2.80 wt.%F),4 PT(7.18 wt.%F)and 8 PT(11.90 wt.%F)were studied.When the content of F increased from 2.80 wt.%to 11.90 wt.%,the minimum explosive concentration MEC decreased from380 g/m^(3)to 140 g/m^(3),due to the dual effects of increased internal active aluminum and enhanced reactivity.The average flame propagation velocities increased as the percentage of F increased.The maximum explosion pressure Pmof 500 g/m3aluminum-based activated fuels increased from 247 k Pa to299 kPa.Scanning electron microscopy demonstrated that with the increase of PTFE content,the reaction was more complete.On this basis,the explosion mechanism of aluminum-based activated fuels was revealed.
基金Sponsored by the National Natural Science Foundation of China (10772032)
文摘An infrared colorimetric radiation thermometrical system was established based on the theory of optical radiation. The dynamic temperature history of fuel air explosive (FAE) was measured to obtain the temperature responses of primary initiation FAE and secondary initiation FAE in real time. And the characteristics of their temperature history curves were compared and analyzed. The results show that the primary initiation FAE has higher explosion temperature and longer duration compared to the secondary initiation FAE.
文摘With different structural forms of ventilation pipes have various attenuation effects on incident shock waves while meeting ventilation requirements.The attenuation mechanism and the propagation law of shock waves in ventilation pipes of different structures are investigated by experiments and numerical simulations.Furthermore,for the same structure,the effects of peak pressure and positive pressure time on the attenuation rate are discussed.It is found that the attenuation rate increases with the incident shock wave pressure,and the shock wave attenuation rate tends to reach its limiting value k for the same structure and reasonably short positive pressure time.Under the same conditions,the attenuation rate is calculated using the pressure of the shock wave as follows:diffusion chamber pipe,branch pipe and selfconsumption pipe;the attenuation rate per unit volume is calculated as follows:self-consumption pipe,branch pipe and diffusion chamber pipe.In addition,an easy method is provided to calculate the attenuation rate of the shock wave in single and multi-stage ventilation pipes.Corresponding parameters are provided for various structures,and the margin of error between the formulae and experimental results is within 10%,which is significant for engineering applications.
基金Sponsored by the National Natural Science Foundation of China (10672080)
文摘The method of two-dimensional viscous space-time conservation element and solution element (CE/SE) can be used to calculate the gas-liquid two-phase interior flow field in pulse detonation engine (PDE). In this paper, the evolution of the detonation wave and the distribution of its physical parameters were analyzed. The numerical results show that the change of axial velocity of gas is the same as that of detonation pressure. The larger the liquid droplet radius is, the longer the time to get stable detonation wave is. The calculated results coincide with the experimented results better.
文摘To further explore the damage characteristics and impact response of the shaped charge to the solid rocket engine(SRE) in storage or transportation, protective armor was designed and the shelled charges model(SCM)/SRE with protective armor impacting by shaped charge tests were conducted. Air overpressures at 5 locations and axial acceleration caused by the explosion were measured, and the experimental results were compared with two air overpressure curves of propellant detonation obtained by related scholars. Afterwards, the finite element software AUTODYN was used to simulate the SCM impacted process and SRE detonation results. The penetration process and the formation cause of damage were analyzed. The detonation performance of TNT, reference propellant, and the propellant used in this experiment was compared. The axial acceleration caused by the explosion was also analyzed.By comprehensive comparison, the energy released by the detonation of this propellant is larger, and the HMX or Al particles contained in this propellant are more than the reference propellant, with a TNT equivalent of 1.168-1.196. Finally, advanced protection armor suggestions were proposed based on the theory of woven fabric rubber composite armor(WFRCA).
文摘In order to study and apply the penetration performance of jetting penetrator charge at long stand-off distance, three jetting penetrator charges(JPC), including spherical cone liner, truncated wide-angle liner and spherical segment liner, are designed. The numerical simulation analysis of the formation, elongation and penetration processes of rod-like jet is conducted by using LS-DYNA software. And the penetrating test is carried out at long stand-off distance. The test results show that the rod-like jet formed by the optimized spherical segment liner can pierce through a 90mm thick 45# steel target at 20 charge diameters(CD) stand-off distance when the charge detonation mode is a central point initiation, and the penetration depth can be up to 1.6CD. It is concluded that, at 20 CD stand-off distance, the penetration performance of JPC with spherical segment liner is the best, that of truncated wide-angle liner takes second place, and that of spherical cone liner is the worst.
文摘With respect to the problems of that the shaped charge warhead currently uses a cover method to improve the penetration power, a method using an explosive network technology as the detonation mode of shaped charge warhead is proposed. In the context of some shaped charge warhead, a synchronous explosive network prototype is designed according to some charge structure parameters, such as the liner and main grain. From the performance comparison test, it can be known that the explosive network not only stably detonates, but also largely improves the penetration power and stability. Experimental results show that explosive network technology is an effective method for improving the penetration power. The results lay a solid foundation for the engineering application of the technology in the shaped charge warhead.
基金funded by the National Natural Science Foundation of China (Grant No.11972018)sponsored by the Defense Pre-Research Joint Foundation of Chinese Ordnance Industry (Grant No. 6141B012858)。
文摘In this study, 40 Cr Mn Si B steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A midexplosion recovery experiment for the metal cylinder under internal explosive loading was designed, and the wreckage of the casings at the intermediate phase was obtained. The effects of different tempering temperatures on the macroscopic and microscopic fracture characteristics of 40 Cr Mn Si B steel were studied. The influence of tempering temperatures on the fracture characteristic parameters of the recovered wreckage were measured and analyzed, including the circumferential divide size, the thickness and the number of the circumferential divisions. The results show that as the tempering temperature was increased from 350 to 600 ℃, at first, the degree of fragmentation and the fracture characteristic parameters of the recovered wreckage changed significantly and then became essentially consistent. Scanning electron microscopy analysis revealed flow-like structure characteristics caused by adiabatic shear on different fracture surfaces. At the detonation initiation end of the casing, fracturing was formed by tearing along the crack, which existed a distance from the initiation end and propagated along the axis direction. In contrast, the fracturing near the middle position consists of a plurality of radial shear fracture units. The amount of alloy carbide that was precipitated during the tempering process increased continuously with tempering temperature, leading to an increasing number of spherical carbide particles scattered around the fracture surface.
文摘To study a new shaped charge of perforator, the jet formation and penetration processes in concrete targets are simulated numerically by using LS-DYNA finite element analysis software. The results show that the cylindrical liner can form jet and most materials on top of liner form the tip of jet, while the others form the tail of jet. The jet has a better continuity, and the ratio of cumulative jet length to the liner diameter can reach to 7.56. Furthermore, the ratio of bore diameter to the liner diameter is from 0.36 and 1, and the ratio of penetration depth to the liner diameter can be up to 5.5.
基金Sponsored by the National Nature Science Foundation of China (10302102)
文摘The expansion process of ablation plasma jet in liquid was experimentally investigated by using high speed digital camera. The sequential pictures show that, in the initial stage of the jet, the Taylor cavity expands in the axial and radial directions simultaneously, and then, is subjected to the constraint of chamber wall, in axial direction mainly. The maximum axial speed of the cavity's head ranges from 240m/s to 280m/s. Some strong heat conduction and mass transmission effects can be found in the surface of Taylor cavity, where the plasma cools down and condenses as solid particles while the liquid vaporizes as gas. Compared the expansion processes of the cavities among the different discharge energies and the nozzle diameters, it can be seen that the expansion speed of the cavity is directly proportional to the discharge energy and inversely to the nozzle diameter, and the effect of the discharge energy is stronger than that of the nozzle diameter. A set of equations describing the expansion process of ablation plasma jet was derived under the assumption of momentum conservation. The calculated results by use of the equations coincide with the experimented results better.
基金Sponsored by the 11th Five Years Foundation for Military Advance Research (40103050103)
文摘The mechanical performance of ultra-high molecular weight polyethylene fiber (UHMWPE) and its composites were proposed. Penetrated properties of different thicknesses UHMWPE FRP laminates (URP) impacted by 3.3g cubic high velocity fragments were studied. According to the ballistic experimental results and theoretical analysis, the linear relation between ballistic limit vBL and area density AD was confirmed. The relative parameters of showing experientially residual velocity vr were expressed by the function of AD. In the end, versatile experiential expression between vr and AD was found. Prediction of vr and vBL using obtained expressions under the above stated condition of impacting URP was consistent with the experimentaled results. Consequently, the two experiential relations can be used to predict the residual velocity and ballistic limit of cubic high velocity fragments impacting URP. The residual characteristic of high-velocity steel fragments penetrating UHMWPE FRP laminates can be more exactly forecasted by the two derived experiential formulas.
