Pressure histories were tested in a 500-L chamber to identify the pressure load in confined explosion from aluminized explosives. Different aluminized explosives with Al/O, ranging from 0.25 to 1.23, were used. The re...Pressure histories were tested in a 500-L chamber to identify the pressure load in confined explosion from aluminized explosives. Different aluminized explosives with Al/O, ranging from 0.25 to 1.23, were used. The recorded pressure curves could express the reflection of initial shock wave and the after burning combustion of aluminum. As there is no objective way to gain quasi-static pressure(P_(QS)),method of multipoint averaging was used in smoothing the original pressure curves to gain the P_(QS). The P_(QS),rising time of pressure(t_(QS)) which stands for the duration of the initial reflected shock wave, and attenuation coefficient(ω) which stands for the supportive effects of the combustion of aluminum to the P_(QS) are used to characterize the pressure load in the confined explosion from aluminized explosives. The research results showed that the Al/O significantly affected the three characteristic quantities. With the increase of Al/O, the P_(QS) increased at first and decreased later, gaining maximum at Al/O=0.99; the t_(QS)sustained growth and the ω decreased at first and increased later, gaining minimum at AI/O=0.99.展开更多
The effects of the addition of rare earth （RE） elements on the void band in the diffusion layer, and the re sistances to both oxidation and spalling of aluminized steel were investigated through high temperature oxi...The effects of the addition of rare earth （RE） elements on the void band in the diffusion layer, and the re sistances to both oxidation and spalling of aluminized steel were investigated through high temperature oxidation and spalling tests. The results showed that RE had significant effects on the void band in the diffusion layer and the properties of aluminized steel. After diffusion treatment, a considerable number of the voids between the middle layer and transitional layer of pure aluminized coating, aggregated into wavy-line-shaped void bands parallel to the outer surface. For the RE added aluminized coating, only a few voids aggregated into intermittent block shapes. During high temperature oxidation at 800 ℃ for 200 h, the wavy void band of pure aluminized coating aggregated further into a linear crack parallel to the outer surface, and the internal oxidation occurred within them; the open cracks perpendicular to the surface penetrated through the diffusion layer. For the RE added aluminized coating, only a few voids aggregated into intermittent meniscus shapes. During cyclic spalling tests, the peeling, spallation, and pulver ulent cracking occurred along the void band in the diffusion layer of pure aluminized coating, but only a little spallation occurred in the diffusion layer of the RE-added aluminized coating, in which cracks perpendicular to the surface were much smaller than those of pure aluminized coating and did not penetrate through the diffusion layer. It is evident that RE addition can restrain the formation and aggregation of voids and subsequently improve the resistances to oxidation and spalling. The mechanism of the RE effect on the void band in the diffusion layer is also discussed.展开更多
Taking CL-20(Hexanitrohexaazaisowurtzitane)-based aluminized explosives with high gurney energy as the research object, this research experimentally investigates the work capability of different aluminized explosive f...Taking CL-20(Hexanitrohexaazaisowurtzitane)-based aluminized explosives with high gurney energy as the research object, this research experimentally investigates the work capability of different aluminized explosive formulations when driving metal flyer plates in the denotation wave propagation direction.The research results showed that the formulations with 43 μm aluminum(Al) powder particles(The particle sizes of Al powder were in the range of 2~43 μm) exhibited the optimal performance in driving flyer plates along the denotation wave propagation direction. Compared to the formulations with Al powder 13 μm, the formulations with Al powder 2 μm delivered better performance in accelerating metal flyer plates in the early stage, which, however, turned to be poor in the later stage. The CL-20-based explosives containing 25% Al far under-performed those containing 15% Al. Based on the proposed quasi-isentropic hypothesis, relevant isentropy theories, and the functional relationship between detonation parameters and entropy as well as Al reaction degree, the characteristic lines of aluminized explosives in accelerating flyer plates were theoretically studied, a quasi-isentropic theoretical model for the aluminized explosive driving the flyer plate was built and the calculation methods for the variations of flyer plate velocity, Al reaction degree, and detonation product parameters with time and axial positions were developed. The theoretical model built is verified by the experimental results of the CL-20-based aluminized explosive driving flyer plate. It was found that the model built could accurately calculate the variations of flyer plate velocity and Al reaction degree over time. In addition, how physical parameters including detonation product pressure and temperature varied with time and axial positions was identified. The action time of the positive pressure after the detonation of aluminized explosives was found prolonged and the downtrend of the temperature was slowed down and even reversed to a slight r展开更多
Afterburning behind the detonation front of an aluminized explosive releases energy on the millisecond timescale,which prolong the release of detonation energy and the energy release at different stages also shows sig...Afterburning behind the detonation front of an aluminized explosive releases energy on the millisecond timescale,which prolong the release of detonation energy and the energy release at different stages also shows significant differences.However,at present,there are few effective methods for evaluating the energy release characteristics of the middle reaction stage of such explosives,which can have a duration of tens to hundreds of microseconds.The present work demonstrates an approach to assessing the midstage of an aluminized explosive detonation based on a water push test employing a high degree of confinement.In this method,the explosive is contained in a steel cylinder having one end closed that is installed at the bottom of a transparent water tank.Upon detonation,the gaseous products expand in one direction while forcing water ahead of them.The resulting underwater shock wave and the interface between the gas phase products and the water are tracked using an ultra-high-speed framing and streak camera.The shock wave velocity in water and the expansion work performed by the gaseous detonation products were calculated to assess the energy release characteristics of aluminized explosives such as CL-20 and RDX in the middle stage of the detonation reaction.During the middle stage of the detonation process of these aluminized explosives,the aluminum reaction reduced the attenuation of shock waves and increased the work performed by gas phase products.A higher aluminum content increased the energy output while the presence of oxidants slowed the energy release rate.This work demonstrates an effective means of evaluating the performance of aluminized explosives.展开更多
Aluminized explosives exhibit excellent performance because the oxidation of aluminum(Al)powders enhances the pressure and temperature of detonation products.However,the equation of state(EOS)of detonation products ha...Aluminized explosives exhibit excellent performance because the oxidation of aluminum(Al)powders enhances the pressure and temperature of detonation products.However,the equation of state(EOS)of detonation products has not been understood well.In the present study,we conducted long-time tests(approximately 1 ms)of a metal rod driven by detonation products of RDX,RDX/Li F,and RDX/Al.In addition,we used laser velocimetry(PDV)to measure the freesurface velocity of the rod.Thermochemical code DLCHEQ was successfully applied to the hydrodynamic program SSS to perform the roddriven test,and a novel method was established to study the EOS of detonation products from the perspective of composition.The reliability of DLCEHQ was validated by a small deviation(<10%)between the experimental rod free-surface velocity of RDX and the calculated results;the deviation was considerably less than that from the results obtained using the JWL EOS and ideal-gas EOS.The endothermic process and the reaction of Al powders(Al+H_(2)O+NO+CO_(2)→CO+H_(2)+N_(2)+Al_(2)O_(3))were analyzed by calculating the rod free-surface velocity of RDX/Li F and RDX/Al,respectively.The results of the present study demonstrated that the thermodynamic state of Al powders has notable influence on the EOS of aluminized detonation products,and the findings were compared with those of previous studies.First,the temperature equilibrium between Al powders and CHNO products is not always achieved,and the disequilibrium is more obvious when the reaction of Al powders is stronger.Second,the reaction rate of Al powders depends on pressure and Al content.Finally,the endothermic process of Al powders has a high contribution to the decrease in the work ability of RDX/Al instead of the gasconsumption mechanism of the Al reaction.More than half of the reaction heat of Al powders is used to heat itself,whereas the gas consumption during the reaction is negligible.展开更多
Natural aluminum particles have the core-shell structure.The structure response refers to the mechanical behavior of the aluminum particle structure caused by external influences.The dynamic behavior of the structural...Natural aluminum particles have the core-shell structure.The structure response refers to the mechanical behavior of the aluminum particle structure caused by external influences.The dynamic behavior of the structural response of aluminum core-shell particles before combustion is of great importance for the aluminum powder burning mechanism and its applications.In this paper,an aluminum particle combustion experiment in a detonation environment is conducted and analyzed;the breakage factors of aluminum particles shell in detonation environment are analyzed.The experiment results show that the aluminum particle burns in a gaseous state and condenses into a sub-micron particle cluster.The calculation and simulation demonstrate that the rupture of aluminum particle shell in the detonation environment is mainly caused by the impact of the detonation wave.The detonation wave impacts the aluminum particles,resulting in shell cracking,and due to the shrinkage-expansion of the aluminum core and stripping of the detonation product,the cracked shell is fractured and peeled with the aluminum reacting with the detonation product.展开更多
Aluminum was deposited by diffusion into Cu-Al-Y alloy substrates by the pack-cementation process.Diffusion was carried out in two kinds of container with pot-type and can-type,and the results are presented.The effect...Aluminum was deposited by diffusion into Cu-Al-Y alloy substrates by the pack-cementation process.Diffusion was carried out in two kinds of container with pot-type and can-type,and the results are presented.The effects of various time and temperature on the coating characteristics of Cu-Al-Y was also investigated.The result shows that the diffusion layer is nearly 170-200μm in thickness by aluminizing treatment at 900-950℃for 6-8 h in pot-type container.The aluminized layers were observed by a scanning electron micrograph(SEM),we can found:A uniform coating was achieved on Cu-Al-Y alloy surface,relatively uniform thickness and even interfaces between the layers and the substrate.The diffusion coefficient of Al in Cu-Al-Y alloys at 900℃in pot-type container can be calculated is 3.65×10-12 m 2 /s.展开更多
To investigate the shock wave characteristics of RDX-based aluminized explosives,air blast tests were conducted for measuring the parameters of 10 kg aluminized explosives which contained 0-40% aluminum.The results sh...To investigate the shock wave characteristics of RDX-based aluminized explosives,air blast tests were conducted for measuring the parameters of 10 kg aluminized explosives which contained 0-40% aluminum.The results showed that with the increasing of aluminum content,the overpressures and impulses increase at first and then decrease within 7 m or 5 m,which reached the maximum when aluminum content was 20% or 30%.Power exponential formulas are used to fit the shock wave parameters vs scaled distance,where an equal weight of TNT is used to calculate the scaled distance.The overpressures of HL0 and TNT in tested locations not only conform to the similar law,but also conform to the same attenuation law after gaining the scaled distances of equal TNT mass.The pre-exponential factors of overpressure and impulse,kp and kI,decrease along with the increasing of Al content and keep the same pace as the calculated PCJ）.The attenuation coefficients a_P and aIincrease at first and decrease later with the increasing of aluminum content,and they reached the maximal values with30% Al containing,which keeps the same pace as the calculated QV.展开更多
In order to give the energy output structure of typical explosives near-ground explosion in real ground conditions,the free-field shockwave,ground reflection shockwave and Mach wave overpressure time history of compos...In order to give the energy output structure of typical explosives near-ground explosion in real ground conditions,the free-field shockwave,ground reflection shockwave and Mach wave overpressure time history of composition B explosive,RDX explosive and aluminized explosive were measured by air pressure sensors and ground pressure sensors.The shape of the free-field shock wave,ground reflection shock wave,and Mach wave and explosion flame were captured by high-speed camera.The experimental results show that,at the same horizontal distance from the initiation point,the peak overpressure of explosive shock wave of composition B explosive,both in the air and on the ground,is less than that of RDX and aluminized explosives.At a distance of 3.0 m from the initiation point,the peak overpressure of aluminized explosives is slightly less than that of RDX explosives.Owing to the exothermic effect of aluminum powder,the pressure drop of aluminized explosives is slower than that of RDX explosives.At 5.0 m from the initiation point,the peak overpressure of aluminized explosives is larger than that of RDX explosives.At the same position from the initiation point,among the three kinds of explosives,the impulse of aluminized explosives is the maximum and the impulse of composition B explosives is the minimum.With the increase of the horizontal distance from the initiation point,the height of Mach triple-points(Mach steam)of the three explosives increases gradually.At the same horizontal distance from the initiation point,there is poorly difference in the height of Mach triple-points between aluminized explosive and RDX explosive,and the height of Mach triple-points of composition B explosive is much smaller than that of other two explosives.The maximum diameter and duration of the fireball formed by aluminized explosives are the largest,followed by composition B explosive,and the maximum diameter and duration of the fireball formed by RDX explosive are the smallest.展开更多
Cis-and trans-1,3,4,6-tetranitroglycouril(TNGU, Sorguyl) have been considered for density functional treatment at the levels of B3LYP/6-31 G(d,p) and B3LYP/cc-PVDZ. Cis-TNGU has been found to be more stable than its t...Cis-and trans-1,3,4,6-tetranitroglycouril(TNGU, Sorguyl) have been considered for density functional treatment at the levels of B3LYP/6-31 G(d,p) and B3LYP/cc-PVDZ. Cis-TNGU has been found to be more stable than its trans isomer. Then, mono and dialuminized(cis-TNGU + Al and cis-TNGU+2Al) have been subjected to theoretical treatment at the level of B3LYP/6-31 + G(d). The spin states of the aluminized cis-TNGU composites have been considered as well. Although, cis-TNGU + Al(doublet) is found to be structurally stable, cis-TNGU+2Al singlet and triplet composites undergo certain bond cleavages.Structural and some quantum chemical properties, IR-UV spectra etc. have been presented.展开更多
The Gurney method is widely used in the conceptual design stage of explosive fragmentation warheads employed in various weapons systems.This method states that the peak fragment velocity(V_0) is a function of the Gurn...The Gurney method is widely used in the conceptual design stage of explosive fragmentation warheads employed in various weapons systems.This method states that the peak fragment velocity(V_0) is a function of the Gurney velocity((2E_G)^(1/2)) and the charge-to-metal weight ratio(C/M).The current study is concerned with finding a practical approach for computing the Gurney velocity of pure and mixed high explosives which will eventually help warhead designers to select the best explosive to fulfill the needs of a particular mission.Using multiple regression analysis technique,a four-variable model was derived and used thereafter to estimate the Gurney velocity of aluminized and non-aluminized explosive formulations.The results show that the new model is particularly accurate in predicting the Gurney velocity of combined effects explosives,which are relatively a new class of high blast,high metal acceleration capability explosive compositions.展开更多
文摘Pressure histories were tested in a 500-L chamber to identify the pressure load in confined explosion from aluminized explosives. Different aluminized explosives with Al/O, ranging from 0.25 to 1.23, were used. The recorded pressure curves could express the reflection of initial shock wave and the after burning combustion of aluminum. As there is no objective way to gain quasi-static pressure(P_(QS)),method of multipoint averaging was used in smoothing the original pressure curves to gain the P_(QS). The P_(QS),rising time of pressure(t_(QS)) which stands for the duration of the initial reflected shock wave, and attenuation coefficient(ω) which stands for the supportive effects of the combustion of aluminum to the P_(QS) are used to characterize the pressure load in the confined explosion from aluminized explosives. The research results showed that the Al/O significantly affected the three characteristic quantities. With the increase of Al/O, the P_(QS) increased at first and decreased later, gaining maximum at Al/O=0.99; the t_(QS)sustained growth and the ω decreased at first and increased later, gaining minimum at AI/O=0.99.
基金Item Sponsored by Key Science and Technology Plan Foundation of Henan of China (0423023500) and Natural ScienceFoundation of Henan Province (0511021600)
文摘The effects of the addition of rare earth （RE） elements on the void band in the diffusion layer, and the re sistances to both oxidation and spalling of aluminized steel were investigated through high temperature oxidation and spalling tests. The results showed that RE had significant effects on the void band in the diffusion layer and the properties of aluminized steel. After diffusion treatment, a considerable number of the voids between the middle layer and transitional layer of pure aluminized coating, aggregated into wavy-line-shaped void bands parallel to the outer surface. For the RE added aluminized coating, only a few voids aggregated into intermittent block shapes. During high temperature oxidation at 800 ℃ for 200 h, the wavy void band of pure aluminized coating aggregated further into a linear crack parallel to the outer surface, and the internal oxidation occurred within them; the open cracks perpendicular to the surface penetrated through the diffusion layer. For the RE added aluminized coating, only a few voids aggregated into intermittent meniscus shapes. During cyclic spalling tests, the peeling, spallation, and pulver ulent cracking occurred along the void band in the diffusion layer of pure aluminized coating, but only a little spallation occurred in the diffusion layer of the RE-added aluminized coating, in which cracks perpendicular to the surface were much smaller than those of pure aluminized coating and did not penetrate through the diffusion layer. It is evident that RE addition can restrain the formation and aggregation of voids and subsequently improve the resistances to oxidation and spalling. The mechanism of the RE effect on the void band in the diffusion layer is also discussed.
基金National Natural Science Foundation of China(Grant No.11872120).
文摘Taking CL-20(Hexanitrohexaazaisowurtzitane)-based aluminized explosives with high gurney energy as the research object, this research experimentally investigates the work capability of different aluminized explosive formulations when driving metal flyer plates in the denotation wave propagation direction.The research results showed that the formulations with 43 μm aluminum(Al) powder particles(The particle sizes of Al powder were in the range of 2~43 μm) exhibited the optimal performance in driving flyer plates along the denotation wave propagation direction. Compared to the formulations with Al powder 13 μm, the formulations with Al powder 2 μm delivered better performance in accelerating metal flyer plates in the early stage, which, however, turned to be poor in the later stage. The CL-20-based explosives containing 25% Al far under-performed those containing 15% Al. Based on the proposed quasi-isentropic hypothesis, relevant isentropy theories, and the functional relationship between detonation parameters and entropy as well as Al reaction degree, the characteristic lines of aluminized explosives in accelerating flyer plates were theoretically studied, a quasi-isentropic theoretical model for the aluminized explosive driving the flyer plate was built and the calculation methods for the variations of flyer plate velocity, Al reaction degree, and detonation product parameters with time and axial positions were developed. The theoretical model built is verified by the experimental results of the CL-20-based aluminized explosive driving flyer plate. It was found that the model built could accurately calculate the variations of flyer plate velocity and Al reaction degree over time. In addition, how physical parameters including detonation product pressure and temperature varied with time and axial positions was identified. The action time of the positive pressure after the detonation of aluminized explosives was found prolonged and the downtrend of the temperature was slowed down and even reversed to a slight r
基金supported by the National Natural Science Foundation of China(Grant No.11832006)。
文摘Afterburning behind the detonation front of an aluminized explosive releases energy on the millisecond timescale,which prolong the release of detonation energy and the energy release at different stages also shows significant differences.However,at present,there are few effective methods for evaluating the energy release characteristics of the middle reaction stage of such explosives,which can have a duration of tens to hundreds of microseconds.The present work demonstrates an approach to assessing the midstage of an aluminized explosive detonation based on a water push test employing a high degree of confinement.In this method,the explosive is contained in a steel cylinder having one end closed that is installed at the bottom of a transparent water tank.Upon detonation,the gaseous products expand in one direction while forcing water ahead of them.The resulting underwater shock wave and the interface between the gas phase products and the water are tracked using an ultra-high-speed framing and streak camera.The shock wave velocity in water and the expansion work performed by the gaseous detonation products were calculated to assess the energy release characteristics of aluminized explosives such as CL-20 and RDX in the middle stage of the detonation reaction.During the middle stage of the detonation process of these aluminized explosives,the aluminum reaction reduced the attenuation of shock waves and increased the work performed by gas phase products.A higher aluminum content increased the energy output while the presence of oxidants slowed the energy release rate.This work demonstrates an effective means of evaluating the performance of aluminized explosives.
基金financial support provided by the National Natural Science Foundation of China(Grant No.11902276)the Natural Science Foundation of Sichuan Province(Grant No.2022NSFSC1802)+2 种基金the National Key Laboratory for Shock Wave and Detonation Physics of China(Grant No.JCKYS2019212007)the Original Scientific Research Instrument and Equipment Development Project of Southwest Jiaotong University(Grant No.XJ2021KJZK055)Sichuan Science and Technology Development Project(Grant No.2021ZYD0027)。
文摘Aluminized explosives exhibit excellent performance because the oxidation of aluminum(Al)powders enhances the pressure and temperature of detonation products.However,the equation of state(EOS)of detonation products has not been understood well.In the present study,we conducted long-time tests(approximately 1 ms)of a metal rod driven by detonation products of RDX,RDX/Li F,and RDX/Al.In addition,we used laser velocimetry(PDV)to measure the freesurface velocity of the rod.Thermochemical code DLCHEQ was successfully applied to the hydrodynamic program SSS to perform the roddriven test,and a novel method was established to study the EOS of detonation products from the perspective of composition.The reliability of DLCEHQ was validated by a small deviation(<10%)between the experimental rod free-surface velocity of RDX and the calculated results;the deviation was considerably less than that from the results obtained using the JWL EOS and ideal-gas EOS.The endothermic process and the reaction of Al powders(Al+H_(2)O+NO+CO_(2)→CO+H_(2)+N_(2)+Al_(2)O_(3))were analyzed by calculating the rod free-surface velocity of RDX/Li F and RDX/Al,respectively.The results of the present study demonstrated that the thermodynamic state of Al powders has notable influence on the EOS of aluminized detonation products,and the findings were compared with those of previous studies.First,the temperature equilibrium between Al powders and CHNO products is not always achieved,and the disequilibrium is more obvious when the reaction of Al powders is stronger.Second,the reaction rate of Al powders depends on pressure and Al content.Finally,the endothermic process of Al powders has a high contribution to the decrease in the work ability of RDX/Al instead of the gasconsumption mechanism of the Al reaction.More than half of the reaction heat of Al powders is used to heat itself,whereas the gas consumption during the reaction is negligible.
基金Project supported by the National Natural Science Foundation of China(Grant No.11772058)
文摘Natural aluminum particles have the core-shell structure.The structure response refers to the mechanical behavior of the aluminum particle structure caused by external influences.The dynamic behavior of the structural response of aluminum core-shell particles before combustion is of great importance for the aluminum powder burning mechanism and its applications.In this paper,an aluminum particle combustion experiment in a detonation environment is conducted and analyzed;the breakage factors of aluminum particles shell in detonation environment are analyzed.The experiment results show that the aluminum particle burns in a gaseous state and condenses into a sub-micron particle cluster.The calculation and simulation demonstrate that the rupture of aluminum particle shell in the detonation environment is mainly caused by the impact of the detonation wave.The detonation wave impacts the aluminum particles,resulting in shell cracking,and due to the shrinkage-expansion of the aluminum core and stripping of the detonation product,the cracked shell is fractured and peeled with the aluminum reacting with the detonation product.
基金Basic Research Priorities Program of the Science and Technology Committee of Shanghai(03JC14063)Shanghai Leading Academic Discipline Project(J50503)Innovative Program of the Education Commission of Shanghai(11YZ112)
文摘Aluminum was deposited by diffusion into Cu-Al-Y alloy substrates by the pack-cementation process.Diffusion was carried out in two kinds of container with pot-type and can-type,and the results are presented.The effects of various time and temperature on the coating characteristics of Cu-Al-Y was also investigated.The result shows that the diffusion layer is nearly 170-200μm in thickness by aluminizing treatment at 900-950℃for 6-8 h in pot-type container.The aluminized layers were observed by a scanning electron micrograph(SEM),we can found:A uniform coating was achieved on Cu-Al-Y alloy surface,relatively uniform thickness and even interfaces between the layers and the substrate.The diffusion coefficient of Al in Cu-Al-Y alloys at 900℃in pot-type container can be calculated is 3.65×10-12 m 2 /s.
文摘To investigate the shock wave characteristics of RDX-based aluminized explosives,air blast tests were conducted for measuring the parameters of 10 kg aluminized explosives which contained 0-40% aluminum.The results showed that with the increasing of aluminum content,the overpressures and impulses increase at first and then decrease within 7 m or 5 m,which reached the maximum when aluminum content was 20% or 30%.Power exponential formulas are used to fit the shock wave parameters vs scaled distance,where an equal weight of TNT is used to calculate the scaled distance.The overpressures of HL0 and TNT in tested locations not only conform to the similar law,but also conform to the same attenuation law after gaining the scaled distances of equal TNT mass.The pre-exponential factors of overpressure and impulse,kp and kI,decrease along with the increasing of Al content and keep the same pace as the calculated PCJ）.The attenuation coefficients a_P and aIincrease at first and decrease later with the increasing of aluminum content,and they reached the maximal values with30% Al containing,which keeps the same pace as the calculated QV.
基金supported by the National Natural Science Foundation of China(No.11732003)Beijing Natural Science Foundation(No.8182050)+1 种基金Science Challenge Project(No.TZ2016001)National Key Research and Development Program of China(No.2017YFC0804700)。
文摘In order to give the energy output structure of typical explosives near-ground explosion in real ground conditions,the free-field shockwave,ground reflection shockwave and Mach wave overpressure time history of composition B explosive,RDX explosive and aluminized explosive were measured by air pressure sensors and ground pressure sensors.The shape of the free-field shock wave,ground reflection shock wave,and Mach wave and explosion flame were captured by high-speed camera.The experimental results show that,at the same horizontal distance from the initiation point,the peak overpressure of explosive shock wave of composition B explosive,both in the air and on the ground,is less than that of RDX and aluminized explosives.At a distance of 3.0 m from the initiation point,the peak overpressure of aluminized explosives is slightly less than that of RDX explosives.Owing to the exothermic effect of aluminum powder,the pressure drop of aluminized explosives is slower than that of RDX explosives.At 5.0 m from the initiation point,the peak overpressure of aluminized explosives is larger than that of RDX explosives.At the same position from the initiation point,among the three kinds of explosives,the impulse of aluminized explosives is the maximum and the impulse of composition B explosives is the minimum.With the increase of the horizontal distance from the initiation point,the height of Mach triple-points(Mach steam)of the three explosives increases gradually.At the same horizontal distance from the initiation point,there is poorly difference in the height of Mach triple-points between aluminized explosive and RDX explosive,and the height of Mach triple-points of composition B explosive is much smaller than that of other two explosives.The maximum diameter and duration of the fireball formed by aluminized explosives are the largest,followed by composition B explosive,and the maximum diameter and duration of the fireball formed by RDX explosive are the smallest.
文摘Cis-and trans-1,3,4,6-tetranitroglycouril(TNGU, Sorguyl) have been considered for density functional treatment at the levels of B3LYP/6-31 G(d,p) and B3LYP/cc-PVDZ. Cis-TNGU has been found to be more stable than its trans isomer. Then, mono and dialuminized(cis-TNGU + Al and cis-TNGU+2Al) have been subjected to theoretical treatment at the level of B3LYP/6-31 + G(d). The spin states of the aluminized cis-TNGU composites have been considered as well. Although, cis-TNGU + Al(doublet) is found to be structurally stable, cis-TNGU+2Al singlet and triplet composites undergo certain bond cleavages.Structural and some quantum chemical properties, IR-UV spectra etc. have been presented.
文摘The Gurney method is widely used in the conceptual design stage of explosive fragmentation warheads employed in various weapons systems.This method states that the peak fragment velocity(V_0) is a function of the Gurney velocity((2E_G)^(1/2)) and the charge-to-metal weight ratio(C/M).The current study is concerned with finding a practical approach for computing the Gurney velocity of pure and mixed high explosives which will eventually help warhead designers to select the best explosive to fulfill the needs of a particular mission.Using multiple regression analysis technique,a four-variable model was derived and used thereafter to estimate the Gurney velocity of aluminized and non-aluminized explosive formulations.The results show that the new model is particularly accurate in predicting the Gurney velocity of combined effects explosives,which are relatively a new class of high blast,high metal acceleration capability explosive compositions.
