RBOE is a new type of DNAN-based high-energy melt-cast mixed explosive,whose safety under thermal stimulation is significantly affected by heating conditions and venting area of the warhead.Based on the thermal decomp...RBOE is a new type of DNAN-based high-energy melt-cast mixed explosive,whose safety under thermal stimulation is significantly affected by heating conditions and venting area of the warhead.Based on the thermal decomposition reaction characteristics and combustion characteristics of each component of RBOE explosive,the cook-off calculation models of RBOE warhead before and after ignition were established.In addition,closed and vented warheads were designed,as well as fast and slow cook-off test devices.The cook-off characteristics and thermal safety venting area of RBOE warhead were extensively studied.The results showed that the closed RBOE warhead underwent deflagration reaction under both slow and fast cook-off conditions.The calculation result of the shell wall temperature before slow cookoff ignition response of the warhead was 454.06 K,with an error of+1.75%compared to the test result of462.15 K,and the temperature rise rate calculated was in good agreement with the test.The calculated ignition time of RBOE warhead under fast cook-off was 161 s,with an error of+8.8%compared to the test result of 148 s,which verified the accuracy of cook-off model of RBOE warhead before ignition.According to the cook-off calculation model of the warhead after ignition and cook-off test of the vented warhead,it was determined that the thermal safety venting area was 1124.61 mm^(2)for fast cook-off and 530.66 mm~2 for slow cook-off,effectively preventing the reaction of warhead above combustion.Therefore,this study provides a scientific basis for the thermal safety design and evaluation of insensitive warheads.展开更多
The present study is devoted to researching the thermal security problems of large-scale solid rocket motor with Ammonium perchlorate/Hydroxyl-terminated polybutadiene(AP/HTPB). A two-dimensional axisymmetric model fo...The present study is devoted to researching the thermal security problems of large-scale solid rocket motor with Ammonium perchlorate/Hydroxyl-terminated polybutadiene(AP/HTPB). A two-dimensional axisymmetric model for the cook-off of solid rocket motor is established. The reaction kinetics for the cook-off process of AP/HTPB is described by the two-step global chemical mechanism. Numerical predictions of the cook-off behavior for the propellant are conducted at fast heating rate of 1.45-2.45 K/s,and slow heating rate of 0.001-0.003 K/s, respectively. The results show that in the fast cook-off condition. the initial ignition position of AP/HTPB occurs in the annular region of the outer wall of propellant without exception, and the center point in the region is(889.1,149.5). For the region, the axial width is1.8 mm and radial thickness is 0.8 mm. However, in the slow cook-off condition, the ignition center position is shifted along the axial direction toward the right end face of the propellant with the increase of heating rate. Therefore, the influence of heating rate on ignition temperature and ignition delay time is nonnegligible within a certain range.展开更多
The response characteristics of the warhead under thermal stimuli conditions are important to the safety improvement.The goal of this study is to obtain data on the warhead in the fast cook-off process.In this paper,a...The response characteristics of the warhead under thermal stimuli conditions are important to the safety improvement.The goal of this study is to obtain data on the warhead in the fast cook-off process.In this paper,a numerical calculation method is proposed,whose reliability is supported by comparison with experimental results.Through the numerical calculation,the temperature distribution,temperature change,and ignition time are acquired.The numerical results show that the ignition time is 76 s after the warhead started to burn and that the maximum temperature of the explosive’s outer surface is 238.3℃ at the ignition time.The fast cook-off experiment of the warhead is implemented so as to get the flame temperature and reaction grades that are not available through numerical calculation.The experimental results show that the overpressure fails to reach the preset minimumvalue which is equivalent to 6 kg of TNT and that the reaction grade is deflagration.The research results have reference value for the design of the warhead and the reduction of detonation risks.展开更多
In order to investigate thermal response of explosive at fast cook-off environment, the fast cook-off tests for GHL explosive, subjected to external fire scenario, were carried out. The ignition time was measured. A t...In order to investigate thermal response of explosive at fast cook-off environment, the fast cook-off tests for GHL explosive, subjected to external fire scenario, were carried out. The ignition time was measured. A thermal reaction model of GHL explosive was established. The external flame flow and decomposing heat of explosive were considered. The numerical simulation of cook-off test was conducted by computational fluid dynamics（CFD） software, FLUENT. Comparing the calculated results with the measured, external heat flow and kinetic parameters of GHL explosive were achieved. Ignition temperature, ignition position and temperature distribution in explosive were analyzed. The optimization of fuel pool size was also discussed by calculations. The measured results show that only burning reactions occurred during the tests. The ignition time and ignition temperature were 43 s and 583 K respectively. The ignition position lied in the underside of both ends of cylindrical explosive, which was placed horizontally. The modeled results indicate that the optimum fuel pool is 1 000 mm wide, which can ensure complete engulfment of explosive cylinder by external fire and save fuel oil.展开更多
The experimental investigations of the effect of contact time/temperature on initiating the cook-off using 7.62 mm calibre cartridge cases(CC) were conducted previously.These cartridges were hlled with commercial off-...The experimental investigations of the effect of contact time/temperature on initiating the cook-off using 7.62 mm calibre cartridge cases(CC) were conducted previously.These cartridges were hlled with commercial off-the-shelf(COTS) double based(DB) propellant(Bulls Eye)and were loaded in a hot chamber.The thermal explosion temperature is of great significance to both weapon designers and safety inspectors as it provides the operational limit and safe operating temperature.For CC under test,it was found that the cook-off temperatures of this propellant were encountered with the heat transfer profile of the simulated gun barrel between 151.4 ℃ and 153.4 ℃,with a reaction occurring in less than300 s after the round was chambered.Usefully,each experiment was found to be consistent and repeatable.展开更多
为了减少荔枝汁在加热后产生的“蒸煮”异味,筛选了邻苯三酚、没食子酸、迷迭香酸、儿茶素、抗坏血酸及葡萄糖氧化酶六种抑制剂,从色泽、pH、香气轮廓、电子鼻、挥发性成分、降硫率以及总酚、总黄酮、抗氧化特性等角度去评价六种抑制剂...为了减少荔枝汁在加热后产生的“蒸煮”异味,筛选了邻苯三酚、没食子酸、迷迭香酸、儿茶素、抗坏血酸及葡萄糖氧化酶六种抑制剂,从色泽、pH、香气轮廓、电子鼻、挥发性成分、降硫率以及总酚、总黄酮、抗氧化特性等角度去评价六种抑制剂对荔枝汁风味及营养品质的影响。结果显示抗坏血酸和没食子酸抑制剂处理的样品与新鲜汁相比的色差值最小;整体香气轮廓显示葡萄糖氧化酶抑制蒸煮异味效果最佳,其次为迷迭香酸;电子鼻结果显示葡萄糖氧化酶处理的荔枝汁与新鲜汁最为接近,其次是儿茶素和邻苯三酚。挥发性成分的主成分分析结果显示抗坏血酸抑制剂处理的样品与新鲜汁最接近,其次为没食子酸、儿茶素、迷迭香酸。降硫率结果显示葡萄糖氧化酶的降硫效果最为显著,对二甲基硫醚、二甲基三硫醚、甲硫基丙醛的抑制率均达到100%,对二甲基二硫醚的抑制率为61.11%。营养品质方面,多酚类抑制剂与抗坏血酸处理的总酚、总黄酮含量和抗氧化性较新鲜汁均显著上升(P<0.05),而葡萄糖氧化酶处理的总酚、总黄酮含量较新鲜汁上升但抗氧化活性与新鲜汁无显著差异。综合色泽、pH、香气轮廓、营养品质以及降硫效果等因素进行偏最小二乘判别分析(partial least squares discriminant analysis,PLS-DA),发现葡萄糖氧化酶对荔枝汁整体品质影响最好。本研究可为荔枝以及其他热敏性水果加工过程中品质提升提供参考依据。展开更多
引信热防护技术与等效试验技术是提升引信快速烤燃安全性与热防护多轮优化设计效率的关键。根据引信一维热传导模型,构建炸药及引信壳体径向温度分布方程,建立基于铝-硅气凝胶的航空炸弹引信热防护模型,通过引信快速烤燃仿真模拟研究,...引信热防护技术与等效试验技术是提升引信快速烤燃安全性与热防护多轮优化设计效率的关键。根据引信一维热传导模型,构建炸药及引信壳体径向温度分布方程,建立基于铝-硅气凝胶的航空炸弹引信热防护模型,通过引信快速烤燃仿真模拟研究,获得引信内部炸药经历20 min 800℃烤燃环境的温度变化曲线。隔铝-硅气凝胶的临界厚度为3 mm,炸药最终温度比其5 s爆发点(280℃)低87.8℃,可以保证引信的热安全性。以铝-硅气凝胶包覆的引信为验证主体,结合快速烤燃标准试验方法建立基于仿真分析-高温火焰喷射试验平台的引信快速烤燃等效试验方法。试验结果表明,标准试验的引信易损点测温数据与仿真数据对比,精度优于91%;等效试验下引信易损点测量温度与标准试验测量结果对比,精度优于95%。试验结果表明,标准试验的引信易损点测温数据与仿真数据对比,标准试验精度优于91%;等效试验下引信易损点测量温度与标准试验测量结果对比,等效试验精度优于95%。展开更多
In order to study the relationship between charge size and thermal initiation critical temperature of explosive in defined conditions,cook-off test about JH explosive was carried out at a heating rate of 1 ℃/min usin...In order to study the relationship between charge size and thermal initiation critical temperature of explosive in defined conditions,cook-off test about JH explosive was carried out at a heating rate of 1 ℃/min using self-designed cook-off experiment setup based on thermostatic control technology.Numerical simulation was conducted to study the effects of different charge sizes on thermal initiation critical temperature of explosives with FLUENT software.Experiment results show that there is a thermal initiation critical temperature in cook-off bomb.Simulation results show that when the ratio of the length to diameter of explosives grains is a fixed value,the thermal initiation critical temperature of explosives decreases with the increase of the diameter of explosives grains.When the grains diameter of explosives increase up to a certain value,the influence of charge size on thermal initiation critical temperature tends to be weakened.Charge size has no influence on the ignition point of explosives.The ignition point is always in the center of the grain.展开更多
基金National Natural Science Foundation of china(Grant No.12402468)。
文摘RBOE is a new type of DNAN-based high-energy melt-cast mixed explosive,whose safety under thermal stimulation is significantly affected by heating conditions and venting area of the warhead.Based on the thermal decomposition reaction characteristics and combustion characteristics of each component of RBOE explosive,the cook-off calculation models of RBOE warhead before and after ignition were established.In addition,closed and vented warheads were designed,as well as fast and slow cook-off test devices.The cook-off characteristics and thermal safety venting area of RBOE warhead were extensively studied.The results showed that the closed RBOE warhead underwent deflagration reaction under both slow and fast cook-off conditions.The calculation result of the shell wall temperature before slow cookoff ignition response of the warhead was 454.06 K,with an error of+1.75%compared to the test result of462.15 K,and the temperature rise rate calculated was in good agreement with the test.The calculated ignition time of RBOE warhead under fast cook-off was 161 s,with an error of+8.8%compared to the test result of 148 s,which verified the accuracy of cook-off model of RBOE warhead before ignition.According to the cook-off calculation model of the warhead after ignition and cook-off test of the vented warhead,it was determined that the thermal safety venting area was 1124.61 mm^(2)for fast cook-off and 530.66 mm~2 for slow cook-off,effectively preventing the reaction of warhead above combustion.Therefore,this study provides a scientific basis for the thermal safety design and evaluation of insensitive warheads.
文摘The present study is devoted to researching the thermal security problems of large-scale solid rocket motor with Ammonium perchlorate/Hydroxyl-terminated polybutadiene(AP/HTPB). A two-dimensional axisymmetric model for the cook-off of solid rocket motor is established. The reaction kinetics for the cook-off process of AP/HTPB is described by the two-step global chemical mechanism. Numerical predictions of the cook-off behavior for the propellant are conducted at fast heating rate of 1.45-2.45 K/s,and slow heating rate of 0.001-0.003 K/s, respectively. The results show that in the fast cook-off condition. the initial ignition position of AP/HTPB occurs in the annular region of the outer wall of propellant without exception, and the center point in the region is(889.1,149.5). For the region, the axial width is1.8 mm and radial thickness is 0.8 mm. However, in the slow cook-off condition, the ignition center position is shifted along the axial direction toward the right end face of the propellant with the increase of heating rate. Therefore, the influence of heating rate on ignition temperature and ignition delay time is nonnegligible within a certain range.
文摘The response characteristics of the warhead under thermal stimuli conditions are important to the safety improvement.The goal of this study is to obtain data on the warhead in the fast cook-off process.In this paper,a numerical calculation method is proposed,whose reliability is supported by comparison with experimental results.Through the numerical calculation,the temperature distribution,temperature change,and ignition time are acquired.The numerical results show that the ignition time is 76 s after the warhead started to burn and that the maximum temperature of the explosive’s outer surface is 238.3℃ at the ignition time.The fast cook-off experiment of the warhead is implemented so as to get the flame temperature and reaction grades that are not available through numerical calculation.The experimental results show that the overpressure fails to reach the preset minimumvalue which is equivalent to 6 kg of TNT and that the reaction grade is deflagration.The research results have reference value for the design of the warhead and the reduction of detonation risks.
基金Sponsored by the Ministerial Level Foundation(203040)
文摘In order to investigate thermal response of explosive at fast cook-off environment, the fast cook-off tests for GHL explosive, subjected to external fire scenario, were carried out. The ignition time was measured. A thermal reaction model of GHL explosive was established. The external flame flow and decomposing heat of explosive were considered. The numerical simulation of cook-off test was conducted by computational fluid dynamics（CFD） software, FLUENT. Comparing the calculated results with the measured, external heat flow and kinetic parameters of GHL explosive were achieved. Ignition temperature, ignition position and temperature distribution in explosive were analyzed. The optimization of fuel pool size was also discussed by calculations. The measured results show that only burning reactions occurred during the tests. The ignition time and ignition temperature were 43 s and 583 K respectively. The ignition position lied in the underside of both ends of cylindrical explosive, which was placed horizontally. The modeled results indicate that the optimum fuel pool is 1 000 mm wide, which can ensure complete engulfment of explosive cylinder by external fire and save fuel oil.
文摘The experimental investigations of the effect of contact time/temperature on initiating the cook-off using 7.62 mm calibre cartridge cases(CC) were conducted previously.These cartridges were hlled with commercial off-the-shelf(COTS) double based(DB) propellant(Bulls Eye)and were loaded in a hot chamber.The thermal explosion temperature is of great significance to both weapon designers and safety inspectors as it provides the operational limit and safe operating temperature.For CC under test,it was found that the cook-off temperatures of this propellant were encountered with the heat transfer profile of the simulated gun barrel between 151.4 ℃ and 153.4 ℃,with a reaction occurring in less than300 s after the round was chambered.Usefully,each experiment was found to be consistent and repeatable.
文摘为了减少荔枝汁在加热后产生的“蒸煮”异味,筛选了邻苯三酚、没食子酸、迷迭香酸、儿茶素、抗坏血酸及葡萄糖氧化酶六种抑制剂,从色泽、pH、香气轮廓、电子鼻、挥发性成分、降硫率以及总酚、总黄酮、抗氧化特性等角度去评价六种抑制剂对荔枝汁风味及营养品质的影响。结果显示抗坏血酸和没食子酸抑制剂处理的样品与新鲜汁相比的色差值最小;整体香气轮廓显示葡萄糖氧化酶抑制蒸煮异味效果最佳,其次为迷迭香酸;电子鼻结果显示葡萄糖氧化酶处理的荔枝汁与新鲜汁最为接近,其次是儿茶素和邻苯三酚。挥发性成分的主成分分析结果显示抗坏血酸抑制剂处理的样品与新鲜汁最接近,其次为没食子酸、儿茶素、迷迭香酸。降硫率结果显示葡萄糖氧化酶的降硫效果最为显著,对二甲基硫醚、二甲基三硫醚、甲硫基丙醛的抑制率均达到100%,对二甲基二硫醚的抑制率为61.11%。营养品质方面,多酚类抑制剂与抗坏血酸处理的总酚、总黄酮含量和抗氧化性较新鲜汁均显著上升(P<0.05),而葡萄糖氧化酶处理的总酚、总黄酮含量较新鲜汁上升但抗氧化活性与新鲜汁无显著差异。综合色泽、pH、香气轮廓、营养品质以及降硫效果等因素进行偏最小二乘判别分析(partial least squares discriminant analysis,PLS-DA),发现葡萄糖氧化酶对荔枝汁整体品质影响最好。本研究可为荔枝以及其他热敏性水果加工过程中品质提升提供参考依据。
文摘引信热防护技术与等效试验技术是提升引信快速烤燃安全性与热防护多轮优化设计效率的关键。根据引信一维热传导模型,构建炸药及引信壳体径向温度分布方程,建立基于铝-硅气凝胶的航空炸弹引信热防护模型,通过引信快速烤燃仿真模拟研究,获得引信内部炸药经历20 min 800℃烤燃环境的温度变化曲线。隔铝-硅气凝胶的临界厚度为3 mm,炸药最终温度比其5 s爆发点(280℃)低87.8℃,可以保证引信的热安全性。以铝-硅气凝胶包覆的引信为验证主体,结合快速烤燃标准试验方法建立基于仿真分析-高温火焰喷射试验平台的引信快速烤燃等效试验方法。试验结果表明,标准试验的引信易损点测温数据与仿真数据对比,精度优于91%;等效试验下引信易损点测量温度与标准试验测量结果对比,精度优于95%。试验结果表明,标准试验的引信易损点测温数据与仿真数据对比,标准试验精度优于91%;等效试验下引信易损点测量温度与标准试验测量结果对比,等效试验精度优于95%。
文摘In order to study the relationship between charge size and thermal initiation critical temperature of explosive in defined conditions,cook-off test about JH explosive was carried out at a heating rate of 1 ℃/min using self-designed cook-off experiment setup based on thermostatic control technology.Numerical simulation was conducted to study the effects of different charge sizes on thermal initiation critical temperature of explosives with FLUENT software.Experiment results show that there is a thermal initiation critical temperature in cook-off bomb.Simulation results show that when the ratio of the length to diameter of explosives grains is a fixed value,the thermal initiation critical temperature of explosives decreases with the increase of the diameter of explosives grains.When the grains diameter of explosives increase up to a certain value,the influence of charge size on thermal initiation critical temperature tends to be weakened.Charge size has no influence on the ignition point of explosives.The ignition point is always in the center of the grain.
