To accelerate the practicality of electromagnetic railguns,it is necessary to use a combination of threedimensional numerical simulation and experiments to study the mechanism of bore damage.In this paper,a three-dime...To accelerate the practicality of electromagnetic railguns,it is necessary to use a combination of threedimensional numerical simulation and experiments to study the mechanism of bore damage.In this paper,a three-dimensional numerical model of the augmented railgun with four parallel unconventional rails is introduced to simulate the internal ballistic process and realize the multi-physics field coupling calculation of the rail gun,and a test experiment of a medium-caliber electromagnetic launcher powered by pulse formation network(PFN)is carried out.Various test methods such as spectrometer,fiber grating and high-speed camera are used to test several parameters such as muzzle initial velocity,transient magnetic field strength and stress-strain of rail.Combining the simulation results and experimental data,the damage condition of the contact surface is analyzed.展开更多
喷雾热解法是制备纳米CeO_(2)粉体的途径之一,但液滴在高速高温气流中发生的蒸发、破碎和热解行为影响了最终产品的性能和品质。本文基于VOF(Volume of fluid)蒸发传质模型与有限速率化学反应模型的耦合方法,研究了热解中液滴形貌以及...喷雾热解法是制备纳米CeO_(2)粉体的途径之一,但液滴在高速高温气流中发生的蒸发、破碎和热解行为影响了最终产品的性能和品质。本文基于VOF(Volume of fluid)蒸发传质模型与有限速率化学反应模型的耦合方法,研究了热解中液滴形貌以及流场的变化和产物分布随时间的全过程。结果表明:当入口气流速度为60 m/s、温度为650℃时,液滴在破碎前的形貌发生了变化,即液滴表面先出现波纹状起伏,然后加剧为褶皱状起伏,最后转变为沟壑状起伏;液滴迎风面与背风面存在压力差,流场中局部(液滴边缘)气流速度最大为67 m/s;子液滴数量沿X轴正方向不断减少且周围有产物CeO_(2)生成,计算域内产物CeO_(2)含量随时间的延长而逐渐增大;产物CeO_(2)主要生成于气相与氧化剂的交界面处,而非直接附着在液滴表面。展开更多
文摘To accelerate the practicality of electromagnetic railguns,it is necessary to use a combination of threedimensional numerical simulation and experiments to study the mechanism of bore damage.In this paper,a three-dimensional numerical model of the augmented railgun with four parallel unconventional rails is introduced to simulate the internal ballistic process and realize the multi-physics field coupling calculation of the rail gun,and a test experiment of a medium-caliber electromagnetic launcher powered by pulse formation network(PFN)is carried out.Various test methods such as spectrometer,fiber grating and high-speed camera are used to test several parameters such as muzzle initial velocity,transient magnetic field strength and stress-strain of rail.Combining the simulation results and experimental data,the damage condition of the contact surface is analyzed.
文摘喷雾热解法是制备纳米CeO_(2)粉体的途径之一,但液滴在高速高温气流中发生的蒸发、破碎和热解行为影响了最终产品的性能和品质。本文基于VOF(Volume of fluid)蒸发传质模型与有限速率化学反应模型的耦合方法,研究了热解中液滴形貌以及流场的变化和产物分布随时间的全过程。结果表明:当入口气流速度为60 m/s、温度为650℃时,液滴在破碎前的形貌发生了变化,即液滴表面先出现波纹状起伏,然后加剧为褶皱状起伏,最后转变为沟壑状起伏;液滴迎风面与背风面存在压力差,流场中局部(液滴边缘)气流速度最大为67 m/s;子液滴数量沿X轴正方向不断减少且周围有产物CeO_(2)生成,计算域内产物CeO_(2)含量随时间的延长而逐渐增大;产物CeO_(2)主要生成于气相与氧化剂的交界面处,而非直接附着在液滴表面。
