Aim To study the dynamic failure of the plastic spherical shell impacted by a missile. Methods The deformation mode of spherical shells was given by introducing isometric transformation. The governing equation of mo...Aim To study the dynamic failure of the plastic spherical shell impacted by a missile. Methods The deformation mode of spherical shells was given by introducing isometric transformation. The governing equation of motion of the rigid plastic spherical shell was given by energy balance. This equation was solved by using Runge Kutta method. Results The relationships between the impact force, dimple radius, central point deflection and time were obtained. The response time initial velocity, the maximal impact force permanent initial velocity, the central point deflection initial velocity and the dimple radius initial velocity characteristics were respectively plotted. Conclusion A comparison made between the theoretical results and the experimental ones indicates that the two groups of results are in conformity with each other.展开更多
Motion behavior of grinding balls plays a vital role in improving efficiency of particle crushing.A method of preparing micro-particles by changing ball-motion behavior in a flutter mill is proposed and multiple grind...Motion behavior of grinding balls plays a vital role in improving efficiency of particle crushing.A method of preparing micro-particles by changing ball-motion behavior in a flutter mill is proposed and multiple grinding experiments are conducted.Crushing performance parameters,such as breakage rate Si,production rates of fine particles Fi and Fi*,are studied in different motion conditions.From the results,a better crushing performance is attained in the coupled motion modes of rotating speed ratio of 85%,with a vibrating amplitude of 8 mm and a frequency of 12 Hz.In addition,the influence of ball-motion behavior on particle crushing performance is discussed.The ball-motion behaviors,such as the collision energy loss E,among grinding balls have some relationship with the particle crushing performance of Si.Therefore,this study not just provides an efficiency way of accumulating micro-particles,but also reveals how the ball-motion behavior influence particle crushing performance in the flutter mill.展开更多
We presented an experimental apparatus combining the H-atom Rydberg tagging time-of-flight technique and the laser detonation source for studying crossed beam reactions at hyperthermal collision energies. The prelimin...We presented an experimental apparatus combining the H-atom Rydberg tagging time-of-flight technique and the laser detonation source for studying crossed beam reactions at hyperthermal collision energies. The preliminary study of the F+D2→DF+D reaction at hyperthermal collision energy of 23.84 kJ/mol was performed. Two beam sources were used in this study: one is the hyperthermal F beam source produced by a laser detonation process, and the other is D2 beam source generated by liquid-N2 cooled pulsed valve. Vibrational state-resolved di erential cross sections (DCSs) of product for the title reaction were determined. From the product vibrational state-resolved DCS, it can be concluded that products DF(v'=0, 1, 2, 3) are predominantly distributed in the sideway and backward scattering directions at this collision energy. However, the highest vibrational excited product DF(v'=4), is clearly peaked in the forward direction. The probable dynamical origins for these forward scattering products were analyzed and discussed.展开更多
Primary breakup in a liquid-liquid pintle injector element at different radial jet velocities is investigated to elucidate the impingement morphology,the formation of primary breakup spray half cone angle,the pressure...Primary breakup in a liquid-liquid pintle injector element at different radial jet velocities is investigated to elucidate the impingement morphology,the formation of primary breakup spray half cone angle,the pressure distribution,the liquid diameter distribution,and the liquid velocity distribution.With a sufficient mesh resolution,the liquid morphology can be captured in a physically sound way.A mushroom tip is triggered by a larger radial jet velocity and breakup happens at the tip edge first.Different kinds of ligament breakup patterns due to aerodynamic force and surface tension are captured on the axial sheet.A high pressure core is spotted at the impinging point region.A larger radial jet velocity can feed more disturbances into the impinging point and the axial sheet,generate stronger vortices to promote the breakup process at a longer distance,and form a larger spray half cone angle.Because of the re-collision phenomenon the axial sheet diameter does not decrease monotonically.The inner rim on the axial sheet shows a larger diameter magnitude and a lower velocity magnitude due to surface tension.This paper is expected to provide a reference for the optimum design of a liquid-liquid pintle injector.展开更多
文摘Aim To study the dynamic failure of the plastic spherical shell impacted by a missile. Methods The deformation mode of spherical shells was given by introducing isometric transformation. The governing equation of motion of the rigid plastic spherical shell was given by energy balance. This equation was solved by using Runge Kutta method. Results The relationships between the impact force, dimple radius, central point deflection and time were obtained. The response time initial velocity, the maximal impact force permanent initial velocity, the central point deflection initial velocity and the dimple radius initial velocity characteristics were respectively plotted. Conclusion A comparison made between the theoretical results and the experimental ones indicates that the two groups of results are in conformity with each other.
基金the National Natural Science Foundation of China(Nos.51675484,51275474)Zhejiang Provincial Natural Sci⁃ence Foundation of China(No.LZ12E05002)。
文摘Motion behavior of grinding balls plays a vital role in improving efficiency of particle crushing.A method of preparing micro-particles by changing ball-motion behavior in a flutter mill is proposed and multiple grinding experiments are conducted.Crushing performance parameters,such as breakage rate Si,production rates of fine particles Fi and Fi*,are studied in different motion conditions.From the results,a better crushing performance is attained in the coupled motion modes of rotating speed ratio of 85%,with a vibrating amplitude of 8 mm and a frequency of 12 Hz.In addition,the influence of ball-motion behavior on particle crushing performance is discussed.The ball-motion behaviors,such as the collision energy loss E,among grinding balls have some relationship with the particle crushing performance of Si.Therefore,this study not just provides an efficiency way of accumulating micro-particles,but also reveals how the ball-motion behavior influence particle crushing performance in the flutter mill.
基金supported by the National Natural Science Foundation of China (No.21473015, No.21203016, No.41574101, No.21673232, No.21773213)the Foundation for the Author of National Excellent Doctoral Dissertation of China (No.201222)
文摘We presented an experimental apparatus combining the H-atom Rydberg tagging time-of-flight technique and the laser detonation source for studying crossed beam reactions at hyperthermal collision energies. The preliminary study of the F+D2→DF+D reaction at hyperthermal collision energy of 23.84 kJ/mol was performed. Two beam sources were used in this study: one is the hyperthermal F beam source produced by a laser detonation process, and the other is D2 beam source generated by liquid-N2 cooled pulsed valve. Vibrational state-resolved di erential cross sections (DCSs) of product for the title reaction were determined. From the product vibrational state-resolved DCS, it can be concluded that products DF(v'=0, 1, 2, 3) are predominantly distributed in the sideway and backward scattering directions at this collision energy. However, the highest vibrational excited product DF(v'=4), is clearly peaked in the forward direction. The probable dynamical origins for these forward scattering products were analyzed and discussed.
基金supported by the National Natural Science Foundation of China(No.11572346)。
文摘Primary breakup in a liquid-liquid pintle injector element at different radial jet velocities is investigated to elucidate the impingement morphology,the formation of primary breakup spray half cone angle,the pressure distribution,the liquid diameter distribution,and the liquid velocity distribution.With a sufficient mesh resolution,the liquid morphology can be captured in a physically sound way.A mushroom tip is triggered by a larger radial jet velocity and breakup happens at the tip edge first.Different kinds of ligament breakup patterns due to aerodynamic force and surface tension are captured on the axial sheet.A high pressure core is spotted at the impinging point region.A larger radial jet velocity can feed more disturbances into the impinging point and the axial sheet,generate stronger vortices to promote the breakup process at a longer distance,and form a larger spray half cone angle.Because of the re-collision phenomenon the axial sheet diameter does not decrease monotonically.The inner rim on the axial sheet shows a larger diameter magnitude and a lower velocity magnitude due to surface tension.This paper is expected to provide a reference for the optimum design of a liquid-liquid pintle injector.
