Projected area and drag coefficient of high velocity irregular fragments that rotate or tumble  

作　　者：John F. Moxnes 0yvind Fr0 yland Ivar J. 0ye Tom I. Brate Eva Friis Gard 0degardstuen Tallak H. Risdal 

机构地区：[1]Norwegian Defence Research Establishment, Land Systems Division, P.O. Box 25, 2027 Kjeller, Norway [2]Nammo Raufoss AS, P.O. Box 162, 2831 Raufoss, Norway [3]HPVisTech AS, Bj0rnstadgutua 21, 2092 Minnesund, Norway

出　　处：《Defence Technology（防务技术）》2017年第4期269-280,共12页Defence Technology

摘　　要：3 degrees of freedom(DOF)exterior ballistic computer models are used in fragment studies to calculate individual trajectories of each fragment based on drag coefficient and the projected(presented)area in the direction of velocity of center of mass.The expectation of a randomly distributed projected area is commonly used for fragments that tumble(random rotation)during flight.We forecast a model where the expected drag coefficient is dependent of shape and Mach number.Rotation or tumbling only affects the expected projected area.Models of projected areas during tumbling and rotation are presented.An examination of the data by Mc Cleskey(1988)indicates that the volume of the fragment to the power of2/3 is a better parameter to characterize the drag coefficient of the fragments than the maximum projected area.Hydrocode simulations are used to verify results and to study projected area and drag coefficient of fragments.3 degrees of freedom(DOF)exterior ballistic computer models are used in fragment studies to calculate individual trajectories of each fragment based on drag coefficient and the projected(presented)area in the direction of velocity of center of mass.The expectation of a randomly distributed projected area is commonly used for fragments that tumble(random rotation)during flight.We forecast a model where the expected drag coefficient is dependent of shape and Mach number.Rotation or tumbling only affects the expected projected area.Models of projected areas during tumbling and rotation are presented.An examination of the data by Mc Cleskey(1988)indicates that the volume of the fragment to the power of2/3 is a better parameter to characterize the drag coefficient of the fragments than the maximum projected area.Hydrocode simulations are used to verify results and to study projected area and drag coefficient of fragments.

关 键 词：FRAGMENTS Form factor MACH number Drag coefficient CAUCHY area TUMBLING 

分 类 号：TJ01[兵器科学与技术—兵器发射理论与技术]