We consider the effects of the aspect ratio L/H (where<em> L</em> is the length of a prism, and <em>H</em> is the height of a prism normal to the flow direction) and the size of additional stru...We consider the effects of the aspect ratio L/H (where<em> L</em> is the length of a prism, and <em>H</em> is the height of a prism normal to the flow direction) and the size of additional structures (which are a plate and a fin on the surface of a prism) on a vibration characteristic of a cantilevered rectangular prism. The present research is intended to support the analysis of energy harvesting research on the flow-induced vibration in water flow using a magnetostrictive phenomenon. The prisms are constructed from stainless steel and mounted elastically to a plate spring attached to the ceiling wall of the water tunnel. The prisms with aspect ratios of<em> L/H</em> ≥ 5 have reasonably identical vibration characteristics. However, the difference in the vibration characteristic appears distinctly on a rectangular prism with an aspect ratio of <em>L/H </em>= 2.5. The rectangular prism with an aspect ratio of <em>L/H</em> = 10 and a side ratio of <em>D/H</em> = 0.2 has a stable and large response amplitude and oscillates with a lower velocity. The length of the added plate and the size of the added fin influence the velocity of vibration onset. If the length of the added plate and fin size on the rectangular prism with <em>D/H</em> = 0.2 becomes large, the curve of the response amplitude shifts to that of the rectangular prism with <em>D/H</em>= 0.5. The response amplitude of the rectangular prism with/without plate or fin is found to be related to the second moment of area of the prism.展开更多
In order to study the impacts of warhead geometry and initiation pattern on the lethality of aimable warhead,multi-point synchronous initiated hexagonal prism and cylindrical warheads were compared through numerical s...In order to study the impacts of warhead geometry and initiation pattern on the lethality of aimable warhead,multi-point synchronous initiated hexagonal prism and cylindrical warheads were compared through numerical simulation,combined with theoretical formulas of fragment deceleration and target plugging.Enhancements of fragment velocity,kinetic energy and density toward the target and target destructions were analyzed.The results show that hexagonal prism warhead can produce dense fragment beams and enhance average velocity and kinetic energy with asymmetric eight-point initiation by 24.13% and54.52%respectively,which are higher than those of the isometric or same weight cylindrical warhead.The effective fragments are still relatively concentrated in an area of 8m×2mfor the hexagonal prism warhead when the distance between warhead and target is 40m.展开更多
文摘We consider the effects of the aspect ratio L/H (where<em> L</em> is the length of a prism, and <em>H</em> is the height of a prism normal to the flow direction) and the size of additional structures (which are a plate and a fin on the surface of a prism) on a vibration characteristic of a cantilevered rectangular prism. The present research is intended to support the analysis of energy harvesting research on the flow-induced vibration in water flow using a magnetostrictive phenomenon. The prisms are constructed from stainless steel and mounted elastically to a plate spring attached to the ceiling wall of the water tunnel. The prisms with aspect ratios of<em> L/H</em> ≥ 5 have reasonably identical vibration characteristics. However, the difference in the vibration characteristic appears distinctly on a rectangular prism with an aspect ratio of <em>L/H </em>= 2.5. The rectangular prism with an aspect ratio of <em>L/H</em> = 10 and a side ratio of <em>D/H</em> = 0.2 has a stable and large response amplitude and oscillates with a lower velocity. The length of the added plate and the size of the added fin influence the velocity of vibration onset. If the length of the added plate and fin size on the rectangular prism with <em>D/H</em> = 0.2 becomes large, the curve of the response amplitude shifts to that of the rectangular prism with <em>D/H</em>= 0.5. The response amplitude of the rectangular prism with/without plate or fin is found to be related to the second moment of area of the prism.
文摘In order to study the impacts of warhead geometry and initiation pattern on the lethality of aimable warhead,multi-point synchronous initiated hexagonal prism and cylindrical warheads were compared through numerical simulation,combined with theoretical formulas of fragment deceleration and target plugging.Enhancements of fragment velocity,kinetic energy and density toward the target and target destructions were analyzed.The results show that hexagonal prism warhead can produce dense fragment beams and enhance average velocity and kinetic energy with asymmetric eight-point initiation by 24.13% and54.52%respectively,which are higher than those of the isometric or same weight cylindrical warhead.The effective fragments are still relatively concentrated in an area of 8m×2mfor the hexagonal prism warhead when the distance between warhead and target is 40m.
