As one of the major damage modes of an aircraft fuel tank,the hydrodynamic ram may cause a catastrophic destroy to the fuel tank structure.In order to analyze the multi-fragment impact on the fuel tank under actual combat circumstance,a validated full-filled fuel tank model under single fragment impact is firstly established.The impact situations of multi-fragment hit at the same time,double fragments hit with different spaces,and double fragments hit at different times are studied by using the finite element analysis software of ANSYS/LS-DYNA.The following parameters are carefully analyzed,including the pressure inside the fuel tank,the fragment velocity decay,the total energy absorbed by the water and the deformation of the fuel tank walls.The results show that,the peak pressure of the fluid in the tank is derived from the shock wave which is produced by the fragment;the superposition effect of pressure is enhanced under multi-fragment impact condition;the tank walls significantly deform with the growth of the number of incident fragments.Moreover,the residual velocity of the incident fragment will be increased by the latish one.%作为飞机燃油箱的一种主要损伤模式,水锤效应可能引起油箱结构灾难性的破坏.针对实战环境中多枚破片冲击同一油箱的常见现象,在建立与试验对比一致的单枚破片冲击满水油箱数值模型后,以箱内液体特定单元压力峰值、破片速度衰减、箱内液体吸收的总能量以及油箱壁板变形作为对比参量,分别开展数值模拟,分析其在2枚破片不同间距打击、2枚破片不同时间间隔打击以及多枚破片同时打击时的水锤效应.结果表明:箱内液体的压力峰值来源于破片入水后形成的冲击波,多枚破片入射时液体压力有明显的叠加效应;2枚破片不同时入射将导致先入射破片剩余速度增高;油箱壁板的变形随入射破片数量的增加显著增大.
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