双向抗高过载微流体惯性开关

Microfluidic Inertial Switch Capable of Bidirectional Anti-High Overload

为实现微流体惯性开关在智能弹药引信系统中的应用,提出一种双向抗高过载微流体惯性开关,解决高冲击作用下由水银液滴分离造成的开关接触不稳定问题.基于微通道内水银液滴所受毛细力原理,设计蛇形缓冲通道与三级毛细阀结构.分析收缩型毛细阀与扩张型毛细阀中水银液滴的受力状态,建立矩形截面通道中水银液滴的静态阈值模型;采用用户定义函数(UDF)施加加速度载荷对开关进行有限元仿真.通过仿真分析可知,该惯性开关在典型正向勤务跌落载荷与典型反向勤务跌落载荷作用下,水银液滴可恢复至初始状态,不会产生液滴分离现象,表明开关具备可靠的抗高过载能力.采用两次离心试验完成微小水银液滴的制备与注液,对所制作的微流体开关样机进行Machete落锤冲击试验.试验结果表明:开关在典型正向冲击载荷与典型反向冲击载荷作用后,水银液滴未发生液滴分离现象,与仿真结果一致.

In order to realize the stable application of microfluidic inertial switch in the intelligent ammunition fuze system,a bidirectional anti-high overload microfluidic inertial switch is proposed to solve the problem of switch contact instability caused by the mercury droplet separation under high impact.The structures of snake-shaped buffer channel and three-stage capillary valve are designed based on the principle of capillary force applied to the mercury droplet in microchannel.The force state of the mercury droplets in the contraction type and the expansion type of capillary valves is analyzed.The static threshold model of the mercury droplet in the rectangular channel is established.The user defined function(UDF)is used to apply acceleration load to the finite element simulation of the switch.The simulation analysis suggests that under the action of typical forward service drop load and typical reverse service drop load,the mercury droplets can be restored to its initial state without droplet separation,indicating that the switch has a reliable anti-high overload ability.Two centrifugal experiments are conducted to complete the preparation and injection of tiny mercury droplets.The microfluidic switch prototype is used in the impact test of the Machete drop hammer.The results show that the mercury droplet separation does not occur in the switch under the action of typical forward impact load and typical reverse impact load,which are consistent with the simulation results.