考虑压缩空气边界的爆炸箔起爆器飞片运动模型

A Motion Model of Flyer in Exploding Foil Initiator Considering Compressed Air Boundary

为了研究爆炸箔起爆器中的飞片运动规律,对爆炸桥箔蒸气驱动飞片的过程机理进行了研究。在假设爆炸箔电爆炸后形成的蒸气均匀膨胀以及飞片进行一维刚体运动的基础上,考虑桥箔蒸气内部的压力梯度,引入了压缩空气边界条件,进行飞片运动速度的计算,得到特定发火电路中以桥箔长度、桥箔厚度、飞片厚度以及发火电压为自变量的飞片运动速度模型。根据实测飞片速度的PDV(光子多普勒测速仪)测试结果,引入能量利用率对飞片运动速度曲线进行修正,并且拟合得到了能量利用率关于上述4种自变量的经验公式。结果表明:电爆炸推动飞片运动过程中,能量利用率与桥箔厚度和飞片厚度正相关,而与桥箔长度和发火电压负相关;初期,桥箔蒸气内部具有明显的压力梯度,最大压力可达10 GPa数量级;压缩空气段长度随着时间由0逐渐增大;在桥箔长度与加速膛厚度之比为0.41.2、桥箔厚度与加速膛厚度之比为0.0020.010、飞片厚度与加速膛厚度之比为0.0250.160的范围内,减小桥箔长度、桥箔厚度以及飞片厚度对提高加速膛出口飞片速度、降低爆炸箔起爆器的发火能量具有积极的作用。

In order to study the motion law of flyer in exploding foil initiator(EFI),the process mechanism of flyer driven by exploding bridge foil steam was studied.Assuming the uniform expansion of the steam formed after the electric explosion of the exploding foil and the one-dimensional rigid body movement of the flyer,and considering the pressure gradient inside the bridge foil steam,the boundary condition of compressed air was introduced to calculate the velocity of the flyer.The flyer velocity model with the width of bridge foil,thickness of bridge foil,thickness of impactor and firing voltage as independent variables under a specific firing circuit was obtained.According to the PDV test results of the flyer velocity,the energy utilization rate was introduced to modify motion velocity curves of flyer,and the empirical formula of the energy utilization rate about the above four independent variables was obtained by fitting.Results indicate that the energy utilization rate is positively correlated with the thickness of bridge foil and the thickness of flyer,but inversely correlated with the length of bridge foil and the firing voltage during the process of electric explosion driving the flyer.There is a significant pressure gradient inside the bridge foil steam at the initial stage,and the maximum pressure peak can reach up to 10 GPa orders of magnitude.The length of compressed air section increases from 0 gradually with time.In the range of the ratio of bridge foil length to the thickness of accelerating chamber is 0.4-1.2,the ratio of bridge foil thickness to the thickness of accelerating chamber is 0.002-0.010,and the ratio of flyer thickness to the thickness of accelerating chamber is 0.025-0.160,reducing the length,thickness of bridge foil and the thickness of flyer has a positive effect on improving the velocity of flyer at the exit of accelerating chamber and reducing the ignition energy of EFI.