聚能射流对固体火箭发动机的冲击起爆

为研究聚能金属射流对固体火箭发动机的冲击响应，开展了聚能装药空射实验及某尺寸发动机在无防护情况下的射流冲击实验，使用高速摄影仪记录了爆炸响应过程，并测量了不同距离及方向的空气超压和破片速度。利用AUTODYN有限元计算软件对实验过程进行了数值模拟，通过调整流固耦合的网格大小，避免了耦合泄漏。实验结果表明，火箭发动机受到射流冲击后，会发生剧烈爆炸，推进剂完全反应，破片速度达4 700 m/s以上，距离发动机爆炸中心1 m处的空气超压达到19.78 MPa，爆炸中心温度达到3 000 ℃以上，该推进剂爆炸能量略高于常规炸药。模拟结果显示，射流以头部速度7 000 m/s的速度冲击发动机壳体后，射流头部的尖端被严重烧蚀，且速度降至约5 600 m/s；推进剂在受到射流侵彻1～2 mm后，发生剧烈反应；爆炸冲击波以球形沿圆柱孔装药传播，并通过圆柱形中心孔冲击另一侧推进剂，发生装药的二次冲击起爆，同时伴有回爆现象，在推进剂中心的高斯点出现了3次超压波峰；距离发动机中心1 m处3个高斯点的平均空气压力峰值为18.75 MPa，与实验结果吻合较好。

Impact initiation of a solid-rocket engine by a shaped-charge jet

In order to study the impact of the metal jet formed by a shaped charge on a solid-rocket engine, the shaped-charge blasting experiment was carried out, and the jet impingement experiment was performed for the shaped jet impacting a certain-size engine without protection. A high-speed camera was used to record the response processes of the explosions. Air overpressures and fragment velocities were measured at different distances and in different directions. The jet forming process and the jet-impacting-motor process were numerically simulated by using the finite element software AUTODYN. And in the simulation, the problem of fluid-solid coupling grid leakage was avoided by adjusting the grid thickness. The experimental results show that when the rocket engine was impacted by the jet, it exploded violently and the propellant reacted completely. The steel equipment fixing the rocket engine after the explosion was almost destroyed completely. The velocity of fragments reached above 4 700 m/s. The air overpressure at 1 m away from the explosion center of the engine reached 19.78 MPa. Through the pictures collected by the high-speed camera, it could be judged that the temperature in the explosion center reached above 3 000 ℃. According to the peak of the air overpressure and the law of air similarity, the energy produced by this type of propellant explosion was slightly higher than those produced by explosives such as 8701 and TNT. The simulated results show that when the jet impinged on the engine shell at the head velocity of 7 000 m/s, the tip of the jet head was severely ablated, and the velocity of the jet head decreased to about 5 600 m/s; the propellant reacted violently while being penetrated 1?2 mm by the jet; the shock wave propagated along the propellant in a spherical shape, and the propellant on the other side underwent shock initiation twice with a retonation; there were three overpressure peaks at the Gauss point located in the center of the propellant. The first peak was generated by the shock wave from the left side; the second peak was due to the shock wave hitting the solid wall of the propellant and a certain wave surface reflection was generated, causing a pressure rise; the third peak was caused by a new shock wave generated by the retonation. The simulated average air overpressure peak is 18.75 MPa at the three Gauss points set at 1 m from the center of the engine, which is in good agreement with the experimental results.