聚龙一号上磁驱动铝飞片发射实验的数值分析与再设计

Numerical analysis and redesign of magnetically driven aluminum flyer plate on PTS accelerator

聚龙一号上PTS-151发次实验中,磁驱动加速370μm厚飞片测得的最大速度为18km/s,磁驱动加速482μm厚飞片测得的最大速度为19km/s。采用MDSC2程序,对PTS-151发次实验进行了数值分析,结果表明:PTS-151发次实验中测量的最大速度的含义不同于以往文献中飞片的最大速度。以往文献中发射飞片在测试过程中自由面未被烧蚀,测试的最大速度为飞片自由面速度;PTS-151发次实验中两个飞片在测量过程中自由面被烧蚀,实验测量的最大速度为飞片被完全烧蚀前的一瞬间飞片内部最后一个固体面的速度。在飞片自由面未被烧蚀之前,370μm厚飞片的计算最大自由面速度仅为7km/s,482μm厚飞片的计算最大自由面速度仅为11.8km/s,远低于测量值。对PTS-151发次实验条件下飞片尺寸进行了再设计,飞片厚度为680μm时最优,既能保证自由面未烧蚀,又使得飞片的速度最大,达到17.5km/s。

In the shot PTS-151 experiments the maximum velocity measured on the magnetically driven aluminum flyer plate with a thickness of 370μm was 18 km/s, while that with a thickness 482μm was 19 km/s. In this work, the data from the shot PTS-151 experiments on PTS were simulated and analyzed using the two dimensional magneto-hydro dynamics code MDSC2. The numerical simulation shows that the meaning of the maximum velocity measured in the shot PTS-151 should be different from that of the maximum velocity as reported in the related literatures where, as the free surface of the flyer plate was not ablated during the experiment, the maximum velocity measured was the flyer plate＇s free surface velocity. In the shot PTS-151 experiments the free surface was ablated in the measurement of the two flyer plates, and therefore the maximum velocity measured by VISAR was the velocity of the last solid surface inside them just before they were totally ablated. In our simula- tion, if the initial free surface is not ablated, the maximum initial free surface velocity calculated is 7 km/s with the 370/lm thick flyer plate and 11.8 km/s with the 482 μm thick flyer plate, far below the velocity actually measured in the shot PTS-151 experiments. A new flyer plate was re-designed on the basis of the current condition of the shot PTS-151, with 680 μm as the optimal thickness, which would both prevent the free surface from ablation and achieve the maximum velocity of 17.5 km/s.