柱形装药条件下锥形水中爆炸激波管内的冲击波特性

锥形水中爆炸激波管是进行水中爆炸实验的一种装置，该装置能够通过较小装药量在相同距离处实现自由场水中较大装药量爆炸的冲击波峰值。为了获得柱形装药条件下锥形水中爆炸激波管内的冲击波特性，本文通过数值计算的方式，对不同圆锥角和不同柱形装药质量下锥形激波管内的冲击波传播过程进行了模拟，通过对不同工况下激波管内冲击波特性进行分析，发现其初始冲击波的衰减规律符合自由场水中的指数衰减形式，并拟合得到了与自由场水中爆炸相容的冲击波峰值、比冲量和能流密度经验公式；发现其二次脉动压力周期与炸药质量呈反常规的变化规律，并引入等效静水压深度解释了这一现象；发现其二次脉动压力幅值与初始冲击波幅值之比比自由场水中更大，而二次脉动压力的比冲量与初始冲击波冲量之比与自由场水中相当。

Shock wave characteristics in a conical water explosion shock tube under cylindrical charge condition

A conical shock tube is a kind of underwater explosive devices which uses small conical explosive charge to form high intensity shock pressure. Theoretically, the shock wave pressure in the conical shock tube is the same as that generated by a virtual spherical explosive charge in free field water. However, considering the effect of practical factors, the characteristics of shock wave in the actual device and the theoretical device are different to some extent. In order to investigate the shock wave characteristics in the conical water explosion shock tube under a cylindrical charge condition, and to obtain the variation rules of the peak pressure value, the specific impulse and the energy flux density, a series of numerical calculations with different cone angles and different quality of cylindrical charges were conducted. The reliability of the simulation methods was verified by comparing with the published experimental data. Through the analysis of the pressure data obtained by the validated simulation method, it is found that the shock wave in the tube follows the same scaling law as it is in the free field underwater explosion. The constants k and n of the empirical expressions for peak pressure, the impulse and the energy flux density for the shock wave in shock tube are obtained by data fitting. Furthermore, the relationships among the coefficient k, index n and cone angle α were deduced, and the result shows that the coefficients k have well linear relationship with constructed angle coefficient β, and the indexes n can be quantitatively expressed by cone angle α. Regarding the free field as a special case with a cone angle of 360°, it’s constants k and n also conform to the obtained relationships. It is also found that the secondary pulsation pressure period shows an anomalous change rule with explosive mass, which can be well explained by the significant increasement of the equivalent hydrostatic pressure depth. The ratio between the secondary impulse pressure peak and initial pressure peak is bigger than that in free field while the ratio between the secondary impulse pressure’s impulse to the initial pressure impulse is almost the same. These results can provide support for the application of conical shock tubes.