电磁发射高速旋转弹丸马格努斯效应

和传统火药发射弹丸相比,电磁发射弹丸具有初速高、射程远等优势,但尾部的电枢臂槽会使弹丸部流场不再轴对称,产生独特的气动力特性。基于三维非定常Navier-Stokers方程,采用滑移网格技术,分析电磁发射弹丸的气动力特性。研究表明,对于高速旋转的电磁发射弹丸,马格努斯效应来源于激波层内流场畸变和电枢臂的迎风面积变化的共同作用；电枢臂迎风面积的周期性变化是导致气动力和力矩周期性变化的原因,马格努斯力矩在滚转角45°和135°时分别达到最小值和最大值；电枢臂槽的存在既加剧了马格努斯效应(135°时增加50%以上),又使得压心周期性前移(绝对前移量达5%),并且随着转速的增加,马格努斯力矩增加和压心前移效果越来越显著,不利于弹丸的动稳定。

Magnus effect of electromagnetic launch hypervelocity spinning projectile

Compared with the traditional gunpowder bullets, electromagnetic launch bullets have the advantages of high muzzle velocity and long fire range. However, the bullet shape is no longer axisymmetric because of the armature groove at the tail, resulting in unique aerodynamic characteristics. Based on the three-dimensional unsteady Navier-Stokers equation, the aerodynamic characteristics of electromagnetic projectile were analyzed by using the sliding grid technique. Results show that for the hypervelocity spinning electromagnetic projectile, the Magnus effect comes from the interaction of shock layer distortion and the upwind area variation of the armature arm. The aerodynamic force and the moment varies periodically with the roll angle due to the periodic variation of the upwind area of the armature arm, and the Magnus moment reaches the minimum and the maximum at the roll angle of 45° and 135°, respectively. The influence of the armature arm groove is remarkable, which not only worsens the Magnus effect (increased by more than 50% at 135°), but also makes the pressure center move forward periodically (the absolute forward amount is up to 5%). Furthermore, with the increase of spinning speed, the increase of the Magnus moment and the pressure center move-forward effect become more and more significant, which is harmful to the dynamic stability of the projectile.