基于多块结构重叠网格的电磁轨道发射器动态发射过程流场分析

Numerical Simulation and Analysis of Flow Field during Dynamic Launching of Electromagnetic Rail Launcher Based on Overlapping Multi-block Structured Mesh

为了研究电磁轨道发射器动态发射过程流场,采用多块结构重叠网格方法、六自由度运动模型和Java程序,建立了高超声速弹丸二维运动瞬态模型。以双椭球模型为研究对象,验证了所提出非定常计算方法和重叠网格数据交互可靠性。对电磁轨道发射器4种不同运动工况下弹丸动态发射过程流场进行了数值模拟。研究结果表明:电磁轨道发射器动态发射过程是含复杂激波系流场,涉及弹前激波、移动球心球形激波、冠状激波共同作用;弹前激波出膛口到弹体尾部出膛口过程中,弹体头部中点压力分布呈现"对称性",阻力系数分布和弹体头部中点压力分布具有相关性,弹前激波出膛口后呈现先减小、后增大"弱对称性",弹体尾部出膛口时达到峰值;弹丸在空气域运动时,近壁面压力监测点反射后峰值会超过初始监测点压力峰值,距离弹轴距离越远,反射周期越小,监测点峰值压力衰减越慢。

The airflow distribution and law of muzzle flow field during the dynamic launching of electromagnetic rail launcher are studied. A two-dimensional transient model of projectile under high Mach number is established based on overlapping multi-block structured mesh,DFBI and Java program. The unsteady numerical method and the reliability of data interaction are validated by taking double ellipsoid model as the object of study. The flow fields in the dynamic launching processes of four cases are simulated. The numerical results show that the complex flow fields due to the interaction of projectile nose shock wave,spherical shock wave with moving center and coronal shock wave are generated in the dynamic launching process of electromagnetic rail launcher. The shock wave is out of the muzzle from the front projectile to the tail of projectile,and the pressure distribution at the midpoint of projectile nose presentssymmetry. The resistance coefficient is related to the pressure distribution which presents a weak symmetry after the shock wave being out of the muzzle,which reachs a peak at the tail of projectile. When the projectile moves in the air,and the second peak pressure is greater than the first because of the superposition of the shock wave and its reflection. The farther the distance is,the smaller the reflection period is,the slower the pressure decays.