Abstract: In order to study the flow field characteristics of large diameter ultra-high speed balance gun，a 2-D axisymmetric numerical simulation model was established based on the finite volume method，using the holistic movement of a partitioned mesh processing method，combining with the structured dynamic grid technique，and using navier-stokes equation with realizable k-ε turbulence model. Taking the 300mm balanced gun as an example，the flow field characteristics of two different velocities which one is 1.72km/s and the other is 794m/s were researched. The calculation results show that the flow field of 1.72km/s is similar to that of 794m/s，but the structure is more obvious like“narrow”slightly as a whole. The powder gas velocity reaches 2.5km/s but it can not pursue and surround projectile. The projectile velocity reaches Ma=4.03，and gets rid of the influence of flow field at 1.0ms mostly. But the flow field structure of conventional velocity projectile is like a “ball”，the powder gas makes a greater impact on projectile and the function time is much longer than that of hypervelocity firing. The projectile velocity reaches Ma=1.27，and gets rid of the influence of flow field mostly at 1.5ms.

Key words: Large diameter ultra-high speed；Muzzle flow field；Dynamic mesh；Characteristic analysis

摘要： 为了研究大口径超高速平衡炮的膛口流场特性，基于有限体积法，采用分块网格划分的整体运动处理方法，结合结构动网格技术，并采用N-S方程结合Realizable k-ε湍流模型，建立了膛口流场二维轴对称数值仿真模型。以300mm平衡炮为例，研究了1.72km/s，794m/s两种速度下的膛口流场特性。计算结果对比表明: 1.72km/s初速的弹丸膛口流场与794m/s初速弹丸膛口流场结构相似，但其射流结构更加明显，流场结构整体略呈“狭长”状，火药燃气速度达到2.5km/s，但不能追赶并包围弹丸，弹丸速度达到Ma=4.03，1.0ms时基本摆脱了流场对其运动的影响。而常规初速弹丸流场结构呈“圆球”状，火药燃气对弹丸的影响较大，作用时间大于超高速发射情况，速度达到Ma=1.27，1.5ms时基本摆脱了流场对其运动的影响。

关键词: 大口径超高速;膛口流场;动网格;特性分析