截面边数和运动速度对水下声弹运动特性的影响

Influences of the Number of Cross-Section Edges and Velocity on the Motion Characteristics of Underwater Acoustic Projectile

声弹作战效能的好坏很大程度上取决于声弹的运动特性。文中基于FLUENT软件中S-A湍流模型的分离涡仿真(DES)模型,以雷诺数Re=2.5×10^6为例,研究了水下声弹运动的流场特性,并与已知的研究成果进行了对比,确定了DES模型应用在高雷诺数下仿真的准确性。并在此基础上研究了平均阻力系数、升力系数及斯特劳哈尔数受水下声弹表面截面边数和运动速度的影响。研究可知:1)平均升力系数随着运动速度的增大而减小,斯特劳哈尔数随着运动速度的增大而增大;2)当雷诺数相等、截面边数不同时,平均阻力系数随着截面边数的增加而减小,斯特哈尔数随着截面边数的增加而增大;3)正四边形和圆形声弹涡街脱落的频率单一固定,故相比其他结构的声弹,容易引发弹体共振,产生破坏;4)正六边行和正八边形声弹涡街脱落的频率不固定,结构不易产生破坏。文中的研究可为合理设计声弹结构、提高作战效能提供参考。

The operational effectiveness of an acoustic projectile depends largely on its motion characteristics.Based on the detach eddy simulation(DES)model of the S-A turbulence model in FLUENT software,the flow field characteristics of underwater acoustic projectile motion are investigated with Reynolds number Re=2.5×10^6 as an example,and the accuracy of the simulation on the basis of the DES model under the high Reynolds number is demonstrated by comparing the investigation results with the known research results.The influences of the number of underwater acoustic projectile cross-section edges and motion velocity on the average drag coefficient,lift coefficient and Strouhal number are analyzed.The results show that:1)the average lift coefficient decreases but the Strouhal number increases with the increase of the motion velocity;2)when the Reynolds number is equal and the number of cross-section edges is different,the average drag coefficient decreases but the Strouhal number increases with the increase of the number of cross-section edges;3)compared with other acoustic projectile structures,the square and circular structures have single and fixed falling-off frequency of vortex street,so they are easy to cause resonance and damage of projectile;and 4)the vortex street falling-off frequencies of the hexagonal and octagonal acoustic projectiles are not fixed,and these two structures are not easy to be damaged.This research may provide reference for rational design of acoustic projectile structure and improvement of operational effectiveness.