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

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=2.5×106 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.