Experimental investigation on interference characteristics of projectiles launched successively underwater

In the successive underwater launch, the interference between two projectiles will significantly affect their attitudes and trajectories. To understand the law of the interference, we perform an experimental study on the successive underwater launch with a transport speed. The dynamic sensor and high-speed camera record the surface pressure and attitude of the projectile in these experiments, respectively. After a trial error evaluation, the effect of the launch interval Δt^∗ on the interference between two conical-nosed projectiles is analyzed. The results show that the second shot's surface pressure and pitch attitude gradually approach those of the single-launched projectile as the launch interval increases under the influence of the first shot's wake and transverse flow. The trajectories and force coefficients also tell the same. It indicates that the influence of the first shot weakens as the launch interval increases and reaches a negligible level at Δt^∗=2.26. The effect of the nose shape on the interference is also investigated by conducting the same cases on the ellipsoidal-nosed projectile. The ellipsoidal-nosed projectile has a larger pitch attitude and a more potent interference between them. Therefore, the conical-nosed projectile has a stronger anti-interference ability and a more stable trajectory than the ellipsoidal-nosed projectile.