Experimental study on asynchronous parallel high-speed oblique water entry of cylinders

This study presents the construction of a high-precision, high-speed parallel water entry experimental system and proposes a more accurate optical correction method. An experiment is conducted on parallel high-speed oblique water entry to analyze different time intervals that affect cavity development, interference, and coupling modes. This study found three squeezing modes between the cavities when the first projectile is located on the downstream side. Model 3 will cause a lateral jet phenomenon in the second cavity among them. The maximum diameter of the second cavity first increases and then decreases as the time interval increases. Additionally, this study discovered that the wake of the first cavity pinches off the second cavity when the first projectile is on the upstream side. The pinching process consists of five stages: wake generation, interference, destruction, penetration, and pinched-off. The cavity pinched-off time increases with the increase in asynchronous time intervals. This study uncovers the wake bifurcation phenomenon and elucidates its underlying mechanism. The second cavity squeezes the initial round cross-section of the first cavity, forming a ‘Half-moon Shape’ cavity cross-section that gradually transitions into a ‘Crescent-moon Shape.’ Eventually, the crescent-shaped cavity collapses, leading to the wake bifurcation phenomenon.