Numerical Simulation Study on High-Speed Oblique Water Entry of Dual Navigator in Series-Parallel Configurations

Objectives This study aims to gain a comprehensive understanding of the dynamic performance and cavity evolution characteristics of multiple supercavitating vehicles during high-speed oblique water entry in both parallel and series configurations. A numerical simulation approach was employed to conduct a systematic analysis of the high-speed oblique water entry process of dual vehicles in both parallel and series arrangements. Methods Using the CFD software Star - CCM+, this study applied the Realizable k - ε turbulence model to solve the Reynolds - averaged equations and integrated overlapping grid technology to accurately capture flow field characteristics. To track cavity evolution, the volume of fluid (VOF) method was combined with the Schnerr - Sauer cavity model. Numerical simulations of the high - speed oblique water entry process for dual vehicles in parallel and series configurations were conducted under various angles of attack and clearance conditions. The research thoroughly analyzed the velocity variation, pressure load distribution, and cavity evolution of the vehicles across these conditions. Results Numerical results show that parallel dual vehicles at 8°–18° exhibit a complete ricochet motion. As the attack angle increases, the ricochet phenomenon is delayed, along with increased cavity outer wall pressure and cavitation intensity. For parallel dual vehicles, at a clearance of 1.2D, significant fusion occurs in the cavities and wakes of the two vehicles. When the clearance increases to 3.2D, cavity evolution resembles that of a single vehicle, improving motion stability and intensifying the ricochet phenomenon. Series dual vehicles with the lead vehicle at 8°–18° can cause ricochet, with the vehicle fully jumping out of the water at 8° and 13°. As the attack angle increases, the cavity morphology transitions from an open, merged, slender cavity to independent cavity development for each vehicle. For series dual vehicles, 35D is a critical clearance value. Beyond this, the interference between the two vehicles significantly weakens. Before 35D, the following vehicle enters the lead vehicle's wake earlier, causing cavity breakup and instability. After 35D, the interference diminishes, the following vehicle encounters a more stable flow field, and the cavity approximates that of a single vehicle entry. Conclusions When dual vehicles enter water at high speeds in different configurations, the flow field and cavity morphology change accordingly. The findings provide theoretical support and practical references for the design and application of supercavitating vehicles.