Experimental Technology and Management

[Objective] Cross-medium impact dynamics is a core compulsory course for ship and ocean engineering, aerospace engineering, and related majors. It deals with complex physical phenomena such as underwater ejection of navigating bodies, cavitating multiphase flow, and water-exit impact. Traditional theoretical teaching relies primarily on formula derivation and lacks effective visualization tools, making it difficult for students to understand the intricate ice–flow–solid coupling mechanisms and cavitation evolution laws involved in the process. Although cross-medium experimental teaching has been explored domestically and internationally, research on experimental teaching with a focus on cavitation morphology evolution during the high-speed water-exit icebreaking process of a navigating body is lacking. This study aims to fill this gap by integrating the high-speed water-exit icebreaking experiment of navigating bodies with course teaching: systematically observing the entire experimental process; analyzing key characteristics, including changes in the velocity of the navigating body, wake cavitation morphology evolution, and ice layer fragmentation rules; and developing an intuitive experimental teaching case to overcome the insufficiency of intuitiveness of traditional teaching and improve the experimental operation skills and scientific thinking ability of students. [Methods] An integrated experimental and teaching system was constructed. The experimental system comprised a high-speed water-exit icebreaking system, a data acquisition system, and an ice-making device. A transparent acrylic water tank(80 × 80 × 120 cm) was filled with tap water to a depth of 80 cm; prefabricated ice layers(8 layers in all, each 40 × 40 × 1.5 cm, prepared 2 days in advance) were placed on the water surface. The navigating body(length: 257 mm, diameter: 38 mm) was ejected by 150 kPa high-pressure air from a gas tank(controlled by a PLC panel and solenoid valve). Two Phantom VEO 710L high-speed cameras(10,000 frames/s, 448 × 800 resolution, and 50 μs exposure) and two 2000 W thermal headlamps captured images at horizontal and oblique overhead angles; the data were processed by PCC software. The experiment followed 10 standardized steps, and teaching adopted a three-stage model: pre-class preparation(teachers prepared equipment/outlines; students previewed), in-class group experiments(role rotation for camera operation, PLC control, and phenomenon observation), and post-class assignments. Velocity was calculated as displacement divided by the time interval using high-speed camera frame data. [Results] The experiment accurately reproduced the underwater movement, ice collision, penetration, and water–air interface crossing of the navigating body. Velocity increased initially and then decreased, rising from 7.41 m/s(head exit) to 8.15 m/s(tail exit), then dropping to 7.41 m/s(ice collision), 5.13 m/s(ice penetration, a 31% decrease), and finally 4.76 m/s(tail water-exit). Cavitation evolved in five stages: stable aggregation(pre-collision), irregular mushroom-shaped disturbance(collision), intense fragmentation with vacuum zones(icebreaking), asymmetric elongation/shedding(penetration), and gradual dissipation(water-exit). Ice cracks developed from intact surfaces(pre-collision) to microcracks(initial collision), reticulated main cracks(icebreaking), expanded networks with shedding(penetration), and complete fragmentation into small pieces(post-water-exit). In the teaching process, visualization substantially improved students' understanding, and group rotation ensured mastery of all key equipment operations. [Conclusions] This study successfully established an innovative experimental teaching method for the free-ejection high-speed water-exit icebreaking movement of navigating bodies. Experimental results revealed complex multiphase flow coupling characteristics, providing important data for polar underwater vehicle design. Integrating experiments with teaching overcomes the poor intuitiveness of traditional theoretical teaching, improves students' grasp of cross-medium dynamics principles(e.g., cavitation evolution and ice–flow–solid coupling), and cultivates practical skills in equipment operation, data processing, and error analysis. Standardized procedures and interactive design make the teaching method applicable to ship and ocean engineering, aerospace engineering, and other majors. Post-class open questions stimulate students' innovative thinking, enrich cross-medium experimental teaching resources, and lay a solid foundation for talent cultivation in related disciplines.