A new experimental method on simulating the combined action of cavitation erosion and abrasion was proposed to investigate the erosion mechanism of overflow structure induced by the said processes. An automatic sand mixing device was invented for high-pressure and high-speed flow based on the characteristics of Venturi cavitation generator and hydraulic Bernoulli principle. The experimental system for the combined action of cavitation erosion and abrasion was designed and constructed, and high-speed sand mixing flow only appeared in the test section. A series of tests on the combined and single action of cavitation erosion and abrasion on hydraulic concrete and cement was carried out by using the invented experimental device. Results show that the wear of concrete surface exhibited the combined characteristics of cavitation erosion and abrasion under their joint action. The damage degree of concrete surface under the combined action was more severe than that under a single action. The mass loss of concrete under the combined action was higher than sum of mass losses of concrete under two single actions. The promotion and enhancement between cavitation erosion and abrasion existed in high-speed sand mixing flow. A power exponential relationship was observed between erosion mass loss and flow speed, and the velocity indexes approximated 4.5. Small and light sand particles easily follow water flow. Thus, the strong coupling effect of cavitation erosion and abrasion resulted from the presence of small sand particles. Given the different mechanisms of cavitation erosion and abrasion, presenting the skeleton structure formed by cavitation erosion was notably difficult under the action of abrasion. Meanwhile, abrasion wear easily occurred under the impact of cavitation erosion, and this result is due to the mechanism of the combined action of both processes.

In implementing ship channels in mountainous rivers with complex topography, navigation safety has become paramount for facilitating efficient tunnel operations. The security of large vessels in tunnels has recently been the focus of a considerable amount of research in the inevitable trend of vessel upsizing. This study analyzes the characteristics of unpowered coasting distance for ten-thousand-ton bulk carriers through ship simulations. The study discovered a positive correlation between coasting length and variables including tunnel width, water depth, and sectional coefficient. Moreover, it explores the maneuvering characteristics throughout the tunnel traversal process. It proposes a vessel-following model based on car-following theory and defines different types of following distances to determine the transportation capacity of the tunnel. The research findings greatly enhance tunnel navigable safety and optimize ship tunnel operations.

With the widespread use of sector gates in tidal river locks, there is a growing interest in the operating force during the gate operation. This study investigates the characteristics of operating forces in a sector gate hydraulic cylinder system using prototype testing and focuses on the effects of different heads and flow velocities under the operating forces. The results reveal significant differences in the opening processes between normal and reverse heads, with head differentials and direction playing crucial roles in determining the operating force under flowing conditions. In still water, both gate opening and closing processes are divided into four and three stages, respectively, with the operating force remaining stable during the low-force operation stage. In particular, during gate closure under flowing conditions, flow velocity emerges as a key factor influencing the operating force, with the force during the small gate opening stage exhibiting a parabolic relationship with flow velocity. These findings provide valuable insights for the design and selection of hydraulic gate control systems, contributing to the safe operation of gates and efficient navigation of waterways.

In the present paper, the WC-Cr₃C₂-Ni based composite coatings with different kinds of graphene were prepared for the purpose of exploring the role of graphene in modulating ultrasonic cavitation erosion (UCE) mechanisms and corrosion dynamics. The WC-Cr₃C₂-Ni powder was functionalized with graphene nanoflakes and graphene oxide using polyvinyl, followed by deposition of distinct composite coatings via high-velocity oxygen-fuel (HVOF) spray technology. UCE and electrochemical experiments were utilized to analyze the UCE and corrosion behaviors of the composite coatings in marine-simulated 3.5 % NaCl electrolyte. The data revealed that the incorporation of graphene oxide effectively improves the resistance of the WC-Cr₃C₂-Ni coating to UCE, consequently reducing its cumulative volume loss (5.58 mm³) compared with the coating without graphene oxide (15.07 mm³) after 30 h UCE. The graphene oxide-modified coating's charge transfer resistance (3.29 × 10⁵ Ω·cm²) was larger than that of the WC-Cr₃C₂-Ni coating (2.96 × 10⁵ Ω·cm²) and the graphene nano flakes-modified WC-Cr₃C₂-Ni coating (2.11 × 10⁵ Ω·cm²). The graphene oxide-modified WC-Cr₃C₂-Ni coating had a decreased corrosion propensity as well as a lower material dissolution rate compared to other two coatings.

Polymeric coatings are used to protect concrete hydropower structures from damage by particle-laden, fast-moving water. In this research, a new experimental method is proposed to simulate this tribosystem. Test materials are submerged in an agitated vessel containing basalt particles and abraded for a fixed time. This paper describes the use of this test to screen polyurea coatings of various types of hardness. The use of such test on rubbers is also described. Results present that the wear process of the polyurea is stable and the wear loss is linear with the erosion time. When the hardness of the polyurea or seal rubber increases, the erosion resistance indicates a downward trend and the surface becomes smooth from rough. A polyurea hardness of Shore D30 and a seal rubber hardness of Shore A70 produce the best slurry erosion resistance. The erosion resistance of the polyurea is much better than that of the high-performance concrete. If the wear thickness is regarded as the evaluation indicator, then the erosion resistance of the polyurea of Shore D30 is approximately 60 times more than that of the high-performance concrete.