The oscillating hydrofoil, a device used for collecting environmentally friendly tidal energy, is the focus of the study. The flexibility of the hydrofoil's trailing edge can impact its surface pressure distribution, lift, and moment characteristics. To improve the energy harvesting performance of oscillating hydrofoils, it is important to conduct thorough research on their energy harvesting mechanism. Therefore, numerical analysis is employed to develop a numerical model of the fully passive oscillating hydrofoil with the flexible trailing edge. The dynamic development behavior of surface vortices on hydrofoils is analyzed, demonstrating that the fluid–structure interaction between the hydrofoil and the surrounding fluid alters the hydrofoil's motion. The vortex patterns and pressure distribution on the hydrofoil surface are also affected, ultimately influencing the energy harvesting performance. By optimizing the flexibility coefficient of the fully passive oscillating hydrofoil with a flexible trailing edge, the energy harvesting performance of the oscillating hydrofoil is improved. When the maximum chord offset δm= 0.1c and the flexibility coefficient n= 2, the energy harvesting efficiency is 31.37%, and the average power coefficient is 1.17. Therefore, increasing the tail flexibility can be considered to enhance energy harvesting performance when designing the fully passive oscillating hydrofoil. The research provides a comprehensive analysis of energy harvesting performance, addressing the dynamic problem of the fully passive oscillating hydrofoils with flexible trailing edges. The findings of this study may provide guidance for the design and optimization of tidal energy harvesting devices with similar structures.

Spring-loaded pressure safety valves are the key devices used for protecting pressure vessels and systems. In order to facilitate the design progress of spring-loaded pressure safety valves and get a better understanding of the flow forces, this paper conducted a series of numerical simulations for predicting the flow forces acting on the disc at various valve opening positions for different pressures ranging from 3 to 4 bar. 2D and 3D geometries as well as different turbulence models have been developed for improving the accuracy of the simulation. The results indicate that the two-dimensional model along with transition on SST model can simulate the turbulent flow within the flow domain effectively , according to the comparison with experimental data. In addition , it reveals that this study can be of great help to predict flow forces at the similar mechanical structure.

As the essential part of a pressure system, the pressure safety valve (PSV) is widely used in the fields of chemical industry and nuclear power. However, few closely attention have been paid on the life coefficient of valve disc. Therefore, a measurement system of safety valves hat been established for investigating the influence of different positions of disc and the load cell is used to measure the lift force of valve disc. Specially, the micrometer mechanism and the laser displacement sensor which can improve the precision of the adjustment of the position of disc, have been used for the feed and feedback. Besides cantrolling the NI-DAQ for real-time data acquisition, the data acquisition system programmed by Lab VIEW also can achieve the data processing. And compared with the experimental results, it is shown that the measurement system has strong repeatability and can reasonably capture the lift force under different pressures and positions of valve disc.

The main steam relief isolation valve (MSRIV) is one type of high-end nuclear valve in nuclear power plants, whose operation is mainly determined by the dynamics of the pilot valves mounted on it. To analyse the mechanism of this influence, an in-depth numerical and experimental study is carried out in this paper. Transient simulations of MSRIV opening were conducted using the UDFs-based fluid–structure interaction method to accurately predict valve disc dynamics. A full-scale prototype test was conducted prior to the simulation analysis, and the test results confirmed the accuracy of the numerical model. The validated model was used to analyse MSRIV internal dynamics. Results indicate that pilot valve actuation rapidly redistributes pressure, generating the differential pressure that drives disc motion. This mechanism induces a distinct delay before the onset of motion. As the pilot valve opening time increases, both the actuation delay and full-stroke opening times for single-pilot MSRIV (SP-MSRIV) and dual-pilot MSRIV (DP-MSRIV) configurations exhibit a near-linear increase. Notably, the dual-pilot configuration builds the pressure differential faster and significantly reduces response time. More specifically, pilot valve timing mainly affects the initial pressure-difference buildup stage, with limited influence after disc motion begins. This study clarifies the effects of pilot valve configurations on MSRIV dynamic response, providing a basis for optimising the rapid-response design of nuclear-class pressure control valves.