In high-pressure hydrogen systems, the check valve is one of the most easy-to-damage components. Generally, the high-pressure hydrogen flow can generate a strong impact on the check valve, which can cause damage and failure. Therefore, it is useful to study the transient flow characteristics of the high-pressure hydrogen flow in check valves. Using dynamic mesh generation and the National Institute of Standards and Technology (NIST) real hydrogen gas model, a transient-flow model of the high-pressure hydrogen for the check valve is established. First, the flow properties of high-pressure hydrogen during the opening process is investigated, and velocity changes and pressure distribution of hydrogen gas flow are studied. In addition, the fluid force, acceleration, and velocity of the valve spool are analyzed quantitatively. Subsequently, the effect of the hydrogen inlet-pressure on the movement characteristic of the valve spool is investigated. The results of this study can improve both the design and applications of check valves in high-pressure hydrogen systems.

Recently, the Trailing-Edge Flap with Micro-Tab (TEF with Micro-Tab) has been exploited to enhance the performance of wind turbine blades. Moreover, it can also be used to generate more lift and delay the onset of stall. This study focused mostly on the use of TEF with Micro-Tab in wind turbine blades using NREL’s S-809 as a model airfoil. In particular, the benefits generated by TEF with Micro-Tab may be of great interest in the design of wind turbine blades. In this paper, an attempt was made to evaluate the influence of TEF with Micro-Tab on the performance of NREL’s S-809 airfoils. Firstly, a computational fluid dynamics (CFD) model for the airfoil NREL’s S-809 was established, and validated by comparison with previous studies and wind tunnel experimental data. Secondly, the effects of the flap position (H) and deflection angle (α_F) on the flow behaviors were investigated. As a result, the effect of TEF on air-flow behavior was demonstrated by augmenting the pressure coefficient at the lower surface of the airfoil at flap position 80% chord length (C) and α_F = 7.5°. Thirdly, the influence of TEF with Micro-Tab on the flow behaviors of the airfoil NREL’s S-809 was studied and discussed. Different Micro-Tab positions and constant TEF were examined. Finally, the effects of TEF with Micro-Tab on the aerodynamic characteristics of the S-809 with TEF were compared. The results showed that an increase in the maximum lift coefficient by 25% and a delay in the air-flow stall were accomplished due to opposite sign vortices, which was better than the standard airfoil and S-809 with TEF. Therefore, it was deduced that the benefits of TEF with Micro-Tab were apparent, especially at the lower surface of the airfoil. This particularly suggests that the developed model could be used as a new trend to modify the designs of wind turbine blades.

Hydrogen energy is regarded as an ideal energy source due to its high efficiency, environmental friendliness, and renewability. Liquid hydrogen energy storage is considered a cost-effective method for long-distance transportation and large-volume storage of hydrogen. The liquid hydrogen ball valve regulates flow and directs the liquid hydrogen system. Understanding the flow characteristics in the ball valve is crucial for ensuring the stability and safety of liquid hydrogen storage systems. In this study, computational fluid dynamics (CFD) is used to establish a comprehensive model of the liquid hydrogen ball valve. The distributions of pressure, velocity, and vorticity under varying opening degrees are examined to elucidate the fluid dynamics within the valve. Furthermore, the study investigates the flow resistance coefficient and flow coefficient for the liquid hydrogen ball valve to assess its performance characteristics. Results indicate that with increasing ball opening, the pressure difference between the ball inlet and outlet diminishes, leading to the gradual disappearance of vortex formations within the valve. Quantitatively, the pressure difference remains relatively stable at approximately 10,500 Pa between 20° and 60°, but drops sharply by 80.99% from 60° to 90°. The flow resistance coefficient decreases drastically from 689.057 at 20° to 0.546 at 80°, while the flow coefficient increases from 0.042 to 3.356. Notably, at a ball opening of 80°, vortex formations are nearly eliminated. This investigation contributes valuable research insights and theoretical foundations for the optimal design of valves within liquid hydrogen storage systems.