This article introduces a comprehensive methodology that combines physical prototyping and computational modeling to analyze the hydrodynamics and design of a semi-direct acting solenoid valve for water applications. A transparent, injection-molded valve model was used to experimentally measure diaphragm displacement, which exhibited linear behavior at flow rates up to 10.1 L/min. Beyond this threshold, the diaphragm reached maximum displacement, constraining flow control accuracy. These experimental results informed the creation of a computational domain for detailed CFD analysis, demonstrating strong validation against experimental pressure drop data. The CFD simulations identified critical inefficiencies, such as uneven pressure distribution on the diaphragm due to inlet flow, flow imbalances, and vortex formation within the chamber and outlet channel. These issues were traced to specific design limitations. To address these design flaws, this study suggests optimizing the inlet geometry, implementing a symmetric chamber design, and modifying the outlet channel with smoother transitions to enhance flow control and improve operational efficiency.

This study numerically investigates the flow-induced vibration (FIV) of a single-degree-of-freedom transverse vibration and pivoted rotation of a square cylinder with the Reynolds number (Re) range of 0.7 × 104 to 6 × 104. Different FIV phenomena with Re increasing are reported. In the vortex-induced vibration (VIV) branch, the amplitude and energy harvest efficiency of the transverse vibration are higher than those of the pivoted rotation, and the situation is opposite in the VIV-galloping transition and galloping branches. Checking the wake vortex indicated that the change in the angle of attack caused by the pivoted rotation of the square cylinder was the cause of these phenomena. The most significant feature was that, at the maximum amplitude, a pair of co-rotating vortices (C mode) shed. The transverse vibration had larger vibration amplitudes and lower aerodynamic force and energy harvest efficiency compared with the pivoted rotation in galloping, and the energy harvest efficiency no longer increased with higher Re. The energy harvest efficiency of the pivoted rotation had two outstanding peaks at maximum pivot angles of θmax = 29° and 41.2°, followed by a decreasing trend. For the transverse vibration, the force induced by the vortices cancels each other out so that the energy harvest efficiency almost does not change. For the pivoted rotation, the amplitude, which does not increase, makes it easier for the wake vortex to interact and interfere with the energy harvest procedure.

The article presents the qualitative and quantitative composition results of mechanical admixtures in the aircraft hydraulic fluid. An experimental study w