A numerical and experimental methodology to characterize the gaseous cavitation in spool valves with U-notches

The performance of spool valves can deteriorate and noise can occur due to cavitation. The noise sound levels caused by cavitation are influenced by many parameters, among which the most important is not-optimal geometry of components. In this paper, a 2 ways – 2 positions directional control valve was studied using experimental and numerical approaches. Tests were performed on a plexiglass body and steel spool analyzing the cavitating area that develops in U-notches. A dedicated test rig was equipped with a high-speed camera placed directly in front of the area of interest where cavitation occurs. Different working conditions were tested by varying the upstream pressure to encourage the development of cavitation. Images were acquired and post-processed, focusing the contour extraction between the liquid and gaseous phases. The images were compared with results from three-dimensional CFD numerical simulations performed using commercial software. The numerical estimation of flow characteristics corroborated the results from investigations carried out using a fast camera, including periodic cavitation structures. This study demonstrates the importance and usefulness of using a three-dimensional CFD approach during the prototyping phase to create quieter component designs