Hydrodynamic behavior of an offshore OWC power station under dam-break flows: Numerical and experimental study

Abstract

The hydrodynamic behavior of a three-dimensional oscillating water column (OWC) device subjected to dam-break flow incidents was investigated using numerical and experimental methods. Load characteristics and flow field distributions were analyzed under various opening ratios of the air chamber and angles of incident flow. Numerical results were validated against experimental measurements of impact loads and water surface elevation at a 45° incident angle, and extended to six additional incident angles: 0°, 15°, 30°, 60°, 75°, and 90°. The peak impact load and air chamber pressure occurred at 90°, both decreasing as the incident angle varied to 0°. The peak horizontal resultant force decreased by 43.4 %, 55.3 %, and 65.9 % at 60°, 45°, and 30°, respectively, while peak air pressure decreased by up to 68 % at 0°. Loads on internal and external walls were of similar magnitudes, highlighting the importance of considering internal wall forces in structural design. Flow field analysis revealed complex flow contours and an inclined water surface inside the chamber, which became more pronounced as the incident angle decreased. Moreover, increasing the opening ratio of the air chamber significantly reduced peak impact loads and air pressure, especially in the range of 0 % to 3.5 %. However, larger opening ratios may reduce energy capture efficiency. Thus, selecting an appropriate opening ratio that balances load reduction with energy capture efficiency is crucial for OWC design.