Author(s): Hui Li; Xu Qiu
Linked Author(s): Hui Li
Keywords: Monopile foundation; Spoiler structure; Local scour; Horseshoe vortex; Bed shear stress
Abstract: As a marine structure, monopile foundations can significantly alter the hydrodynamic conditions surrounding the piles. The main causes of local scour around monopile foundations are the horseshoe vortex, downward flow and wake vortex. This study focuses on a large-diameter monopile foundation used in offshore wind power and proposes a spoiler structure. A three-dimensional numerical model is established to investigate the influence mechanism of the spoiler structure on local scour around the monopile. The influence of length L and height H of the spoiler on the location and strength of local horseshoe vortex is discussed, and the distribution characteristics of the bed shear stress are obtained. Comparing the distribution of local horseshoe vortex and bed shear stress with and without the spoiler, it is found that the spoiler ribs can significantly reduce the strength of the horseshoe vortex and the regional shear stress between ribs. The local horseshoe vortex exhibits three flow mechanisms under different geometric spoiler structures, namely independent horseshoe vortex, disturbed horseshoe vortex, and separated horseshoe vortex. In these three states, the protected bed area shows a linear relationship with the spoiler geometric length or height. In addition, the spoiler has a good scour protection characteristics with an H/L ratio of 1. By analyzing the flow field characteristics around the spoiler, the influence mechanism of ribs on the horseshoe vortex and shear stress distribution around the monopile foundation is revealed. Overall, the spoiler structure effectively protects against local erosion, providing valuable insights for the design of monopile foundations.
Year: 2023