Scour processes around a horizontal axial tidal stream turbine supported by the tripod foundation

Tidal stream turbines may suffer severe scour in the marine environment, which poses a threat to their structural stability. However, there has been limited research conducted on the scour processes around tidal stream turbines. In order to address this gap, physical experiments are conducted to investigated scour development around a tripod-supported tidal stream turbine. The experimental results reveal that the scour pattern around the turbine model is greatly influenced by the alignment angle, as it affects the interaction between the incoming flow and the tripod foundation. Substantial scour holes are formed on the lateral sides downstream of the turbine model, indicating highly turbulent flow in this region. Furthermore, under simulated tidal current conditions, fluctuations in the temporal scour depth are observed due to the reversing flow direction and the migration of ripples. Additionally, it is found that the flow velocity exhibits a linear relationship with the scour depth, regardless of the flow conditions. Taking into consideration the influence of the tripod foundation and the turbine rotor, a prediction equation based on the effective flow work is proposed to estimate the final scour depth of the turbine model. The equation is applicable to both the steady and simulated tidal current conditions.