Integral approach for modelling offshore bubble curtains

The construction of offshore wind turbine foundations in the North Sea with impulsive hammers is related to high noise emission. For the protection of the maritime environment, the German government constituted limits of 160 dB in 750 m distance to the pile. To meet the regulations, noise mitigation systems are often combined which results in an increase of the related costs nowadays. The bubble curtain is one of the most utilized systems in particular due to the possibility to place it in a greater distance to the pile and combine it with near-pile systems. Besides the intensive utilization of the bubble curtain, the main effect of the noise reduction has not been understood especially under offshore conditions. A model of the bubble curtain has been developed which takes into account the local variation of the physical properties and the impact of the upper bottom layers. Comparisons with offshore measurements and a sensitivity study are presented.