Abstract
Pile driving of state-of-the-art piles for offshore wind-farms requires the application of noise-mitigation systems to assure that sound pressure levels fulfill official regulations. Currently applied are mainly sound mitigation systems reducing the propagation of the emitted sound, e.g., bubble curtains, rather than reducing the sound generation itself. However, rapidly increasing dimensions of wind turbines with even higher pile diameters demand additional measures to keep sound pressure levels within the defined limits. Therefore, the design of the hammer regarding its acoustic characteristics has recently gained attention. To optimize the hammer design, it is required to model the underwater sound pressure caused by the hammer impact. Here, the modelling time is crucial to the overall optimization time. However, currently applied models to estimate the underwater sound pressure are either computationally expensive (finite element models) or do not allow for a detailed hammer design (analytical models).Within this contribution, a computationally low-cost model, which is able to take modifications of the hammer into account, is presented. The model consists of two steps: In the first step, a finite element model is applied to compute the pile head acceleration. In the second step, a transfer function is used to obtain the sound pressure level based on the pile head acceleration.