Design of a numerical model to analyse a wave energy dissipation device for hydropower

Abstract

Hydropower is a key technology for generating electricity. International goals of shifting to a more sustainable power production, elevates the future importance of this technology with low allocated emissions of greenhouse gases. Despite the long-term usage of hydropower, issues related to high wave energy level located in the stilling basin of the hydropower plant have not been given much attention earlier. One of these issues is the disturbance of nearby residents, mainly by infrasound pollution. The purpose of this thesis is to investigate the possibility to reduce wave energy in the outlet by a floating hinged-raft device. The suggested device will dissipate energy through interconnected piston dampers. The study is based on numerical simulations and the dissipation efficiency is to be calculated. Simplifications have been made throughout the investigation, hence the numerical simulations exclusively considers linear regular waves with an incident angle of zero. Six different samples with varying raft length and submerged area were investigated in order to find a satisfactory design. It has been found that the presented raft structure could dissipate wave energy significantly. It is recommended to optimize the design further and also broader the investigation area, e.g. simulate according to irregular wave theory, by introducing a mooring system and adding supplementary rafts in attempts to increase the dissipation efficiency.