Numerical Study of Non-Linear Dynamic Behavior of an Asymmetric Rotor for Wave Energy Converter in Regular Waves

Yoon-Jin Ha,Seung-Ho Shin,Ji-Yong Park

doi:10.3390/pr9081477

Abstract

This study conducted a numerical investigation on the non-linear motion problems between a Salter duck-type rotor and large waves using CFD simulations. Regular waves of five different wave heights were generated. First, the linear motion of the rotor from the CFD simulation was verified by comparing it with the existing experimental and frequency domain analysis results. Then, a series of CFD simulations were performed to investigate the non-linear motions of the rotor. In the case of a lower wave height, the CFD simulation results were in good agreement with the experimental and frequency domain analysis results. However, as the wave height increased, the resonance periods were different in each other. In addition, the magnitudes of normalized pitch motions by the wave heights decreased as the wave heights increased. To investigate the aforementioned phenomena, the pitch motion equation was examined using separate CFD simulations. The results showed that changing the restoring moments induced changes in the maximum pitch motions and magnitudes of the normalized pitch motions. In the case of a higher wave height, non-linear phenomena and the changing restoring moments induced non-linear motion.

Highlights

Marine Renewable Energy Research Division, Korea Research Institute of Ships and Ocean Engineering, Citation: Ha, Y.-J.; Park, J.-Y.; Abstract: This study conducted a numerical investigation on the non-linear motion problems between a Salter duck-type rotor and large waves using computational fluid dynamics (CFD) simulations
Wave energy converters (WEC) can be classified into five types: floating body type, oscillating water column type (OWC), pressure type, overtopping type, and set-up type from [1]
WECs using a floating body are relatively simple, and the manufacturing cost is low owing to their smaller size

Summary

Introduction

Marine Renewable Energy Research Division, Korea Research Institute of Ships and Ocean Engineering, Citation: Ha, Y.-J.; Park, J.-Y.; Abstract: This study conducted a numerical investigation on the non-linear motion problems between a Salter duck-type rotor and large waves using CFD simulations. The linear motion of the rotor from the CFD simulation was verified by comparing it with the existing experimental and frequency domain analysis results. To evaluate a floating body for an energy conversion system, a time-domain simulation was employed using the equation in [7]. This is because the time-domain analysis can be necessary owing to the control mechanism, non-linearity of the power take-off (PTO)

Methods

Results

Conclusion