| The vast ocean contains a wealth of wave energy resources.In the context of the depletion of fossil energy and the imminent development of renewable energy,how to effectively develop wave energy has become a hot issue for scholars concerned.The Oscillating Water Column(OWC)wave energy conversion device has been favored by scholars for its simple structure and durability.However,the OWC device has not been widely promoted and used,due to the high construction cost and relative limited economic benefits.Improving its economy and improving its energy conversion efficiency are of great significance for the development of the OWC device.In this paper,the wave tank test and the Particle Image Velocimetry(PIV)technology were used to study the OWC breakwater,which can realize wave energy extraction function and wave elimination function.Firstly,by conducting a wave tank test,the effects of incident wave elements,power take-off(PTO)damping and water level on the hydrodynamic characteristics and energy conversion characteristics of the OWC breakwater were analyzed.Then,based on the wave tank test,the oscillating flow field was measured by the PIV technology.The characteristics of oscillating flow field were quantitatively analyzed,and the relationship between oscillating flow field characteristics and energy dissipation was discussed..The results of the wave tank test show that when the relative air chamber width B/L is greater than 0.080 and the PTO damping is small(the top plate opening ratio is greater than 0.685%),the OWC breakwater can have a good wave-eliminating effect at 40 cm water level.At 40 cm water level,when the top plate opening ratio is in the range of 1.217%to 1.902%,the OWC breakwater has a good energy extraction performance.Besides,the top plate opening ratio of 1.217%is the optimal PTO damping parameter with the best energy extraction performance.In addition,the increase of wave height promotes the reflection effect of the OWC breakwater,and reduces the peak of energy extraction efficiency.Moreover,the increase in water level reduces the peak energy extraction efficiency and narrows the efficient frequency domain bandwidth.The PIV test results show that the extreme value of the outflow velocity of the water is higher than the extreme value of the inflow velocity of the water.The extreme value of the counterclockwise vortex vorticity in the flow field is higher than the extreme value of the clockwise vortex vorticity.The intensity of the outflow process of water in the flow field is higher than the intensity of the inflow process of the water.The decrease of PTO damping increases the inflow and outflow velocity of the water,the extreme value of the vortex vorticity,and the energy dissipation in the flow field.The increase of the water level enhances the intensity of the inflow and the outflow process of the water,and promotes the energy dissipation in the flow field. |
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