Flow Characteristics and Power Generation Effect of a Seawater Intake Caisson Integrated with a Wave-Energy Converter | Journal of Waterway, Port, Coastal, and Ocean Engineering | Vol 149, No 3

AbstractSeawater intake caissons are a kind of structure widely used in seawater extraction. Many existing seawater intake caissons have problems with poor water quality and large power consumption. In this paper, a new type of seawater intake caisson with an oscillating water column wave-energy conversion device is proposed to improve water quality and electricity compensation. A wave-energy conversion device at the front end of the structure can reduce the disturbance of wave energy to the rear water intake area, which is conducive to sediment deposition. In the meantime, it can also realize a certain compensation for the electricity consumption required for pumping water. Based on the two-phase flow solver (OpenFOAM-4.x), through a comparison and analysis of streamlining and flow velocity in the rear water intake area, it was found that the water purification effects of the integrated structure proved more effective than those of the traditional structure, and the overall average velocity of the flow field reduced by 10%–40%. The optimal energy conversion efficiency of the integrated structure was obtained by optimizing different parameters such as the ratio of the chamber width to the wavelength, the orifice size, the draft of the front wall, and the draft of the intermediate baffle.Practical ApplicationsSeawater intake systems are widely used for seawater extraction. Many seawater intake structures suffer from poor water quality and large power consumption due to the large volume of water extraction. A new structure is proposed, which sets an oscillating water column wave energy–converting device on the front side of the traditional seawater intake caisson to capture wave energy. The working process is divided into three stages: firstly, waves enter the device. Wave surface oscillation causes air exhalation and suction to drive the blade rotation, and the generator rotor also rotates to generate electricity; secondly, the flow enters the water intake area and wave energy is significantly weakened by the reflection from the front and back walls of the chamber; finally, the relatively pure seawater is lifted through the pump to the water intake pipeline. The performance of the proposed device is evaluated by comparing the flow field changes of the proposed device and the traditional one and analyzing the energy conversion efficiency of the proposed device. The new structure is verified to have the dual effects of water purification and wave-energy conversion.

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