Study On The Cassion Breakwater With Contracted Channel And OWC Modeling

Caisson breakwater is a common port structure to protect the port, it block the wave impact and maintain the water winthin the basin keeping smooth water surface. OWC (Oscillating Water Column) device is a wave energy power generation device, It has simple structure,high marine environment adaptability and power generation efficiency. Combinating caisson breakwater and OWC device, for the similary structure of caisson compartment and OWC chamber, can reduce the wave loads that load on the breakwater, and lower the reflect wave height in front of the caisson wall, and generate electricity that obsorbed from wave energy.This paper designs a caisson contraction combined with contracted waterways and OWC device, and study in depth of its work performance with use of physical model test and3D numerical modeling. The main objective of this study is to improve the wave energy conversion efficiency of the device in the process that wave energy converteing to air kinetic energy.Physical model test study on the influencing factors to the device work efficiency which inclueding contracted waterways structure, incident wave elements and shape parameters of the chamber.The test was carried out in the wave flume, with the oscillation amplitude of the water in the chamber, the point pressure on the top of the chamber and the wave reflectivity before the structure wall being the investigated parameters. Experimental results show that there are great influence, which was made by contracted waterways structure, incident wave elements and shape parameters of the chamber, on the work efficiency of the chamber. Model with contraction water has better wave energy absorbing efficiency with respect to the model without contraction water; Incident wave with highter wave height and longer wave period made a great mount of wave energy; Increasing the length of the waterway, augmenting the inclination angle of the front wall and increasing the chamber inlet width can enhance the efficiency of wave energy conversion of the device, in which increasing the chamber inlet width is the most obvious, the length of the chamber has a complex impact on the work efficiency of the chaber, it should be considered in conjunction with the incident wave period. 3D numerical modeling research on the impact on the wave energy conversion efficiency of the device which was made by waterways contraction coefficient, waterways form and the area of the airflow passage with the oscillation amplitude of the water in the chamber, the point pressure on the top of the chamber and air velocity in the airflow passage being the investigated parameters. Waterways contraction coefficient has a great influence on the performance of the structure, waterways with contracted sides has a better performance than waterways with parallel sides, but the waterways contraction coefficient is not the smaller the better, theoretically, there should be a preferred contraction coefficient; waterways form with broken line sides is better than the one with straight line sides; with the area of the airflow passage decrease, the water oscillations inside the chamber reducing, but the point pressure on the top of the chamber and the air velocity in the airflow passage increase, and the work efficiency of the device was enhancement.