Numerical Analysis For Hydrodynamic Characteristics Of Pendulum Wave Energy Converters

Scientists of many coutries have investigated wave energy-a kind of clean, renewable energy, and it has advanced significantly over the past few decades. At present, many kind of wave energy converters(WECs) have produced, and several are currently being deployed commercially.The pendulum WEC investigated in this paper is hinged on the bascic building in the sea floor of the open waters, the oscillating motion of waves cause a pendulum plate to swing back and forth. This motion is then used to drive a hydraulic piston stretching, and generate a high-pressure flow by compressing the fluid in the hydraulic system. The high pressure flow then drives the hydraulic turbine installed on the shore generating power. This device has excellent merits:it has simple structures, a large wide range of frequency response and a stong adaptability under extreme loads. Also, its conversion dfficiency is high in usual sea condition, and its construction cost is low. This device in foreign countries is still in the test phase of study, needs further application and promotion.Combined with the motion law of the plate and the working principle of the hydraulic system in the WEC, this paper firstly analyses wave interaction with pendulum wave energy converters (WECs) based on the potential theory, and secondly sets up a frequency-domain and a time-domain models of WECs for analysing hydrodynamic characteristics. Finally, a examination and research is carried out for amplitude of plate, the action force of piston, power output, capture efficiency and structure stress of WECs. The objectives of this thesis are as follows:1) The influences of water depth, the size and the shape of WECs, and characteristic parameters of hydraulic systems are investigated systematically, capture efficiency, amplitude of plate, the action force of piston and power output are simulated in different parameters, and the reasonable range of the designed parameters are gained from the analysis of data.2) The time-domain model is used for output performance of the WEC under the action of irregular waves, and the time histories of amplitude of plate, the action force of piston and power output of WECs are gained.3) Numerical studys are carried out for structure stress of WECs from two respects of the stress of the plate surface and the action of the rotating axis, it can give the principle for the security design of WECs.