Application of the Smart Material on the Overtopping Type Wave Energy Converter
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Date
2017-12-08
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Abstract
This thesis presents a method of applying “Shape Memory Alloy” (SMA) on an overtopping wave energy converter (OWEC). A control system which can fit all sea states is necessary for OWEC to adapt to a mutative wave condition and achieve an optimal overtopping discharge rate. Among all the parameters affecting the overtopping discharge rate, the crest freeboard height is the most influential one. To change the crest freeboard height, commonly used old methods include installation of a hinge at the bottom and adjustment of the floating height of the entire device. Both of them will inevitably affect other parameters while changing the crest freeboard height. To fill this gap, the application of SMA springs, which can solely adjust the crest freeboard height, will benefit the optimization of the OWECs.
In a laboratory test, a scaled down physical model is placed in a water tank. The entire model is set to be fixed in the water tank and there are two boards, which are connected by the SMA springs, represent as a ramp that waves need to overcome. The SMA springs are able to change their length by the temperature change. A LabVIEW program sent spectra-wave signals to the wave maker and a pumping system is used to calculate the mean overtopping discharge rate.
The result of non-using SMA springs follows the rule of the overtopping discharge rate. But, there are some differences with the general formula of the OWEC which comes from the different experimental setups and the limitation of the water tank. However, this result is useful to become the reference of the result of using SMA springs which shows that there is no significant change at the mean overtopping discharge rate and the errors are acceptable. All of the results and comparisons indicate that the concept of applying the SMA springs on the OWEC is proven.
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Smart material, Overtopping wave energy converter