Test at AAU

Building of a 1:40 scale model of the WEC

Research and testing of small prototypes was finished in April 2005. Hereafter building of sub components started, procure of materials, preparation of production equipment and new arrangement of work shop. The glassfibre casting was started mid June. Mid September the WEC was ready for test.

The model is 6 meter wide and consist of two parts each 4.2 meter long.

Functiontest at Aalborg University (AAU)

In September 2005 a function test on the 1:40 scale model was made in the wave tank at AAU.

At the function test the energy production was meassured both when the WEC was supported at the bottom of the wave tank and when the WEC was floating. The efficiency was meassured to be in avereage 0.22 in regular waves. This is a little lower than meassured in the 5 meter wave tank. This is expected to be due to pressure loss in the hoses that led the air to the meassuring point, and because there for economical and practical reason was chosen a different meassuring method that loads the WEC in a different way. In urregulary waves the efficiency was meassured to 0.16. This meassurement is uncertain as the pressent meassurent equipment was not suited to meassure waves that came so unregulary. This meassurement has to be done as a average over a longere time period.

The energy meassurement in the 5 meter wave tank was made by letting the air flow into two cylinders. This gave a very uniform air pressure load on the WEC. It collected the air over a longer time span which gave a very precise meassurement. At AAU the energy production was calculated out by meassuring the air pressure and the air flow. The decided air pressure, that was known to be the most optimal in a given wave higth, was achieved by squeising the end of the hoses so much that the air pressure was on the level that was wanted. In regular waves this was usable. There was some pulsation in pressure and flow but it was a steady pulsation. But in unregulary waves the pulsation was big and gave an uncertain meassurement. There was no time for optimatization to see if some changes in conditons could give a higher energy output.

The WEC was very stable as a floating WEC. As a floating WEC in 6 cm waves and 0.9s period time the up and down movement in the uttermost points was less than 1 cm.

The deept adjustment of the WEC also worked as well as predicted.

The anchoring load in the tip was between 10 Newton and 20 Newton. This low value is achieved because during a wave period there is first some forward forces on the tubes later in the wave period there is some backward forces on the tubes. Theese are almost of the same value. The average value from all the tubes, when the WEC streches over more than one wave length, is then very low.