Abstract
Aalborg University carried out wave tank testing a 1:20 scale model of Langlee, an oscillating wave-surge type of Wave Energy Converter (WEC). Langlee is designed to operate in deep water, with the hinged flaps attached to a, moored, semi-submerged reference frame. Langlee has a novel flap arrangement, with the flaps placed symmetrically opposing each other on a floating reference structure. This minimises the net force on the reference frame and increases the stability of the reference frame under optimal wave conditions.
This paper presents the results and analysis from the wave tanks, which addressed the following: The Power Take Offs (PTOs) were simulated using a motor to resist the motion of the wings, according to the damping profile. Torque and velocity measurements were used to predict the wave- to mechanical-power conversion efficiency of the device. A number of wing types and configurations were tested to compare their power conversion efficiency. The power production for five selected irregular wave states was used to estimate the power matrix of the full scale the device, by making certain assumptions about the power conversion efficiencies dependency on the peak wave height and mean period of the waves. Ultrasonic sensors were used to obtain motion data in three degrees-of-freedom, from which the free oscillation and the response to irregular waves were determined. Load cells were used to measure the mooring forces and used to obtain a statistical description of them.
The buoyancy of the flaps was found to have a large impact on efficiency, and surface piercing flaps were found to increase the efficiency over a fully submerged flap configuration. A peak efficiency of approximately 35 % was found with the mean wave length of the irregular wave state equal to approximately twice the length of the device. From the natural oscillation tests the natural periods in heave and pitch was found to be approximately 2.4 s (in lab. scale), which is an approximately 10% improvement over the previous iteration of Langlee.
This paper presents the results and analysis from the wave tanks, which addressed the following: The Power Take Offs (PTOs) were simulated using a motor to resist the motion of the wings, according to the damping profile. Torque and velocity measurements were used to predict the wave- to mechanical-power conversion efficiency of the device. A number of wing types and configurations were tested to compare their power conversion efficiency. The power production for five selected irregular wave states was used to estimate the power matrix of the full scale the device, by making certain assumptions about the power conversion efficiencies dependency on the peak wave height and mean period of the waves. Ultrasonic sensors were used to obtain motion data in three degrees-of-freedom, from which the free oscillation and the response to irregular waves were determined. Load cells were used to measure the mooring forces and used to obtain a statistical description of them.
The buoyancy of the flaps was found to have a large impact on efficiency, and surface piercing flaps were found to increase the efficiency over a fully submerged flap configuration. A peak efficiency of approximately 35 % was found with the mean wave length of the irregular wave state equal to approximately twice the length of the device. From the natural oscillation tests the natural periods in heave and pitch was found to be approximately 2.4 s (in lab. scale), which is an approximately 10% improvement over the previous iteration of Langlee.
| Original language | English |
|---|---|
| Title of host publication | 9th ewtec 2011 : Proceedings of the 9th European Wave and Tidal Conference, Southampton, UK, 5th-9th September 2011 |
| Editors | AbuBakr S. Bahaj |
| Number of pages | 6 |
| Publisher | University of Southampton |
| Publication date | 2011 |
| Publication status | Published - 2011 |
| Event | The 9th European Wave and Tidal Energy Conference : EWTEC 2011 - Southampton, United Kingdom Duration: 5 Sept 2011 → 9 Sept 2011 |
Conference
| Conference | The 9th European Wave and Tidal Energy Conference : EWTEC 2011 |
|---|---|
| Country/Territory | United Kingdom |
| City | Southampton |
| Period | 05/09/2011 → 09/09/2011 |
Bibliographical note
Published on a cd.Keywords
- Wave Tank Testing
- Power Matrix
- Performance Evaluation
- Dynamic Response
- Power Conversion Efficiency