MARIN collaborated with Econowind, a ship design and engineering firm focused on wind-assisted ship propulsion, to test the effectiveness of two VentiFoils, aerodynamic wing-shaped pieces integrated with smart suction that provide a strong propulsive force, under real-world wind conditions.
The MV Ankie, a cargo ship plying the coastal waters of Europe, has VentiFoils mounted on its forecastle.
Scanning lidar wind measurements inspired the two groups to begin this measuring campaign. Without the need for other wind measuring instruments, scanning lidar makes it possible to obtain a high-resolution 3D wind field, which is crucial for evaluating the actual performance of a wind propulsion system in the field. Insight into the benefits of lidar for use during shipboard measurement campaigns would also be gained from these findings.
For the first time, MARIN installed lidar aboard a ship to directly measure wind speeds for a wind-powered propulsion system.
MARIN opted for the Vaisala WindCube Scan to carry out the offshore surveying. The company set up the lidar alongside ultrasonic anemometers, Motion Reference Units (MRU), and other devices to ensure accuracy and performance during testing.
The trial lasted for a single day and took place in international waters near the Netherlands. Both MARIN and Econowind ran tests with the VentiFoils upright and inverted, subjecting the devices to varying degrees of wind. WindCube Scan was used to compare the forward mast anemometer readings to those taken in various patterns such as PPI (horizontal), RHI (vertical), and DBS (vertical upward).
RHI’s ability to extract vertical wind profiles during head winds sheds light on the undisturbed wind’s true behavior. For a fair comparison with forecasts at the right input wind speed and direction, PPI scans indicate the undisturbed wind field outside the impact of the ship. All metrics can be compared to a known value thanks to pre-run DBS scans.
Future studies
All of the tests came out well. The operators of the VentiFoil gained new understanding about precisely managing power to take full advantage of wind conditions by employing extensive lidar wind data.
WindCube Scan has been validated as a reliable tool for collecting wind data at long range. The lidar gave a decent comparison to the wind readings at the same location as the anemometer in the forward mast, and it was simple to identify familiar objects like the VentiFoils and the mast. The DBS scan patterns provided researchers with vertical wind profiles, which were then compared to the power law assumption. Using the most up-to-date Volume wind method, they were also able to successfully derive wind vectors (magnitude and direction) from the radial wind speed data obtained in the PPI horizontal scans.
All of this data is crucial for gaining an overall picture of the wind profile, adjusting settings, and checking results. The experiments were carried out in calm settings where there were no major fluctuations in ship motion. MARIN plans to keep testing lidar readings under increasingly challenging settings, and if they find that larger ship motions are skewing the results, they may come up with a correction approach based on synchronous motions data.
Image source: MARIN
