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Isel LES 5 ball screw linear actuators used to move the cameras. Photo credits: Max Fuhrmann/TU Braunschweig

Four cameras and LEDs are attached to the construction of Isel Automation LES 5 ball screw linear actuators, which weighs around 800 kilograms. Picture credits Max Fuhrmann/TU Braunschweig


Multiple Isel LES 5 ball screw linear actuators in inspection and data colletion application. Photo credits: Max Fuhrmann/TU Braunschweig

 
Isel Cartesian Robot helps to measure “Furry piles in the wave channel.”

The "EnviSim4Mare" research project was formed to investigate how the growth of mussels, algae and other small sea creatures influences the load-bearing capacity of offshore wind turbines and other maritime structures. For this purpose, a new saltwater-capable large-scale research facility is being built at the Leichtweiß Institute for Hydraulic Engineering (LWI). A new Isel Cartesian Robot measuring device in the Leichtweiß Institute for Hydraulic Engineering (LWI) for flow tests in the "EnviSim4Mare" project is used for taking measurements.  Offshore wind turbines are exposed to extreme forces from waves, wind and ocean currents.. In addition, mussels and algae collect on these structures and influence the load capacity of the structures. Scientists from the (LWI) are investigating the effects of this growth in the "EnviSim4Mare" research project. To do this, the researchers are now using the Isel Cartesian Robot positioning system to measure the flow around the underwater structures.
Isel LES 5 ball screw linear actuators
Isel LES 5 ball screw linear actuators used to move the cameras. Photo credits: Max Fuhrmann/TU Braunschweig

The so-called Shake-The-Box 4D-PTV system was set up on a wave channel in the LWI's test hall. The construction, to which the camera arm, four cameras and LEDs are attached, weighs around 800 kilograms. The high-tech device cost around 300,000 euros. What initially appears unspectacular from the outside turns out to be a highly complex system. In the first few weeks, Mario Welzel and Clemens Krautwald were mainly busy getting to know the measuring device. "We therefore planned a little more time in the run-up to the first tests," says Mario Welzel, research associate in the "EnviSim4Mare" project. "We have to make numerous settings on the 4D-PTV system for the measurements."
 
Four cameras and LEDs
Four cameras and LEDs are attached to the construction of Isel Automation LES 5 ball screw linear actuators, which weighs around 800 kilograms. Picture credits Max Fuhrmann/TU Braunschweig

Piles with "Fur"
But not only that: the wave channel and the poles around which the current is measured also have to be prepared. The scientists want to test 18 different shafts – per post. In total, they prepared eight posts. Some are simply painted black, others are covered with sandpaper of different grit, and some in turn have received a "fur". The project team used carpet in several lengths for this purpose. The piles - from smooth to fluffy - simulate the foundation structures of offshore wind turbines and various types of vegetation. Now the water in the wave channel washes around them. The first wave rolls slowly towards the black painted pole. A wide purple stripe from the meter's LEDs illuminates above the channel.
 
Multiple Isel LES 5 ball screw linear actuators
Multiple Isel LES 5 ball screw linear actuators in inspection and data colletion application. Photo credits: Max Fuhrmann/TU Braunschweig

The actual events take place on the computer monitor. Mario Welzel and Clemens Krautwald watch the screen intently while the wave flows around the pole. Tiny particles floating in the water are visible, following either the smooth orbital motion of the wave or the turbulence caused by the pile surface. The two scientists distributed thousands of plastic beads in the measuring area around the pole in the water in order to use them to study the velocity fields in the waves and around the structures. "With the 4D flow field measurement, we can measure the flow without influencing it as with other methods," says Mario Welzel. The researchers observe and analyze the processes from a distance using only optical means. They vary the waves again and again and use the different stakes in the canal.
 
Experiments in the new salt water wave current channel
The focus is on the effects of force, shedding vortices and flow patterns. Due to the different roughness of the pile, the force acting on the structure will also change. This means that the possible growth of mussels and algae must be taken into account during the planning and construction of a wind turbine. “We need a better understanding of the system here. Because the less we know about the processes and influences, the more safety factors have to be built in,” explains Welzel. "In addition to the piles of the huge, firmly anchored wind turbines, cables and pipelines are also affected by mussel growth," adds Clemens Krautwald: "These basic tests of different piles are intended to improve understanding of the process, which is necessary in several areas."
The scientists planned around 400 experiments with different camera settings. When the new saltwater wave flow channel is in the test hall in the coming year, the measuring device will be moved with a crane in order to continue the tests there. The project team has already deployed test bodies at various offshore locations in the North Sea around Heligoland and Nordergründe. Algae, barnacles and mussels are to settle here in order to later examine them in the completed research facility at the LWI.
 
EnviSim4Mare
The "EnviSim4Mare" research project is investigating how the growth of mussels, algae and other small sea creatures influences the load-bearing capacity of offshore wind turbines and other maritime structures. For this purpose, a new saltwater-capable large-scale research facility is being built at the Leichtweiß Institute for Hydraulic Engineering (LWI).
 
"EnviSim4Mare" has been funded by the Federal Ministry for Economic Affairs and Energy (BMWi) for three years since December 1, 2019. The Leichtweiß Institute of the TU Braunschweig, Department of Hydromechanics, Coastal Engineering and Maritime Engineering, will receive around 4 million euros from the total funding for the sub-project.
 
In addition to the Leichtweiß Institute, the research network also includes the working group of Professor Bela H. Buck from the Alfred Wegener Institute Helmholtz Center for Polar and Marine Research (AWI) in Bremerhaven and the two companies Jörss-Blunck-Ordemann GmbH and Ocean Breeze Energy GmbH & Co. KG as well as other associated industrial partners and authorities.
 
Here is a link to original article in German. 
https://magazin.tu-braunschweig.de/m-post/pelzige-pfaehle-im-wellenkanal/