SHADOWShip Hydromechanics Augmented with Diagnostical Optics in Waves

Contactgegevens: Jerry Westerweel
Mekelweg 15

Future challenges such as floating offshore energy and food production require a next generation research infrastructure that deals with current and waves with directional spreading on the one hand, and forward speed of maritime vessels on the other. SHADOW features a towing tank with a wave maker and a basin with segmented wave boards and flow pumps that are used in combination with beyond-the-state-of-the-art optical laser diagnostics. The infrastructure is first-of-its-kind for being completely see-through. SHADOW provides optical access to every part of the facilities and unique opportunities for measuring the full flow field and deriving the complete pressure distribution with unprecedented precision. Stewart platforms with complex control algorithms are used to manipulate the motions of floating structures so that their complete fluid-structure interaction can be studied. The infrastructure is unique in providing fundamental research quality data for upcoming marine applications.

The infrastructure is to be located at TU Delft, and operated by the Ship Hydromechanics group together with the Fluid mechanics group. In order to make optimal use of the capabilities of modern laser-based optical diagnostics in experimental fluid mechanics, the facilities will have fully transparent side walls and bottom. This makes it possible to keep all measurement equipment out of the water. The main measurement technique are: (i) tomographic particle image velocimetry (TOMOPIV), which yields the full three-dimensional time-dependent fluid velocity field, and (ii) scanning laser-doppler velocimetry for measuring time-dependent structural motions and deformations. As a new standard, the pressure distribution on an object is to be reconstructed from the TOMOPIV data to augment conventional measurements in which only the total force is measured. Both towing tank and basin are to equipped with advanced wave generation methods. The basin will feature segmented wave boards for generating seas with directional spreading in the presence of an underlying current induced by flow pumps. Modern optical methods to measure and characterize the water surface will be used to take time-dependent wave field measurements rather than point probe measurements. With these methods the facility will allow for unprecedented fundamental research of wave-current interaction. Stewart platforms with complex control algorithms are to be used for manipulating the motions of model structures so that their fluid-structure interaction can be investigated in detail. The combination of TOMOPIV for the flow and scanning laser-doppler velocimetry for the structural deformations has not been available before in this field nor at this scale of application.

The infrastructure is suitable for investigating a wide range of structures from the fields of maritime, offshore, civil and aerospace engineering. The detailed data will open up new opportunities for investigating ship hydromechanics at model scale. The high accuracy of TOMOPIV makes it possible to investigate smaller models at higher (model-scale) velocities, i.e. much higher Froude numbers than currently can be reached in conventional towing tanks. Because the full pressure distribution is measured by default, a unique opportunity arises to reconstruct forces on free-moving self-propelled objects, such as submersible robots, (robot-)fish and autonomous ships. The facility will be well suited for investigating innovations for hydrofoils, airplane models and models of floating offshore wind turbines, in particular for studying flow control methods that reduce drag and control lift and the (far) wakes of these objects and structures. An upcoming field is to take measurements for performance prediction and improvement of sports in water, such as rowing and swimming. The infrastructure envisaged is going to take that field to an entirely new level of scale and accuracy.

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