The FELIX 3D Display belongs to the class of volumetric displays using the swept volume technique. It is designed to display images created by standard CAD applications, which can be easily imported and interactively transformed in real-time by the FELIX control software. The images are drawn on a spinning screen by acousto-optic, galvanometric or polygon mirror deflection units with integrated lasers and a color mixer. The modular design of the display enables the user to operate with several equal or different projection units in parallel and to use appropriate screens for the specific purpose. The FELIX 3D Display is a compact, light, extensible and easy to transport system. It mainly consists of inexpensive standard, off-the-shelf components for an easy implementation. This setup makes it a powerful and flexible tool to keep track with the rapid technological progress of today. Potential applications include imaging in the fields of entertainment, air traffic control, medical imaging, computer aided design as well as scientific data visualization.The FELIX 3D project team has evolved from a scientific working group of students and teachers at a normal High School in Germany. Despite minor funding resources within this non-commercial group considerable results have been achieved.

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FELIX is described which represents a physical volume three-dimensional display. A modulated colored laser beam is directed via mirrors and a computer controlled x-y scanning unit towards a transparent enclosure containing a helical shaped projection screen. To describe a physical space this screen is rotated about its vertical axis so that it occupies a cylindrical volume over time. Due to the translucent property of the screen the hitting laser beam will be scattered and visible to the observer. The position of each voxel (volume pixel) is determined by the momentary location of the laser beams intersection with the rotating helix, thus providing a volumetric display medium through which scanned laser pulses are projected. The receptors in the human eye have a temporal persistence because of a mental processing delay, and this causes the eyes to fuse the light scattered from the moving two-dimensional element into a three-dimensional image. Since the images are generated within a given display space rather than on a stationary surface, they are intrinsically 3D and may be observed directly from any position. The introduced image generation technique ensures that human factors regarding depth sensation are satisfied automatically without the need for special viewing glasses to be worn by the observer. A true 3D volume display as described will complement the broad range of 3D visualization tools such as volume-rendering packages, stereoscopic and virtual reality techniques which have become widely available in recent years. Potential applications for this development range from air traffic control to various medical uses (e. g. Magnetic Resonance Imaging), entertainment and education visualization as well as imaging in the field of engineering, Computer Aided Design (CAD) and Rapid Prototyping.

Experiments were carried out in a 50‐m3 cylindrical tank to determine the influence of strong momentum on the formation of large‐scale gas‐core vortices. Gas‐core lengths were measured for varying volume flow rates and submergence depths. The critical Froude numbers were also determined and the efficiency of different vortex suppressors on the gas‐core formation was investigated. The horizontal velocity field inside the vortex core region was additionally recorded using particle image velocimetry. The experimental results were used to verify numerical simulations and compared to vortex models and correlations from literature.