Water test channel inspired by Ludwig Prandtl

2014/06/26

Water test channel inspired by Ludwig Prandtl

Students develop water test channel for flow visualization

During an Advanced Design Project (ADP), students from the institute of Fluid Mechanics and Aerodynamics (SLA) have designed and constructed a water test channel for flow visualization. The channel can be used to demonstrate basic flow experiments and visualize them in the lecture hall. The group was inspired by the water test channel of Ludwig Prandtl (1875-1953).

The water test channel of the institute Fluid Mechanics and Aerodynamics. The channel can be used in the lecture hall to visualize flow. Photo: S. Keuth
The water test channel of the institute Fluid Mechanics and Aerodynamics. The channel can be used in the lecture hall to visualize flow. Photo: S. Keuth

The project began in March 2014 with a visit to the DLR School Lab in Göttingen, Germany. The lab has a reproduction of Prandtl's original test channel. Inspired by the visit and bringing in their own ideas the ADP group (Andreas Bauer, Christoph Schäfer, Matthias Schäfer, Christian Wolf) has developed a channel in which water circulates horizontally in an acrylic glass track.

The channel is about the size of a table and can be used to demonstrate basic flow experiments during the technical fluid mechanics lectures of Prof. Cameron Tropea and to visualize them in the lecture hall. The group was supported and supervised by Tim Gelhaar from the SLA workshop and the research assistants Daniel Freudenhammer, Rüdiger Röhrig and Florian Wassermann.

Particle paths on the lecture hall screen

The flow is generated by a paddle wheel that can be propelled either by an electric motor or a crank. To visualize the flow, the water is seeded with aluminium particles which remain on the surface and reflect the light. A black and white camera with a suitable lens records the image from above the track.

Adjusting the frame rate and exposure time, the reflecting aluminium particles get a motion blur during the flow experiments and can be observed as particle paths. This helps students to better understand the somewhat “dry” theory behind the phenomena.

Ludwig Prandtl 1904 with the so-called Prandtl channel. Photo: DLR-Archiv Göttingen
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Ludwig Prandtl 1904 with the so-called Prandtl channel. Photo: DLR-Archiv Göttingen

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