| Category | Description |
|---|---|
| Responsible | Dr.-Ing. André Bauknecht |
| Type | continuous, atmospheric Eiffel-type |
| Test Section Size | 0.6 m x 0.4 m x 1.5 m |
| Max. Velocity | 19 m/s |
| Turbulence Level | < 0.1% at 10 m/s |
| Flow uniformity | 1% |
| Power | 3 kW |
The LNB is a continuously operating Eiffel-type wind tunnel with a closed test section. The settling chamber with nozzle, the diffuser, and the motor mounting are made of fiberglass. The test section features transparent walls to allow the use of optical measuring systems. The wind tunnel is installed in a room that is 8.2 meters long, allowing for proper flow circulation. The ceiling of the room is covered with open-celled acoustic foam to reduce noise levels. To minimize vibrations, the wind tunnel is mounted on rubber absorbers fastened to a steel structure. The motor and fan are decoupled from the rest of the tunnel.
The top, bottom, and one side wall of the test section are made of glass to enable the use of optical measurement systems (e.g., PIV). A vane anemometer is employed to control the flow velocity within the test section. Flow uniformity is determined using a traversable Prandtl probe at three cross-sectional locations. The measured velocity deviations are within 1% at a flow speed of 10 m/s. The turbulence intensity along the vertical symmetry axis of the test section is less than 0.1% at 10 m/s.
The nozzle has a rectangular cross-section, designed according to Börger's method. It features a contraction ratio of 16. The walls are reinforced with sandwich panels and lined with acoustic foam to suppress low-frequency vibrations. A 30 mm thick fleece layer, a honeycomb structure, and a turbulence screen are employed to ensure low turbulence levels. The honeycomb has an average cell diameter of 14 mm and a depth of 133 mm.
The LNB is intended for research on low Reynolds number and unsteady flow regimes. This includes, for example, detailed investigations of laminar separation bubbles and studies on the interaction of coherent flow structures within boundary layers.
Shaqarin, T., et al. "Drag reduction of a D-shaped bluff-body using linear parameter varying control." Physics of Fluids 33.7 (2021). DOI:10.1063/5.0058801
Shaqarin, Tamir, et al. "Closed-loop drag reduction over a D-shaped body via Coanda actuation." Fluid-Structure-Sound Interactions and Control: Proceedings of the 5th Symposium on Fluid-Structure-Sound Interactions and Control 5. Springer Singapore, 2021. DOI:10.1007/978-981