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A novel tethered-sphere add-on to enhance grid turbulence

Vonlanthen, Richard ; Monkewitz, Peter

In: Experiments in Fluids, 2011, vol. 51, no. 3, p. 579-585

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    Titre
    • A novel tethered-sphere add-on to enhance grid turbulence
    Auteur
    • Vonlanthen, Richard. Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
    • Monkewitz, Peter. Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
    Type de document
    • Postprint
    Classification
    • Technologie, Sciences de l'ingénieur
    Identifiant OAI-PMH
    • oai:doc.rero.ch:322510
    Summary
    The new turbulence generator consists of a standard uniform grid with tethered spheres attached to its nodes and is capable of producing approximately twice the turbulence energy per unit pressure drop coefficient C p than the same bare grid without the spheres. At the same time, the Reynolds number Reλ based on the Taylor microscale is also amplified by a factor of roughly 2, and the turbulence anisotropy is reduced to a constant level of 10% at all downstream distances without further flow conditioning after the grid. The new grid's simple design makes it suitable for a variety of fluid-flow facilities, in particular smaller water tunnels. Its performance in comparison with the plain grid is documented by measurements of the streamwise decay of turbulence energy and velocity spectra in the Reλ range of 50-100