VDAS H13 - Experiment


An experimental apparatus to allow the visualisation and investigation of the phenomena of free and forced vortices.

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The TecQuipment Vortex Apparatus enables students to produce both free and forced vortices, and measure the vortex water surface profile.

The equipment consists of a transparent vessel on a support frame, which mounts on a TecQuipment hydraulic bench (Gravimetric or Volumetric Hydraulic Benches, H1 or H1D - available separately). It may also work with another suitable clean water supply and drain.

A low-voltage, variable-speed motor rotates the vessel about its vertical axis. A speed-control unit (included), sited away from the main apparatus, controls the speed of rotation.

To produce a forced vortex, students add water to the rotating vessel until it is about half full. A forced vortex forms. After a few minutes the vortex becomes constant, and students can measure the surface profile using the traverse probe. The traverse probe can move both horizontally and vertically, and both axes have linear scales. Students can also measure distribution of total head by replacing the traverse probe with a Pitot tube.

To produce a free vortex, students place a smaller, perforated transparent cylinder inside the main vessel. This forms an annulus into which a continuous water supply is directed. When the vessel rotates, water passes through the perforations and spirals slowly inwards to a small hole in the centre of the base of the vessel. The surface falls rapidly towards the centre and produces an air core. Students measure the surface profile using the traverse probe.

Learning outcomes

  • Determination of the surface profile of a forced vortex
  • Determination of the surface profile of a free vortex
  • Determination of the total head variation in a forced vortex
  • Comparison of results with theoretical predictions
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Essential Base Units


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