Free surface flow rate measurement

Free surface flow rate measurements are found using a combination of level measurements, speed measurements and channel shape. The flow rate is therefore obtained by combining the flow rates in each part of the wetted section.

Composition of a measuring point

A measuring point consists of:

  • 1 converter,
  • 1-2 level sensors,
  • 1-8 speed measurement chords.

The amount and position of the probes depends on:

  • the height of the structure,
  • the tide range,
  • the specific features upstream and downstream of the site in question,
  • the required precision.

Diagram illustrating the measurement principle

Coming soon!

Advantages of ultrasound transit time measurements

Ultrasound measurements present several advantages for this type of application:

  • reliable process unaffected by the nature of the fluid and its temperature,
  • highly dynamic measurements: good results at both low and high water levels,
  • takes into account different velocity profiles (up to 8 chords),
  • takes into account the entire section of the structure,
  • defines the section precisely using 20 points incorporating left and right width/height,
  • can be used to take measurements in very wide structures (200 m).

This measurement principle can also be applied to partially filled pipes.