Venturi flume

A venturi flume is a critical-flow open flume with a constricted flow which causes a drop in the hydraulic grade line, creating a critical depth.[1][2]

It is used in flow measurement of very large flow rates, usually given in millions of cubic units. A venturi meter would normally measure in millimetres, whereas a venturi flume measures in metres.[3]

Measurement of discharge with venturi flumes requires two measurements, one upstream and one at the throat (narrowest cross-section), if the flow passes in a subcritical state through the flume.[4] If the flumes are designed so as to pass the flow from subcritical to supercritical state while passing through the flume, a single measurement at the throat (which in this case becomes a critical section) is sufficient for computation of discharge. To ensure the occurrence of critical depth at the throat, the flumes are usually designed in such a way as to form a hydraulic jump on the downstream side of the structure. These flumes are called 'standing wave flumes'.

Comparison with weirs

Venturi flumes have two advantages over weirs where the critical depth is created by a vertical constriction. First, the hydraulic head loss is smaller in flumes than in weirs. Second, there is no dead zone in flumes where sediment and debris can accumulate; such a dead zone exists upstream of weirs.

References
  1. "Venturi flume: Definition from Answers.com". answers.com. Retrieved 2015-04-21.
  2. "Archived copy". Archived from the original on 2008-12-12. Retrieved 2009-06-07.CS1 maint: archived copy as title (link)
  3. de Sa, D.O. (2001). Instrumentation Fundamentals for Process Control. Taylor & Francis. p. 9. ISBN 9781560329015. Retrieved 2015-04-21.
  4. Prof. B.S. Thandaveswara (17 September 2006). "Hyraulics – Measuring Flumes" (PDF). Indian Institute of Technology Madras. Archived from the original (PDF) on 15 October 2009. Retrieved 2015-04-21.
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