Hydraulic - flow inside a pipe, how to know the direction?

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Discussion Overview

The discussion revolves around determining the direction of flow inside a pipe, exploring both practical methods and theoretical considerations. It includes inquiries about non-invasive techniques and alternative approaches when specialized devices are unavailable.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant suggests using a non-invasive flow monitor that operates on the Doppler effect to determine flow direction.
  • Another participant explains that the Doppler effect involves bouncing ultrasound off the fluid and measuring frequency changes.
  • A participant questions the availability of alternative methods for determining flow direction without specialized devices.
  • One contributor expresses skepticism about finding cheaper alternatives that do not require cutting the pipe.
  • A different perspective suggests that pressure drops away from the source can indicate flow direction, alongside the potential for local turbulence to create pressure differentials.
  • A participant notes that their input is speculative and presents the idea as a thought experiment rather than a definitive solution.

Areas of Agreement / Disagreement

Participants present multiple viewpoints on how to determine flow direction, with no consensus on a single method or approach. The discussion remains unresolved regarding practical alternatives to specialized devices.

Contextual Notes

Some assumptions about the flow conditions and the specific context of the inquiry are not fully articulated, which may affect the applicability of the proposed methods.

amrfd
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hydraulic -- flow inside a pipe, how to know the direction?

if you have a flow inside a pipe, how to know the direction?
 
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welcome to pf!

hi amrfd! welcome to pf! :smile:

google "non invasive flow monitor" :wink:

(i think they all use the doppler effect)​
 


tiny-tim said:
hi amrfd! welcome to pf! :smile:

google "non invasive flow monitor" :wink:

(i think they all use the doppler effect)​

thank you for your reply but what do you mean with doppler effect?
 
they bounce ultrasound off the water, and measure the change in frequency of the sound …

do that google search, and you'll find out how :wink:
 


thank you very much
if i don't have this device,is there another way to know the direction of flow?
 
i doubt there's anything cheaper :redface:

(that doesn't involve cutting a hole in the pipe)
 


Are you asking from a practical perspective or just for information?

There should be a drop in pressure the further from the source you go (as long as there is flow).

Could also cause local turbulence in the line with a small "wall" and put sensors behind and in front of the wall. The wall is causing the turbulence - would see pressure differential as long as there is flow. Think about an airplane wing and pressure differential top to bottom - only sideways :)

(I'm no expert - but this is a fun thought experiment!)
 

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