What is the use of a butterfly valve in axial compressor

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Discussion Overview

The discussion revolves around the function of a butterfly valve in the context of an axial compressor setup used in a laboratory experiment. Participants explore its role in managing flow and pressure dynamics, particularly in relation to surge prevention and performance measurement.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant suggests that the butterfly valve is used to prevent flow reversal and potential damage to the compressor during surge conditions.
  • Another participant proposes that the valve reduces the exit flow area, which increases back pressure on the compressor, affecting pressure rise during tests.
  • There is a discussion about the implications of closing the valve too much, which could lead to compressor surge.
  • Participants express uncertainty about the instructions for closing the valve and how it relates to the testing procedure.
  • Clarification is sought regarding the interpretation of the experimental instructions related to the valve's position during tests.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the exact purpose of the butterfly valve, with differing views on its role in surge prevention and pressure management. The discussion remains unresolved regarding the specific operational implications of the valve's adjustments during testing.

Contextual Notes

There are limitations in understanding the detailed mechanics of axial compressor theory and performance charts, which may affect the interpretation of the valve's function. The instructions for the experiment may also be ambiguous, leading to confusion about the valve's operation during tests.

Who May Find This Useful

This discussion may be useful for students or individuals new to axial compressors and those interested in experimental setups involving flow control mechanisms in engineering applications.

MattH150197
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Homework Statement


In the image I have included it shows a diagram of the setup we used in a lab and you can see that at the right hand side there is a butterfly valve so I am wandering what would be the use of the valve in this situation. Since its after the compressor I was thinking that its there in case of surge to prevent the direction of flow reversing and going back to the compressor and maybe damaging it, is this right or is it for a another purpose. Thanks.
 

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The butterfly valve is there to reduce the exit flow area . As the valve is closed more the back pressure on the compressor gets higher .

Not understanding how this works may account for the low value of pressure rise described in your previous posting . If the valve were wide open during a test the pressure rise across the compressor would be very small .

Note though that if the valve is closed too much the compressor may go into surge .
 
Thanks for the quick response!
 
Do you know anything about axial compressor theory and axial compressor performance charts ?
 
Only the very basics, I am new to the subject.
 
OK .
 
I wonder if you could help me grasp the understanding of this, the image shows the instructions we were set for the experiment, in 4.) it says to close the butterfly valve one full revolution and in 5.) it says to continue closing it at one revolution intervals and you can see from the results set up we had in the other image we took 10 readings so does that mean at the beginning of each reading the valve would have been closed?
 

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Not quite sure what you are asking about here ?

The instruction sheet tells you to perform a series of tests with each test being for a different steady state running condition .

For each test you preset the butterfly valve to required position and leave it set at that position for the duration of that test .

For each successive test the valve is closed more fully but for the duration of anyone test valve remains in a fixed position .
 
Last edited:
Yeah that makes sense thanks, the part confusing was where it says continue closing it at one revolution intervals which sounded like turn the valve 360 degrees between each interval which didn't make any sense. Thanks for clearing it up
 

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