Can someone help me to calculate the velocity at Stack Tip?

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SUMMARY

The discussion centers on calculating the velocity at the stack tip for a system with a larger diameter of 2.5 m. The equation V1A1 = V2A2 is initially considered, but participants clarify that this formula is applicable only to incompressible fluids, while flue gases are compressible. The correct interpretation of units is emphasized, with velocities needing to be in m/s rather than m3/s. The final calculated velocity at the stack tip is determined to be 17.82 m/s.

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  • Familiarity with compressible versus incompressible fluid behavior.
  • Knowledge of unit conversions, particularly between volumetric flow rates and velocities.
  • Basic grasp of gas laws applicable to flue gases.
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Suradanai
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Homework Statement


How can we calculate the velocity at stack tip if the distance of larger diameter is 2.5 m?
I think i cannot use the equation of V1A1 = V2A2 because they may have some effect from 2.5 m of distance.
Thank you very much.

Homework Equations


Q1=Q2

The Attempt at a Solution


V1A1 = V2A2
45.74*2.4 = V2*6.16
V2 = 17.82 m/s
 

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Suradanai said:

Homework Statement


How can we calculate the velocity at stack tip if the distance of larger diameter is 2.5 m?
I think i cannot use the equation of V1A1 = V2A2 because they may have some effect from 2.5 m of distance.
I think you're right. That formula applies to incompressible fluids like water. The flue gases are of course compressible.

I'm afraid I must leave this one to other helpers.
 
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There seems to be some confusion in the diagram. It shows a "velocity" in m3/s, asks about another such in the same units, but also quotes a "flow rate" in those units at the "exhaust temperature". How does that relate to the two velocities?
I have a suspicion the two "velocities" are supposed to be m/s. Given the diameter, that would seem to be consistent with the volumetric flow rate. If so, it makes the question much easier; you can ignore most of the information.
 
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rude man said:
I think you're right. That formula applies to incompressible fluids like water. The flue gases are of course compressible.

I'm afraid I must leave this one to other helpers.
Thank you very much, now I am looking the gas equation also that can apply this issue.
 
haruspex said:
There seems to be some confusion in the diagram. It shows a "velocity" in m3/s, asks about another such in the same units, but also quotes a "flow rate" in those units at the "exhaust temperature". How does that relate to the two velocities?
I have a suspicion the two "velocities" are supposed to be m/s. Given the diameter, that would seem to be consistent with the volumetric flow rate. If so, it makes the question much easier; you can ignore most of the information.
Oh!, that's my mistake, the right should be (m/s) as you said.
Thank you very much
 
Suradanai said:
Oh!, that's my mistake, the right should be (m/s) as you said.
Thank you very much
"The right"? Do you mean the "flow rate"? I would have thought that was m3/s, and the two "velocities" should be m/s.
 

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