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

## 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.

Q1=Q2

## The Attempt at a Solution

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

#### Attachments

• Exhaust Stack.JPG
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rude man
Homework Helper
Gold Member

## 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.

• haruspex
Homework Helper
Gold Member
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.

• 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.

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

haruspex