Find the Formula for Diameter of 3 Pipes

[emutudeng]

Homework Statement

My vocabulary is pretty bad in specialized English, so I have to post a picture of problem

There are three pipes, the cross-section changes and all measures are illustrative, I need to find an easy formula to find the diameter of d3, so I can create formula in Excel and by changing numbers it calculates the answer.

δ[adm]=2%(l1+l2+l3)

Homework Equations

Formulas are from topic of momentum and forces,
Maybe this helps
δ= M/W ⩽ δ[adm]

The Attempt at a Solution

It should become something like ω/M max * some coefficients, but I haven't found anything form books.

 

[NascentOxygen]

δ[adm]=2%(l1+l2+l3)

Perhaps if you were to explain in words what this formula is about, someone might recognize what you are trying to do.

 

[emutudeng]

It means that the max refraction is 2%. The point is to find diameter of the upper pipe. It depends of the two others.