Formula for the Equivalent Diameter of elliptical pipe 1

[LHA]

Does anyone know the formula for the Equivalent Diameter of elliptical pipe? Not the hydraulic radius. A source would be appreciated. Thanks.

Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve

 

[swayze]

The concrete pipe design manual has a table showing sizes.

 

[francesca]

If you don't mean hydraulic radius, then surely you take the area of the el1ipse and apply circle geometry to it. (So if the area of the ellipse is 3.14, then the equivalent radius is sqrt(3.14/pi) = 1.)

You can get the area of an ellipse here: A = pi*A*B (where A and B are the semi-major and semi-minor axes).

This would leave you with an equation:

R' = sqrt(A * B)

This source agrees with that definition of an equivalent radius. Of course, it's not an hydraulics site...

 

[gbam]

That approach may work for an eliptical pipe but be carefull with arch pipes (three diff radii). I allways have a table available for just that situation.

Remember to check the conveyance which is more important than area. especially when dealing with open channel flow.

 

[LHA]

swayze:
I know, I just don't have one with me.

francesca:
Thank you, that's exactly what I needed.

gbam:
Point is correct an well taken. I have ellipses though.

Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve