Sizing (submerged) bypass conduit 1

[mark0514]

I am looking for a formula to calculate the maximum flow capacity of a submerged conduit that will interconnect two structures, bypassing an open channel.

 

[bimr]

Use the Hazen-Williams formula:

http://www.engineeringtoolbox.com/hazen-williams-water-d_797.html

 

[mark0514]

Thanks for responding. I had looked at Hazen Williams, along with many others. Using it, and assuming some things, here is what I came up with:

With 25 lf of 21" I.D. pipe with a roughness constant of 140, I can flow 9,000 gpm, but my head loss will be .22 ft...meaning tank A will be 2.64" higher than tank B (reducing freeboard). It also shows my flow velocity will be 8.34 ft/s.

 

[cvg]

dont forget the inlet loss as well as any minor losses. this may have a greater effect on your freeboard than the friction losses

 

[mark0514]

Thats where I start going in circles. I found this formula to calculate the head loss.

 

[bimr]

That formula is for flow through an orifice, not flow through a pipe.

 

[mark0514]

So how would I figure the additional head loss created by the entrance?

 

[bimr]

Here are some examples:

http://www.peerlessxnet.com/documents/tibs/TIB-7_How-to-use-head-curves.pdf

http://johndfenton.com/Lectures/Hydraulics/Q09.pdf

http://johndfenton.com/Lectures/Hydraulics/A09.pdf

 

[RRichardson]

Thanks bimr for the examples