Restriction in flow of Penstock

[jan63]

Working in a hydel power station.head is 430 ft.We had an irrigation tunnel.The flow of the tunnel was through outlet gates and with full head and full opening the discharge capability was 90000 cusecs.
After some years it was decided to have a power house on the tunnel.so penstock was built and connected to the tunnel.Four units were installed.
The question is after building the penstock the flow was restricted to 60000 cusecs.Why?
Tried to get answer.but did not.
Is it mainly to restrict the velocity through the penstock?

 

[Latexman]

Four units were installed.

4 turbines?

If so, the turbines restricted flow and work was extracted.

Good Luck,
Latexman

 

[jan63]

Four turbines and four relief valves.But scheme is that if flow exceeds 60000 cfs,one unit will trip to keep discharge below 60000 cfs.So my question still is the velocity in penstock a factor

 

[LittleInch]

Can you add a drawing and provide some technical information, like dimensions, velocities etc.....

That's a lot of water!

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[hacksaw]

Branch connections as you have alluded to alter the the main flow even if all branch valves are closed.

Your CFD simulation will demonstrate this using RANS or LES methods. You may need to introduce a bypass branch to maintain the penstock rating for the dam.

 

[1503-44]

What's the velocity at 90? Or the xsect area of the tunnel.
Velocity changes need to be slow and pressure surges minimised.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[jan63]

I have attached layout of Penstock for information

 

[hacksaw]

Your flow data demonstrates that a bypass is required to obtain the original flow capacity.

The branch connection designs as shown disrupt the flow patterns and result in reduced flow capacity.

 

[LittleInch]

Can you attach as a .zip file please. I can't open .rar and don't want to download a reader.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[hacksaw]

the file "Penstock_arrangement.rar" downloads, when you click on it, you'll see that it contains a zip file which you can open.

 

[LittleInch]

Well mine doesn't open. Can you load the zip file back?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.