Hydroelectric Penstocks

You need the following data:

1. Off seat and on seat pressure

2. Dimension of Openning

3. Highest water level in the reservoir

4. Is it modulating or non modulating penstock

5. Invert to coping elevation

6. Details of installation whether floor mounted or wall mounted penstock

Hello popoy

I think you're using the wrong definition of penstock. The one you describe is a gate type valve common in e.g. water and sewage treatment plants.

In hydroelectric parlance a penstock is a pipe or duct feeding water to the turbine.

OP - can you confirm please?

Cheers..........Codey

Issues like water hammer have to be taken into account.

Please see if this report helps:

http://www.uttarakhandjalvidyut.com/projects_pdf/kaliganga-annex-13.1.pdf

Bioramani

Hello;

Thanks very much for your answer. The document is very usefull, although it's not complete. There is a printing problem from the 7th page. One of the aspects which is important for me to know is instability calculation of the penstock pipe by effect of succion (depression). I had a code named CECT but lost it. Is there any standard or code that studies that subject.

Thanks

Not being a civil engineer am not too conversant witht this aspect of suction or depression. The only explanation I came up with was, in a high head reservoir penstock if there is a closure of the inlet at the head, then the entire hydrostatic head becomes a negative pressure near the top of the pipe. If this is correct then the pipe wall thickness has to stand this reverse stress. Since a pippe is stronger in compression than in tension, there is nothing to worry as the pipe will have been designed for water hammer conditions.

As I said in the beginning, I may be way off in what I have written here.

Can you see if this document is at all helpful?

http://www.karun3.com/related_info/about_hydro/hydropower_machinery/chapter4.pdf

Saying that simple, I can agree. But in compression, the pipe strenth is reduced by buckling instability of the shell. This is the main problem in design of such equipement. In addition to pressure value including hammer effect, we have to take in account some aspects such as roudness defaults, local deformation of the shell ... These aspects generates moments on the shell and the design is complicated by deformation of the second order. The code I mentioned above clarifies these things.