Pipe Sizing for Hydro Station

This sounds like something you should have learned in school.

There are a number of free pipe sizing calculators on the web.

Good Luck.

It all depends on what your acceptable headlosses are and a what you set as an acceptable pipe velocity....

Making some assumptions, I get roughly 3.3-3.5 meters in Diameter. This is based on:

• Flow-rate of 17m^3/S
• Velocity of 2 M/S
• Fluid Density of 1000Kg/M³

This puts the pipe at 3289.76mm Diameter, with an area of 8,500,000mm^{2.
I have not factored in the actual gradient, to figure out the true velocity, I made a quick assumption which may or may not be even in the same state as the ball park} .
_{(Don't trust everything you read on the Internet)}

Hmmnmnmm.

I thought it was a trick question. I put down 1.8 kilometers on my homework.

It's not a trick question, it's a joke. After looking at the OP's history, I'm convinced it's homework, copied directly from the book.

There I go again. Ragging on innocent posters.

^{Do your own homework! Do your own homework!}

I tried i got 1.5 to 2 mtrs but do you think it is practically applicable??????????...............it seems simple but i gues it is not?..........point about the head losses considered ,...........but the velocity we need to find out............

I tried i got 1.5 to 2 mtrs but do you think it is practically applicable??????????

We haven't any idea because we have no clue as to budget, site conditions, etc.

...............it seems simple but i gues it is not?..........

This is because you haven't defined exactly what your constraints are. It is a simple problem if you know what you want/need.

There would seem to be a fundamental error in the original data.

If the downward slope is 1m fall per 1000 run, then the head would only be 1.8m. (That is actually less thanthe pipe diameter suggested by some others already.)

If the downward slope is 1m traverse for 1000m fall, then somewhere in the world he has a 1.8km waterfall.

2 bar presure implies at least 20m fall, so first option is out (since the change in elevation is less than this) and the second optionis out since pressure would be significantly higher than nominated.

Please look at your request again and clarify.

hey thnks for the reply........1.8 m is the head.....but parameters (specifically regarding the pressure) which i received from my boss were doubtful (a Non technical person). I m finding it difficult to convince him ......he jst needs size of the pipe.....Hope he undrstands ...anyways thnks for the reply!!!!!!!!!!!!!!!!

This is hopeless.

The blind, leading the blind.

Hire a consultant who knows what he's doing.

Boy, would I ever like to attain a flow rate of 17 cum/sec.

I'd vote you off color, if such a catagory existed.

Just based on Manning's Equation and a roughness coefficient of 0.015 I come up with a diameter of 3.501 meters but the question is somewhat ambiguous as I am not sure what role this pipe plays in the hydro power station. Is it simply to convey the flow to the station or is power somehow being generated across the fall? It does not seem possible as the pressure is approximately equal to the head difference across the length of the pipe.

You need to use a nomograph to get an estimated pipe size for starters, then refine it with calculations....

BUT, assuming that the pipe inlet is submerged you need to know what the total head of water (water depth) is above the pipe inlet centerline at the dam face, plus inlet conditions, outlet conditions (submerged vs. un-submerged vs. partial water depth vs. free fall?), and the type of pipe material in order to ascertain a friction coefficient (use aged pipe value for future conditions, not a new pipe f).

Use Bernoulli's Theorem to calculate the most efficient pipe diameter, by trial and error over several reiterations.

[still seems to me a "homework" problem. If not, the OP should have learned how to do this in Hydraulics class long ago and not on the job.....]

If the pipe is 1.8 km long, with a slope of 1:1000, then the difference in elevation is only 1.8 M. Where does the 2 bar come from? A drawing of the pipe and the assumed water levels would help.

Why such a long pipe in the first place?

A rule-of-thumb for liquid pipework: Consider only average velocity -

• If it is more than 3m/sec then the diameter is too small.
• If it is less than 1m/sec then the diameter is too big.

The rest is calculation. Invitation declined.