Part full line - water hammer estimation

Gents + 1

I am looking at a water pipeline 2.8km long, flow rate 60l/s, ID 227mm.
The inlet is atmospheric from a tank. For the first 800m, the line drops 150m in elevation. For the remaining 2km, the line is near enough to horizontal, discharging into a pond. The friction loss under full pipe conditions will be about 30m (dirty). This means that the water will drop the first 120m (vertical) the line will run part full, with fairly high velocities. At the -120m point the line will become full with a fairly sharp head rise due to the sudden velocity rise forming a sort of hydraulic jump. I can take a rough stab at the part full velocity (using open channel flow theory) and I know the full pipe velocity. To get the surge rise, I thought I may be able to use Joukowsky's formula; delta H = a delta V /g; a is celerity. However, I think the result will be overly conservative,and would need to do a fair bit of work before being confident about the result. This is a fairly common operating condition, but I do not seem to have a clear estimation procedure for this.

Can anyone point me to a book or other reference?

Cheers

Steve Received on Thu Jun 17 06:23:00 2004