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Surge shaft in 14km water conductor system in hyro project

dear all,

i am designing one way surge tank in my water conductor system. i m having some troble in giving turbine data in transient flow conditions. after initial conditions have been ran,( sinsioidal flow) the how will have to give transient data? the transient data have " time and head variable" but i have only " the discharge -time data" i.e the wicket falling time in opening ang closing of turbine.

salient feeature of my system:

discharge -175 cumec

gross head 810m -(head losses around 30m)

head race tunnel around -14km( 7.7m dia) circular- concrete lined

pressure tunnels( 4m dia)circular -1.5km (2nos). 2 no of each pressure shaft trifurcates into 2.5m dia. 40 m lond each( total 6)- steel lined

surge shaft of of 13m dia 150 m high -concrete lined in junction of pressure tunnel and head race tunnel

vertical pelton turbine

closing time - 20 s

opening tme- 120s

  • Hi - I just replied to your other post, but didn't see that you had added more information here. I am not sure I understand your question fully (for example, why is the flow sinusoidal?), but here are some general comments...

    Because you have an impulse turbine, the best way to model this in HAMMER is to approximate the gate closure by using a 'Discharge to Atmosphere' element:

    The data shown above will close an initially open valve over 20 seconds. This should approximate your turbine gates closing over 20 seconds. As the valve shuts, the pressure will rise in the upstream pipeline.

    If you want more control over the valve closure, you could use a TCV element instead. The TCV allows you to enter a curve of valve (gate) closure versus time. For example you could have the gates close quickly until they are 30% open, then close slowly for the final 30%.