hydraulic analysis of sluiceway
hydraulic analysis of sluiceway
(OP)
We are attempting to verify a stage discharge rating curve for a large sluiceway. About 10 foot high by 20 foot wide with maximum water depth upstream of the control / orifice of about 30 feet.
Can anyone point to a reference that would deal with this sort of "low head" orifice and give a methodology for estimating the orifice flow coefficient?
Can anyone point to a reference that would deal with this sort of "low head" orifice and give a methodology for estimating the orifice flow coefficient?
RE: hydraulic analysis of sluiceway
RE: hydraulic analysis of sluiceway
RE: hydraulic analysis of sluiceway
This isn't a culvert - see diagram below
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RE: hydraulic analysis of sluiceway
Check out http://chl.wes.army.mil/library/publications/hydraulic_...
RE: hydraulic analysis of sluiceway
RE: hydraulic analysis of sluiceway
Sorry your diagram is not clear.
From what you now say you have a sqaure orifice with the downstream section the same width as the orifice.
The situation would appear to be similar to that for a vertical lift sluice gate. For the tailwater not to have an affect the flow will have to be free flow. i.e the momentum force immediately after the orifice exceeds the momentum force in the downstream section. (free flow sluice gate).
Brian
RE: hydraulic analysis of sluiceway
A further thought the flow conditions will change from simple subcritivcal flow through a restricted opening to a supercritical jet at your maximum upstream level of 30 ft above the orifice. - You say that tailwater is not a concern - but from your explanation it would appear that the jet is supported by the invert of the sluicway and the tailwater is a major factor.
The driving head through the orifice is is the difference in head between the upstream and downstream water levels.
If the orifice is operating with supercritical free flow or even if there is a submerged jump the water level immediately downstream of the orifice will reduce with increasing upstream head.
The water level downstream of the orifice will reduce with increasing upstream head thus the driving head will increase more than the rise in water level and, as you say, the orifice will become more effecientwith increasing head.
You need to calculate the downstream level to get the driving head -
For free flow you can assume no head loss through the orifice and calculate the depth from Barnoulli.
You then need to make an hydraulic jump calculation and determine whether a jump is formed and if so whether it submerges the jet.
However, I could be completely misunderstanding the problem !!
Brian