Installtion of a stilling plate within a 2m wide channel

[JohnWeal]

I am providing an engineering design for the installation of a 'stilling plate' within a sewage channel. The channel is 2 metres wide and the water depth is 3m. The stilling plate is the full width of the channel and 1.5m deep. The top edge is located 100mm above the 3m top water level (TWL)

The velocity of the incoming flow is 3 m/s. The plate is supported on the two sides only and I cannot find a calculation anywhere including Roarks.

Can anyone provide me with any leads?

Regards
John

 

[structSU10]

This sounds like a simply supported beam to me, but maybe a sketch of the situation would clarify what you mean. What I picture is this stilling plate to span from wall to wall, with water flowing into it. Is that correct?

 

[JedClampett]

I agree with the above post. If the plate is supported on the sides only it is a simply supported member.
But you have me confused with some of the other information. If the top of plate is 100 mm above the water level and velocity is 3 m/s, how does that work? Where does the water travelling at 3 m/s (by the way, that's rocketing!) go? Over the plate? Under the plate? Down a different channel?
If you need the pressure from the flowing water, that's v^2/2g.

 

[JohnWeal]

Thanks for the replies, Just to clarify things:

The stilling plate is 1.5m deep which is approx 1.5m above the base of the channel.
ie, when the flow is at its lowest, it is the same level (1.5m) as the underside of the plate. At top water level, the plate is almost submerged. Therefore yes, the water will pass underneath.

This has been modelled by a hydraulics department.

Perhaps as a worst case, I could treat this as a closed square conduit as if pumping against a 'dead head' and use the v2/2g calculation.


Regards
John

 

[dicksewerrat]

I thought a 'stilling structure' was to slow down and smooth out the flow. This arrangement will force 18 cubic meters of liquid through a 3.2 square meter space. It will speed up or overflow.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[cvg]

what you have is an undershot weir. it will cause "stilling" as well as in increase in depth, upstream of the weir. And downstream will be high velocity flow.