Reducing outlet flow using orifice
Reducing outlet flow using orifice
(OP)
I am trying to regulate the amount of flow that can outlet my stormwater system due to release rate restrictions. I modelled the structure where I want to regulate the flow as a pond with an orifice outlet only, then modelled the outlet pipe as a reach. The orifice I am using is an 8" and the outlet pipe is 12". The problem is that the capacity of the outlet pipe is regulating the outlet flow and not the orifice. Changing the orifice size only seems to affect the hydraulic grade line elevations. The warning I am getting is that my outlet pipe reach is at 225% manning's capacity. I am not understanding why the 8" orifice is not regulating the flow to the 12" outlet pipe. How can the flow be greater than the capacity of the pipe. Any help would be much appreciated.
RE: Reducing outlet flow using orifice
Why not model the outlet control structure with a culvert as Primary Routing, then an orifice routed to that?
Engineering is the practice of the art of science - Steve
RE: Reducing outlet flow using orifice
Device #1 = Culvert, Routing = Primary
Device #2 = Orifice, Routing = Device #1
For full details please see the riser modeling example at www.hydrocad.net/pond1.htm Your case is less complex, but the principles are the same.