The Orifice Design uses the methodology described in HEC-22 Manual. The orifice flow is determined as:
Q = Co Ao (2 g Ho)0.5
This command designs an orifice structure and calculates its
stage-discharge curve. Select Orifice
Design from the Structure menu in the Hydrology Module to display the
design dialog. Select the Section Type of the orifice, Circular or
Rectangular.
Enter the dimension for the orifice. In the Invert Elev box, type the
absolute elevation at which the orifice will be attached to a
reservoir. The attachment point is at the bottom of the orifice. In the
Coefficient box, type a roughness coefficient for the orifice. The
coefficient ranges from 0.4 to 0.6 (HEC-22). In the Number of Openings
box, enter the number of orifices you want to combine.
In the Headwater and Tailwater boxes, type the absolute headwater
surface elevation and tailwater surface elevation respectively. Click
on the Calculate button, the maximum
discharge and flow velocity through the orifice would be computed and
displayed.
Click on the Stage-Discharge Result button to display the
stage-discharge curve in the Stage-Discharge Result Dialog. This dialog
allows you to write the stage-discharge data to a stage-discharge
file(.STG), and draw the stage-discharge curve on the screen.
From the Stage-Discharge Curve Draw Settings dialog , you can specify
how to
draw the curve.
Orifice Design Dialog |
Stage-Discharge Limits Dialog |
Stage-Discharge Result Dialog |
Stage-Discharge Curve Draw
Settings Dialog |
Orifice Design dialog: Fill in values.
Pulldown Menu Location:
Structure > Orifice Design
Keyboard Command: orifice
Prerequisite: None
File Name:\lsp\cntr_grd.arx