130 likes | 233 Views
53:071 Principles of Hydraulics Laboratory Experiment #3 Analysis of Open-Channel Flow Transitions Using Specific Energy Diagram. Li-Chuan Chen, Marian Muste, and Larry Weber. Objective. To observe the changes in the behavior of the free surface when subjected to changes in the channel bed.
E N D
53:071 Principles of HydraulicsLaboratory Experiment #3Analysis of Open-Channel Flow Transitions Using Specific Energy Diagram Li-Chuan Chen, Marian Muste, and Larry Weber
Objective • To observe the changes in the behavior of the free surface when subjected to changes in the channel bed.
ybump (ft) 0.24 x (ft) 5 5.87 6.96 7.78 Apparatus — Obstruction For x 5 ybump = 0 For 5 < x 5.87 ybump = 0.276x – 1.38 For 5.87 < x 6.96 ybump = 0.24 For 6.96 < x 7.78 ybump = 2.28 - 0.293x For x > 7.78 ybump = 0
What are we going to do? • We are going to measure the water surface elevation along a open channel.
Procedures • Establish a stabilized discharge in the system. • Measure the water level difference on the differential manometer for computing discharge. • Measure the water surface elevation upstream, above, and downstream of the obstruction. • Change the flow rate and repeat Step 2 and 3 for another flow condition. • Observe the ripples formed at the tip of the point gage.
Flow Situation I Flow Situation II h= (ft); Q = (cfs); yc1= (ft) h= (ft); Q = (cfs); yc1= (ft) Track (ft) Water Surface Elevation (ft) Bump Geometry (ft) Actual depth (ft) Track (ft) Water Surface Elevation (ft) Bump Geometry (ft) Actual depth (ft) Data Sheet
Analysis • Plot the water surface elevation in the vicinity of the channel transition. • Construct the specific energy diagram using the measured data. • Compare theoretical specific energy diagrams with the experimental curves. • Comment on the flow behavior in the two flow situation.
Further Considerations • What are the main assumptions associated with the use of the specific energy diagram? • Comment on the differences noticed on the ripples produced by the point gage upstream and downstream the obstruction. • Analyze the water surface behavior for the same unit discharges used in your experiment hypothesizing the flow enters in the obstruction as supercritical flow.