29-05-2013, 02:42 PM
Momentum Applications in Open Channel Flow
Momentum Applications.ppt (Size: 2.29 MB / Downloads: 100)
Momentum
Considering a short section so that Rf is negligible and the channel slope is small so that sinQ is near zero the equation.
M is called the momentum function or the specific force plus momentum.
For a constant q, M can be plotted against depth to create a curve similar to the specific energy curve.
Under steady conditions, M is constant from point to point along a channel reach.
Hydraulic Jumps
Occurs when there is a sudden transition from supercritical (y < yc) to subcritical (y > yc) flow.
Examples of where this may occur are :
At the foot of a spillway
Where a channel slope suddenly turns flat.
Example
Example 3.18, Streeter, et al.
If 12 m3/sec of water per meter of width flows down a spillway onto a horizontal floor and the velocity is 20 m/sec, determine (a) the downstream depth required to cause a hydraulic jump, (b) the loss in energy head, and © the losses in power by the jump per meter of width.