A hydraulic jump stilling basin, equipped with baffle blocks, is to be tested in laboratory to determine the dissipation characteristics for various flow rates. The maximum prototype discharge will be 220m3/s and the rectangular channel will be 10 m wide. (Assume the channel bed to be horizontal and concrete lined, i.e. smooth.) A 40:1 scale model of the stilling basin is to be built. Discharges ranging between the maximum flow rate and 10% of the maximum flow rate are to be reproduced in the model. 1. What similitude should be used? (Justify your selection.) 2. Determine the maximum model discharge required. 3. Determine the minimum prototype discharge for which negligible scale effects occur in the model. (Comment on your result.) For one particular inflow condition, the laboratory flow conditions are upstream flow depth of 0.019 m, upstream flow velocity of 2.38 m/s and downstream flow depth of 0.122 m.
A hydraulic jump stilling basin, equipped with baffle blocks, is to be tested in laboratory to determine the dissipation characteristics for various flow rates. The maximum prototype discharge will be 220m3/s and the rectangular channel will be 10 m wide. (Assume the channel bed to be horizontal and concrete lined, i.e. smooth.) A 40:1 scale model of the stilling basin is to be built. Discharges ranging between the maximum flow rate and 10% of the
maximum flow rate are to be reproduced in the model.
1. What similitude should be used? (Justify your selection.)
2. Determine the maximum model discharge required.
3. Determine the minimum prototype discharge for which negligible scale effects occur in the model. (Comment on your result.) For one particular inflow condition, the laboratory flow conditions are upstream flow depth of 0.019 m, upstream flow velocity of 2.38 m/s and downstream flow depth of 0.122 m.
4. Compute the model force exerted on the baffle blocks. (State the basic principle(s) involved.)
5. What is the direction of force in (d) i.e. upstream or downstream?
6. What will be the corresponding prototype force acting on the blocks?
7. Compute the prototype head loss. Operation of the basin may result in unsteady wave propagation downstream of the stilling basin.
8. What will be the scale for the time ratio?
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