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Chapter 4 - Experimental setup and test procedure
4.1.3 Inlet box
At the upstream end of the channel a water supply pipe ( ∅ = 30 cm) was connected to the inlet
box (1 m wide, 2 m long and 1.10 m high). The connection was made through a 80 cm long perforated
cylinder ( ∅ = 40 cm). This cylinder (2) had about 2000 holes with a diameter of 10 mm
(Fig. 4.3 and Fig. 4.8). An overfall at the inlet (between the inlet box and the entry reach) prevented
the sediments of the channel to fall back into the inlet box. For the preliminary tests, an
assembly of 25 cm long small pipes (3) was put on top of the overfall (4) to direct the flow; they
had a diameter of 40 mm in the upper half and 20 mm in the lower part. The battery of small pipes
was removed for the main tests and replaced by a floating polystyrene plate to quieten the water
surface.
Units in mm
3
4
1
2
3
4
4
3
2
1
1
2
1. Water supply pipe, 2. Perforated cylinder, 3. Assembly of small pipes, 4. Overfall
(CENTER TOP: elevation, CENTER BOTTOM: situation, LEFT: downstr.-view, RIGHT: upstr.-view)
Figure 4.8: Inlet box with perforated cylinder and assembly of small pipes
page 74 / November 9, 2002
Wall roughness effects on flow and scouring