(a) Where does most of the energy loss occur in a Venturi meter, and why is this the case? (b) A Venturi meter is being calibrated in the laboratory. The meter has a diameter of 75mm at the entrance and 50mm at the throat. The differential head is 1.574m. The flow rate is obtained by…

The tank in question 5.4 is covered with an airtight lid and the air space above the water is pressurised so that the flow increases to 0.00093m3 /s. If the other details remain the same, what is the pressure of the air? Question 5.4 (a) Explain the hydraulic difference between a small orifice and a…

A reservoir must discharge to the atmosphere via a short pipeline. The entrance to the pipeline is sharp, and the diameter is 0.3m for the first 10m. The pipeline then expands suddenly to 0.45m diameter for the last 10m. For both pipes l = 0.06. If 0.5m3 /s of water must be discharged from the…

Water flows between two adjacent parts of a vertically sided service reservoir through a submerged 0.3m diameter orifice (CD = 0.60) in a common dividing wall. The first reservoir measures 45m by 30m in plan and initially contains water to a height of 5.0m above the centre of the orifice. The second tank is 20m…

Water flows down a trapezoidal open channel that has a bottom width B of 4.0m and a water surface width BS of 17.2m when the depth of flow on the channel centreline is 3.3m. (a) Without using any charts or tables, calculate the value of the wetted perimeter, the hydraulic radius and the hydraulic mean…

(a) Explain how it is possible for the flow at a particular cross-section in a channel to occur at two significantly different (alternate) depths of flow at the same discharge. (b) Water flows down a rectangular channel 4.0m wide at a depth of 1.7m. The discharge is 15.0m3 /s. (i) Determine whether the flow is…

A weir built to supply water to an old paper mill raises the water level in the river for some distance upstream. To reduce flooding it is proposed that the weir should be removed, but the effect of this needs to be determined first. Just upstream of the weir the depth is 3.722m when the…

Repeat question 8.11 above using the direct step method. Assume that the required change in water level is (3.722 – 1.250) = 2.472m divided into eight steps of DD = 0.309m. (a) Compare the chainages at which the upstream depth in the two questions first becomes 1.250m. Is there a significant difference? (b) Why might…

The design discharge for a culvert is 13.8m3 /s when the normal depth in the rectangular river channel is 1.9m. The channel has a bankful width of 4.2m, a slope of 1 in 300 and a Manning’s n of about 0.040s/m1/3. The maximum permissible upstream depth is 2.2m (i.e. 2.5m less 0.3m freeboard). The culvert…

(a) With respect to a broad crested weir, what is meant by the ‘submergence ratio’ and why is it important? (b) Water flows along a rectangular channel in which there is a broad crested weir with a horizontal crest. The channel is 9.0m wide, and upstream of the weir the depth of flow measured from…