The discharge passing over an ogee spillway is given by (where, L is effective length of spillway crest and H is the total head over the spillway crest including velocity head.)

Statement (I): The ogee spillway is a control weir having an S-shaped crest profile which provides a high discharge coefficient without causing cavitations. Statement (II): The crest profile of ogee spillway conforms to the lower nappe of flow over a ventilated sharp-crested weir and ensures a constant discharge coefficient for all heads.

A

Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)

B

Both Statement (I) and Statement (II) are individually true but Statement (II) is not the correct explanation of Statement (I)

C

Statement (I) is true but Statement (II) is false

D

Statement (I) is false but Statement (II) is true (II) is true:

Two centrifugal pumps P and R are available for use in a pipe flow system and their head-discharge characteristics are as follows. Pump P Pump R Discharge (cumecs) Head (m) Discharge (cumecs) Head (m) 0 40 0 45 0.12 35 0.14 40 0.2 28 0.24 35 0.3 18 0.3 28 The following statements (S1, S2, and S3) pertain to the head and discharge values during actual operation. Neglect losses in the system. Which of the following statements are correct? S1: When the two pumps P and R are connected in parallel, the discharge is 0.36 cumecs corresponding to a head of 35 m. S2: When the two pumps P and R are connected in parallel, the discharge is 0.36 cumecs corresponding to a head of 70 m. S3: When the two pumps P and R are connected in series, the discharge is 0.3 cumecs corresponding to a head of 46 m.

A

S2 only

B

S1 and S3

C

S1 and S2

D

S2 and S3

An ogee spillway of a concrete gravity dam having FRL of 328 m and MWL of 340 m is provided with vertical gates between piers erected on the spillway. The effective length of the spillway is 60 m. The discharge through the spillway when gates are opened up to the actual reservoir level of 331.0 m will be_____________

A

850 cumecs

B

1700 cumecs

C

2800 cumecs

D

1000 cumecs

Calculate the effective length of the spillway which consists of 6 spans having a clear width of 10 m each. The thickness of each pier may be taken as 2.5 m and the total design head on the crest including velocity head is 16.3 m. Assuming 90° cut water nose piers and rounded abutments.

A

55 m

B

60 m

C

65 m

D

75 m

For discharge over ogee weir discharge is directly proportional to length but for discharge over narrow crested weir it is inversely proportional to length.

A

True

B

False

The W.E.S downstream profile of an ogee spillway can be represented by an equation: Xn = K Hd n-1. Y Where x and y are the coordinates of the points on the crest profile and K and n for a vertical upstream spillway would respectively be___________________

A

2.0 and 1.85

B

0.5 and 1.85

C

2.0 and 0.85

D

0.5 and 0.85

The discharge passing over an ogee spillway per unit length of its apex line is proportional ___________________

A

H

B

H2

C

H1/2

D

H3/2

Arrange the following stages in a sequence, such that they result in an ogee curve between two parallel lines AB and CD, such that they are the tangents to the arc. m) Join the adjacent ends B and C with a straight line. n) Divide the line BC into four parts using the points P1, P2, P3. o) Draw lines such that they pass through the points P1, P2, P3, and are perpendicular to the line BC. p) Draw the perpendicular lines through the points B and C such that they cut the lines passing through P1, P3 respectively at E and F. q) With the center E draw an arc BP2 and with center F draw an arc P2C, thus arc BP2C is required ogee curve.

A

m, n, o, p, q

B

m, o, p, q, n

C

m, n, p, q, o

D

p, q, o, n, m

Identify the spillway crest gate, which consists of a hollow steel cylinder or drum spanning between the piers constructed on the crest of the spillway.

A

Flash boards.

B

Rolling gates.

C

Sliding vertical gates.

D

Stoplogs and Needles.

The suction pressure on an ogee spillway is caused when the head on the spillway is:

A

< the design head

B

Equal to the design head

C

≥ the design head

D

> the design head

The discharge passing over an ogee spillway is given by (where, L is effective length of spillway crest and H is the total head over the spillway crest including velocity head.)

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