Hydraulics
Exam Duration: 45 Mins Total Questions : 30
A steady flow occurs in an open channel with in flow qm3/s per unit width as show in figure . The mass conservation equation is
- (a)
\(\frac{\partial q}{\partial x}\) = 0
- (b)
\(\frac{\partial Q}{\partial x}\) = 0
- (c)
\(\frac{\partial Q}{\partial x}\) - q = 0
- (d)
\(\frac{\partial Q}{\partial x}\) + q = 0
Steady flow in a channel exists when the
- (a)
flow in a uniform
- (b)
depth does not change with time
- (c)
channel is frictionless
- (d)
channel bed si not curved
A steep channel is inclined at 450 to the horizontal and carries a flow at a depth of 0.75 m. The pressure at the bed of the channel is
- (a)
7358 N/m2
- (b)
3679 N/m2
- (c)
5203 N/m2
- (d)
10401 N/m2
A channel with slope is followed by a horizontal channel and then by a steep channel. What gradually varied profile will occur
- (a)
\({ M }_{ 1 }{ ,H }_{ 1 },{ S }_{ 1 }\)
- (b)
\({ M }_{ 2}{ ,H }_{ 2 },{ S }_{ 2 }\)
- (c)
\({ M }_{ 1 }{ ,H }_{ 2 },{ S }_{ 3 }\)
- (d)
\({ M }_{ 1 }{ ,H }_{ 2 },{ S }_{ 2 }\)
In a channel the bed slope changes from steep to adverse the resulting GVF profiles are
- (a)
\({ S }_{ 1 },{ A }_{ 3 }\)
- (b)
\({ S }_{ 2 },{ A }_{ 2 }\)
- (c)
\({ S }_{ 2 },{ A }_{ 3 }\)
- (d)
\({ S }_{ 1 },{ A }_{ 2 }\)
Given figure shows a GVF situation in an open channel flow with a break in bed slope types of water surface profile occuring from left to right are
- (a)
\({ H }_{ 3 },{ S }_{ 2 }\)
- (b)
\({ H }_{ 3 },{ S }_{ 3 }\)
- (c)
\({ H }_{ 2 },{ M }_{ 2 }\)
- (d)
\({ H }_{ 2 },{ S }_{ 2 }\)
A spillway discharges flood flow at a rate of \(9{ m }^{ 3 }/s\) per metre width. if the depth of flow on the horizontal apron at the toe of the spillway is 46 cm, the tail water depth needed to foem a hydraulic jump is approximately given by
- (a)
2.54 m
- (b)
4.90 m
- (c)
5.77 m
- (d)
6.23 m
A hydraulic jump occurs when there is a break in grade from a
- (a)
mild slope to steep slope
- (b)
steep slope to mild slope
- (c)
steep slope to steeper slope
- (d)
mild slope to milder slope
In a hydraulic jump taking place in a horizontal rectangular channel the sequent depths are 0.30 m and 1.50 m respectively.The energy loss in the jump is
- (a)
1.92 m
- (b)
1.50 m
- (c)
0.96 m
- (d)
1.20 m
Superitical flow in a rectangular channel at adepth of flow 0.63 m occurs at F = 2.0 .The critical depth in meter is
- (a)
0.857
- (b)
0.735
- (c)
1.000
- (d)
0.500
The Froude number of a flow in a rectangular channel is 0.73 . If a depth of flow is 1.50 m, the specific energy in metre is
- (a)
1.90
- (b)
1.50
- (c)
1.83
- (d)
0.73
On which of the following the Chezy's constant C generally depends upon?
- (a)
Relative roughness of surface
- (b)
Shape of channel cross-section
- (c)
Reynolds number
- (d)
All of the above
The critical depth of a rectangular channel section is given by the expression
- (a)
\(h_{ c }=\frac { { v }^{ 2 } }{ 2g } \)
- (b)
\(h_{ c }=\frac { { v }^{ 2 } }{ g } \)
- (c)
\(h_{ c }=\frac { { v } }{ g } \)
- (d)
\(h_{ c }=\frac { {2 v }^{ 2 } }{ g } \)
The critical depth of the channel is the depth at which
- (a)
specific energy is maximum
- (b)
specific energy is minimum
- (c)
specific energy is critical
- (d)
velocity is subcritical
See the channel section below, if the discharge is 8 cumec, then the specific energy will be equal to
- (a)
1.20 m
- (b)
3.10 m
- (c)
2.01 m
- (d)
1.12 m
The free water surface will rise abnormally in front of jump known as hydraulic jump, when the rate of change of depth \(\frac { dy }{ dx } \)with respect to channel is
- (a)
0
- (b)
\(\infty \)
- (c)
negative
- (d)
positive
The depth of water when hydraulic jump is formed is given by the expression
- (a)
\({ y }_{ 2 }=\frac { -{ y }_{ 1 } }{ 2 } +\sqrt { \frac { { y }_{ 1 }^{ 2 } }{ 4 } +\frac { 2q^{ 2 } }{ gy_{ 1 } } } \)
- (b)
\({ y }_{ 2 }=\frac { -{ y }_{ 1 } }{ 2 } +\sqrt { \frac { { y }_{ 1 }^{ 2 } }{ 4 } +\frac { 2{ y }_{ 1 }{ v }_{ 1 }^{ 2 } }{ g } } \)
- (c)
\({ y }_{ 2 }=\frac { { y }_{ 1 } }{ 2 } \left[ \sqrt { 1+\left( 1+8{ F }_{ 1 }^{ 2 } \right) } \right] \)
- (d)
All of the above
The ratio of Froude's number on the upper side and down side of jump is expressed as
- (a)
\(\frac { { F }_{ 1 } }{ { F }_{ 2 } } =\left( \frac { { y }_{ 2 } }{ { y }_{ 1 } } \right) ^{ 3/2 }\)
- (b)
\(\frac { { F }_{ 1 } }{ { F }_{ 2 } } =\left( \frac { { y }_{ 1 } }{ { y }_{ 2 } } \right) ^{ 2/3 }\)
- (c)
\(\frac { { F }_{ 1 } }{ { F }_{ 2 } } =\left( \frac { { y }_{ 2 } }{ { y }_{ 1 } } \right) ^{ 5/2 }\)
- (d)
\(\frac { { F }_{ 2 } }{ { F }_{ 1 } } =\left( \frac { { y }_{ 2 } }{ { y }_{ 1 } } \right) ^{ 3/2 }\)
A rectangular channel 3.6 m wide had badly damaged surfaces and had a manning's n = 0.030. As a first phase of repair, its ed was lined with concrete ( n = 0.015 ). If the depth of flow remains same at 1.2 m before and after the repair,the percentage increase in discharge will be
- (a)
3.89 %
- (b)
1.63%
- (c)
38.9%
- (d)
28.7%
A trapezoidal channel coefficient over years of use. This would represent, corresponding to the same stage as at the beginning, a change in discharge of
- (a)
+10%
- (b)
-10%
- (c)
+11%
- (d)
-9.1%
For the given discharge, the critical flow depth in an open channel depends on
- (a)
channel geometry only
- (b)
channel geometry and bed slope
- (c)
channel geometry, bed slope and roughness
- (d)
channel, geometry, bed slope, roughness and Reynolds number
A wide channel is 1m deep and has a velocity of flow v as 2.13 m/s. If a disturbance is caused, an elementary wave can travel upstream with a velocity of
- (a)
1.00 m/s
- (b)
2.13 m/s
- (c)
3.13 m/s
- (d)
5.28 m/s
A rectangular open channel of width 4.5 m is carrying a discharge of \(100m^{ 3 }/s\). The critical depth of the channel is
- (a)
7.09 m
- (b)
3.69 m
- (c)
2.16 m
- (d)
1.31 m
Match List I (Flow reaction type) with List II ( Critical discharge is proportional to ) and select the correct answer using the codes given below the lists
List I | List II | |
P. | Shallow parabolic | 1. y(z)3/2 |
Q. | Triangular | 2. y3/2 |
R. | Rectangular | 3. y5/2 |
S. | Trapezoidal | 4. y2 |
- (a)
P Q R S 2 3 4 1 - (b)
P Q R S 4 1 2 3 - (c)
P Q R S 2 1 4 3 - (d)
P Q R S 4 3 2 1
The flow rate in a wide rectangular open channel is \(2.0{ m }^{ 3 }/s\) per metre width. The channel bed slope is 0.002. The Manning's roughness coefficient is 0.012. The slope of the channel is classified as
- (a)
critical
- (b)
horizontal
- (c)
mild
- (d)
steep
The height of a hydraulic jump in the stilling pool of 1.25. Scale model was observed to be 10 cm. The corresponding prototype height of jump is
- (a)
Not determinable from given data
- (b)
2.5 m
- (c)
0.5 m
- (d)
0.1 m
The flow profile under the gate as shown in figure is classified as
- (a)
\({ M }_{ 2 }\)
- (b)
\({ H }_{ 1 }\)
- (c)
\({ H }_{ 2 }\)
- (d)
\({ H }_{ 3 }\)
If the specific energy at the upstream section of a rectangular channel is 3m and minimum specific energy is 2.5 m, the maximum height of jump without causing afflux will be
- (a)
0.50 m
- (b)
1.20 m
- (c)
2.50 m
- (d)
5.50 m
In a 2 m wide rectangular channel uniform flow occurs at a depth of 2m, the velocity of flow being \(\sqrt { 2g } m/s\). The height of hump which can be raised without causing afflux will be
- (a)
0
- (b)
1 m
- (c)
2 m
- (d)
3 m
Water flows a velocity of 1 m/ s and a depth of 2m in an open channel of rectangular cross section 3 m wide. At a certain section the width is reduced to 1.8 m and the bed is raised by 0.126 m . If height of hump is raised 0.65 m then what will be new upstream depth ?
- (a)
2.101 m
- (b)
2.171 m
- (c)
2.211 m
- (d)
No change