Unit 1 - Fluids and Their Properties

Faculty of Degree Engineering-083 Department of Mechanical Engineering – 19

Multiple Choice Questions (Fluid Mechanics and Hydraulic Machines – 3141906)

Unit 1 - Fluids and Their Properties

1. The branch of Engineering-science, which deals with water at rest or in motion is called

(a) hydraulics

(b) Fluid mechanics

(c) Applied mechanics

(d) Kinematics.

2. A solid can resist which of the following stresses?

(a) Tensile

(b) Compressive

(c) Shear

(d) All of the above.

3. .......... possesses no definite volume and is compressible.

(a) Solid

(b) Liquid

(c) Gas

(d) Vapour.

4. 4. A real practical fluid possesses which of the following?

(a) Viscosity

(b) Surface tension

(c) Compressibility

(d) Density

(e) All of the above

5. The ratio of the specific weight of the liquid to the specific weight of a standard fluid is known as

(a) Specific volume

(b) Weight density

(c) Specific gravity

(d) Viscosity.

6. The property of a fluid which determines its resistance to shearing stress is called

(a) Viscosity

(b) Surface tension

(c) Compressibility

(d) None of the above.

7. Newton’s law of viscosity is given by the relation:


(a) τ = 𝜇2 𝑑𝑢

𝑑𝑦

(b) τ = √𝜇 𝑑𝑢

𝑑𝑦

(c) τ = 𝜇 𝑑𝑢

𝑑𝑦

(d) τ = 𝜇3/2 𝑑𝑢

𝑑𝑦

8. Fluids which do not follow the linear relationship between shear stress and rate of deformation are termed

as.... fluids.

(a) Newtonian

(b) Non-Newtonian

(c) Dilatant

(d) ideal

9. The printer’s ink is an example of

(a) Newtonian fluid

(b) Non-Newtonian

(c) Thixotropic substance

(d) Elastic solid.

10. The viscosity of liquids ..... with increase in temperature.

(a) Decreases

(b) Increases

(c) First decreases and then increases

(d) First increases and then decreases.

11. Surface tension is caused by the force of ..... at the free surface.

(a) Cohesion

(b) Adhesion

(c) Both (a) and (b)


12. Which of the following is an example of phenomenon of surface tension?

(a) Rain drops

(b) Rise of sap in a tree

(c) Break up of liquid jets


13. Surface tension is expressed in

(a) N/m

(b) N/m2

(c) N2/m

(d) N/m3.

14. Pressure inside a water droplet is given by the relation


(a) p = 4𝜎/d

(b) p = 3𝜎/d

(c) p = 8𝜎/d

(d) p = 16𝜎/d

15. . ...... is a phenomenon by which a liquid rises into a thin glass tube above or below its general level.

(a) Surface tension

(b) Capillarity

(c) Cohesion

(d) Adhesion.

16. The capillary rise of water in the glass tube is given by

(a) h = 2σ/wd

(b) h = 3σ/wd

(c) h = 4σ/wd

(d) h = 6σ/wd

17. Elasticity of fluids is measured in terms of

(a) Young’s modulus of elasticity

(b) Shear modulus of elasticity

(c) Bulk modulus of elasticity


18. Compressibility is the reciprocal of

(a) Bulk modulus of elasticity

(b) Shear modulus of elasticity

(c) Young’s modulus of elasticity

(d) Any of the above.

19. Bulk modulus of elasticity is the ratio of

(a) Tensile stress to tensile strain

(b) Compressive stress to compressive strain

(c) Compressive stress to volumetric strain


20. The value of bulk modulus of elasticity .......... with increase of pressure.

(a) Increases

(b) Decreases

(c) Either of the above


21. The force per unit area is called

(a) Pressure

(b) Strain


(c) Surface tension


22. The pressure of a liquid on a surface will always act ...... to the surface.

(a) Parallel

(b) Normal

(c) 45°

(d) 60°.

23. The pressure ....... as the depth of the liquid increases.

(a) Increases

(b) Decreases

(c) Remain unchanged


24. The intensity of pressure in a liquid due to its depth will vary .... with depth.

(a) Directly

(b) Indirectly



25. The height of the free surface above any point is known as

(a) Static head

(b) Intensity of pressure



26. “The intensity of pressure at any point in a liquid at rest is the same in all directions.” The above statement

is known as

(a) Kirchhoff’s law

(b) Pascal’s law



27. Any pressure measured above the absolute zero of pressure is termed as

(a) Atmospheric pressure

(b) Gauge pressure


(d) None of the above

28. The fundamental S.I. unit of pressure is N/m2; this is also known as ......

(a) Pascal

(b) Stoke

(c) Poise


Unit 2 - Static Forces on Surface and Buoyancy

29. The intensity of pressure p is related to specific weight w of the liquid and vertical depth h of the point

by the equation

(a) p = wh

(b) h = pw

(c) p = wh2

(d) p = wh3.

30. The point of application of the total pressure on the surface is

(a) Centroid of the surface

(b) Centre of pressure



31. If A is the area of the immersed surface, w is the specific weight of the liquid and ͞x is the depth of

horizontal surface from the liquid surface, then the total pressure P on the surface is given by

(a) p = wA2 ͞x

(b) p = w2A ͞x

(c) p = wA ͞x

(d) p = wA ͞x2

32. Centre of pressure (͞h) in case of an inclined immersed surface is given by

(a) ͞h = 𝐼𝐺 𝑠𝑖𝑛𝜃

𝐴 ͞x + ͞x

(b) ͞h = 𝐼𝐺𝑠𝑖𝑛𝜃

𝐴2 ͞x + ͞x

(c) ͞h = 𝐼𝐺

2𝑠𝑖𝑛𝜃

𝐴 ͞x + ͞x

(d) ͞h = 𝐼𝐺𝑠𝑖𝑛2𝜃

𝐴 ͞x + ͞x

33. The side of the dam to which the water from the river or the stream approaches is known as

(a) Downstream

(b) Upstream



34. Which of the following is a possibility of dam failure?

(a) Failure due to sliding along its base

(b) Failure due to tension or compression


(c) Failure due to shear at the weakest section

(d) Failure due to overturning

(e) All of the above.

35. Lock gates are provided to

(a) Change the water level in a canal or river for irrigation

(b) Store water for irrigation purpose



36. The term........ means the study of pressure exerted by a fluid at rest.

(a) Hydrostatics

(b) Fluid mechanics

(c) Continuum

(d) Kinetics

37. The tendency for an immersed body to be lifted up in the fluid, due to an upward force opposite to the

action of gravity is known as

(a) Buoyancy

(b) Centre of buoyancy

(c) Buoyant force


38. The magnitude of the buoyant force can be determined by

(a) Newton’s second law of motion

(b) Archimedes’ principle

(c) Principle of moments


39. When a body is immersed in a fluid, partially or completely, the force of buoyancy is equal to

(a) The weight of the body

(b) The weight of the fluid displaced by the body

(c) The weight of the volume of the fluid equal to the volume of body


40. The point of application of the force of buoyancy on the body is known as

(a) Centre of gravity

(b) Centre of buoyancy

(c) Metacenter


41. “When a body is immersed in a fluid either wholly or partially, it is buoyed or lifted up by a force which

is equal to the weight of fluid displaced by the body”. This principle was enunciated by

(a) Archimedes


(b) Newton

(c) Pascal

(d) Kirchhoff.

42. A floating body is in stable equilibrium when

(a) The metacentre is below its centre of gravity

(b) The metacentre is above its centre of gravity

(c) The metacentric height is zero.

(d) Its centre of gravity is below the centre of buoyancy.

43. An ice-cube is floating in glass of water. As the cube melts the water level

(a) Remain constant

(b) Falls

(c) Rises


44. If the position of metacenter M remains lower than c.g. of the body, G, the body will remain in a state of

(a) Stable equilibrium

(b) Unstable equilibrium

(c) Neutral equilibrium

(a) Any of the above.

45. Metacentric height can be determined by

(a) Only analytical method

(b) Only experimental method



46. If a body does not return to its original position from the slightly displaced angular position and heels

farther away, when given a small angular displacement; such an equilibrium is called

(a) Stable equilibrium

(b) Unstable equilibrium

(c) Neutral equilibrium

(d) Any of the above


Unit-3 Motion of Fluid Particles and Streams

47. The motion of fluid particles may be described by which of the following methods?

(a) Langrangian method

(b) Eulerain method



48. In which of the following methods, the observer concentrates on a point in the fluid system?

(a) Langrangian method

(b) Eulerian method

(c) Any of the above


49. Normal acceleration in fluid-flow situation exists only when

(a) The flow is unsteady

(b) The flow is two-dimensional

(c) The streamlines are straight and parallel

(d) The streamlines are curved.

50. In a steady flow the velocity

(a) Does not change from place to place

(b) At a given point does not change with time

(c) May change its direction but the magnitude remains unchanged


51. The flow in a pipe whose valve is being opened or closed gradually is an example of

(a) Steady flow

(b) Unsteady flow

(c) Rotational flow

(d) Compressible flow.

52. The type of flow in which the velocity at any given time does not change with respect to space is called

(a) Steady flow

(b) Compressible flow

(c) Uniform flow

(d) Rotational flow.

53. Flow in a pipe where average flow parameters are considered for analysis is an example of

(a) Incompressible flow

(b) One-dimensional flow

(c) Two-dimensional flow

(d) Three-dimensional flow.


54. The flow in a river during the period of heavy rainfall is

(a) Steady, non-uniform and three-dimensional

(b) Steady, uniform, two-dimensional

(c) Unsteady, uniform, three-dimensional

(d) Unsteady, non-uniform and three-dimensional.

55. Flow between parallel plates of infinite extent is an example of

(a) One-dimensional flow

(b) Two-dimensional flow

(c) Three-dimensional flow

(d) Compressible flow.

56. If the flow is irrational as well as steady it is known as

(a) Non-uniform flow

(b) One-dimensional flow

(c) Potential flow


57. High velocity flow in a conduit of large size is known as

(a) Laminar flow

(b) Turbulent flow



58. 12. If the Reynolds number is less than 2000, the flow in a pipe is

(a) Laminar flow

(b) Turbulent flow

(c) Transition flow


59. The path followed by fluid particle in motion is called a

(a) Streamline

(b) Path line

(c) Streak line


60. A....is an imaginary line within the flow so that the tangent at any point on it indicates the velocity at that

point.

(a) Streak line

(b) Stream line

(c) Path line


61. A stream line is one


(a) In which stream function does not change

(b) In which the flow cannot cross the bounding surface

(c) Which has a constant area throughout its length so that the velocity remains constant.


62. ...... is a curve which gives an instantaneous picture of the location of the fluid particles which have passed

through a given point.

(a) Path line

(b) Stream line

(c) Streak line


63. In fluid mechanics, the continuity equation is a mathematical statement embodying the principle of

(a) Conservation of momentum

(b) Conservation of mass

(c) Conservation of energy


64. An irrational flow is one in which

(a) The stream lines of flow are curved and closely spaced

(b) The fluid does not rotate as it moves along

(c) The net rotation of fluid particles about their mass centres remains zero


65. In a fluid-flow the stream lines are lines

(a) Along which the vorticity is zero

(b) Along which the stream function ψ = constant

(c) Which are parallel to the equipotential lines

(d) Which exist in irrotional flow only.

66. ....... is defined mathematically as the line integral of the tangential velocity about a closed path (contour).

(a) Circulation

(b) Vorticity



67. The concept of stream function which is based on the principle of continuity is applicable to

(a) Irrotational flow only

(b) Two-dimensional flow only

(c) Three-dimensional flow

(d) Uniform flow only.

68. The motion is described as ......when the components of rotation or vorticity are zero throughout certain

point of the fluid.


(a) Rotational

(b) Irrotational



69. ........ is defined as a scalar function of space and time such that its negative derivative with respect to any

direction gives the fluid velocity in that direction.

(a) Velocity potential function

(b) Stream function

(c) Circulation

(d) Vorticity.

70. If velocity potential (φ) satisfies the Laplace equation, it represents the possible..... flow.

(a) Unsteady, compressible, rotational

(b) Steady, compressible, irrotational

(c) Unsteady, incompressible, rotational

(d) Steady, incompressible, irrotational.

71. A flow net is a graphical representation of strea lines and equipotential lines such that these lines

(a) Intersect each other orthogonally forming curvilinear squares

(b) Intersect each other at various different angles forming irregular-shaped nets

(c) Indicate the direction and magnitude of vector


72. The flow-net analysis can be used to determine

(a) The stream lines and equipotential lines

(b) Quantity of seepage and upward lift pressure below hydraulic structures

(c) The efficient boundary shapes, for which the flow does not separate.

(d) The velocity and pressure distribution for given boundaries of flow (provided the velocity distribution

and pressure at any reference section are known).

(e) All of the above


Unit 4 - The Energy Equation and its Application

73. Velocity head is given by

(a) V/g

(b)V2/2g

(c)V3/2g

(d)V2/2g2

74. Which of the following assumptions is made in the derivation of Bernoulli’s equation?

(a) The liquid is ideal and incompressible

(b) The flow is steady and continuous

(c) The flow is one-dimensional

(d) The velocity is uniform over the section and is equal to mean velocity

(e) All of the above.

75. Euler’s equation (in differential form) is written as:

(a) dp/ρ + v2 .dv + g.dz = 0

(b) dp/ρ + v.dv + g.dz = 0

(c) dp/ρ + v.dv + g2 .dz = 0

(d) dp/ρ2 + v.dv + g.dz = 0

76. In which of the following measuring devices Bernoulli’s equation is used:

(a) Venturimeter

(b) Orificemeter

(c) Pitot tube

(d) All the above.

77. The co-efficient of discharge of an orificemeter is ......that of a venturimeter.

(a) Equal to

(b) Much smaller than

(c) Much more than

(d) Any of these.

78. The piezometric head is the summation of :

(a) Velocity head and pressure head

(b) Pressure head and elevation head

(c) Velocity head and elevation head


79. The total energy-line is always higher than the hydraulic gradient line, the vertical distance between the

two representing:

(a) The pressure head

(b) The piezometric head

(c) The velocity head



80. The total-energy-line in pipe flow is a graphical representation of the Bernoulli’s equation and represents

the sum of velocity head, pressure head and the elevation head above:

(a) The top of the pipeline

(b) The arbitrary horizontal datum

(c) The centre line of pipe

(d) The bottom of the pipe.

81. The total energy represented by the Bernoulli’s equation (p/ρg +V2/2g +z) has the units:

(a) Nm/s

(b) Ns/m

(c) Nm/m

(d) Nm/N.

82. The Bernoulli’s equation written in the conventional form p/ρg + V2/2g + z = constant total energy per

unit of certain quantity. Identify this quantity from the choices given below:

(a) Energy per unit mass

(b) Energy per unit weight

(c) Energy per unit volume

(d) Energy per unit specific weight.

83. A venturimeter is used for measuring:

(a) Pressure

(b) Flow rate

(c) Total energy

(d) Piezometric head.

84. The co-efficient of discharge (Cd) of venturimeter lies within the limits:

(a) 0.95 to 0.99

(b) 0.8 to 0.85

(c) 0.7 to 0.8

(d) 0.6 to 0.7

85. A Pitot-tube is used for measuring:

(a) Velocity of flow

(b) Pressure of flow

(c) Flow rate

(d) Total energy.

86. When a Pitot-tube is put to use it must be ensured that its alignment is such that:

(a) The horizontal leg should be inclined at 45° in plan

(b) Its horizontal leg is at right angles to the flow direction

(c) Its opening faces upstream and the horizontal leg is perfectly aligned with the direction of flow



87. The hydraulic gradient-line indicates the variation of which of the following:

(a) Velocity head in flow direction

(b) Piezometric head in the direction of flow

(c) Total energy of flow in the direction of flow


88. The momentum correction factor β is used to account for:

(a) Change in direction of flow

(b) Change in total energy

(c) Non-uniform distribution of velocities at inlet and outlet sections

(d) Change in mass rate of flow.

89. The change in moment of momentum of fluid due to flow along a curved path results in:

(a) A change in pressure

(b) Torque

(c) A change in the total energy


90. Which of the following is an example of free vortex flow?

(a) A whirlpool in a river

(b) Flow of liquid through a hole provided at the bottom of a container

(c) Flow of liquid around a circular bend in a pipe.


91. In case of forced vortex, the rise of liquid level at the ends is .... the fall of liquid level at the axis of

rotation.

(a) Less than

(b) More than

(c) Equal to


92. In case of a closed cylindrical vessel sealed at the top and the bottom the volume of air before rotation is

...... the volume of air after:

(a) More than

(b) Less than

(c) Equal to



Unit 5 - Dimensional Analysis and Similarities

93. Dimensional analysis is used to

(a) Test the dimensional homogeneity of any equation of fluid motion

(b) Derive rational formulae for a flow phenomenon

(c) Derive equations expressed in terms of non– dimensional parameters


94. Which of the following is an advantage of dimensional analysis?

(a) It expresses the functional relationship between the variables in dimensionless terms

(b) In hydraulic model studies it reduces the number of variables involved in a physical phenomenon,

generally by three

(c) By the use of dimensional analysis design curves can be developed from experimental data or direct

solution of the problem


95. dimensionally homogeneous equation is applicable to

(a) C.G.S. system only

(b) F.P.S. system only

(c) M.K.S. and SI systems

(d) All systems of units.

96. In which of the following methods of dimensional analysis, a functional relationship of some variables is

expressed in the form of an exponential equation, which must be dimensionally homogeneous?

(a) Buckingham’s π-method

(b) Rayleigh’s method

(c) Bridgman’s method

(d) Matrix–tensor method.

97. In dimensional analysis the Buckingham’s π–theorem is widely used and expresses the resulting equation

in terms of

(a) The repeating variables

(b) Geometric, kinematic and dynamic variables

(c) (n – m) dimensionless parameters

(d) n dimensionless parameters.

98. To apply Buckingham’s π–theorem, m repeating variables are selected from amongst the n variables

influencing the phenomenon. The repeating variables are selected such that they

(a) Belong to kinematic and dynamic category of variables

(b) Must always contain the dependent variables

(c) In combination contain each of the m fundamental dimensions involved in the problem.



99. In order that results obtained in model studies correctly represent the behaviour of the prototype, which

of the following similarities must be ensured between the model and the prototype?

(a) Geometric similarity

(b) Kinematic similarity

(c) Dynamic similarity


100. Dynamic similarity between the model and prototype is the

(a) Similarity of motion

(b) Similarity of lengths

(c) Similarity of forces


101. ...... is equal to the product of shear stress due to viscosity and surface area of flow.

(a) Viscous force

(b) Inertia force

(c) Pressure force

(d) Gravity force.

102. Kinematic similarity between model and prototype is the

(a) Similarity of discharge

(b) Similarity of shape

(c) Similarity of streamline pattern


103. ......... is the ratio of the inertia force to the viscous force.

(a) Froude’s number

(b) Weber’s number

(c) Reynolds number

(d) Mach’s number.

104. ........ is the square root of the ratio of the inertia force to the pressure force.

(a) Reynolds number

(b) Mach’s number

(c) Euler’s number

(d) Froude’s number.

105. Euler number is important in which of the following flow situations?

(a) Discharge through orifices, mouthpieces and sluices

(b) Pressure rise due to sudden closure of valves

(c) Flow through pipes

(d) All of the above

106. Mach’s number is defined as the square root of the ratio of the


(a) Inertia force to the pressure force

(b) Inertia force to the surface tension force

(c) Inertia force to the elastic force


107. ...... is important in compressible fluid flow problems at high velocities, such as high velocity flow in

pipes or motion of high-speed projectiles and missiles.

(a) Euler’s number

(b) Mach’s number

(c) Reynolds number

(d) Froude’s number.

108. Distorted models are required to be prepared for which of the following?

(a) Rivers

(b) Dams across very wide rivers

(c) Harbours


109. The scale effect in models can be

(a) Positive only

(b) Negative only

(c) Both positive and negative



Unit 6 - Viscous and Turbulent Flow

110. The laminar/viscous flow is characterized by Reynolds number which is

(a) less than the critical value

(b) Equal to critical value

(c) More than critical value


111. The laminar flow is characterized by

(a) Existence of eddies

(b) Irregular motion of fluid particles

(c) Fluid particles moving in layers parallel to the boundary surface


112. Which of the following is an example of laminar flow?

(a) Underground flow

(a) Flow past tiny bodies

(c) Flow of oil in measuring instruments

(d) All of the above

(e) None of the above.

113. In case of laminar flow, the loss of pressure head is proportional to

(a) Velocity

(b) Velocity2

(c) Velocity3


114. The pressure gradient in the direction of flow is equal to the shear gradient in the direction

(a) Parallel to the direction of flow

(b) Normal to the direction of flow



115. …... studied the laminar flow through a circular tube experimentally

(a) Prandtl

(b) Pascal

(c) Hagen and Poiseuille


116. …... is the most commonly used equation for the velocity distribution for laminar flow through pipes.

(a) u = umax [1 – (r/R)]

(b) u = umax [1- (r/R)2]

(c) u = umax [1 – (r/R)3]

(d) u = u2max [1 – (r/R)2]


117. In laminar flow the pressure drop per unit length of pipe (∆p/L) is given as

(a) 32𝜇 ͞u/D2

(b) 2𝜇 ͞u/D2

(c) 32𝜇 ͞u/D3

(d) None of above.

118. The K.E. correction factor a for a circular pipe is equal to

(a) 2

(b) 3

(c) 4

(d) 6.

119. The momentum correction factor b for a circular pipe is to equal to

(a) 1/3

(b) 2/3

(c) 4/3

(d) 5/3

120. The shear stress distribution in pipe flow is given as

(a) τ = - (𝜕𝑝

𝜕𝑥)

𝑟

2

(b) τ = 𝑟 (𝜕𝑝

𝜕𝑥)

(c) τ = - 2r (𝜕𝑝

𝜕𝑥)


121. For viscous flow the co-efficient of friction is given by

(a) f = 8/Re

(b) f = 16/Re

(c) f = 32/Re

(d) f = 60/Re.

122. In case of viscous flow through circular pipes

(a) u͞ = 2 umax

(b) u = (3/2) umax

(c) u = umax/2

(d) none of the above.

123. The maximum velocity in a circular pipe when flow is laminar occurs at

(a) The top of the pipe

(b) The bottom of the pipe

(c) The centre of the pipe

(d) Not necessarily at the centre.


124. The flow is said to be turbulent when Reynolds number is

(a) Less than 1000

(b) Equal to 2000

(c) Greater than 4000

(d) Between 1000 to 4000.

125. The shear in turbulent flow is mainly due to

(a) Heat transfer

(b) Mass transfer

(c) Momentum transfer


126. Which of the following statements is correct? Wall turbulence occurs

(a) In immediate vicinity of solid surfaces and in the boundary layer flows where the fluid has a negligible

mean acceleration

(b) In jets, wakes, mixing layer etc.

(c) Where there is conversion of potential energy into kinetic energy by the process of mixing


127. Turbulence in flow is characterised by which of the following?

(a) Fluctuating components of velocities

(b) High Reynolds number

(c) Cross currents and eddies with intermixing of particles

(d) Excess energy dissipation with rise in temperature

(e) All to the above.

128. The flow in town water supply pipes is generally

(a) Laminar

(b) Turbulent

(c) Transition

(d) Any of the above.

129. The most essential feature of a turbulent flow is

(a) High velocity

(b) Velocity at a point remains constant with time

(c) Large discharge

(d) Velocity and pressure at a point exhibit irregular fluctuations of high frequency.

130. In turbulent flow the velocity distribution is a function of the distance y measured from the boundary

surface and shear friction velocity uf, and follows a

(a) Linear law

(b) Hyperbolic law

(c) Parabolic law

(d) Logarithmic law.


131. A turbulent flow is considered steady when

(a) The algebraic sum of velocity fluctuations is zero

(b) The velocity at a point does not change with Time

(c) Temporal mean velocity at a point remains constant with time

(d) The discharge remains constant.

132. The Darcy-Weisbach friction factor f which is a direct measure of resistance to flow in pipes depends on

which of the following?

(a) Relative roughness, velocity and viscosity

(b) Relative roughness, diameter and viscosity

(c) Roughness height, diameter and velocity

(d) Roughness height, diameter, velocity and kinematic viscosity.

133. Commercial cast-iron and steel pipes carrying fluids under pressure are regarded as hydraulically smooth

when

(a) The laminar layer is thin as compared to the average height of roughness elements

(b) The height of the roughness projections is low

(c) The roughness elements are all completely covered by the laminar sublayer


134. Intensity of turbulence is

(a) The average K.E. of turbulence

(b) The violence of turbulent fluctuations and is measured by the root mean square value of velocity

fluctuations

(c) The mean time interval between the reversals in the sign of velocity fluctuation


135. Which of the following factors determine the friction factor for turbulent flow in a rough pipe?

(a) Mach number and relative roughness

(b) Froude’s number and Mach’s number

(c) Reynolds number and relative roughness

(d) Froude’s number and relative roughness.

136. In case of turbulent flow of a fluid through a circular tube (as compared to the case of laminar flow at the

same flow rate) the maximum velocity is ....., shear stress at the wall is ....., and the pressure drop across

a given length is ....., the correct words for the blanks are, respectively

(a) lower, higher, lower

(b) lower, higher, higher

(c) higher, lower, lower

(d) higher, higher, higher.


Unit 7 - Flow through pipes

137. In a laminar flow, Reynold’s number is

(a) Less than 2000

(b) More than 2000

(c) More than 2000 but less than 4000


138. In a turbulent flow, Reynold’s number is

(a) Less than 4000

(b) More than 4000

(c) Between 2000 and 4000


139. In case of a laminar flow, the loss of pressure head is

(a) Proportional to (velocity) 2

(b) Proportional to velocity

(c) Proportional to (velocity) 1/2


140. In case of a turbulent flow, the loss of head is approximately proportional to

(a) Velocity

(b) (Velocity) ^1/2

(c) (Velocity) ^3/4

(d) (Velocity) ^2

141. Darcy-Weisbach equation is used to find loss of head due to :

(a) Sudden enlargement

(b) Sudden contraction

(c) Friction


142. Chezy’s formula is given as

(a) V = C √𝑚2 i

(b) V = C2 √𝑚𝑖2

(c) V = C√𝑚𝑖

(d) V = C √𝑚2𝑖3

143. Loss of head due to sudden enlargement is given as

(a) (𝑉1−𝑉2)3

2𝑔


(b) (𝑉1−𝑉2)2

2𝑔

(c) (𝑉1

2−𝑉22)

2𝑔

(d) √(𝑉1−𝑉2)

2𝑔

144. Loss of head due to sudden contraction is given as

(a) 𝑉2

𝑔 (

1

𝐶𝑐− 1)

2

(b) 𝑉2

2

2𝑔 (

1

𝐶𝑐− 1)

2

(c) 𝑉2

𝑔2 (1

𝐶𝑐− 1)

2

(d) 𝑉2

2

2𝑔 (

1

𝐶𝑐− 1)

145. Loss of head due to an obstruction is given as

(a) [𝐴

𝐴−𝑎− 1]

2 𝑉2

2𝑔

(b) [𝐴

𝐶𝑐(𝐴−𝑎)− 1]

𝑉2

2𝑔

(c) [𝐴

𝐶𝑐𝑎− 1]

2 𝑉2

2𝑔

(d) [𝐴2

𝐴−𝑎− 1]

2𝑉2

2𝑔

146. Loss of head at entrance to a pipe is given as

(a) 𝑉2

2𝑔

(b) 𝑉

𝑔

(c) 0.5 𝑉2

2𝑔

(d) 𝑉3

2𝑔

147. Loss of head at exit of a pipe is given as

(a) 𝑉2

2𝑔


(b) 𝑉2

𝑔

(c) 𝑉3

𝑔

(d) 𝑉3

2𝑔

148. The power transmitted through the pipe is maximum when head lost due to friction in the pipe is equal

to

(a) (1/3) rd of the total supply head

(b) (1/4) th of the total supply head

(c) (1/5) th of the total supply head

(d) (1/8) th of the total supply head

149. Diameter of nozzle (d) for maximum transmission of power is equal to

(a) (𝐷5

4𝑓𝑙)

1 4⁄

(b) (𝐷5

8𝑓𝑙)

1 4⁄

(c) (𝐷4

8𝑓𝑙)

1 4⁄

(d) (𝐷3

8𝑓𝑙)

1 4⁄

150. The energy loss in a pipeline is due to

(a) Surface roughness only

(b) Viscous action only

(c) Friction offered by pipe wall as well as by viscous function


151. In a pipe flow the minor losses are those

(a) Which depend on the length of the pipeline

(b) Caused by friction and are thus also called friction losses.

(c) Which have a small magnitude

(d) Which are caused on account of total disturbance produced by such fittings as valves, bends, etc.

152. In flow through pipe bends the pressures on inner and out radii

(a) Stand at the same level increasing gradually towards the pipe center.

(b) Vary, it being more on the inner core.

(c) Are different, pressure increases with increase in radius and is, therefore, more at the outer radius.

(d) Do not vary and are the same as at the center of the pipe.


153. The condition for maximum transmission of power through a pipeline is that one-third of the available

head must be consumed in friction. The corresponding efficiency of the pipeline is

(a) 33·3%

(b) 66·67%

(c) 90%

(d) 100%.

154. For achieving continuous flow through a system, no position of the pipe should be higher than

(a) 20 m

(b) 6 m

(c) 7·6 m

(d) 10 m.

measured above the hydraulic gradient line.

155. For turbulent flow in smooth pipes, the entrance length is taken as

(a) 20

(b) 50

(c) 80

(d) 115.

156. The entrance length or length of establishment of flow is

(a) The length in which the boundary layer remains uniform

(b) The pipe length inside the reservoir

(c) The length of pipe from its entrance in which the flow may be assumed irrotational

(d) The initial length in which the flow develops fully such that the velocity profile does not change

downstream.

157. Due to which of the following phenomena water hammer is caused?

(a) Incompressibility of fluid

(b) Sudden opening of a valve in a pipeline

(c) The material of the pipe being elastic

(d) Sudden closure (partial or complete) of a valve in pipe flow.

158. Under which of the following conditions the closure of valve is considered rapid?

(a) The duration of valve closure is greater than 2L/C

(b) The duration of valve closure is less than L/C

(c) The duration of valve closure is less than 2L/C


(where L = length of pipe, C = velocity of pressure wave produced due to water hammer.)


Unit 8 - Impact of Jet and Hydraulic Turbines

159. The force exerted by a jet of water on a stationary vertical plate in the direction of jet is given by

(a) ρaV

(b) ρaV2

(c) ρa2V

(c) ρaV3.

160. The force exerted by a jet of water on a moving vertical plate, in the direction of motion of plate is given

by

(a) ρaV2

(b) ρaV3

(c) ρa (V – u)2

(d) ρa (V – u)3.

161. When a steady jet impinges on a fixed inclined surface

(a) The flow is divided into parts proportional to the angle of inclination of the surface

(b) No force is exerted by the jet on the vane

(c) The momentum component is unchanged parallel to the surface


162. For maximum efficiency of a series of curved vanes, the speed is

(a) Equal to the jet speed

(b) 3/4 of the jet speed

(c) 1/2 of the jet speed

(d) 1/3 of the jet speed.

163. The efficiency of jet propulsion with inlet orifices at right angles to the direction of motion of ship is

given by

(a) 2u/ (V + u)

(b) 2V/ (V + u) 2

(c) 2Vu/ (V + u) 2

(d) 2u (V-u)/V3

164. For an impulse turbine which of the following statements is correct :

(a) It makes use of a draft tube

(b) It is not exposed to atmosphere

(c) It is most suited for low head installations

(d) It operates with initial complete conversion of pressure head to velocity head.

165. Which of the following statements is correct in case of a Pelton wheel :

(a) It can operate at optimum efficiency at all high speeds

(b) It is kept entirely submerged in water below the tail race.

(c) It gives optimum efficiency at runaway speed


(d) It operates by converting the available energy fully into kinetic energy before entering the rotor.

166. The effective (or net) head at the turbine is

(a) The sum of gross head plus head loss in penstock and the velocity head at the turbine exit.

(b) The difference between gross head minus the head loss in penstock

(c) The difference between the gross head minus head loss in penstock and the velocity head at the turbine

exit

(d) The sum of gross head plus the head loss in the penstock.

167. The difference between the power obtained from the turbine shaft and power supplied by water at its

entry to the turbine is equal to

(a) Sum of hydraulic and mechanical losses

(b) Sum of mechanical and volumetric losses

(c) Mechanical losses

(d) Hydraulic losses.

168. Which of the following statements is a definition of the hydraulic efficiency of a turbine?

(a) The ratio of power available at the turbine shaft to that supplied to it by runner.

(b) The ratio of the power supplied by the runner to the power available at the shaft.

(c) The ratio of power utilized by runner to that supplied by the water at entry to the turbine.

(d) The ratio of power supplied by water at entry to the power utilized by runner.

169. The power which appears in the expression for the specific speed is the:

(a) Shaft power

(b) Water power

(c) Power into the turbine


170. Which of the following statements is correct: Runaway speed of a hydraulic turbine is the speed

(a) At which there would be no damage to the turbine runner

(b) At which the turbine runner can be allowed to run freely without load and with wicket gates wide

open

(c) Corresponding to maximum overload permissible

(d) At full load.

171. The specific speed of a turbine is expressed as

(a) 𝑁√𝑃

𝐻

(b) 𝑁√𝑃

𝐻2

(c) 𝑁√𝑃

𝐻3

4⁄

(d) 𝑁√𝑃

𝐻5

4⁄


172. Which of the following statements is correct for a reaction turbine?

(a) The outlet must be above the tail race.

(b) Water may be allowed to enter a part or whole of wheel circumference.

(c) Flow can be regulated without loss.

(d) There is only partial conversion of available head to velocity head before entry to rotor.

173. In a reaction turbine the function of a draft tube is to

(a) Provide safety to turbine

(b) Prevent air from entering

(c) Reconvert the kinetic energy to flow energy

(d) Increase the rate of flow

174. Which of the following statements with respect to a reaction water turbine is incorrect:

(a) The spiral casing serves to uniformly distribute water into guide blades

(b) The water leaves the turbine at atmospheric pressure

(c) The draft tube allows setting of the turbine above the tail race with minimum reduction of available

energy

(d) The guide vanes direct the flow at proper angle.

175. Which of the following turbines is suitable for specific speed ranging from 300 to 1000 and heads below

30 m:

(a) Francis

(b) Kaplan

(c) Propeller

(d) Pelton.

176. Specific speed of a turbo-machine

(a) Relates the shape rather than the size of the machine

(b) Remains unchanged under different condi tions of operation

(c) Has the dimensions of rotational speed

(d) Is the speed of a machine having unit dimensions.

177. In an outward radial flow turbine energy conversion process is

(a) Purely by reaction only

(b) Purely by impulse only

(c) Partly by impulse and partly by reaction


178. Which of the following turbines is least efficient under part load conditions:

(a) Propeller

(b) Kaplan

(c) Francis

(d) Pelton.


179. A surge tank is used to

(a) Prevent occurrence of hydraulic jump

(b) Smoothen the flow

(c) Relieve the pipeline of excessive pressure transients

(d) Avoid reversal of flow.

180. Which of the following turbines is most efficient at partload operation?

(a) Kaplan

(b) Propeller

(c) Francis

(d) Pelton wheel.

181. With respect to a Kaplan turbine which of the following statements is incorrect?

(a) It employs large guide vane angles than is the case for a Francis turbine.

(b) It is designed for flow velocity of mixed flow type.

(c) It has blades of small camber to prevent separation.

(d) It can adjust both guide vane and blade angles according to rate of discharge.

182. Specific speed of an impulse turbine (Pelton wheel) ranges from

(a) 12 to 70

(b) 80 to 400

(c) 300 to 1000

(d) 1000 to 1200.

183. A turbo-machine becomes more susceptible to cavitation if

(a) Velocity attains a high value

(b) Pressure become very high

(c) Temperature rises above the critical value

(d) Thomas’s cavitation parameter exceeds a certain limit

(e) Pressure falls below the vapour pressure.

184. Cavitation damage in turbine runner occurs near the

(a) Inlet on the convex side of blades

(b) Outlet on the convex side of blades

(c) Inlet on the concave side of blades

(d) Outlet on the concave side of blades.

185. Which of the following serious problems arise from cavitation?

(a) Noise and vibration.

(b) Damage to blade surface.

(c) Fall in efficiency.


186. Which of the following statements is correct?


(a) Muschel curves are the performance plots pertaining to constant efficiency.

(b) Operating characteristics curves of a turbine refer to the performance curves drawn at constant speed.

(c) Main characteristic curves of a turbine are the performance curves obtained under condition of

constant head.


(e) None of the above.

187. A Kaplan turbine is

(a) An inward flow impulse turbine

(b) Low head axial flow turbine

(c) High head axial flow turbine

(d) High head mixed flow turbine.

188. An impulse turbine requires

(a) High head and small quantity of flow

(b) Low head and small quantity of flow

(c) Low head and high rate of flow


189. ......of a turbine is defined as the ratio of power available at the turbine shaft to the power supplied by the

water jet.

(a) Mechanical efficiency

(b) Hydraulic efficiency

(c) Overall efficiency

(d) Volumetric efficiency.

190. The ratio of power developed by the runner to the power supplied by the jet at entrance to the turbine is

known as

(a) Hydraulic efficiency

(b) Mechanical efficiency

(c) Volumetric efficiency

(d) Overall efficiency.

191. The water which acts on the runner blades of a reaction turbine is under a pressure

(a) Equal to atmospheric

(b) Below atmospheric

(c) Above atmospheric


192. The runner passages of a reaction turbine are

(a) Partially filled with water

(b) Always completely filled with water

(c) Never filled with water



193. The value of speed ratio (Ku) in case of a Francis turbine ranges from

(a) 0.2 to 0.3

(b) 0.4 to 0.5

(c) 0.6 to 0.9


194. The value of flow ratio (Kf) in case of a Francis turbine varies from:

(a) 0.1 to 0.14

(b) 0.15 to 0.30

(c) 0.35 to 0.5

(d) 0.6 to 0.9.

195. A Kaplan turbine claims which of the following advantages over a Francis turbine?

(a) More compact in construction and smaller in size.

(b) Partload efficiency is considerably high.

(c) Low frictional losses.


196. Which of the following draft tubes is suited particularly for helical flow?

(a) Conical type draft tube.

(b) Elbow type draft tube.

(c) Moody’s spreading draft tube.


197. Which of the following surge tank is also called a throttled surge tank?

(a) Inclined surge tank.

(b) Expansion chamber surge tank.

(c) Restricted orifice surge tank.



Unit 9 - Centrifugal Pumps

198. Which of the following types of impeller is used for centrifugal pumps dealing with muds?

(a) One-side shrouded

(b) Two -sides shrouded

(c) Double section

(d) Open.

199. Which of the following statements is correct with reference to an impeller with backward curved vanes?

(a) It has a falling head - discharge characteristic.

(b) It has rising head - discharge characteristic

(c) It is easier to fabricate.

(d) It cannot run at speeds other than the design speed.

200. The head developed by a centrifugal pump may be expressed as

(a) H = (Vw2 u2 + Vw1 u2)/g

(b) H = Vw2 u2 /g

(c) H = Vw1 u1 /g


201. With reference to a centrifugal pump which of the following statements is incorrect?

(a) The discharge control valve is fitted in the delivery pipe.

(b) The suction pipe is provided with a foot valve and a strainer.

(c) The suction pipe has larger diameter as compared to the discharge pipe.

(d) The discharge control valve is fitted in the suction pipe.

202. A centrifugal pump should be so installed above the water level in the sump such that

(a) The negative pressures are not allowed to develop in the impeller

(b) The negative pressures do not reach as low a value as the vapour pressure

(c) Its height is more than 10·28 m at ordinary temperature of liquid


203. The specific speed of a pump is defined as the speed of unit of such a size that it

(a) Produces unit power with unit head available

(b) Delivers unit discharge at unit head

(c) Requires unit power to develop unit head

(d) Delivers unit discharge at unit power.

204. Which of the following statements pertaining to a given centrifugal pump is correct?

(a) Discharge varies as the square of speed

(b) Power varies as the square of speed

(c) Discharge varies directly as speed

(d) Head varies inversely as speed.


205. The delivery valve, while starting centrifugal pump, is kept

(a) Fully closed

(b) Fully open

(c) Half open

(d) In any position.

206. Which of the following is not a dimensionless parameter?

(a) Friction factor

(b) Specific speed

(c) Thoma’s cavitation parameter

(d) Pressure co-efficient.

207. With reference to manometric head which of the following statements is correct?

(a) It is the head developed by the pump.

(b) It is the height to which water is lifted by the pump measured above the pump centreline.

(c) it is the difference in elevation between the water surface in the high level reservoir and the water

level in the sump.

(d) It is the difference in the piezometric heads between the points on the delivery and suction pipes as

close to the pump as possible.

208. Higher specific speeds (160 to 500) of centrifugal pump indicate that the pump is of

(a) Radial flow type

(b) Axial flow type

(c) Mixed flow type

(d) Any of these types.

209. What will happen if requirements of net positive suction head (NPSH) for a given pump are not satisfied?

(a) The pump will get cavitated.

(b) The pump will consume more power.

(c) The pump will not develop head.

(d) The pump will have a low efficiency

210. In centrifugal pumps, cavitation is reduced by

(a) Increasing the flow velocity

(b) Reducing the discharge

(c) Throttling the discharge

(d) Reducing the suction head.

211. Which of the following statements pertaining to a centrifugal pump is incorrect?

(a) The suction lift of a pump can be upto 10·3 m or even more.

(b) The impellers of a multi-stage pump are arranged in parallel to discharge a large quantity of liquid.

(c) The volute casing of the pump maintains the velocity of flow constant, prevents eddies and converts

velocity head to pressure head.


(d) The manometric head refers to the difference between the total energy of liquid at exit from and at

inlet to the pump.

212. Regarding cavitation which of the following statements in incorrect?

(a) Cavitation affects the performance of a turbine to a lesser degree than that of a pump.

(b) Thoma’s cavitation parameter has different expressions for turbines and pumps.

(c) With the increase in pump speed, there is increase in its minimum net positive suction head

requirement.

(d) The leading edge of blades in pumps and the trailing edge of blades in water turbines are more

susceptible to cavitation damage

213. A centrifugal pump is taking much of power, the probable reason may be

(a) Liquid being pumped is heavy

(b) Speed of the pump is low

(c) There is leakage of air

(d) Ineffective strainer and foot valve arrangement.

214. In rotodynamic pumps, the increase in energy level is due to

(a) Centrifugal energy only

(b) Pressure energy only

(c) Kinetic energy only

(d) Combination of a, b and c.

215. In a pump there is

(a) Accelerating flow

(b) Decelerated flow



216. In a centrifugal pump the regulating valve is provided on

(a) The suction pipe

(b) Delivery pipe

(c) The casing


217. In a centrifugal pump the sum of suction head and delivery head is known as

(a) Monomeric head

(b) Total head

(c) Static head


218. Regarding manometric head (Hmano) which of the following relations is correct?

(a) Hmano= head imparted by the impeller to the liquid – loss of head in the pump

(b) Hmano= static head + losses in pipes + Vd2/2g


(c) Hmano= total head at outlet of the pump - total head at inlet of pump


219. The ratio of power outlet of the pump to the power input to the pump is known as

(a) Mechanical efficiency

(b) Overall efficiency

(c) Monomeric efficiency


220. The flow ratio in case of a centrifugal pump varies from

(a) 0.1 to 0.25

(b) 0.25 to 0.40

(c) 0.40 to 0.50

(d) 0.50 to 0.65


Unit 10 - Hydraulic Machines

221. ..... is a device which increases the intensity of pressure of a given liquid with the help of low pressure

liquid of large quantity.

(a) Hydraulic press

(b) Hydraulic crane

(c) Hydraulic accumulator

(d) Hydraulic intensifier.

222. Which of the following devices is used to store energy of liquid under pressure and make this energy

available to hydraulic machines?

(a) Hydraulic coupling

(b) Hydraulic accumulator

(c) Hydraulic ram

(d) Hydraulic press.

223. .... is a device which is employed for transmission of power from one shaft to another through a liquid

medium.

(a) Hydraulic intensifier

(b) Hydraulic torque converter

(c) Hydraulic coupling

(d) Hydraulic press

224. Which of the following devices is used for transmitting increased or decreased torque from one shaft to

another?

(a) Hydraulic ram

(b) Hydraulic coupling

(c) Hydraulic intensifier

(d) Hydraulic torque converter

225. ..... is a device with which small quantities of water can be pumped to higher levels from the available

large quantity of water of low head.

(a) Hydraulic accumulator

(b) Hydraulic intensifier

(c) Hydraulic ram

(d) Air lift pump.

226. The function of which of the following hydraulic devices is analogous to that of the flywheel of a

reciprocating engine and an electric storage battery?

(a) Hydraulic ram

(b) Hydraulic accumulator

(c) Hydraulic intensifier

(d) Hydraulic coupling.


227. Which of the following statements with regard to the purposes served by hydraulic units is incorrect?

(a) Hydraulic torque converter is used for transmitting increased or decreased torque to the driven shaft.

(b) Hydraulic ram is a pump that is used to lift small quantities of water to greater heights from large

quantity of water available at small heights.

(c) Hydraulic intensifier stores the energy of fluid in the form of pressure energy and is used for lifting

heavy weights.

(d) Hydraulic accumulator stores the energy of a fluid in the form of pressure energy; that helps to reduce

the capacity of power house where there is intermittent demand for power.

228. The working of which of the following hydraulic units is based on Pascal’s law?

(a) Air lift pump

(b) Jet pump

(c) Hydraulic coupling

(d) Hydraulic press.

229. With regard to hydraulic ram, which of the following statements is incorrect?

(a) It works automatically

(b) It requires very little maintenance

(c) Its running cost is high

(d) It has no moving parts


Answers:

1. A 2. D 3. C 4. E 5. C

6. A 7. C 8. B 9. C 10. A

11. A 12. D 13. A 14. A 15. B

16. C 17. C 18. A 19. C 20. A

21. A 22. B 23. A 24. A 25. A

26. B 27. C 28. A 29. A 30. B

31. C 32. D 33. B 34. E 35. A

36. A 37. A 38. B 39. B 40. B

41. A 42. B 43. B 44. B 45. C

46. B 47. C 48. D 49. B 50. B

51. B 52. C 53. B 54. D 55. B

56. C 57. B 58. A 59. B 60. B

61. B 62. C 63. B 64. C 65. B

66. A 67. B 68. B 69. A 70. D

71. A 72. E 73. B 74. E 75. B

76. D 77. B 78. B 79. C 80. B

81. D 82. B 83. B 84. A 85. A

86. C 87. B 88. C 89. B 90. D

91. C 92. C 93. D 94. D 95. D

96. B 97. C 98. C 99. D 100. C

101. A 102. C 103. C 104. C 105. D

106. C 107. B 108. D 109. C 110. A

111. C 112. D 113. A 114. B 115. C

116. B 117. A 118. A 119. C 120. A

121. B 122. B 123. C 124. C 125. C

126. A 127. E 128. B 129. D 130. D

131. C 132. D 133. C 134. B 135. C

136. B 137. A 138. B 139. B 140. D

141. C 142. C 143. B 144. B 145. B

146. C 147. A 148. A 149. B 150. C

151. D 152. D 153. B 154. C 155. B

156. D 157. D 158. C 159. B 160. C

161. A 162. C 163. B 164. D 165. D

166. C 167. A 168. C 169. A 170. B

171. D 172. D 173. C 174. B 175. B

176. A 177. D 178. A 179. C 180. A

181. B 182. A 183. E 184. B 185. D

186. D 187. B 188. A 189. C 190. A

191. C 192. B 193. C 194. B 195. D

196. C 197. C 198. D 199. A 200. B

201. D 202. B 203. B 204. C 205. A

206. B 207. D 208. B 209. A 210. D

211. A 212. B 213. A 214. D 215. A

216. B 217. C 218. D 219. B 220. A


221. D 222. B 223. C 224. D 225. C

226. B 227. C 228. D 229. C

Unit 1 - Fluids and Their Properties

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Transcript of Unit 1 - Fluids and Their Properties