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Multiple choice question for engineering

Set 1

1. In a Kaplan turbine, what is the direction of water flow?
a) Axial and then axial
b) Radial and then axial
c) Tangential and then axial
d) Tangential and then radial

View Answer

Answer: a [Reason:] The Kaplan turbine is an axial flow reaction turbine. The water inlet is axial and the water outlet is axial too.

2. For which of the following values of available heads may Kaplan turbine be used?
a) 250 m
b) 100 m
c) 80 m
d) 50 m

View Answer

Answer: d [Reason:] The Kaplan turbine is said to be a Low head turbine. The low head ranges from 0 to 60 m. Only 50 m falls in this range and hence, it’s the correct option.

3. In this type of low head turbine, the guide vanes are fixed to the hub of the turbine and are not adjustable. What is this type of turbine called?
a) Francis turbine
b) Kaplan Turbine
c) Propeller Turbine
d) Pelton turbine

View Answer

Answer: a [Reason:] In a Kaplan turbine, the guide vanes are adjustable and not fixed to the hub of the turbine. Francis and Pelton turbines are not low head turbines. In a propeller turbine, the guide vanes are fixed to the hub of the turbine.

4. The velocity of flow through a Kaplan turbine is 10 m/s. The outer diameter of the runner is 4 m and the hub diameter is 2 m. Find the volume flow rate of the turbine in m3/s?
a) 95
b) 75
c) 85
d) 105

View Answer

Answer: a [Reason:] The volume flow rate is given by hydraulic-machines-questions-answers-velocity-diagram-q4 Substituting the given values in the above equation, we get Q = 95 m3/s.

5. The velocity of the flow at the inlet of Kaplan turbine is V. In an experimental setup, what could be the possible value of the velocity of the flow at the outlet of Kaplan turbine?
a) V
b) 0.8V
c) 1.2V
d) 2V

View Answer

Answer: b [Reason:] The flow velocity of turbine at the outlet of the Kaplan turbine will be lesser than that of the inlet due to effects of friction in the blade. Hence, practically a lower value would be obtained. 0.8V is the only option lower than V.

6. Which of the following turbines will have the lowest number of blades in it?
a) Pelton turbine
b) Steam turbine
c) Francis turbine
d) Kaplan turbine

View Answer

Answer: d [Reason:] As the head for Kaplan turbine is low, the discharge of water through the turbine is high and hence, blade resistance should be low. That’s why Kaplan turbine will have the lowest number of blades.

7. The velocity of the flow through the Kaplan turbine is 25 m/s. The available head of the turbine is 60 m. Find the flow ratio of the turbine (take g = 10 m/s2).
a) 0.65
b) 0.72
c) 0.69
d) 0.75

View Answer

Answer: b [Reason:] Flow ratio is given by ψ = Vf1 / sqrt(2gH). The given of head and flow velocity must be substituted in this equation to obtain the flow ratio which comes out to be 0.72.

8. A Kaplan turbine requires a speed ratio of 2. The available head of the turbine is 5 m. What should be the blade velocity of the turbine such that a speed ratio of 2 is maintained (take g = 10 m/s2)?
a) 75.75 m/s
b) 63.25 m/s
c) 23.35 m/s
d) 50.00 m/s

View Answer

Answer: b [Reason:] The speed ratio φ = U/ sqrt(2gH). Substitute the value for speed ratio and available head in this equation and rearrange to find U = 63.25 m/s.

9. The flow ratio of a Kaplan turbine is given as 0.7. The available head is 30 m. The outer diameter of the runner is 3.5 m and the hub diameter is 2 m. Find the volume of water flowing through the turbine per second (m3/s)?
a) 90
b) 111
c) 125
d) 168

View Answer

Answer: b [Reason:] We know that hydraulic-machines-questions-answers-velocity-diagram-q4 We can write V as ψ*(sqrt(2gH)). Now, substitute the values in the modified equation to find Q which comes out to be around 111 m3/s.

10. In which of the following type of runners in a Kaplan turbine the velocity of whirl at inlet is smaller than the blade velocity?
a) Such a case is practically impossible
b) Slow Runner
c) Medium Runner
d) Fast Runner

View Answer

Answer: d [Reason:] Considering the velocity diagram of a Kaplan turbine at the inlet for a fast runner, we notice that the whirl velocity is lower the blade velocity along the same direction. They are equal in case of a medium runner.

11. In the outlet velocity triangle of a Kaplan turbine, β2 = 30o. Vf2 = 5 m/s. What is the relative velocity of the flow at outlet?
a) 10 m/s
b) 5.77 m/s
c) 8.66 m/s
d) 2.88 m/s

View Answer

Answer: a [Reason:] In the outlet velocity triangle, sin (β2) = Vf2/ Vr2. Therefore, Vr2 = 5/sin(30) = 10 m/s.

12. In the inlet velocity triangle of a Kaplan turbine, α1 = 45o. The velocity of flow at inlet = 10 m/s. Find the whirl velocity of water at the inlet of Kaplan turbine?
a) 5 m/s
b) 10 m/s
c) 12.5 m/s
d) 15 m/s

View Answer

Answer: b [Reason:] In the inlet velocity triangle, tan (α1) = Vf1/ Vw1o, Vf1 = Vw1 = 10 m/s.

13. The whirl velocity of water at the inlet of the Kaplan turbine is 15 m/s. The velocity of water at inlet of the turbine is 20 m/s. Find the guide vane angle at inlet (In degrees).
a) 53.13
b) 36.86
c) 45
d) 41.41

View Answer

Answer: d [Reason:] cos (α1) = Vw1/ V1o.

14. The relative velocity of water at the inlet of the Kaplan turbine is 7 m/s. β1 = 75o. The whirl velocity of the water at inlet is 10 m/s. Find the blade velocity of the turbine?
a) 26.124 m/s
b) 40 m/s
c) 36.124 m/s
d) 60 m/s

View Answer

Answer: c [Reason:] cos (β1) = (u – Vw1)/ Vr1. Substituting the given values in the above equation and rearranging to find the value of u, we get 36.124 m/s.

15.For the figure given below, find the missing terms in the order of (1), (2), (3) and (4).
hydraulic-machines-questions-answers-velocity-diagram-q15
a) Vr1, α1, β1, Vw1
b) Vw1, β1, α1, Vr1
c) Vw1, α1, β1, Vr1
d) Vr1, β1, α1, Vw1

View Answer

Answer: c [Reason:] Vw1 is along the direction of u. Hence (1) will be replaced by Vw1. The angle between V1 and u is α1, Hence α1 replaces (2). (4) will then be replaced by Vr1 and (3) will be replaced by β1, since β1 is the angle between Vr1 and u.

Set 2

1. The characteristic curves of a centrifugal pump, plots ______ required by the pump.
a) Velocity
b) Pressure
c) NPSH
d) Velocity and pressure

View Answer

Answer: c [Reason:] The characteristic curves of a centrifugal pump, plots net positive suction head required by the pump. These curves play an important role in determining the efficiency of a centrifugal pump.

2. What is the shape of the diffuser in the centrifugal pump?
a) Round
b) Dough nut
c) Rectangle
d) Cylindrical

View Answer

Answer: b [Reason:] The shape of the diffuser passing present in the centrifugal pump is doughnut shaped. It is made into that shape as it allows the device to scroll up and down. Due to this, the casing decelerates the flow.

3. When the casing in a centrifugal pump decelerates the flow, what increases?
a) Pressure
b) Temperature
c) Volume
d) Flow rate

View Answer

Answer: a [Reason:] When the casing in a centrifugal pump decelerates the flow, pressure in the turbine increases. The diffuser helps this happen. The shape of the diffuser passing present in the centrifugal pump is doughnut shaped.

4. Which among the following is not a characteristic curve for centrifugal pump?
a) Transfer speed vs Transfer pressure
b) Head vs Flow rate
c) Power input vs pump efficiency
d) Specific speed vs pump efficiency

View Answer

Answer: a [Reason:] The primary objective of a centrifugal pump is to transfer energy. Centrifugal pump is a turbomachinery. Transfer speed vs Transfer pressure is not considered as a correct characteristic curve.

5. The consequence of Newtons second law is _________
a) Conservation of angular momentum
b) Conservation of mass
c) Conservation of potential energy
d) Conservation of kinetic energy

View Answer

Answer: a [Reason:] The consequence of Newtons second law is the conservation of angular momentum. This, in accordance with newtons second law, provides the basic details to define parameters in the centrifugal pump.

6. Which of the following is taken into account during a characteristic curve?
a) Flow rate
b) Cavitation
c) Tolerances
d) Casing

View Answer

Answer: a [Reason:] Flow rate is an important parameter that is taken into account for a characteristic curve. These curves play an important role in determining the efficiency of a centrifugal pump.

7. The normal operating range of centrifugal pump is sufficient to plot the characteristic curve.
a) True
b) False

View Answer

Answer: a [Reason:] The normal operating range of centrifugal pump is sufficient to plot the characteristic curve. Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies.

8. The inlet passage of water entry is controlled by ________
a) Head race
b) Gate
c) Tail race
d) Pump

View Answer

Answer: b [Reason:] The inlet passage of water entry is controlled by the gate opening. The gate opening is an opening that sends only a percentage of fluid through the inlet passages for water to enter to the turbine.

9. As the specific speed increases, the slope of HQ curve _______
a) Decreases
b) Increases
c) Independent
d) Remains the same

View Answer

Answer: c [Reason:] As the specific speed increases, the slope of HQ curve increases. It becomes steeper with the corresponding increase in the specific speed.

10. The primary selection tool is called as _______
a) Pump curve
b) Speed curve
c) Power curve
d) Fluid curve

View Answer

Answer: a [Reason:] The primary selection tool is called as pump curve. It plays an essential role in determining efficiency.

11. In case of centrifugal turbines with low specific speed, the efficiency curve is _________
a) Pointed
b) Small
c) Steep
d) Flat

View Answer

Answer: d [Reason:] In case of centrifugal turbines with low specific speed, the efficiency curve is relatively flat in the vertex. These curves play an essential role in determining the overall performance of the turbine.

12. In case of centrifugal turbines with high specific speed, the efficiency curve is
a) Pointed
b) Small
c) Steep
d) Flat

View Answer

Answer: a [Reason:] In case of centrifugal turbines with high specific speed, the efficiency curve is relatively pointed in the vertex. These curves play an essential role in determining the overall performance of the turbine.

13. With the increase in the input power, efficiency _______
a) Increases
b) Decreases
c) Same
d) Independent

View Answer

Answer: b [Reason:] With the increase in the input power, efficiency decreases. As the input power is inversely proportional to the efficiency of the pump.

14. What is unit of standard acceleration?
a) kg/m
b) kg/s
c) kg/m3
d) N/m

View Answer

Answer: c [Reason:] The unit of standard acceleration of the centrifugal pump is kg/m3. It is denoted as g. It is also called as the acceleration due to gravity. Thus, the correct option is ‘c’.

Set 3

1. A gear pump uses ___________
a) Petrochemical pumps
b) Meshing of gears
c) Froth pumps
d) Airlift pumps

View Answer

Answer: b [Reason:] A gear pump uses meshing of gears. This meshing is done to pump fluid by displacement. Gear pumps are widely used in chemical installations.

2. The fundamental significance of all the turbomachinery is _______
a) Conservation of momentum
b) Conservation of mass
c) Conservation of heat
d) Conservation of speed

View Answer

Answer: a [Reason:] The fundamental significance of all the turbomachinery is the conservation of momentum. It plays an important role in various turbomachinery.

3. The most common pump used for hydraulic fluid power application is __________
a) Centrifugal pumps
b) Gear pump
c) Froth pumps
d) Airlift pumps

View Answer

Answer: b [Reason:] The most common pump used for hydraulic fluid power application is gear pump. A gear pump uses meshing of gears. This meshing is done to pump fluid by displacement. Gear pumps are widely used in chemical installations.

4. The change of angular momentum in a pump is equal to the _________
a) Sum of speeds
b) Sum of individual momentum
c) Sum of temperatures
d) Sum of energy transferred from a body

View Answer

Answer: b [Reason:] The change of angular momentum in a pump is equal to the sum of individual momentum.

5. Conservation of angular momentum is described by _______
a) Newtons equation
b) Euler’s equation
c) Rutherford’s equation
d) Maxim equation

View Answer

Answer: b [Reason:] Conservation of angular momentum is described by Euler’s equation. It states that the change of angular momentum in a pump is equal to the sum of individual momentum.

6. Gear pumps are mainly used in chemical installations because they pump ________
a) High viscosity fluids
b) High density fluids
c) High pressure fluids
d) High temperature fluids

View Answer

Answer: a [Reason:] Gear pumps are mainly used in chemical installations because they pump high viscosity fluids. They use two external spur gears for this purpose.

7. Gear pumps convert rotational kinetic energy to hydrodynamic energy.
a) True
b) False

View Answer

Answer: a [Reason:] Gear pumps are used to transport fluids. They transport fluids by conversion of energies. Gear pumps transport fluids by converting rotational Kinetic energy to hydrodynamic energy.

8. The inlet passage of centrifugal pump is controlled by ________
a) Gate
b) Head race
c) Turbine
d) Pump

View Answer

Answer: a [Reason:] The inlet passage of water entry is controlled by the gate opening. The gate opening is an opening that sends only a percentage of fluid through the inlet passages for water to enter to the turbine.

9. Absolute exit velocity in a pump is denoted as ______
a) c2
b) v2
c) p2
d) w2

View Answer

Answer: a [Reason:] Absolute exit velocity in a pump is denoted as ‘c2’.

10. Gear pumps are used to transport ________
a) Pressure
b) Speed
c) Power
d) Fluid

View Answer

Answer: d [Reason:] Gear pumps are used to transport fluids. They transport fluids by conversion of energies. A gear pump uses meshing of gears. This meshing is done to pump fluid by displacement. Gear pumps are widely used in chemical installations.

11. Vertical Centrifugal pumps are also called as _________
a) Cantilever pumps
b) Hydrodynamic pump
c) Mechanical pump
d) Hydroelectric pump

View Answer

Answer: a [Reason:] Vertical Centrifugal pumps are also called as cantilever pumps.

12. With the increase in load, Energy in the turbine________
a) Decreases
b) Increases
c) Remains same
d) Independent

View Answer

Answer: a [Reason:] When there is an increase in the load, the energy in the turbine is drained off. Thus, to increase the energy, the by pass valve is opened to increase the amount of fresh steam entry. This increases the energy in the turbine.

13. The rotational kinetic energy comes from ______
a) Engine motor
b) Pump
c) Tank
d) Draft tube

View Answer

Answer: a [Reason:] Centrifugal pumps transport fluids by converting rotational Kinetic energy to hydrodynamic energy. The rotational kinetic energy comes from engine or electrical motor.

14. When the balancing of the turbine is disturbed, we use ________
a) Throttle governing
b) Steam governing
c) Nozzle governing
d) Emergency governing

View Answer

Answer: d [Reason:] When the balancing of the turbine is disturbed, we use emergency governing. These governors come into action only when there are emergencies in the turbine.

15. Gear pumps are ___________
a) Tangential flow pumps
b) Positive displacement pumps
c) Negative displacement pumps
d) Radial pumps

View Answer

Answer: a [Reason:] Gear pumps are positive displacement pumps or fixed displacement pumps. This means that they pump at a constant amount of fluid each revolution.

Set 4

1. Radial flow reaction turbines are those turbines in which water flows ____________
a) Radial direction
b) Axial direction
c) Tangential direction
d) All of the mentioned

View Answer

Answer: a [Reason:] The name itself indicates the type of flow that is radial direction but the thing that is unknown is whether it is radially inward or outwards.

2. Main parts of radial flow reaction turbines are ______________
a) Casing
b) Guide mechanism
c) Draft tube
d) All of the mentioned

View Answer

Answer: d [Reason:] The main parts in a radial turbine are tight casing to prevent spill of water, runner, guide vanes, guide mechanism to regulate flow and draft to increase inlet pressure.

3. Discharge through radial flow reaction turbine is ______________
a) P1*b1*Vf1
b) P2*b2*Vf2
c) P1*b2*Vf2
d) Both P1*b1*Vf1 & P2*b2*Vf2
Where, P1= perimeter of runner at inlet, P2= perimeter of runner at outlet, b= thickness and Vf= flow velocity

View Answer

Answer: d [Reason:] Discharge of radial flow reaction turbine is product of perimeter of runner, thickness, whirl velocity, at inlet as well as outlet runner vanes.

4. Radial flow reaction turbines contain spiral casing which area ____________
a) Remains constant
b) Gradually decreases
c) Gradually increases
d) Suddenly decreases

View Answer

Answer: b [Reason:] Area of spiral structure gradually decreases because as discharge decreases correspondingly area also decreases. So, runner will rotate with constant velocity.

5. ____________ consists of stationary circular wheel all around the runner of turbine
a) Casing
b) Guide mechanism
c) Runner
d) Drafting

View Answer

Answer: b [Reason:] Guide vanes are placed around the runner to regulate the flow and to provide shock less entry at inlet to runner.

6. The casing of radial flow reaction turbine is made of spiral shape, so that water may enter the runner__________
a) Variable acceleration
b) Constant acceleration
c) Variable velocity
d) Constant velocity

View Answer

Answer: d [Reason:] Area of spiral structure gradually decreases because as discharge decreases correspondingly area also decreases. So, runner will rotate with constant velocity.

7. _____________ allow the water to strike the vanes fixed on runner without shock at inlet
a) Casing
b) Guide vanes
c) Runner
d) Draft tube

View Answer

Answer: b [Reason:] Guide vanes are placed around the runner to regulate the flow and to provide shock less entry at inlet to runner.

8. Runner blades are made up of _____________
a) Cast steel
b) Cast iron
c) Wrought iron
d) Steel

View Answer

Answer: a [Reason:] Runner blades are made up of cast steel because they are less corrosive and highly durable.

9. The pressure at the exit of runner of reaction turbine is generally____________than atmospheric pressure
a) Greater
b) Lesser
c) Constant
d) Equal

View Answer

Answer: b [Reason:] In general, the exit of runner has a low pressure compared to the atmospheric pressure.

10. ___________is a pipe of gradually increasing area used for discharging water from exit of the turbine to the tail race
a) Casing
b) Guide mechanism
c) Draft tube
d) Runner

View Answer

Answer: c [Reason:] Draft is a pipe of gradually increasing area, as water leaving runner has less pressure, draft tube will increase pressure energy of water by decreasing its velocity.

11. ____________and __________of radial flow reaction turbine are always full of water.
a) Casing and runner
b) Casing and penstocks
c) Runner and penstocks
d) Runner and draft tube

View Answer

Answer: a [Reason:] Casing and runner are completely covered by water as it is a reaction turbine in which pressure energy is predominant.

12. ____________governs the flow of water entering the runner blades.
a) Casing
b) Guide vanes
c) Draft tube
d) Runner

View Answer

Answer: b [Reason:] Guide vanes are placed around the runner to regulate the flow and to provide shock less entry at inlet to runner.

13. Spiral casing of reaction turbine will regulate the flow?
a) True
b) False

View Answer

Answer: b [Reason:] Guide vanes are placed around the runner to regulate the flow and to provide shock less entry at inlet to runner.

Set 5

1. The fluid gains _________ while passing through the impeller.
a) Velocity
b) Pressure
c) Temperature
d) Velocity and pressure

View Answer

Answer: d [Reason:] The fluid gains both velocity and pressure while passing through the impeller. Centrifugal pump is a turbomachinery. Turbomachines are machines that transfer energy between a rotor and a fluid, including both turbines and compressors.

2. What is the shape of the diffuser in the centrifugal pump?
a) Round
b) Dough nut
c) Rectangle
d) Cylindrical

View Answer

Answer: b [Reason:] The shape of the diffuser passing present in the centrifugal pump is doughnut shaped. It is made into that shape as it allows the device to scroll up and down. Due to this, the casing decelerates the flow.

3. When the casing in a centrifugal pump decelerates the flow, what increases?
a) Pressure
b) Temperature
c) Volume
d) Flow rate

View Answer

Answer: a [Reason:] When the casing in a centrifugal pump decelerates the flow, pressure in the turbine increases. The diffuser helps this happen. The shape of the diffuser passing present in the centrifugal pump is doughnut shaped.

4. The velocity imparted by the impeller is converted into _________
a) Pressure energy
b) Kinetic energy
c) Momentum
d) Potential energy

View Answer

Answer: a [Reason:] The velocity imparted by the impeller is converted into pressure energy. It is in accordance with the Newtons second law.

5. The consequence of Newtons second law is_________
a) Conservation of angular momentum
b) Conservation of mass
c) Conservation of potential energy
d) Conservation of kinetic energy

View Answer

Answer: a [Reason:] The consequence of Newtons second law is the conservation of angular momentum. This, in accordance with newtons second law, provides the basic details to define parameters in the centrifugal pump.

6. Change of angular momentum is equal to ________
a) Sum of external moments
b) Sum of their potential energies
c) Sum of their kinetic energies
d) Sum of their pressures

View Answer

Answer: a [Reason:] Change of angular momentum is equal to Sum of external moments. This is in accordance with Newtons second law. The consequence of Newtons second law is the conservation of angular momentum.

7. Euler developed the head pressure equation in centrifugal pumps.
a) True
b) False

View Answer

Answer: a [Reason:] Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies. Centrifugal pumps transport fluids by converting rotational Kinetic energy to hydrodynamic energy. Euler developed the head pressure equation in centrifugal pumps.

8. What is a major advantage of centrifugal pump?
a) Cost
b) Simple in construction
c) Efficiency
d) Pump parameters

View Answer

Answer: b [Reason:] The major advantage of the centrifugal pump is that it has got a simple construction when compared to other types of centrifugal pumps.

9. ‘Ht’ means _______
a) Tangential head
b) Horizontally head
c) Theory head pressure
d) Radially head pressure

View Answer

Answer: c [Reason:] ‘Ht’ in the context of centrifugal pump means theory head pressure. It is used in a centrifugal pump equation that was derived by Euler. Euler developed the head pressure equation in centrifugal pumps.

10. Centrifugal pumps are used to transport ________
a) Pressure
b) Speed
c) Power
d) Fluid

View Answer

Answer: d [Reason:] Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies. Centrifugal pumps are a sub class of dynamic axisymmetric work absorbing turbomachinery.

11. Different velocities in a centrifugal pump are determined by using ________
a) Velocity triangle
b) Reynolds number
c) Froude number
d) Overall efficiency

View Answer

Answer: a [Reason:] Different velocities in a centrifugal pump are determined by using velocity triangle. This is an important triangle that determines the way the pump works.

12. Due to its impeller action, centrifugal pumps can cover a wide range of fluid pump applications.
a) True
b) False

View Answer

Answer: a [Reason:] Due to its impeller action, centrifugal pumps can cover a wide range of fluid pump applications. Thus, the impeller action plays an important role.

13. With the increase in the input power, efficiency _______
a) Increases
b) Decreases
c) Same
d) Independent

View Answer

Answer: b [Reason:] With the increase in the input power, efficiency decreases. As the input power is inversely proportional to the efficiency of the pump.

14. What is unit of standard acceleration?
a) kg/m
b) kg/s
c) kg/m3
d) N/m

View Answer

Answer: c [Reason:] The unit of standard acceleration of the centrifugal pump is kg/m3. It is denoted as g. It is also called as the acceleration due to gravity.

15. What does PSP stand for?
a) Pump start procedure
b) Positive start pump
c) Pump start pointer
d) Positive start pointer

View Answer

Answer: a [Reason:] PSP stands for Pump start procedure. It is the basic method to start the pump by lining up the pump valves in a sequence by ensuring that the drain valve is closed.