Geometric similarity is said to exist between the model and the prototype, if both of them

are identical in shape, but differ only in size

The specific speed from 160 to 500 r.p.m. of a centrifugal pump indicates that the pump is

slow speed with radial flow at outlet

medium speed with radial flow at outlet

high speed with radial flow at outlet

high speed with axial flow at outlet

Overall efficiency of a centrifugal pump is the ratio of

energy supplied to the pump to the energy available at the impeller

energy available at the impeller to the energy supplied to the pump by the prime mover

actual workdone by the pump to the energy supplied to the pump by the prime mover

energy supplied to the pump to the energy available at the impeller

manometric head to the energy supplied by the impeller per kN of water

The nozzle efficiency is the ratio of

workdone on the blades to the energy supplied to the blades

workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam

energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam

The diagram efficiency is the ratio of

workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam

workdone on the blades to the energy supplied to the blades

workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam

energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam

A nozzle is said to be a divergent nozzle

when the cross-section of the nozzle decreases continuously from entrance to exit

when the cross-section of the nozzle increases continuously from entrance to exit

when the cross-section of the nozzle decreases continuously from entrance to exit

when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit

The purpose of governing in steam turbines is to

maintain the speed of the turbine

reheat the steam and improve its quality

completely balance against end thrust

De-Laval turbines are mostly used

for small power purposes and low speeds

for small power purposes and high speeds

The effect of supersaturation is that the

mass of the steam discharged increases

entropy and specific volume of the steam increases

When the inlet pressure of steam is equal to the exit pressure, then

there is a pressure drop in the nozzle

pressure drops and fluid flows through the nozzle

there is no pressure drop and fluid does not flow through the nozzle

The effect of friction on the flow of steam through a nozzle is to

increase the exit temperature without any effect on mass flow rate

decrease the mass flow rate and to increase the wetness of steam

increase the mass flow rate and to increase the exit temperature

decrease the mass flow rate and to decrease the wetness of steam

increase the exit temperature without any effect on mass flow rate

In an ideal impulse turbine, the

axial velocity at inlet is equal to that at the outlet

absolute velocity at the inlet of moving blade is equal to that at the outlet

relative velocity at the inlet of the moving blade is equal to that at the outlet

axial velocity at inlet is equal to that at the outlet

whirl velocity at inlet is equalto that at the outlet

In a reaction turbine when the degree of reaction is zero, then there is

maximum heat drop in moving blades

maximum heat drop in fixed blades

The impulse turbine rotor efficiency will have a maximum value of 0.5 cos2 , where is the nozzle exit flow angle, if the

blade velocity coefficient is unity

blades are equiangular and frictionless

4791 + Mcqs in Mechanical Engineering Page 91 McqOptions

4501.	If the compression ratio in I.C. engine increases, then its thermal efficiency will
A.	decrease
B.	increase
C.	remain same
Answer» C. remain same

Discussion

4502.	In a Kaplan turbine runner, the number of blades are generally between
A.	2 to 4
B.	4 to 8
C.	8 to l6
D.	16 to 24
Answer» C. 8 to l6

Discussion

4503.	A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit power of the wheel is
A.	0.25 kW
B.	0.75 kW
C.	1.75 kW
D.	3.75 kW
Answer» D. 3.75 kW

Discussion

4504.	Geometric similarity is said to exist between the model and the prototype, if both of them
A.	have identical velocities
B.	are equal in size and shape
C.	are identical in shape, but differ only in size
D.	have identical forces
Answer» D. have identical forces

Discussion

4505.	Which of the following turbine is preferred for 0 to 25 m head of water?
A.	Pelton wheel
B.	Kaplan turbine
C.	Francis turbine
D.	none of these
Answer» C. Francis turbine

Discussion

4506.	When the speed of the pump increases, its net positive suction head (NPSH) requirement decreases.
A.	Agree
B.	Disagree
Answer» C.

Discussion

4507.	The specific speed from 160 to 500 r.p.m. of a centrifugal pump indicates that the pump is
A.	slow speed with radial flow at outlet
B.	medium speed with radial flow at outlet
C.	high speed with radial flow at outlet
D.	high speed with axial flow at outlet
Answer» E.

Discussion

4508.	In an impulse turbine, the jet of water impinges on the bucket with a low velocity and after flowing over the vanes, leaves with a high velocity.
A.	True
B.	False
Answer» C.

Discussion

4509.	The ratio of quantity of liquid discharged per second from the pump to the quantity of liquid passing per second through the impeller is known as
A.	manometric efficiency
B.	mechanical efficiency
C.	overall efficiency
D.	volumetric efficiency
Answer» E.

Discussion

4510.	Overall efficiency of a centrifugal pump is the ratio of
A.	energy available at the impeller to the energy supplied to the pump by the prime mover
B.	actual workdone by the pump to the energy supplied to the pump by the prime mover
C.	energy supplied to the pump to the energy available at the impeller
D.	manometric head to the energy supplied by the impeller per kN of water
Answer» C. energy supplied to the pump to the energy available at the impeller

Discussion

4511.	A hydraulic intensifier is a device used to increase the intensity of pressure of water by means of energy available from a large quantity of water at a low pressure.
A.	Correct
B.	Incorrect
Answer» B. Incorrect

Discussion

4512.	The discharge through a reaction turbine __________ with the increase in unit speed.
A.	remains same
B.	increases
C.	decreases
Answer» D.

Discussion

4513.	The depth of the bucket for a Pelton wheel is generally __________ the diameter of jet.
A.	equal to
B.	1.2 times
C.	1.8 times
D.	double
Answer» C. 1.8 times

Discussion

4514.	An impulse turbine is used for
A.	low head of water
B.	high head of water
C.	medium head of water
D.	high discharge
Answer» C. medium head of water

Discussion

4515.	In a mixed flow centrifugal pump, the flow through the impeller is a combination of radial and axial flows.
A.	Correct
B.	Incorrect
Answer» B. Incorrect

Discussion

4516.	Which of the following pump is sucessfully used for lifting water to the boilers?
A.	Centrifugal pump
B.	Reciprocating pump
C.	Jet pump
D.	Air-lift pump
Answer» D. Air-lift pump

Discussion

4517.	When the nozzle operates with the maximum mass flow, the nozzle is said to be
A.	choked
B.	underdamping
C.	overdamping
D.	none of these
Answer» B. underdamping

Discussion

4518.	In order to reduce the rotor speed of an impulse turbine, the method employed is
A.	velocity compounding
B.	pressure compounding
C.	pressure-velocity compounding
D.	all of these
Answer» E.

Discussion

4519.	The nozzle efficiency is the ratio of
A.	workdone on the blades to the energy supplied to the blades
B.	workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
C.	energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
D.	none of the above
Answer» D. none of the above

Discussion

4520.	The friction in the nozzle __________ exit velocity of steam.
A.	has no effect on
B.	decreases
C.	increases
Answer» C. increases

Discussion

4521.	A stage, in reaction turbine, is represented by
A.	number of casing
B.	number of entries of steam
C.	number of exits of steam
D.	each row of blades
Answer» E.

Discussion

4522.	The ratio of the workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam is called
A.	blading efficiency
B.	nozzle efficiency
C.	stage efficiency
D.	mechanical efficiency
Answer» D. mechanical efficiency

Discussion

4523.	The diagram efficiency is the ratio of
A.	workdone on the blades to the energy supplied to the blades
B.	workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
C.	energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
D.	none of the above
Answer» B. workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam

Discussion

4524.	The Rankine efficiency depends upon total useful heat drop and total isentropic heat drop.
A.	Correct
B.	Incorrect
Answer» C.

Discussion

4525.	Blading efficiency is also known as
A.	stage efficiency
B.	diagram efficiency
C.	nozzle efficiency
D.	none of these
Answer» C. nozzle efficiency

Discussion

4526.	The reheat factor depends upon
A.	initial pressure and superheat
B.	exit pressure
C.	turbine stage efficiency
D.	all of these
Answer» E.

Discussion

4527.	A nozzle is said to be a divergent nozzle
A.	when the cross-section of the nozzle increases continuously from entrance to exit
B.	when the cross-section of the nozzle decreases continuously from entrance to exit
C.	when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit
D.	none of the above
Answer» B. when the cross-section of the nozzle decreases continuously from entrance to exit

Discussion

4528.	The ratio of the cumulative heat drop to the isentropic heat drop is called reheat factor.
A.	Yes
B.	No
Answer» B. No

Discussion

4529.	The compounding of turbines is done in order to
A.	reduce speed of rotor
B.	improve efficiency
C.	reduce exit losses
D.	all of these
Answer» E.

Discussion

4530.	The pressure of steam, in reaction turbines, is reduced in the fixed blades as well as in moving blades.
A.	Correct
B.	Incorrect
Answer» B. Incorrect

Discussion

4531.	When the cross-section of a nozzle first increases from its entrance to throat, and then decreases from its throat to exit, it is not a convergent-divergent nozzle.
A.	Yes
B.	No
Answer» B. No

Discussion

4532.	The purpose of governing in steam turbines is to
A.	maintain the speed of the turbine
B.	reduce the effective heat drop
C.	reheat the steam and improve its quality
D.	completely balance against end thrust
Answer» B. reduce the effective heat drop

Discussion

4533.	De-Laval turbines are mostly used
A.	where low speeds are required
B.	for small power purposes and low speeds
C.	for large power purposes
D.	for small power purposes and high speeds
Answer» E.

Discussion

4534.	The efficiency ratio is the ratio of total useful heat drop to the total isentropic heat drop.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

4535.	The velocity of steam, in reaction turbines, is increased in the fixed blades as well as in moving blades.
A.	True
B.	False
Answer» B. False

Discussion

4536.	The critical pressure ratio for gases is
A.	0.528
B.	0.546
C.	0.577
D.	0.582
Answer» B. 0.546

Discussion

4537.	The efficiency of a pressure-velocity compounded impulse turbine is __________ as compared to pressure compounded impulse turbine.
A.	same
B.	less
C.	more
Answer» C. more

Discussion

4538.	The effect of supersaturation is that the
A.	mass of the steam discharged increases
B.	entropy and specific volume of the steam increases
C.	exit velocity of steam reduces
D.	all of these
Answer» E.

Discussion

4539.	A single stage turbine is not used because it requires large reduction gearing due to very high rotational speed.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

4540.	In an impulse reaction turbine, the pressure drops gradually and continuously over
A.	fixed blades
B.	moving blades
C.	both fixed and moving blades
D.	none of these
Answer» D. none of these

Discussion

4541.	When the inlet pressure of steam is equal to the exit pressure, then
A.	there is a pressure drop in the nozzle
B.	fluid flows through the nozzle
C.	pressure drops and fluid flows through the nozzle
D.	there is no pressure drop and fluid does not flow through the nozzle
Answer» E.

Discussion

4542.	In velocity compounding of an impulse turbine, the expansion of steam takes place in a nozzle or a set of nozzles from the boiler pressure to condenser pressure.
A.	True
B.	False
Answer» B. False

Discussion

4543.	The effect of friction on the flow of steam through a nozzle is to
A.	decrease the mass flow rate and to increase the wetness of steam
B.	increase the mass flow rate and to increase the exit temperature
C.	decrease the mass flow rate and to decrease the wetness of steam
D.	increase the exit temperature without any effect on mass flow rate
Answer» D. increase the exit temperature without any effect on mass flow rate

Discussion

4544.	In pressure compounding of an impulse turbine, the total pressure drop of the steam does not take place in the first nozzle ring, but is divided equally among all the nozzle rings.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

4545.	In an ideal impulse turbine, the
A.	absolute velocity at the inlet of moving blade is equal to that at the outlet
B.	relative velocity at the inlet of the moving blade is equal to that at the outlet
C.	axial velocity at inlet is equal to that at the outlet
D.	whirl velocity at inlet is equalto that at the outlet
Answer» C. axial velocity at inlet is equal to that at the outlet

Discussion

4546.	During flow through a nozzle, no heat is supplied or rejected by the steam.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

4547.	In a reaction turbine when the degree of reaction is zero, then there is
A.	no heat drop in moving blades
B.	no heat drop in fixed blades
C.	maximum heat drop in moving blades
D.	maximum heat drop in fixed blades
Answer» B. no heat drop in fixed blades

Discussion

4548.	The pressure compounded impulse turbine as compared to velocity compounded turbine require __________ number of stages.
A.	same
B.	less
C.	more
Answer» D.

Discussion

4549.	In a single stage impulse turbine, the velocity of steam approaching nozzles is negligible.
A.	True
B.	False
Answer» B. False

Discussion

4550.	The impulse turbine rotor efficiency will have a maximum value of 0.5 cos2 , where is the nozzle exit flow angle, if the
A.	blades are equiangular
B.	blade velocity coefficient is unity
C.	blades are equiangular and frictionless
D.	blade solidity is 0.65
Answer» D. blade solidity is 0.65

Discussion

Explore topic-wise MCQs in Engineering.

If the compression ratio in I.C. engine increases, then its thermal efficiency will

In a Kaplan turbine runner, the number of blades are generally between

A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit power of the wheel is

Geometric similarity is said to exist between the model and the prototype, if both of them

Which of the following turbine is preferred for 0 to 25 m head of water?

When the speed of the pump increases, its net positive suction head (NPSH) requirement decreases.

The specific speed from 160 to 500 r.p.m. of a centrifugal pump indicates that the pump is

In an impulse turbine, the jet of water impinges on the bucket with a low velocity and after flowing over the vanes, leaves with a high velocity.

The ratio of quantity of liquid discharged per second from the pump to the quantity of liquid passing per second through the impeller is known as

Overall efficiency of a centrifugal pump is the ratio of

A hydraulic intensifier is a device used to increase the intensity of pressure of water by means of energy available from a large quantity of water at a low pressure.

The discharge through a reaction turbine __________ with the increase in unit speed.

The depth of the bucket for a Pelton wheel is generally __________ the diameter of jet.

An impulse turbine is used for

In a mixed flow centrifugal pump, the flow through the impeller is a combination of radial and axial flows.

Which of the following pump is sucessfully used for lifting water to the boilers?

When the nozzle operates with the maximum mass flow, the nozzle is said to be

In order to reduce the rotor speed of an impulse turbine, the method employed is

The nozzle efficiency is the ratio of

The friction in the nozzle __________ exit velocity of steam.

A stage, in reaction turbine, is represented by

The ratio of the workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam is called

The diagram efficiency is the ratio of

The Rankine efficiency depends upon total useful heat drop and total isentropic heat drop.

Blading efficiency is also known as

The reheat factor depends upon

A nozzle is said to be a divergent nozzle

The ratio of the cumulative heat drop to the isentropic heat drop is called reheat factor.

The compounding of turbines is done in order to

The pressure of steam, in reaction turbines, is reduced in the fixed blades as well as in moving blades.

When the cross-section of a nozzle first increases from its entrance to throat, and then decreases from its throat to exit, it is not a convergent-divergent nozzle.

The purpose of governing in steam turbines is to

De-Laval turbines are mostly used

The efficiency ratio is the ratio of total useful heat drop to the total isentropic heat drop.

The velocity of steam, in reaction turbines, is increased in the fixed blades as well as in moving blades.

The critical pressure ratio for gases is

The efficiency of a pressure-velocity compounded impulse turbine is __________ as compared to pressure compounded impulse turbine.

The effect of supersaturation is that the

A single stage turbine is not used because it requires large reduction gearing due to very high rotational speed.

In an impulse reaction turbine, the pressure drops gradually and continuously over

When the inlet pressure of steam is equal to the exit pressure, then

In velocity compounding of an impulse turbine, the expansion of steam takes place in a nozzle or a set of nozzles from the boiler pressure to condenser pressure.

The effect of friction on the flow of steam through a nozzle is to

In pressure compounding of an impulse turbine, the total pressure drop of the steam does not take place in the first nozzle ring, but is divided equally among all the nozzle rings.

In an ideal impulse turbine, the

During flow through a nozzle, no heat is supplied or rejected by the steam.

In a reaction turbine when the degree of reaction is zero, then there is

The pressure compounded impulse turbine as compared to velocity compounded turbine require __________ number of stages.

In a single stage impulse turbine, the velocity of steam approaching nozzles is negligible.

The impulse turbine rotor efficiency will have a maximum value of 0.5 cos2 , where is the nozzle exit flow angle, if the