Category: Steam and Gas Turbines Objective Questions

Automobile Engineering Multiple Choice Questions on “Transmission System – Clutches”.

1. If there are 7 clutch plates in a multi-plate clutch, what is the number of pair of contact surfaces?
a) 5
b) 4
c) 6
d) 8
Answer: c
Clarification: If ‘n’ is the no. of clutch plates in a multi-plate clutch, then, number of pairs of contact surfaces = ‘n-1’. Therefore no. clutches plates = 7 – 1 = 6.

2. External diameter of the clutch facing is limited to 120 mm and the inner diameter may be assumed to be 0.3 times the external diameter. Assume uniform wear theory. What is the effective mean radius?
a) 68
b) 58
c) 98
d) 78
Answer: d
Clarification: External diameter = 120 mm. Given Internal diameter = 0.3*external diameter = 0.3 * 120 = 36 mm. Effective mean diameter = (120 + 36) / 2 = 78 mm ⇒ Effective mean radius = 39 mm.

3. The clutch plate has 160 mm inside and 240 mm outside diameter. The total force provided by the springs is 5 kN, when the clutch is new. The coefficient of friction is 0.4. What is the torque transmitted?
a) 300 Nm
b) 350 Nm
c) 400 Nm
d) 450 Nm
Answer: c
Clarification: inside radius = 80 mm, outside radius = 120 mm ⇒ Effective mean radius = R = (80 + 120) / 2 = 100 mm. Let W = 5 kN = 5000 N and μ = coefficient of friction = 0.4. Torque transmitted = 2 * μ * W * R = 2 * 0.4 * 5000 * 100 = 400 * 10³ Nmm = 400 Nm.

4. Which of the following contains no linkage between the clutch and the pedal?
a) Clutch – by – wire
b) Wet clutch
c) Hydraulic single plate clutch
d) Hydraulic multi-plate clutch
Answer: a
Clarification: In clutch – by – wire system, there is no mechanical linkage between the clutch and the pedal. The ECU and the actuator control the clutch pedal.

5. Where is the clutch located?
a) Between transmission and engine
b) Between transmission and rear axle
c) Between transmission and propeller shaft
d) Between transmission and differential
Answer: a
Clarification: The clutch is in the middle of transmission and engine. So that torque can be transmitted from engine to the transmission whenever required.

6. Which of the following parts of the cover assembly that hold the pressure plate against the clutch plate?
a) Springs
b) Thrust bearings
c) Struts
d) Lever
Answer: a
Clarification: Springs hold the pressure plate against the clutch plate so that pressure can be exerted against the clutch plate and better power transmission can be obtained.

7. Which of the following is the coefficient of friction of the clutch plate?
a) 1.3
b) 0.8
c) 0.4
d) 0.1
Answer: c
Clarification: The coefficient of friction is always less than 1. Most commonly used material for the clutch plate is ceramic in case of racing cars, heavy loads, etc.

8. Which of the following is the disadvantage of the cone clutch?
a) It becomes difficult to disengage the clutch when the cone angle is less than 20°
b) It is silent in operation
c) The normal force on the contact surface is larger than the axial force
d) Same torque can be transmitted for the same size as the plate clutch
Answer: a
Clarification: When the cone angle of the cone clutch is less than 20° than the male part of the clutch join the female part and it difficult to disengage the clutch.

9. The external radius of the cone clutch is 120 mm and the internal radius is 80 mm. The cone angle is kept at 20°. What is the effective mean radius assuming the uniform wear theory?
a) 292 mm
b) 295 mm
c) 100 mm
d) 150 mm
Answer: a
Clarification: r_i = 80 mm, r₀ = 120 mm and θ = 20°. Effective mean radius = (r_i + r_o) / (2*Sin(θ)) = (80 + 120) / (2 * Sin(20°)) = 292.3 mm.

10. The dry clutch can tolerate longer engagement time than a wet clutch.
a) True
b) False
Answer: b
Clarification: Since metal to oil heat transfer is more effective than the metal to the air, the wet clutch acts as a much better heat exchanger and wet clutch can tolerate longer engagement time.

Steam and Gas Turbines Multiple Choice Questions on “Carnot, Rankine and Reheat cycle”.

1. Carnot engine follows ____________
a) Isothermal process
b) Isoentropic process
c) Isothermal and Isoentropic process
d) None of the mentioned
Answer: c
Clarification: Carnot cycle process follows 4 process. They are
Isothermal heat addition
Reversible adiabatic expansion
Reversible isothermal compression
Reversible adiabatic heat rejection.

2. Clausius inequality is applied at _____________
a) reversible isothermal heat addition
b) reversible adiabatic expansion
c) reversible isothermal compression
d) reversible isothermal heat rejection
Answer: c
Clarification: In reversible adiabatic compression entropy is same as from reversible isothermal heat addition and this can be found out by clausius inequality.

3. During reversible adiabatic explansion and compression entropy doesnot change.
a) True
b) False
Answer: a
Clarification: Adiabatic process mean there is no heat transfer and if there is no heat transfer entropy doesnot change.

4. What happens if all the process in carnot cycle be reversed?
a) Works as heat engine
b) PMM1 occurs
c) Works as refrigerator
d) PMM2 occurs
Answer: c
Clarification: When all the process in carnot cycle be reversed heat is absorbed from the body and reduces the temperature of the body which means a refrigerator. When carnot cycle is not reversed it acts as a heat engine.

5. Working fluid of rankine cycle usually _____________
a) Water
b) Methane
c) Hard water
d) None of the mentioned
Answer: a
Clarification: Water is used as working fluid in rankine cycle.

6. Steam turbines work on __________
a) Rankine cycle
b) Carnot cycle
c) Dual cycle
d) None of the mentioned
Answer: a
Clarification: Rankine cycle is generally used where heat energy is to be converted in mechanical energy.

7. In non ideal rankine cycle the compression of pump and expansion of turbine is isoentropic.
a) True
b) False
Answer: b
Clarification: In general isoentropic cases are harder to occur and hence in rankine cycle they doesnot exist as isoentropic process.

8. What is the use of reheat cycle in steam turbines?
a) To remove the moisture from the steam
b) To increase the steam temperature
c) To increase steam pressure
d) None of the mentioned
Answer: a
Clarification: Reheat cycle is worked with rankine cycle to remove the moisture from the steam.

9. In rankine cycle with reheat how mny turbines work?
a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: One turbine is to produce work and the other turbine is to reheat.

10. Reheat temperatures are very close to ______ temperature.
a) inlet
b) outlet
c) intermediate
d) none of the mentioned
Answer: a
Clarification: After passing from the first turbine again the steam enters the boiler to raise their temperature close to the inlet temperature and then enters the low pressure turbine.

Steam and Gas Turbines Multiple Choice Questions on ” Design of Turbine Flow Passages”.

1. A turbine having alternate blades and nozzles is called as _______________
a) Impulse turbine
b) Reaction turbine
c) Impulse & Reaction turbine
d) None of the mentioned
Answer: a
Clarification: When blades and nozzles are arranged in alternate manner pressure loss can be reduced and hence it is called an impulse turbine.

2. Multi stage arrangement of turbines is called as __________
a) Impulse turbine
b) Reaction turbine
c) Compounding
d) None of the mentioned
Answer: c
Clarification: Multi stage arrangement of turbines reduces the pressure loss and velocity losses and hence it is called as compounding.

3. Compounding __________ efficiency at low speed.
a) decrease
b) increase
c) maximizes
d) none of the mentioned
Answer: b
Clarification: Even at low speeds velocity wastage is prevented and hence efficiency is increased.

4. In pressure compounded turbines moving nozzles are followed by turbine blades.
a) True
b) False
Answer: b
Clarification: In pressure compounding fixed nozzles are followed by moving blades.

5. In pressure compounded turbines flow passage is from ______________
a) moving nozzles to fixed blades
b) fixed nozzles to moving blades
c) fixed blades to moving nozzles
d) none of the mentioned
Answer: b
Clarification: In pressure compounded turbines pressure drop is reduced into stages reducing the pressure loss and hence increasing the efficiency. Hence in pressure compounded turbines flow passage if from fixed nozzles to moving blades.

6. In velocity compounded turbines flow passage is from ____________
a) moving blades to fixed nozzles
b) fixed nozzles to moving blades
c) fixed blades to moving nozzles
d) none of the mentioned
Answer: d
Clarification: In velocity compounded turbines velocity drop is maintained in stages and hence reducing velocity loses. Hence in velocity compounded turbines flow passage is from fixed nozzles to multiple rows of moving blades alternating with fixed blades.

7. A velocity compounded impulse turbine is also called as __________
a) Curtis wheel
b) Pressure compounded
c) Curtis wheel & Pressure compounded
d) None of the mentioned
Answer: a
Clarification: Velocity compounded turbines are invented by a scientist called Curtis and hence it is named after his name.

8. Reaction turbine is also called as _________
a) Impulse turbine
b) Curtis wheel
c) Parsons turbine
d) None of the mentioned
Answer: c
Clarification: Reaction turbine was invented by a scientist names Parson and hence it was named after his name.

9. A turbine comprising of fixed blades and moving nozzles is called as reaction turbines.
a) True
b) False
Answer: a
Clarification: In reaction turbines the reaction produced when steam hits the turbine is also utilized to produce power output.

10. Compounding is used for _________ power applications.
a) low
b) high
c) medium
d) none of the mentioned
Answer: b
Clarification: In compounding high powers are produced at low speeds also. Hence for low power production compounding need not be used.

Steam and Gas Turbines Interview Questions and Answers for experienced on “Blade Angle, Gauging and Pitch, Width and Height”.

1. Ram Air turbine generates ________ from air stream.
a) losses
b) power
c) work
d) none
Answer: b
Clarification: Ram Air turbine generates power from air stream.

2. Ram Air turbine can be connected to hydraulic pump.
a) True
b) False
Answer: a
Clarification: Ram air turbine can be connected to generator or hydraulic pump.

3. In steam and gas turbines Casing contains controls for working fluids.
a) True
b) False
Answer: a
Clarification: In steam and gas turbines casing over turbine blades contains controls for working fluids.

4. When pressure drop is in stages then that turbine is called as ________
a) velocity compounded impulse turbine
b) pressure compounded impulse turbine
c) velocity compounded reaction turbine
d) none of the mentioned
Answer: b
Clarification: In pressure compounded impulse turbine pressure drop is in several stages and pressure loss is reduced.

5. Steam velocities in pressure compounding is ______
a) low
b) high
c) velocity has nothing to do with pressure compounding
d) none of the mentioned
Answer: a
Clarification: In pressure compounding the Conversion of kinetic energy in work is in several small stages and hence velocity of steam is low.

6. In parsons turbine to increase area between blades its height is to be ________
a) height has nothing to do with area between blades
b) decreased
c) increased
d) none of the mentioned
Answer: c
Clarification: In parsons turbine velocity is increased and as a result area between the blades is to be increased and it was increased by tapering the blade height.

7. If specific volume of steam increases its blade height _______
a) increases
b) decreases
c) not related with each other
d) none of the mentioned
Answer: a
Clarification: If the specific volume of steam increases its area need to be increased and hence its blade height is increased.

8. Blade entrance angle is measure for __________
a) stationary blades
b) moving blades
c) stationary & moving blades
d) none of the mentioned
Answer: b
Clarification: Steam initially enters moving blades and hence blade entrance angle is measured for moving blades.

9. Blade exit angle is a measure for _________
a) moving & fixed blade
b) moving blade
c) fixed blade
d) none of the mentioned
Answer: c
Clarification: Steam exits the moving blade and then it enters fixed blade and hence blade exit angle is measured at fixed blades.

10. Nozzle exit angle is the measure of angle with which steam is leaving the nozzle.
a) True
b) False
Answer: a
Clarification: Nozzle exit angle is the angle with which steam exits the nozzle.

Steam and Gas Turbines for interviews,

Steam and Gas Turbines Multiple Choice Questions on “Mixed Pressure Turbine Perfomance”.

1. Mixed pressure steam turbines are driven by _________ kinds of steam.
a) 1
b) 2 or more
c) 3
d) 5
Answer: b
Clarification: Mixed pressure turbines are driven by two or more kinds of steam.

2. In mixed pressure turbine existing boiler can be combined with new boiler.
a) True
b) False
Answer: a
Clarification: Both the steams are fed into turbine independently and in this type of turbine existing boiler can be combined with new boiler.

3. In dual heat sources optimum heat for each condition cannot be selected in mixed pressure turbine.
a) True
b) False
Answer: b
Clarification: In dual heat sources optimum heat for each condition can be selected in mixed pressure turbine.

4. Radial turbines gain their high efficiencies at the speed ratio of ___________
a) 0.5
b) 0.7
c) 1
d) 2.6
Answer: c
Clarification: Radial turbines get their peak efficiencies at the speed ratio of 0.7

5. Radial turbine has _______ degree of freedom when compared to mixed flow turbine.
a) more
b) less
c) equal
d) none of the mentioned
Answer: b
Clarification: Radial turbine has less degree of freedom when compared to mixed flow turbine.

6. The blade inlet angle at radial blade section is ________ in mixed flow turbine.
a) non zero
b) zero
c) depends on the mass flow rate
d) none of the mentioned
Answer: a
Clarification: The blade inlet angle at radial blade section is non zero in mixed flow turbine.

7. Stress levels in mixed flow turbine are ________
a) high
b) less
c) medium
d) none of the mentioned
Answer: b
Clarification: Stress levels in mixed flow turbines are less.

8. Mixed flow turbines are designed at ________ inertia.
a) high
b) medium
c) low
d) none of the mentioned
Answer: c
Clarification: Mixed flow turbines are designed at low inertia.

9. Radial turbines are characterized by ____________
a) radial fibers
b) centrifugal compressors
c) radial compressors
d) none of the mentioned
Answer: a
Clarification: Radial turbines are characterized by radial fibers.

10. Turbochargers in automobiles works under _______ pulsation inlet flows.
a) low
b) high
c) medium
d) none of the mentioned
Answer: b
Clarification: Turbochargers in automobiles works under high pulsation inlet flows.

Steam and Gas Turbines MCQs on “The Combustor”.

1. Combustor is also called as _________
a) combustion
b) ramjet
c) inlet manifold
d) none of the mentioned
Answer: a
Clarification: Combustor is also called as a ramjet. Inlet manifold is the inlet pipe provided for adding materials.

2. Combustor can also be called as __________
a) burner
b) ramjet
c) inlet manifold
d) none of the mentioned
Answer: b
Clarification: Combustor can be called as ramjet or burner.

3. Pressure inside the combustor is ________
a) Constant
b) Increases
c) Decreases
d) None of the mentioned
Answer: a
Clarification: Pressure inside the combustor is constant.

4. In _________ air is directly fed to the nozzle.
a) burner & ramjet
b) burner
c) ramjet
d) none of the mentioned
Answer: c
Clarification: In ramjet air is directly fed to the nozzle. Ramjet or burner both mean the same.

5. Flow rates are ________ in combustor.
a) high
b) low
c) medium
d) none of the mentioned
Answer: a
Clarification: Flow rates are high in the combustors. As pressure is high flow rate is also high in the combustor.

6. When 1 kg of jet fuel is produced _______ amount of co₂ is released.
a) 3kg
b) 3.2kg
c) 3.4kg
d) 3.8kg
Answer: b
Clarification: When 1 kg of jet fuel is burned 3.2 kgs of co₂ is released.

7. Fuel that was not completely burnt is called as _______
a) Ramjets
b) UHC
c) Emissions
d) None of the mentioned
Answer: b
Clarification: Incompletely combusted fuels are called as UHC.

8. UHC’s are produced at _________ power levels.
a) high
b) medium
c) low
d) none of the mentioned
Answer: c
Clarification: UHC’s are generally produced at low power levels.

9. Combustors which doesn’t produce more CO doesn’t emit much UHC.
a) True
b) False
Answer: a
Clarification: Combustors that have highly optimized UHC are the combustors which produce low CO emissions.

10. CO produced in combustion is eliminated by __________
a) reduction
b) oxidation
c) reduction & oxidation
d) none of the mentioned
Answer: b
Clarification: CO produced in combustion is eliminated by oxidation.