Mechanical Engineering Test MCQs with answers for mechanical jobs test preparation online.
Mechanical Engineering Test MCQs
The patrol is distilled at a temperature from :
A. 6° to 20°
B. 220° to 345°
C. 65° to 220°
D. 15° to 120°
Which of the following are used in diesel engines and oil fired boilers :
A. Paraffin
B. Gasoline
C. Heavy fuel oils
d) Patrol
The hydraulic turbines are also known as :
A. steam turbines
B. water turbines
C. combustion turbines
D. Gas turbines
Which of the following solid fuel has high carbon content?
A. Coke
B. Coal
C. Peat
D. None of these
Which of the following solid fuel has high caloric value :
A. Wood
B. Peat
C. Bituminous coal
D. Anthracite coal
The average calorific value of wood is about :
A. 33500 KJ/kg
B. 25000 KJ/kg
C. 23000 KJ/kg
D. 19700 KJ/kg
The natural solid fuels are :
A. Wood
B. Peat
C. Lignite
D. All of above
Diesel Cycle is also known as :
A. Constant temperature cycle
B. Constant Volume cycle
C. Constant Pressure Cycle
D. All of above
In the lever of third order, load W, effort P and fulcrum F are oriented as follows :
A. W between P and F
B. F between W and P
C. P between W and F
D. W, P and F all on one side
E. none of the above
Farad is the unit of :
A. inductance
B. voltage
C. capacitance
D. None of these
Atmospheric pressure is equal to :
A. 1.013 bar
B. 760mm of Hg
C. 101.3KN/m2
D. All of these
Ball valves are commonly used to :
A. throttle flow
B. check flow
C. change flow direction
D. start/stop flow
Which tool is used to measure gap size in a rough alignment?
A. Inside calliper
B. Dial indicator
C. Feeler gage
D. Measuring tape
The part of the coupling that actually transmits power and rotation from one shaft to the other shaft is :
A. gap
B. hub
C. key
D. driver
The stress developed in a material at breaking point in extension is called :
A. Breaking stress
B. Fracture stress
C. Yield point stress
D. Proof stress
Which is not correct statement about effect of sulphur in fuel :
A. it has heating value
B. it helps in electrostatic precipitation of ash in flue-gases
C. it leads to corrosion of air heaters, ducting, etc. if flue gas exit temperature is low
D. it erodes furnace walls
E. none of the above
Pick up wrong statement about desired properties of a good fuel :
A. high calorific value
B. produce minimum smoke and gases
C. ease in storing
D. high ignition point
E. ecomomical
Thermal efficiency of a thermal power plant is of the order of :
A. 15%
B. 20%
C. 30%
D. 45%
E. 60%.
The radius of a dished head is taken approximately as :
A. one-fourth
B. half
C. one
D. two
E. three
With increase in load, convection superheater has :
A. drooping characteristic
B. linear characteristic
C. rising characteristic
D. flat characteristic
C. none of the above
The temperature of flue gases at air heater outlet should be :
A. 100°C
B. above dew-point temperature of flue gases
C. below dew-point temperature
D. less than wet bulb temperature
E. above wet bulb temperature
The function of injector used in small capacity boilers is to :
A. create vacuum
B. inject chemical solution
C. pump water, similar to boiler feed pump
D. add make up water
E. none of the above
The height of chimney in a power plant is governed by :
A. the draft to be created
B. limitation of construction facilities
C. control of pollution
D. quantity of flue gases to be handled
E. all of the above
Vacuum for reciprocating steam engines compared to steam turbines is :
A. more
B. equal
C. less
D. could be more or less depending on the size of plant
E. none of the above
In locomotives, the draught is produced by :
A. chimney
B. induced draft fan
C. both combined A. and B.
D. steam jet draught
E. none of the above
The maximum discharge through a chimney occurs when the height of chimney is :
A. infinitely long
B. around 200 meters
C. equal to the height of the hot gas column producing draught
D. outside temperature is very low
E. more than the tallest building nearby
Which device is used in thermal power plants to reduce level of pollution :
A. induced draft fan
B. smoke meter
C. chimney
D. precipitator
E. pulveriser
Ultimate analysis of fuel is determination of percentage of :
A. carbon, hydrogen, nitrogen, sulphur, moisture
B. fixed carbon, ash, volatile matter, moisture
C. higher calorific value
B. lower calorific value
E. best analysis
Sulphur in coal results in :
A. causing clinkering and slagging
B. corroding air heaters
C. spontaneous combustion
D. facilitating ash precipitation
E. all of the above
Green coal, in order to be burnt, must be :
A. heated sufficiently
B. burnt in excess air
C. heated to its ignition point
D. burnt as powder
E. burnt as lumps
The safety valve on boiler drum compared to safety valve on super heater is set at :
A. same value
B. higher value
C. lower value
D. lower/higher depending on steam flow
E. unpredictable
The three “Ts” for good combustion are :
A. temperature, time, and turbulence
B. total air, true fuel
C. thorough mixing, total air
D. total air, time, and temperature
E. none of the above
The capacity of induced draft fan compared to forced draft fan in a boiler is :
A. same
B. more
C. less
D. less or more
E. unpredictable
Feed water conditioning in thermal power plants in done to :
A. reduce hardness and for removal of solids
B. increase efficiency-of thermal power plant
C. increase *heat transfer rate
D. increase steam parameters
E. all of the above
Boiler parameters are expressed by :
A. tonnes/hr. of steam
B. pressure of steam in kg/cm2
C. temperature of steam in °C
D. all of the above
E. none of the above
Calorific value of coal is of the order of :
A. 200-400 kcal/kg
B. 800-1200 kcal/kg
C. 2000-4000 kcal/kg
D. 5000-8000 kcal/kg
E. 8000-10,000 kcal/kg
The condition of steam in boiler drum is always :
A. dry
B. wet
C. saturated
D. supersaturated
E. superheated
Deaeration of feed water is carried out because it reduces :
A. cavitation of .boiler feed pumps
B. corrosion caused by oxygen
C. heat transfer coefficient
D. pH value of water
E. weight of water to be handled
Deaeration of feed water is carried out because it reduces :
A. cavitation of .boiler feed pumps
B. corrosion caused by oxygen
C. heat transfer coefficient
D. pH value of water
E. weight of water to be handled
During storage, the heating value of coal :
A. increases
B. decreases
C. remains constant
D. may increase or decrease
E. none of the above
Film boiling occurs at :
A. very low pressure
B. atmospheric pressures
C. medium pressures
D. very high pressures
E. none of the above
The basic job of feed water treatment in boilers is to overcome the problem of :
A. corrosion
B. scale
C. carryover
D. embrittlement
E. all of the above
In water wall furnace, the heat is transferred to the water-walls by :
A. convection
B. radiation
C. conduction
D. radiation and conduction
E. radiation and convection
Fire tube boilers are limited to a maximum design working pressure of :
A. 1 kg/cm
B. 6 kg/cm
C. 17 kg/cm2
D. 100 kg/cm2
E. 250 kg/cm2
The steam temperature with increase in load in case of a boiler fitted with radiation super heater :
A. increases
B. decreases
C. remains unaffected
D. first increases and then decreases
E. unpredictable
Maximum energy loss in a boiler occurs due to :
A. unburnt carbon in ash
B. incomplete combustion
C. ash content
D. flue gases
E. radiation losses
The balanced draft furnace is one using :
A. induced draft fan and chimney
B. induced draft fan and forced draft fan
C. forced draft fan and chimney
D. any one of the above
E. none of the above
Evaporative capacity of boiler is expressed as :
A. kg of steam produced
B. steam pressure produced
C. kg of fuel fired
D. kg of steam produced per kg of fuel fifed
E. kg of water evaporated
Pulverized fuel is used for :
A. better burning
B. more calorific value
C. less radiation loss
D. medium sized units
E. stoker fired boilers
Incomplete combustion can be best judged by :
A. smoky chimney exit
B. excess air in flue gases
C. measuring carbon mono-oxide in flue gases
D. measuring temperature of flue gases
E. measuring oxygen in flue gases
Caking coals are those which :
A. form lumps or masses of coke
B. burn freely
C. show little or no fusing action
D. burn completely
E. do not form ash
Water and sediment in fuel oil can be removed by :
A. heating the oil in the settling tanks
B. cooling the oil in the settling tanks
C. burning the oil
D. suspension
E. filtering
Presence of moisture in fuel oil would :
A. keep the burner tips cool
B. aid in proper combustion
C. cause sputtering, possibly extinguishing flame
D. clean the nozzles
E. reduce flame length
O2 content in atmospheric air on volume basis is :
A. 21%
B. 23%
D. 30%
D. 40%
E. 70%
The economizer is used in boilers to :
A. increase thermal efficiency of boiler
B. economise on fuel
C. extract heat from the exhaust flue gases
D. increase flue gas temperature
E. to heat feed water by bled steam
For combustion of a fuel, following is essential :
A. correct fuel air ratio
B. proper ignition temperature
C. 02 to support combustion
D. all the three above
E. none of the above
Bomb calorimeter is used to determine :
A. Higher calorific value at constant volume
B. Lower calorific value at constant volume ,
C. Higher calorific value at constant pressure
D. Lower calorific value at constant pressure
E. None of the above
Proximate analysis of fuel is determination of percentage of :
A. carbon, hydrogen, nitrogen, sulphur, moisture
B. fixed carbon, ash, volatile matter, moisture
C. higher calorific value
D. lower calorific value
E. rough analysis
Reheating of steam under ideal conditions takes place at constant :
A. entropy
B. enthaply
C. pressure
D. temperature
E. all of the above
Expanding steam to a very low pressure (high vacuum) in steam engines is :
A. desirable
B. economical
C. essential
D. optional
E. uneconomical
Steam exhaust from high pressure turbine is reheated in :
A. boiler drum
B. superheater tubes
C. economiser
D. a separate coil
E. a separate coil located in convection path
The safety valve at superheater as compared to drum safety valve setting is set at :
A. higher value
B. lower value
C. same value
D. any value
E. none of the above
The pressure of reheat steam after passing through reheater compared to inlet condition is :
A. more
B. less
C. equal
D. may be more or less depending on capacity of reheater
E. none of the above
A safety valve in a locomotive starts leaking. The leaking medium will be :
A. water
B. dry steam
C. wet steam
D. super heated steam
E. supersaturated steam
The diameter of fire tubes in Cochran boiler is of the order of :
A. 2 cm
B. 6 Cm ,
C. 8 cm
D. 12 cm
E. 15 cm
With increase in load, radiant super heater has :
A. drooping characteristic
B. linear characteristic
C. rising characteristic
D. flat characteristic
E. none of the above
The major axis of elliptical manholes on the shell should be provided :
A. longitudinally
B. circumferentially
C. on dished end
D. anywhere
E. vertically
Size of boiler tubes is specified by :
A. mean diameter and thickness
B. inside diameter and thickness
C. outside diameter and thickness
D. outside diameter and inside diameter
E. outside diameter alone
Boiler stays are used to :
A. prevent flat surfaces under pressure from tearing apart
B. take care of failure in shear
C. take care of failure in compression
D. provide support for boiler
E. provide foundation of boiler
Which type of boiler can meet rapid changes of load :
A. vertical fire tube type
B. horizontal fire tube type
C. horizontal water tube type
D. vertical water tube type
E. forced circulation type
It is required to produce large amount of steam at low pressure. Which boiler should be used ?
A. pulverised fuel fired boiler
B. Cochran boiler
C. Lancashire boiler
D. babcock and wilcox boiler
E. stoker fired boiler
Steam in water tube boiler as compared to fire tube boiler :
A. can be raised rapidly
B. is raised at slower rate
C. is raised at same rate
D. could be raised
E. none of the above is true
Fusible plug for boilers is made of fusible metal containing tin, lead, and :
A. bismuth
B. copper
C. aluminium
D. nickel
E. iron
Thermal efficiency of well maintained boiler will be of the order :
A. 20%
B. 40%
C. 50%
D. 75%
E. 90%
The fusible plug in small boilers is located :
A. in the drum
B. in the fire tubes
C. above steam dome
D. over the combustion chamber
E. at the inlet of chimney
The number of drums in Benson steam generator is :
A. one
B. two
C. one steam drum and one water drum
D. no drum
E. none of the above
On Moeller chart, flow through turbine is represented by :
A. horizontal straight line
B. vertical straight line
C. straight inclined line
D. curved line
E. none of the above
On Moeller chart, the constant pressure lines :
A. diverge from left to right
B. diverge from right to left
C. are equally spaced throughout
D. first rise up and then fall
E. none of the above
The bituminous coal is non-caking if its carbon content is :
A. 78-81%
B. 81-85%
C. 85-90%
D. 90-95%
E. 95-100%.
In a throttling process :
A. steam temperature remains constant
B. steam pressure remains constant
C. steam enthalpy remains constant
D. steam entropy remains constant
E. steam volume remains constant
The pressure at which latent heat of vaporisation of water is zero, is :
A. below atmospheric pressure
B. 1 kg/cm2
C. 100 kg/cm2
D. 170 kg/cm2
E. 225.6 kg/cm2
The latent heat of steam with increase of pressure :
A. remains same
B. increases
C. decreases
D. behaves unpredictably
E. none of the above
Adiabatic process is :
A. essentially an isentropic process
B. non-heat transfer process
C. reversible process
D. constant temperature process
E. constant enthalpy process
While steam expands in turbines, theoretically the entropy :
A. remains constant
B. increases
C. decreases
D. behaves unpredictably
E. none of the above
Pick up the wrong statement about critical condition of steam :
A. latent heat is zero
B. liquid directly becomes steam
C. specific volume of steam and liquid is same
D. this is the maximum pressure limit
E. all properties of liquid and steam are same
Mechanical equivalent of heat for 1 kcal or Joule’s equivalent is equal to :
A. 421 kgm
B. 421 kgm
C. 539 kgm
D. 102 kgm
E. 75 kgm
The evaporation of 15.653 kg of water per hour from and at 100°C is called :
A. evaporative capacity
B. factor of evaporation
C. equivalent evaporation
D. one boiler h.p.
E. boiler efficiency
Cochran boiler is a :
A. horizontal fire-tube boiler
B. horizontal water-tube boiler
C. vertical water-tube boiler
D. vertical fire tube boiler
E. forced circulating boiler
Orsat meter is used for :
A. gravimetric analysis of the flue gases
B. volumetric analysis of the flue gases
C. mass flow of the flue gases
D. measuring smoke density of flue gases
E. none of the above
An ideal regenerative cycle is :
A. equal to carnot cycle
B. less than carnot cycle
C. more than carnot cycle
D. could be anything
E. none of the above
Lancashire ‘boiler is a :
A. stationary fire tube boiler
B. stationary water tube boiler
C. water tube boiler with natural/forced circulation
D. mobile fire tube boiler
E. none of the above
One kilowatt-hour energy is equivalent to :
A. 1000 J
B. 360 kJ
C. 3600 kJ
D. 3600 kW/sec
E. 1000 kJ
100% efficiency of a thermal cycle cannot be achieved because of :
A. frictional losses
B. it is not possible to achieve 0°K temperature
C. leakage
D. non-availability of ideal substance
E. none of the above
The diameter of fire tube of Cornish boiler compared to its shell is :
A. one half
B. one third
C. one-fifth
D. two-fifth
E. three-fifth
The change in internal energy in steam engines equals to :
A. work done during the rankine cycle
B. work done during compression.
C. work done during adiabatic expansion
D. change in enthalpy
E. none of the above
Locomotive type’ boiler is :
A. horizontal multi tubular water tube boiler
B. water wall enclosed furnace type
C. vertical tubular fire tube type
D. horizontal multi-tubular fire tube type
E. none of the above types
The number of flue tubes in Lancashire boiler is :
A. zero
B. one
C. two
D. four
E. many
Which of the following is a water tube boiler :
A. locomotive boiler
B. Cochran boiler
C. Cornish boiler
D. Babcock and Wilcox boiler
E. Lancashire boiler
Which of the following coals has the highest calorific value :
A. anthracite coal
B. bituminous coal
C. lignite
D. peat
E. wood
The crown of the fire box is made hemispherical in order to :
A. give maximum space
B. give maximum strength
C. withstand pressure inside boiler ,
D. resist intense heat in fire box
E. enable easy, manufacture
The fire tubes in, a Ciarran and Scotch marine boiler are :
A. horizontal
B. vertical
C. inclined
D. both horizontal and vertical
E. horizontal and inclined
The basic purpose of drum in boiler is to :
A. serve as storage of steam
B. serve as storage of feed water for water wall
C. remove salts from water
D. separate steam from water
E. control level
The function of injector used in small steam plants is to :
A. create vacuum in furnace
B. create vacuum at turbine exhaust
C. pump feed water
D. dose chemicals in feed water
E. control steam temperature
The water tubes in a Babcock and Wilcox boiler are :
A. horizontal
B. vertical
C. inclined
D. horizontal and inclined
E. vertical and inclined
The diameters of fire tubes and superheated tubes in locomotive boiler are :
A. 47.5 mm, 130 mm
B. 32.5 mm, 180 mm
C. 65.5 mm, 210 mm
D. 24.5 mm, 65 mm
Hard coke is produced by carbonisation of coal at :
A. atmospheric temperature
B. 500-600°C
C. 70O-850°C
D. 95O-1100°C
E. 120O-1500°C
Hard coke is used in :
A. cement industry
B. thermal power plant
C. blast furnace
D. domestic use
E. locomotives
Locomotive boiler is of the following type :
A. multitubular
B. horizontal
C. internally fired
D. mobile
E. all of the above
Which of the following varieties of coals is mostly used in steam boilers :
A. non-coking bituminous coal
B. brown coal
C. peat
D. coking bituminous coal
E. none of the above
A boiler in India should conform to safety regulations of :
A. DIN
B. BS
C. ASTM
D. IBR
E. GOST
The shell diameter and length of locomotive boiler are :
A. 1.5 m, 4 m
B. 1.5 m, 6 m
C. 1 m, 4 m
D. 2 m, 4 m
E. 1.5 m, 8 m
In locomotive boiler, maximum steam pressure is limited to :
A. 1 kg/cm2
B. 5 kg/cm2
C. 10 kg/cm2
D. 18 kg/cm2
E. 31 kg/cm2
The diameter of internal flue tubes in a Lancashire boiler compared to its shell is :
A. one-half
B. one-third
C. one-fourth
D. one-fifth
E. two-fifth
The high pressure boiler is producing steam at a pressure more than :
A. atmospheric pressure
B. 5 kg/cm2
C. 10 kg/cm2
D. 40 kg/cm2
E. 75-80 kg/cm2
The biggest size of thermal power unit operating in India is :
A. 30 MW
B. 60 MW
C. 100 MW
D. 210 MW
E. 500 MW
The diameter of cylindrical shell of the Lancashire boiler is of the order of :
A. 1 tp 1.25m
B. 1 to 1.75 m
C. 2 to 4 m
D. 1.75 to 2.75 m
E. 2.25 to 4.5 m
Which of the following is a fire tube boiler :
A. locomotive boiler
B. Babcock and Wilcox boiler
C. Stirling boiler.
D. all of the above
E. none of the above
Lancashire boiler is of :
A. stationary<fire tube-type
B. horizontal type
C. natural cirulation type
D. internally fired type
E. all of the above
Water tube boilers are those in which :
A. flue gases pass through tubes and water around it
B. water passes through the tubes and flue gases around it
C. work is done during adiabatic expansion
D. change in enthalpy
E. none of the above
Steam engine operates on :
A. Carnot cycle
B. joule cycle
C. Stirling cycle
D. Brayton cycle
E. none of the above
The length of Cornish boiler is of the order of :
A. 2-4 m
B. 3-5 m
C. 5-7.5 m
D. 7-9 m
E. 9-11 m
For burning 1 kg of carbon to CO as per chemically correct combustion, amount of air required is :
A. 1 kg
B. 4/3kg
C. 8/3kg
D. 2 kg
E. 16/3 kg
Which of the following gases has the highest calorific value :
A. producer gas
B. coal gas
C. water gas
D. blast furnace gas
E. coke oven gas
Efficiency of a thermal cycle increases by :
A. regeneration
B. reheating of steam
C. both A. and B.
D. cooling of steam
E. none of the above
Efficiency of rankine cycle can be increased by :
A. decreasing initial steam pressure and temperature
B. increasing exhaust pressure
C. decreasing exhaust pressure
D. increasing the expansion ratio
E. increasing number of regenerative heaters
Alkaline pyrogallate is used in Orsat’s apparatus for absorption of :
A. C02
B. CO
C. 02
D. N2
E. none of the above
Hygrometery deals with the :
A. Hygroscopic substances
B. water vapour in air
C. temperature of air
D. pressure of air
E. density measurement
The increase in pressure :
A. lowers the boiling point of a liquid
B. raises the boiling point of a liquid
C. .does not affect the boiling point of a liquid
D. reduces its volume
E. none of the above
Water boils when its vapour pressure :
A. equals that of the surroundings
B. equals 760 mm of mercury
C. equals to atmospheric pressure
D. equals the pressure of water in the container
E. boiling has nothing to do
The state of vapour under saturation condition is described by :
A. pressure alone
B. temperature alone
C. pressure and temperature
D. pressure and dryness fraction
E. dryness fraction alone
Heating wet steam at constant temperature is heating it at constant :
A. volume
B. pressure
C. entropy
D. enthalpy
E. none of the above
At critical point, i.e. p=225.65 kg/cm2, the latent enthalpy of vaporisation is :
A. maximum
B. minimum
C. zero
D. depends on temperature also
E. none of the above
Latent heat of dry steam at atmospheric pressure is equal to :
A. 539 kcal/kg
B. 539 BTU/lb
C. 427 kcal/kg
D. 100 kcal/kg
E. 471 kcal/kg
In a throttling process :
A. heat transfer takes place
B. work is done by the expanding steam
C. internal energy of steam changes
D. all of the above
E. none of the above
A wet vapour can be completely specified by :
A. pressure only
B. temperature only
C. dryness fraction only
D. specific volume only
E. pressure and dryness fraction
The specific heat of superheated steam in kcal/kg is generally of the order of :
A. 0.1
B. 0.3
C. 0.5
D. 0.8
E. 1.0
One kg of steam sample contains 0.8 kg dry steam; it’s dryness fraction is :
A. 0.2
B. 0.8
C. 1.0
D. 0.6
E. 0.5
Equivalent evaporation is the amount of water evaporated in a boiler from and at :
A. 0°C
B. 100°C
C. saturation temperature at given pressure
D. room temperature
E. 20°C
1 kg.m is equal to :
A. 9.81 Joules
B. All Joules
C. 427 Joules
D. 102 Joules
E. 539 Joules
The critical pressure at which latent heat of vaporisation is zero is :
A. 225.65 kgf/cm2
B. 273 kgf/cm2
C. 100 kgf/cm2
D. 1 kgf/cm2
E. – 1 kgf/cm2
The saturation temperature of steam with increase in pressure increases :
A. linearly
B. rapidly first and then slowly
C. slowly first and then rapidly
D. inversely
E. none of the above
Superheating of steam is done at :
A. constant volume
B. constant temperature
C. constant pressure
D. constant entropy
E. constant enthalpy
The coal requirement per kW hour generation in the thermal power plant is of the order of :
A. 0.1 to 0.2 kg
B. 0.2 to 0.4 kg
C. 0.6 to 0.8 kg
D. 1.0 to 1.5 kg
E. 1.5 to 2 kg
The specific volume of steam with increase in pressure decreases :
A. linearly
B. slowly first and then rapidly
C. rapidly first and then slowly
D. inversely
E. none of the above
Which of the following is the unit of kinematic viscosity :
A. pascal
B. poise
C. stoke
D. faraday
E. none of the above
Hot wire anemometer is used to measure :
A. discharge
B. velocity of gas
C. pressure intensity of gas
D. pressure intensity of liquid
Which of the following is not the unit of pressure ?
A. kg/cm
B. ata
C. atmosphere
D. mm of wcl
E. newton
A pair of smith’s tongs is an example of the lever of :
A. zeioth order
B. first order
C. second order
D. third order
E. fourth order
If three forces acting in different planes can be represented by a triangle, these will be in :
A. non-equilibrium
B. partial equilibrium
C. full equilibrium
D. unpredictable
E. none of the above
Which of the following is not the unit of power ?
A. kW (kilowatt)
B. hp (horse power)
C. kcal/sec
D. kg m/sec
E. kcal/kg sec
Which of the following do not have identical dimensions ?
A. Momentum and impulse
B. Torque and energy
C. Torque and work
D. Kinetic energy and potential energy
E. Moment of a force and angular momentum
If two equal forces of magnitude P act at an angle 9°, their resultant will be :
A. P/2 cos 9/2
B. IP sin 9/2
C. 2P tan 9/2
D. IP cos 9/2
E. Psin 9/2
The unit of power in S.I. units is :
A. newton meter
B. watt
C. joule
D. kilogram meter/sec
E. pascal per sec
All the terms of energy in Bernoulli’s equation have dimension of :
A. energy
B. work
C. mass
D. length
E. time
For hypersonic flow, the Mach number is :
A. unity
B. greater than unity
C. greater than 2
D. greater than 4
E. greater than 1
Normal depth in open channel flow is the depth of flow corresponding to :
A. steady flow
B. unsteady flow
C. laminar flow
D. uniform flow
E. critical flow
Buoyant force is :
A. resultant force acting on a floating body
B. equal to the volume of liquid displaced
C. force necessary to keep a body in equilibrium
D. the resultant force on a body due to the fluid surrounding it
E. none of the above
Metacentre is the point of intersection of :
A. vertical upward force through
B. buoyant force and the center line of body
C. mid point between e.g. and center of buoyancy
D. all of the above
E. none of the above
Center of buoyancy is the :
A. centroid of the displaced volume of fluid
B. center of pressure of displaced volume
C. e.g. of floating ‘body
D. does not exist
E. none of the above
Barometer is used to measure :
A. pressure in pipes, channels etc.
B. atmospheric pressure
C. very low pressure
D. difference of pressure between two points
E. rain level
Poise is the unit of :
A. surface tension
B. capillarity
C. viscosity
D. shear stress in fluids
E. buoyancy
Property of a fluid by which molecules of different kinds of fluids are attracted to each other is called :
A. adhesion
B. cohesion
C. viscosity
D. compressibility
E. surface tension
1 m of air at atmospheric condition weighs approximately :
A. 0.5 kg
B. 1.0 kg
C. 1.3 kg
D. 2.2 kg
E. 3.2 kg
Isothermal compression efficiency can be attained by running the compressor :
A. at very high speed
B. at very slow speed
C. at average speed
D. at zero speed
E. isothermally
The- most efficient method of compressing air is to compress it :
A. isothermally
B. adiabatically
C. is entropically
D. isochronically
E. as per law pV
In a forced vortex, the velocity of flow everywhere within the fluid is :
A. maximum
B. minimum
C. zero
D. non-zero finite
E. unpredictable
For pipes, laminar flow occurs when Roynolds number is :
A. less than 2000
B. between 2000 and 4000
C. more than 4000
D. less than 4000
E. none of the above
The fluid forces considered in the Navier Stokes equation are :
A. gravity, pressure and viscous
B. gravity, pressure and turbulent
C. pressure, viscous and turbulent
D. gravity, viscous and turbulent
E. none of the above
The work done per unit mass of air in compression will ‘be least when n is equal to :
A. 1
B. 1.2 ,
C. 1.3
D. 1.4
E. 1.5
What will be the volume of air at 327°C if its volume at 27°C is 1.5 m3/mt ?
A. 3 m3/mt
B. 1.5 m3/mt
C. 18 m3/mt
D. 6 m3/mt
E. 0.75 m3/mt
Inter cooling in compressors :
A. cools the delivered air
B. results in saving of power in compressing a given volume to given pressure
C. is the standard practice for big compressors
D. enables compression in two stages
E. prevents compressor jacket running very hot
Standard air is the air at :
A. atmospheric conditions at any specific location
B. 20°C and 1 kg/cm2 and relative humidity 36%
C. 0°C and standard atmospheric conditions
D. 15°C and 1 kg/cm2
E. 25°C, 1 kg/cm2 and RH of 60%.
Maximum work is done in compressing air when the compression is :
A. isothermal
B. adiabatic
C. polytropic
D. any one of the above
E. none of the above
Rotary compressor is best suited for :
A. large quantity of air at high pressure
B. small quantity of air at high pressure
C. small quantity of air at low pressure
D. large quantity of air at low pressure
E. any one of the above
Which is false statement about air receivers :
A. These are used to dampen pulsations ,
B. These act as reservoir to- take care of sudden demands
C. These increase compressor efficiency
D. These knock out some oil and moisture
E. These reduce frequent on/off operation of compressor
Ratio of indicated h.p. to shaft h.p. in known as :
A. compressor efficiency
B. isothermal efficiency
C. volumetric efficiency
D. mechanical efficiency
E. adiabatic efficiency
Euler’s equation is applicable for :
A. centrifugal compressor
B. axial compressor
C. pumps
D. all of the above
E. none of the above
Which is false statement about multistage compression ?
A. Power consumption per unit of air
B. Volumetric efficiency is high
C. It is best suited for compression
D. The moisture in air is condensed i
E. Outlet temperature is red
Volumetric efficiency of a compressor with clearance volume :
A. increases with increase in compression ratio
B. decreases with increase in compression ratio
C. in not dependent upon compression ratio
D. may increase/decrease
A centrifugal compressor works on the principle of :
A. conversion of pressure
B. conversion of kinetic energy into pressure energy
C. centripetal action
D. generating pressure directly
E. combination of A. and D.
The compressor performance at higher altitude compared to sea level will be :
A. same
B. higher
C. lower
D. dependent on other factors
E. none of the above
An air compressor may be controlled by :
A. throttle control B. clearance control
C. blow-off control
D. any one of the above
E. none of the above
Separators in compressor installations are located :
A. before intercooler
B. after intercooler
C. after receiver
D. between after-cooler and air receiver
Mining industry usually employs following motive power :
A. A.C. electric motor
B. compressed air
C. petrol engine
D. diesel engine
In multistage compressor, the isothermal compression is achieved by :
A. employing intercooler
B. by constantly cooling the cylinder
C. by running compressor at very slow speed
D. by insulating the cylinder
The capacity of compressor will be highest when its intake temperature is :
A. lowest
B. highest
C. anything.
D. atmospheric
Reciprocating air compressor is best suited for :
A. large quantity of air at high pressure
B. small quantity of air at high pressure
C. small quantity of air at low pressure
D. large quantity of air at low pressure
After-cooler is used to :
A. cool the air
B. decrease the delivery temperature
C. cause moisture and oil vapour to drop out
D. reduce volume
During base load operation, the best method of controlling compressor is :
A. start-stop motor
B. constant speed unloader
C. relief valve
D. variable speed
The volumetric efficiency of a compressor is calculated on the basis of :
A. volume of air inhaled at working conditions
B. volume of air inhaled at N.T.P. conditions
C. volume at 0°C and 1 kg/cm2
D. volume at 20°C and 1 kg/cm2
The compressor efficiency is the :
A. isothermal H.P/indicated H.R
B. isothermal H.P./shaft H.R
C. total output/air input
D. compression work/motor input
For a compressor, least work will be done if the compression is :
A. isentropic
B. isothermal
C. polytrophic
D. somewhere in between isentropic and isothermal
To avoid moisture troubles, the compressed air main line should :
A. rise gradually towards the point of use
B. drop gradually towards the point of use
C. be laid vertically
D. be laid exactly horizontally
The thrust on the rotor in a centrifugal compressor is produced by :
A. radial component
B. axial component
C. tangential component
D. resultant component
A compressor at high altitude will draw :
A. more power
B. less power
C. same power
D. more/less power depending on other factors
Diffuser in a compressor is used to :
A. increase velocity
B. make the flow stream-line
C. convert pressure energy into KE
D. convert kinetic energy into pressure energy
Phenomenon of choking in compressor means :
A. no flow of air
B. fixed mass flow rate regardless of pressure ratio
C. reducing mass flow
D. increased inclination of chord w
The ratio of isentropic work to Euler work is known as :
A. pressure coefficient
B. work coefficient
C. polytropic reaction
D. slip factor
The indicated work per unit mass of air delivered is :
A. directly proportional to clearance volume
B. greatly affected by clearance volume
C. not affected by clearance volume
D. inversely proportional to clearance volume
As the value of index is decreased, the volumetric efficiency will :
A. increase
B. decrease
C. remain unaffected
D. may increase/decrease
The advantage of multistage compression over single stage compression is :
A. lower power consumption per unit of air delivered
B. higher volumetric efficiency
C. decreased discharge temperature
D. moisture free air
E. all of the above
The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation :
A. 0.1%
B. 0.5%
C. 1.0%
D. 5%
E. 10%.
The maximum compression ratio in an actual single stage axial flow compressor is of the order of :
A. 1 : 1.2
B. 1 : 2
C. 1 : 5
D. 1 : 10
E. 1 : 1
The ratio of isentropic work to Euler’s work is known as :
A. compressor efficiency
B. isentropic efficiency
C. Euler’s efficiency
D. pressure coefficient
E. pressure ratio
The ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called :
A. slip factor
B. velocity factor
C. velocity coefficient
D. blade effectiveness
Losses in a centrifugal compressor are due to :
A. inlet losses
B. impeller channel losses
C. diffuser losses
D. all of the above
E. none of the above
The criterion of the thermodynamic efficiency for rotary compressor is :
A. isentropic compression
B. isothermal compression
C. polytropic compression
D. any one of the above
E. none of the above
Gas turbines for power generaion are normally used :
A. to supply base load requirements
B. to supply peak load requirements
C. to enable start thermal power plant
D. in emergency
Open cycle gas turbine works on :
A. Brayton or Atkinson cycle
B Rankine cycle
C. Carnot cycle
D. Eriksson cycle
E. Joule cycle
The work ratio of simple gas turbine cycle depends on :
A. pressure ratio
B. maximum cycle temperature
C. minimum cycle temperature
D. all of the above
The volumetric efficiency of compressor with increase in compression ratio will :
A. increase
B. decrease
C. remain same
D. may increase/decrease
Axial flow compressor resembles :
A. centrifugal pump
B. reciprocating pump
C. turbine
D. sliding vane compressor
Atmospheric pressure is 1.03 kg/cm and vapour pressure is 0.03 kg/cm . The air pressure will be :
A. 1.03 kg/cm2
B. 1.06 kg/cm2
C. 1.00 kg/cm2
D. 0.53 kg/cm2
Maximum delivery pressure is a rotary air compressor is of the order of :
A. 6 kg/cm2
B. 10 kg/cm2
C. 16 kg/cm2
D. 25 kg/cm2
The thermodynamic efficiency of rotary compressor is based on :
A. isothermal compression
B. adiabatic compression
C. isentropic compression
D. polytrophic compression
Surging is the phenomenon of :
A. air stream blocking the passage
B. motion of air at sonic velocity
C. unsteady, periodic and reversed flow
D. air stream not able to follow the blade contour
The fuel consumption in gas turbines is accounted for by :
A. low.er heating value
B. higher heating value
C. heating value
D. higher calorific value
The pressure ratio for an open cycle gas turbine compared to closed cycle gas turbine of same h.p. is :
A. low
B. high
C. same
D. low/high depending on make and type
Rotary compressors are suitable for :
A. large discharge at high pressure
B. low discharge at high pressure
C. large discharge at low pressure
D. low discharge at low pressure
Gas turbine works on :
A. Brayton or Atkinson cycle
B. Carnot cycle
C. Rankine cycle
D. Ericson cycle
Gas turbine works on :
A. Brayton or Atkinson cycle
B. Carnot cycle
C. Rankine cycle
D. Ericson cycle
The pressure ratio of an ideal vanned compressor with increase in mass flow rate :
A. increases
B. decreases
C. remains constant
D. first decreases and then increases
E. unpredictable
Actual compression curve is :
A. same as isothermal
B. same as adiabatic
C. better than isothermal and adiabatic
D. in between isothermal and adiabatic
E. none of the above
Surging phenomenon in centrifugal com-pressor depends on :
Pick up wrong statement ?
A. mass flow rate
B. pressure ratio
C. change in load
D. stagnation pressure at the outlet
Efficiency of gas turbine is increased by :
A. reheating
B. inter cooling
C. adding a regenerator
D. all of the above
The hottest point in a gas turbine is :
A. at the base
B. at the tip
C. in the centre
D. between ~ to i of the blade height
Temperature of gases at end of compression as compared to exhaust gases in a gas turbine is :
A. higher
B. lower
C. equal
D. can’t be compared
The pressure ratio in gas turbines is of the order of :
A. 2:l
b. 4:1
C. 61: 1
D. 9 : 1
The thermal efficiency of a gas turbine as compared to a diesel plant is :
A. same
B. more
C. less
D. depends on other factors
Gas turbine blades are given a rake :
A. equal to zero
B. in the direction of motion of blades
C. opposite to the direction of motion of blades
D. depending on the velocity
The air-fuel ratio in gas turbines is of the order of :
A. 7 : 1
B. 15 : 1
C. 30 : 1
D. 40 : 1
E. 50: 1
In jet engines, for the efficient production of large power, fuel is burnt in an atmosphere of :
A. vacuum
B. atmospheric air
C. compressed air
D. oxygen alone
In gas turbines^ high thermal efficiency is obtained in :
A. closed cycle
B. open cycle
C. both of the above
D. closed/open depending
A closed gas turbine in which fuel is burnt directly in the air is not possible because of :
A. high pressure ratio
B. increasing gas temperature
C. high specific volume
D. high friction losses
E. paucity of 02
Water is injected in gas turbine cycle to :
A. control temperature
B. control output of turbine
C. control fire hazards
D. increase efficiency
The closed cycle in gas turbines :
A. provides greater flexibility
B. provides lesser flexibility
C. in never used
D. is used when gas is to be burnt
A gas turbine used in air craft should have :
A. high h.p. and low weight
B. low weight and small frontal area
C. small frontal area and high h.p.
D. high speed and high h.p.
Propulsive efficiency is defined as ratio of :
A. thrust power and fuel energy
B. engine output and propulsive power
C. propulsive power and fuel input
D. thrust power and propulsive power
A rocket engine for the combustion of its fuel :
A. carries its own oxygen
B. uses surrounding air
C. uses compressed atmospheric air
D. does not require oxygen
Which of the following fuels can be used in turbojet engines :
A. liquid hydrogen
B. high speed diesel oil
C. kerosene
D. demethylated spirit
A jet engine works on the principle of conservation of :
A. mass
B. energy
C. flow
D. linear momentum
If infinite number of heaters be used in a gas turbine, then expansion process in turbine approaches :
A. isothermal
B. isentropic
C. adiabatic
D. isochoric
E. isobaric
In jet engines, paraffin is usually used as the fuel because of its :
A. high calorific value
B. ease of atomisation
C. low freezing point
D. A. and C. above
The following property is most important for material used for gas turbine blade :
A. toughness
B. fatigue
C. creep
D. corrosion resistance
Fighter bombers use following type of engine :
A. turbo-jet
B. turbo-propeller
C. rocket
D. ram-jet ,
The weight per horse power ratio for gas. turbine as compared to I.C. engine and steam turbine is :
A. same
B. higher
C. lower
D. uncompilable
In jet propulsion power unit, the inlet duct of diverging shape is used in order to :
A. collect more air
B. convert kinetic energy of air into pressure energy
C. provide robust structure
D. beautify the shape
The air entry velocity m a rocket as compared to aircraft is :
A. same
B. more
C. less
D. zero
Propulsion efficiency of the following order-is obtained in practice :
A. 34%
B. 50%
C. 60%
D. 72%
The maximum propulsion efficiency of a turbojet is attained at around following speed :
A. 550 km/hr
B. 1050km/hr
C. 1700 km/hr
D. 2400km /hr
E. 4000 km/hr
A rocket works with maximum overall efficiency when air craft velocity is equal to the :
A. jet velocity
B. twice the jet velocity
C. half the jet velocity
D. average of the jet velocity
The main purpose of reheating in gas turbine is to :
A. increase temperature
B. reduce turbine size
C. increase power output
D. increase speed
E. increase pressure ratio
Work ratio of a gas turbine may be improved by :
A. decreasing the compression work
B. increasing the compression work
C. increasing the turbine work
D. decreasing the turbine work
E. A. and C. above
In which case the air-fuel ratio is likely to be maximum :
A. 2-stroke engine
B. 4-stroke petrol engine
C. 4-stroke diesel engine
D. multi-cylinder engine
E. gas turbine
High air-fuel ratio is used in gas turbines :
A. to increase the output
B. to increase the efficiency
C. to save fuel
D. to reduce the exit temperature
In jet engines the compression ratio :
A. varies as square root of the speed
B. Varies linearly to the speed
C. varies as square of the speed
D. varies as cube of the speed
Air-fuel ratio in a jet engine will be of the order of :
A. 10: 1
B. 15: 1
C. 20 : 1
D. 60 : 1
The effective power of gas turbines is increased by adding the following in compressor :
A. ammonia and water vapour
B. carbon dioxide
C. nitrogen
D. hydrogen
E. none of the above
The main purpose of reheating in gas turbine is to :
A. increase temperature
B. reduce turbine size
C. increase power output
D. increase speed
Turbofan engine employs :
A. one air stream
B. two or more air streams
C. no air stream
D. solid fuel firing
The compression ratio in a jet engine varies proportional to :
A. speed
B. speed
C. altitude
D. none
For speed above 3000 km/hour, it is more advantageous to use :
A. turbo-jet engine
B. ram-jet engine
C. propellers
D. rockets
The efficiency of jet engine is :
A. higher at ground
B. higher at high altitudes
C. same at all altitudes
D. higher at high speed
E. lower at low speed
In air breathing jet engine, the jet is formed by expanding :
A. gases
B. solids
C. liquid
D. plasma
E. highly heated atmospheric air
Reheating in multistage expansion gas turbine results in :
A. high thermal efficiency
B. reduction in compressor work
C. decrease of heat loss in exhaust
D. maximum work output
Gas turbine cycle with Regenerator :
A. increases thermal efficiency
B. allows high compression ratio
C. decreases heat loss is exhaust
D. allows operation at very high altitudes
E. permits high moisture content fuel to be used
A file removes the metal during :
A. both forward and return strokes
B. forward stroke
C. return stroke
D. none of these
The working fluid in ai turbine is :
A. in two phases
B. in three phases
C. in a single phase
D. in the form of air and water mixture
The compression ratio in a gas turbine is of the roder of :
A. 3.5 : 1
B. 5 : 1
C. 8 : 1
D. 12 : 1
E. 20 : 1
Ram-jet engine :
A. is self-operating at zero flight speed
B. is not self-operating at zero flight speed
C. requires no air for its operation
D. produces a jet consisting of plasma
E. none of the abo
Pressure ratio in gas turbines is the ratio of :
A. compressor pressure ratio
B. highest pressure to exhaust pressure
C. inlet pressure to exhaust pressure
D. pressures across the turbine
E. none of the above
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