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Current Affairs January 2024

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4

The maximum efficiency of a De-Laval turbine is (where α = Nozzle angle)

A. sin²α

B. cos²α

C. tan²α

D. cot²α

Correct Answer :

B. cos²α


Related Questions

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4

For the same diameter and thickness of tube, a water tube boiler compared to a fire tube boiler has

A. More heating surface

B. Less heating surface

C. Equal heating surface

D. Heating surface depends on other parameters

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4

A compound steam engine in which the high pressure and low pressure cylinders have common piston rod, is called

A. Receiver type compound engine

B. Tandem type compound engine

C. Woolf type compound engine

D. None of these

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4

The fittings mounted on the boiler for its proper and safe functioning is a

A. Water level indicator

B. Pressure gauge

C. Safety valve

D. All of these

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4

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. 225.6 kg/cm²

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4

The clearance in the engine cylinder

A. Increases the mean effective pressure

B. Increases the workdone

C. Decreases the efficiency of the engine

D. All of these

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4

During polytropic process

A. Heat transfer takes place across cylinder walls

B. Work is done

C. Steam may be wet, dry or superheated after expansion

D. All of the above

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4

The function of a piston in a steam engine is

A. To guide motion of the piston rod and to prevent it from bending

B. To transfer motion from the piston to the crosshead

C. To convert heat energy of the steam into mechanical work id) to exhaust steam from the cylinder at proper moment

D. None of these

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4

The device attached to the steam chest for preventing explosions due to excessive internal pressure of steam is called

A. Safety valve

B. Water level indicator

C. Pressure gauge

D. Fusible plug

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4

A vessel into which the steam is exhausted and condensed after doing work in an engine cylinder or turbine is known as

A. Steam condenser

B. Steam boiler

C. Steam preheater

D. Economiser

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4

An ideal regenerative cycle is

A. Equal to Carnot cycle

B. Less than Carnot cycle

C. More than Carnot cycle

D. Could be anything

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4

The function of an eccentric rod is

A. To provide reciprocating motion to the slide valve

B. To convert reciprocating motion of the piston into rotary motion of the crank

C. To convert rotary motion of the crankshaft into to and fro motion of the valve rod

D. To provide simple harmonic motion to the D-slide valve

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4

The cylinder condensation or missing quantity may be reduced by

A. The efficient steam jacketing of the cylinder walls

B. Superheating the steam supplied to the engine cylinder

C. Keeping the expansion ratio small in each cylinder

D. All of the above

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4

The fire tubes in a Locomotive boiler has _________ diameter.

A. 4.75 mm

B. 5.47 mm

C. 7.45 mm

D. 47.5 mm

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4

Fire tube boilers are limited to a maximum working pressure of

A. 0.17 MN/m²

B. 1.7 MN/m²

C. 17 MN/m²

D. 170 MN/m²

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4

Expansion ratio is the ratio of

A. Swept volume to the volume at cut-off

B. Clearance volume to the swept volume

C. Volume at cut-off to the swept volume

D. Swept volume to the clearance volume

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4

A single stage impulse turbine with a diameter of 1.2 m runs at 3000 r.p.m. If the blade speed ratio is 0.42, then the inlet velocity of steam will be

A. 79 m/s

B. 188 m/s

C. 450 m/s

D. 900 m/s

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4

Which of the following statement is correct?

A. The efficiency of steam turbines is greater than steam engines

B. A flywheel is a must for steam turbine

C. The turbine blades do not change the direction of steam issuing from the nozzle

D. The pressure of steam, in reaction turbines, is increased in fixed blades as well as in moving blades

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4

A condenser where circulating water flows through tubes which are surrounded by steam, in known as

A. Surface condenser

B. Jet condenser

C. Barometric condenser

D. Evaporative condenser

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4

In a throttling process

A. Heat transfer takes place

B. Work is done by the expanding steam

C. Internal energy of steam changes

D. None of the above

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4

Pour point of fuel oil is the

A. Lowest temperature at which oil will flow under set condition

B. Storage temperature

C. Temperature at which fuel is pumped through burners

D. Temperature at which oil is transported

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4

The reheat factor is the ratio of the

A. Cumulative heat drop to the isentropic heat drop

B. Isentropic heat drop to the heat supplied

C. Total useful heat drop to the total isentropic heat drop

D. None of the above

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4

The draught in locomotive boilers is produced by a

A. Chimney

B. Centrifugal fan

C. Steam jet

D. None of these

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4

In a velocity compounded impulse turbine, when steam flows through the second row of moving blades,

A. Velocity increases

B. Velocity decreases

C. Velocity remains constant

D. Pressure remains constant

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4

The radius of a dished head is taken approximately as

A. One fourth

B. Half

C. One

D. Two

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4

The ratio of the energy required to produce the artificial draught (expressed in metres head or J/kg of flue gas) to the mechanical equivalent of extra heat carried away per kg of flue gases due to natural draught, is known as

A. Efficiency of the boiler

B. Efficiency of the chimney

C. Efficiency of the fan

D. Power of the boiler

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4

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

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4

Natural water circulation, by convection in water tube boilers, with increase in pressure of boiler

A. Increases

B. Decreases

C. Remain unaffected

D. First increases and then decreases

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4

The pressure velocity compounded impulse turbine allows a bigger pressure drop and hence __________ numbers of stages are required.

A. More

B. Less

C. Equal

D. None of these

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4

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

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4

In a Parson's turbine stage, blade velocity is 320 m/s at the mean radius and rotor blade exit angle is 30°. For minimum kinetic energy of the steam leaving the stage, the steam velocity at the exit of the rotor will be

A. 160/3 m/s

B. 320/3 m/s

C. 640/3 m/s

D. 640 m/s