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4

The impulse turbine rotor efficiency will have a maximum value of 0.5 cos 2α, where α 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

Correct Answer :

C. Blades are equiangular and frictionless


Related Questions

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4

A turbine is said to have an axial discharge when the steam leaves the blade tip at _________ to the direction of the blade motion.

A. 60°

B. 90°

C. 180°

D. 270°

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4

Which of the following statement is correct for steam turbines as compared to reciprocating steam engines?

A. A steam turbine develops higher speeds

B. The efficiency of steam turbine is higher

C. The steam consumption is less

D. All of these

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4

The high pressure boiler is one, which produces steam at a pressure more than

A. Atmospheric pressure

B. 5 kg/cm²

C. 10 kg/cm²

D. 7580 kg/cm²

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4

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

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4

The diameter of a cylindrical shell of a Scotch marine boiler varies from

A. 1.5 to 2 m

B. 2.5 to 3.5 m

C. 3.5 to 4.5 m

D. None of these

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4

Over fire burning is the phenomenon of

A. Supply of excess, air

B. Supply of excess coal

C. Burning CO and unburnts in upper zone of furnace by supplying more air

D. Fuel bed firing

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4

The diameter of fire tube of Cornish boiler compared to its shell is

A. One half

B. One third

C. One fourth

D. One fifth

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4

The ultimate analysis of fuel lists

A. Various chemical constituents, carbon, hydrogen, oxygen etc, plus ash as percents by volume

B. Various chemical constituents, carbon, hydrogen, oxygen, etc, plus ash as percents by weight

C. Fuel constituents as percents by volume of moisture, volatile, fixed carbon and ash

D. Fuel constituents as percents by weight of moisture, volatile, fixed carbon and ash

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4

In water tube boilers

A. Water passes through the tubes which are surrounded by flames and hot gases

B. The flames and hot gases pass through the tubes which are surrounded by water

C. Forced circulation takes place

D. None of these

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4

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

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4

In which of the following boilers, the draught in furnace is increased by utilising exhaust steam from engine

A. Lancashire boiler

B. Locomotive boiler

C. Babcock and Wilcox boiler

D. Benson boiler

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4

A safety valve usually employed with stationary boilers is

A. Lever safety valve

B. Dead weight safety valve

C. High steam and low water safety valve

D. All of these

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4

Gusset stays in a boiler are provided to

A. Prevent the bulging of flat surfaces

B. Avoid explosion in furnace

C. Prevent leakage of hot flue gases

D. Support furnace freely from top

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4

In natural circulation type boiler,

A. Heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum

B. Water is supplied in drum and through down comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam

C. Feed pump is employed to supplement natural circulation in water wall type furnace

D. Water is converted into steam in one. Pass without any recirculation

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4

Which of the following is required for a steam condensing plant?

A. Condenser

B. Condensate pump

C. Air extraction pump

D. All of these

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4

Pulverised fuel is used for

A. Better burning

B. More calorific value

C. Less radiation loss

D. Medium sized units

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4

The ratio of the workdone on the blades to the energy supplied to the blades, is called

A. Blading efficiency

B. Nozzle efficiency

C. Gross or stage efficiency

D. Mechanical efficiency

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4

Hard coke is used in

A. Cement industry

B. Thermal power plant

C. Blast furnace

D. Domestic use

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4

The supersaturated flow of steam through a nozzle as compared to a stable flow, the available heat drop

A. Remains the same

B. Increases

C. Decreases

D. Is unpredictable

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4

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

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4

Which of the following substance will have same percentage in both proximate and ultimate analysis?

A. Ash

B. Volatile matter

C. Moisture

D. Hydrogen

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4

The critical pressure ratio for initially dry saturated steam is

A. 0.546

B. 0.577

C. 0.582

D. 0.601

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4

Lancashire boiler is of

A. Stationary < fire tube type

B. Horizontal type

C. Natural circulation type

D. All of the above

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4

Rateau turbine is

A. Simple reaction turbine

B. Velocity compounded turbine

C. Pressure compounded turbine

D. Pressure-velocity compounded turbine

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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

At very low temperature, the melting and boiling temperatures become equal. This temperature is

A. 373°K

B. 273.16°K

C. 303°K

D. 0°K

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4

Boiler H.P. is defined as the

A. Steam evaporation rate per kg of fuel fired

B. Work done in evaporating 1 kg of steam per hour from and at 100°C into dry saturated steam

C. The evaporation of 15.65 kg of water per hour from and at 100°C into dry saturated steam

D. Work done by 1 kg of steam at saturation condition

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4

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

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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

In turbines, the fluid undergoes a continuous steady flow process and the speed of flow is

A. Low

B. Very low

C. High

D. Very high