Steam Boilers, Engines, Nozzles And Turbines MCQ Questions & Answers

Steam Boilers, Engines, Nozzles And Turbines MCQ Questions & Answers | Mechanical Engineering

Learn Steam Boilers, Engines, Nozzles And Turbines MCQ questions & answers are available for a Mechanical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Steam Boilers, Engines, Nozzles And Turbines MCQ question is the important chapter for a Mechanical Engineering and GATE students. Page-9 section-5

In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 mts. and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is

A) 40% B) 25% C) 50% D) 80%

Discuss

Answer & Solution

Answer: Option D

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One kg of steam sample contains 0.8 kg dry steam? Its dryness fraction is

A) 0.2 B) 0.8 C) 1.0 D) 0.6

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Answer & Solution

Answer: Option B

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Hard coke is produced by carburization of coal at

A) Atmospheric temperature B) 500-600°C C) 700-850°C D) 950-1100°C

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Answer & Solution

Answer: Option D

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When the back pressure of a nozzle is below the designed value of pressure at exit of nozzle, the nozzle is said to be

A) Choked B) Under-damping C) Over-damping D) None of these

Discuss

Answer & Solution

Answer: Option A

Solution:

When the back pressure of a nozzle is below the designed value of pressure at the exit of the nozzle, the flow through the nozzle reaches sonic conditions at the throat. This means that the flow velocity at the throat equals the speed of sound. At this point, any further decrease in back pressure will not increase the mass flow rate through the nozzle. This condition is known as choked flow.

In choked flow, the mass flow rate through the nozzle is at its maximum value for the given conditions, and further decreasing the back pressure will not increase the flow rate.

Therefore, when the back pressure of a nozzle is below the designed value of pressure at the exit of the nozzle, the nozzle is said to be choked.

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

A) Choked B) Under-damping C) Over-damping D) None of these

Discuss

Answer & Solution

Answer: Option A

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The maximum discharge of steam through a convergent-divergent nozzle depends upon

A) Area of nozzle at throat B) Initial pressure and volume of steam C) Final pressure of steam leaving the nozzle D) Both (A) and (B)

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Answer & Solution

Answer: Option D

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The variation of steam pressure in the nozzle depends upon

A) Velocity of steam B) Specific volume of steam C) Dryness fraction of steam D) All of these

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Answer & Solution

Answer: Option D

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The efficiency of an impulse turbine is maximum when (where V_b = Blade speed, V = Absolute velocity of steam entering the blade and α = Nozzle angle)

A) V_b = 0.5 V cosα B) V_b = V cosα C) V_b = 0.5 V²cosα D) V_b = V²cosα

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Answer & Solution

Answer: Option A

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

A) sin²α B) cos²α C) tan²α D) cot²α

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Answer & Solution

Answer: Option B

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