Compressors, Gas Turbines And Jet Engines MCQ Questions & Answers

31

A machine used to raise the pressure of air is called

A) Gas turbine B) I.C engine C) Compressor D) Air motor

Discuss

Answer & Solution

Answer: Option C

Solution:

A machine used to raise the pressure of air is called Compressor

32

The efficiency of jet engine is

A) Lower at low speed B) Higher at high altitudes C) Same at all altitudes D) Higher at high speed

Discuss

Answer & Solution

Answer: Option B

Solution:

The efficiency of jet engine is Higher at high altitudes

33

The volume of air delivered in a medium capacity air compressor per unit time is

A) 0.1 to 1.2 m³/s B) 0.15 to 5 m³/s C) Above 5 m³/s D) None of these

Discuss

Answer & Solution

Answer: Option B

Solution:

The volume of air delivered in a medium capacity air compressor per unit time is 0.15 to 5 m³/s

34

The inter-cooler pressure, for minimum work required, for a two stage reciprocating air compressor, is given by (where p₁ = Intake pressure of air, p₂ = Inter-cooler pressure and p₃ = Delivery pressure of air)

A) $${{\text{p}}_2} = {{\text{p}}_1} \times {{\text{p}}_3}$$ B) $${{\text{p}}_2} = \frac{{{{\text{p}}_1}}}{{{{\text{p}}_3}}}$$ C) $${{\text{p}}_2} = \sqrt {{{\text{p}}_1} \times {{\text{p}}_2}} $$ D) $${{\text{p}}_2} = \frac{{{{\text{p}}_3}}}{{{{\text{p}}_1}}}$$

Discuss

Answer & Solution

Answer: Option C

Solution:

The inter-cooler pressure, for minimum work required, for a two stage reciprocating air compressor, is given by $${{\text{p}}_2} = \sqrt {{{\text{p}}_1} \times {{\text{p}}_2}} .$$
Where p₁ = Intake pressure of air, p₂ = Inter-cooler pressure and p₃ = Delivery pressure of air.

35

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

Discuss

Answer & Solution

Answer: Option C

Solution:

Atmospheric pressure is 1.03 kg/cm and vapour pressure is 0.03 kg/cm. The air pressure will be 1.00 kg/cm².

36

For perfect intercooling in a three stage compressor

A) $$\frac{{{{\text{p}}_2}}}{{{{\text{p}}_1}}} = \frac{{{{\text{p}}_3}}}{{{{\text{p}}_2}}} = \frac{{{{\text{p}}_4}}}{{{{\text{p}}_3}}}$$ B) $$\frac{{{{\text{p}}_3}}}{{{{\text{p}}_1}}} = \frac{{{{\text{p}}_4}}}{{{{\text{p}}_2}}}$$ C) $${{\text{p}}_1}{{\text{p}}_2} = {{\text{p}}_3}{{\text{p}}_4}$$ D) $${{\text{p}}_1}{{\text{p}}_3} = {{\text{p}}_2}{{\text{p}}_4}$$

Discuss

Answer & Solution

Answer: Option A

Solution:

For perfect intercooling in a three stage compressor $$\frac{{{{\text{p}}_2}}}{{{{\text{p}}_1}}} = \frac{{{{\text{p}}_3}}}{{{{\text{p}}_2}}} = \frac{{{{\text{p}}_4}}}{{{{\text{p}}_3}}}$$

37

For perfect intercooling in a two stage compressor

A) $$\frac{{{{\text{p}}_2}}}{{{{\text{p}}_1}}} = \frac{{{{\text{p}}_3}}}{{{{\text{p}}_2}}}$$ B) $$\frac{{{{\text{p}}_1}}}{{{{\text{p}}_3}}} = \frac{{{{\text{p}}_2}}}{{{{\text{p}}_1}}}$$ C) $${{\text{p}}_1} = {{\text{p}}_3}$$ D) $${{\text{p}}_1} = {{\text{p}}_2}{{\text{p}}_3}$$

Discuss

Answer & Solution

Answer: Option A

Solution:

For perfect intercooling in a two stage compressor $$\frac{{{{\text{p}}_2}}}{{{{\text{p}}_1}}} = \frac{{{{\text{p}}_3}}}{{{{\text{p}}_2}}}$$

38

The weight per horse power ratio for gas in Turbine as compared to I.C. engine and steam turbine is

A) Same B) Higher C) Lower D) None of these

Discuss

Answer & Solution

Answer: Option C

Solution:

The weight per horse power ratio for gas in Turbine as compared to I.C. engine and steam turbine is lower

39

The volume of air sucked by the compressor during its suction stroke is called

A) Free air delivery B) Compressor capacity C) Swept volume D) None of these

Discuss

Answer & Solution

Answer: Option C

Solution:

The volume of air sucked by the compressor during its suction stroke is called Swept volume

40

A centrifugal compressor works on the principle of

A) Conversion of pressure energy into kinetic energy B) Conversion of kinetic energy into pressure energy C) Centripetal action D) Generating pressure directly

Discuss

Answer & Solution

Answer: Option B

Solution:

So, in a compressor, first additional kinetic energy is imparted to the fluid with the help of a rotating impeller. ... So like this, pressure of a fluid is increased in a centrifugal compressor. So basically it works on the principle of conversation of kinetic energy into pressure energy.

Compressors, Gas Turbines And Jet Engines MCQ Questions & Answers | Mechanical Engineering