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ENGINEERING, AE 2018 HSC 11 MC

What is the most appropriate propulsion system for a long-haul commuter aircraft?

  1. Ramjet
  2. Scramjet
  3. Turbofan
  4. Turboprop
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`C`

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By Elimination:

→ Ramjet and scramjet propulsion systems are both used for aircraft travelling at high speeds, such as rockets or military aircraft (eliminate `A` and `B`).

→ Turboprop propulsion systems are used for smaller planes at lower speeds, altitudes and distances and would not be suited for long haul flights or high commuter payloads (eliminate `D`)

`=>C`

ENGINEERING, AE 2018 HSC 25a

Describe the basic operational principles of jet propulsion. Use a labelled sketch to support your answer.   (3 marks)

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→ Intake air is compressed to a point where it’ s temperature is greater than the ignition point of the fuel.

→ The combustion chamber receives the atomised fuel and through expansion generates a higher velocity gas.

→ Thrust is generating when the high velocity gas is expelled through the exhaust.
 

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→ Intake air is compressed to a point where it’ s temperature is greater than the ignition point of the fuel.

→ The combustion chamber receives the atomised fuel and through expansion generates a higher velocity gas.

→ Thrust is generating when the high velocity gas is expelled through the exhaust.
 

ENGINEERING, AE 2019 HSC 10 MC

The diagram shows the airflow in a venturi.
 

What does this diagram illustrate?

  1. Coriolis effect
  2. Pascal's principle
  3. Dynamic pressure
  4. Bernoulli's principle
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`D`

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→ Bernoulli’s principle states that the higher the pressure is, the lower the velocity will be.

→ This is illustrated in the diagram as it shows that there is a decreased pressure in the thinner, higher velocity section.

`=>D`


♦ Mean mark 55%.

ENGINEERING, AE 2020 HSC 19 MC

Turbofan engines are generally more fuel efficient than turbojet engines.

What causes this efficiency?

  1. Smaller intake area
  2. Higher combustion temperatures
  3. Air bypassing the combustion system
  4. Air directly entering the combustion area
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`C`

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→ Turbofans accelerate higher masses of air than a turbojet without burning additional fuel due to their additional fan.

→ This increases thrust and fuel efficiency.

→ The fan does this by forcing additional air to bypass the engine, increasing its velocity without excessive use of fuel.

`=>C`


Mean mark 51%.