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Module 15 - Gas Turbine Engines > 15.1 - Fundamentals > Flashcards

15.1 - Fundamentals Flashcards

1
Q

What is Entropy?

A

A quantitive measure of energy unavailable to do work (energy lost in a system). It always increases.

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2
Q

What are turbofan engines also known as?

A

Bypass engines

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3
Q

What is Boyle’s law?

A

The volume of a given mass of gas at a constant temperature is inversely proportional to pressure.

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4
Q

What is Charles’ law?

A

The volume of a given mass of gas at constant pressure increases 1/273 of its volume at 0°C for every 1°C rise in temperature.

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5
Q

What is an isobaric process?

A

One of constant pressure

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6
Q

What is an isothermal process?

A

One of constant temperature

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7
Q

What is an isochoric process?

A

One of constant volume

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8
Q

What is the equation for potential energy?

A

E = mgh

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9
Q

What is the equation for kinetic energy?

A

E = 1/2 mv^2

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10
Q

What is the equation of force?

A

F = ma

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11
Q

What is one metric horsepower equivalent to?

A

736watts or
736J/s (joules per second)

The power required to lift 75kg, 1 metre in 1 second

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12
Q

What is the equation for work done?

A

Work done = force x distance

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13
Q

What is Newton’s first law of motion?

A

A body at rest stays at rest unless acted on by an external force

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14
Q

What is Newton’s second law of motion?

A

The rate of change of momentum of a body over time is directly proportional to the force applied (F=ma)

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15
Q

What is Newton’s third law of motion?

A

To every action there is an equal and opposite reaction.

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16
Q

What is the Brayton cycle also known as?

A

The gas turbine cycle

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17
Q

What is the universal gas law?

A

P1 V1 P2 V2

T1 T2

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18
Q

What is the Brayton cycle?

A

The gas turbine cycle. A cycle of continuous combustion. The pressure only marginally drops during combustion. The pressure changes are caused by changes in the velocity of the air.

19
Q

What does a convergent duct do to subsonic gas?

A

Increase velocity, decrease static pressure

20
Q

What does a divergent duct do to subsonic gas?

A

Decrease velocity, increase static pressure

21
Q

What is a choked nozzle?

A

The one exception to the gas flow rules. When the gas is flowing at the speed of sound (sonic velocity) just before it enters a divergent duct; it is impossible to increase the speed any further to supersonic and the nozzle is said to be choked.

22
Q

Approximately how much nitrogen is in a parcel of air at sea level?

A

12 PSI of nitrogen

23
Q

What is the equation for thrust?

A

F = W(Vjet - Vflight)

24
Q

What is adiabatic compression?

A

Compression without the loss or gain of heat

25
Q

Where is the diffuser located?

A

It’s located between the compressor section and the burner section

26
Q

What is the working fluid of a gas turbine engine?

A

Air

27
Q

What happens to air density if pressure and temperature remains constant, but humidity increases?

A

It decreases (less thrust can be produced)

28
Q

Which law relates to the kinetic, pressure and potential energy in a fluid flow?

A

Bernoulli’s theorem

29
Q

What is the purpose of the diffuser in a jet engine?

A

It increases the static pressure of the air before combustion

30
Q

What is the density of gas expressed as in regards to weight and volume?

A

Density = Weight/Volume

31
Q

What is the purpose of a waisted drive shaft?

A

It provides a fuse if the driven component is overloaded

32
Q

What is 1 CHU equal to in ft. lb?

A

778 ft.lb

33
Q

If the LP shaft shears, what happens to the turbine?

A

Turbine runaway occurs

34
Q

What does Nf indicate in a free power turbine dual axial flow compressor system?

A

Free power turbine speed

35
Q

Which section provides proper mixing of the fuel and efficient burning of the gases?

A

The combustion section

36
Q

How is the turbine shaft usually joined to the compressor rotor of a centrifugal compressor?

A

By a splined coupling

37
Q

What part of a jet engine has the most POTENTIAL energy?

A

Just before the combustion chamber

38
Q

Where is the highest PRESSURE in a gas turbine?

A

Just after the last compressor stage, just before the burner

39
Q

What part of a gas turbine engine produces the most amount of DISCREET noise?

A

The turbine

40
Q

As an aircraft climbs, what factor IMPROVES with altitude?

A

The specific fuel consumption

41
Q

What, on an aircraft makes an engine’s compressor stall more likely to be induced during rapid altitude changes?

A

Engine intakes mounted close to the fuselage

42
Q

Why is a modular engine more favourable?

A

It provides total interchangeability of all modules

43
Q

What happens to pressure, temperature and velocity of air in the turbine stages?

A

Temperature, velocity and pressure decrease

Module 15 - Gas Turbine Engines (22 decks)

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