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M15 B1 > 15.1 Fundamentals > Flashcards

15.1 Fundamentals Flashcards

1
Q

What is the definition of energy?

A

Energy is typically defined as something that gives us the capacity to perform work.

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2
Q

What are the two types of energy?

A
  • Potential
  • Kinetic
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3
Q

Define Potential Energy.

A

Potential energy is defined as being energy at rest, or energy that is stored.

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4
Q

List the three groups of Potential Energy.

A
  • Due to position
  • Due to distortion of an elastic body
  • Through chemical action
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5
Q

What is the formula for calculating Potential Energy?

A

PE = mgh

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6
Q

What does ‘m’ represent in the Potential Energy formula?

A

Mass (in kilograms)

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7
Q

What does ‘g’ represent in the Potential Energy formula?

A

Gravitational acceleration of the Earth (9.8 m/sec²)

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8
Q

What does ‘h’ represent in the Potential Energy formula?

A

Height above Earth’s surface (in metres)

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9
Q

Define Kinetic Energy.

A

Kinetic energy is defined as being energy in motion.

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10
Q

What is the formula for calculating Kinetic Energy?

A

KE = 1/2 mv²

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11
Q

What is Newton’s First Law of Motion?

A

A body at rest remains at rest and a body in motion continues to move at a constant velocity unless acted upon by an unbalanced external force.

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12
Q

What is Newton’s Second Law of Motion?

A

The acceleration produced in a mass by a force acting on it is directly proportional to the force and inversely proportional to the mass.

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13
Q

What is the formula for Newton’s Second Law?

A

Force = Mass x Acceleration

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14
Q

What is Newton’s Third Law of Motion?

A

Every action has an equal and opposite reaction.

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15
Q

What is the Brayton Cycle?

A

The thermodynamic cycle of a gas turbine engine that produces thrust, characterized as a variable-volume constant pressure cycle.

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16
Q

List the four stages of the Brayton Cycle.

A
  • Intake (suck)
  • Compression (squeeze)
  • Expansion (bang)
  • Exhaust (blow)
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17
Q

What happens during the intake stage of the Brayton Cycle?

A

Air enters at ambient pressure and leaves at increased pressure and decreased volume.

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18
Q

What occurs during the compression stage of the Brayton Cycle?

A

Air is compressed, resulting in a large increase in pressure and a decrease in volume.

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19
Q

Define isobaric change of state.

A

A process carried out where pressure (p) is constant.

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20
Q

Define isochoric change of state.

A

A process carried out where volume (v) is constant.

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21
Q

Define isothermal change of state.

A

A process carried out where temperature (t) is constant.

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22
Q

Define isentropic change of state.

A

A process carried out in an adiabatic system where neither heat addition nor heat rejection is possible.

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23
Q

Which changes of state are important for gas turbine engines?

A
  • Isobaric
  • Isentropic
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24
Q

What is represented by Point 0 in the pressure-volume diagram for a turbojet engine?

A

Atmospheric conditions - air with both atmospheric pressure and temperature.

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25
What does the process from 0 to 2 in the PV diagram represent?
Isentropic compression of the air.
26
What happens during the process from 2 to 3 in the Brayton Cycle?
Isobaric heating occurs as heat is added to the air at constant pressure.
27
What does the line from 3 to 5 in the Brayton Cycle represent?
Isentropic expansion process where gases expand through the turbine.
28
What is the result of the exhaust process in the Brayton Cycle?
Conversion of expanding volume and decreasing pressure gases to a final high velocity, creating thrust.
29
What is force?
Force is the intensity of a thrust or the intensity of an input.
30
What is the unit for force in the English system?
Pounds (lbs)
31
What is the unit for force in the metric system?
Newtons (N)
32
How many newtons are equal to one pound of force?
4.448 newtons
33
What must be applied for work, power, or torque to exist?
A force
34
What is work?
Work is done when a force is moved through a distance in the direction of the force.
35
What is the SI unit of work?
Joule (J)
36
What is work a measure of?
The energy transferred during the process
37
What two factors are involved in calculating work?
* Force * Movement through a distance
38
What is the formula for calculating work?
force x distance
39
What is power?
The rate of doing work.
40
What is the SI unit of power?
Watt (W)
41
What is horsepower?
An old unit of power replaced by Watts and kilowatts in the SI system.
42
What defines motion?
A continuing change of position or place.
43
What is uniform motion?
Motion where the distance moved remains the same for a given period of time.
44
What is speed?
How fast an object is moving, or how far it travels in a specific time.
45
What is the difference between speed and velocity?
Speed does not include direction, while velocity describes both speed and direction.
46
What is acceleration?
The rate of change of velocity.
47
How is acceleration calculated?
Acceleration (M/S^2) = CHANGE IN VELOCITY (M/S) DIVIDED BY TIME (s)
48
What is a vector?
A quantity represented by a line of specific length, having an arrow indicating direction.
49
What is a resultant vector?
The remaining vector when two velocity vectors are added together.
50
What happens to an object's velocity if it increases from 20 mph to 30 mph?
The object has been accelerated.
51
Fill in the blank: The SI unit of work is _______.
Joule (J)
52
True or False: Velocity is a scalar quantity.
False
53
What is the main function of an aircraft engine?
To create the necessary movement of the aircraft ## Footnote In addition, it supplies hydraulic power, electric power, and bleed air for the pneumatic system.
54
What are the two different types of aircraft engines?
* Piston type engines * Gas turbine engines
55
What is a significant disadvantage of piston type engines compared to gas turbine engines?
Performance decreases at higher altitudes
56
What are the four types of gas turbine engines used on aircraft?
* Turbojet engines * Turbofan engines * Turboprop engines * Turboshaft engines
57
What is a key characteristic of turbojet engines?
High aircraft speeds but very loud due to high exhaust gas velocities
58
What major issue limits the use of pure turbojet engines?
Problems with noise and fuel consumption in the speed range of 0.8 Mach
59
What is the basic operation of a turbojet engine?
A turbine-driven compressor draws in air, compresses it, mixes it with fuel in a combustion chamber, ignites it, and expels gases through a nozzle for thrust.
60
List the advantages of turbojet engines.
* Relatively simple design * Capable of very high speeds * Takes up little space
61
List the disadvantages of turbojet engines.
* High fuel consumption * Loud * Poor performance at slow speeds * Limited in range and endurance
62
What makes turbofan engines an improvement over turbojet engines?
They enable high speeds with better engine efficiency and reduced noise.
63
What percentage of thrust do turbofan engines produce from the large fan?
About 80%
64
What are the two arrangements of turbofan engines?
* Twin spool arrangement * Three spool arrangement
65
What are the advantages of turbofan engines?
* Fuel efficient * Quieter than turbojets * Streamlined appearance
66
What are the disadvantages of turbofan engines?
* Heavier than turbojets * Larger frontal area than turbojets * Inefficient at very high altitudes
67
What is the primary function of turboprop engines?
To produce shaft horsepower to drive a propeller.
68
What is the typical operational speed range for turboprop engines to be most efficient?
Between 250 - 400 knots
69
List the advantages of turboprop engines.
* Very fuel efficient * Most efficient at mid-range speeds * Most efficient at mid-range altitudes of 18,000 - 30,000 feet
70
What are the disadvantages of turboprop engines?
* Limited forward airspeed * Gearing systems are heavy and can break down
71
What is the main purpose of a turboshaft engine?
To produce shaft power to drive machinery instead of producing thrust.
72
Where are turboshaft engines commonly used?
* Helicopters * Auxiliary Power Units (APUs)
73
What is a key difference between turboshaft and turbojet engines?
Turboshaft engines have an additional power section with turbines and an output shaft.
74
List the major components of a typical gas turbine engine.
* Air inlet * Compressor section * Combustion section * Turbine section * Exhaust section * Accessory section
75
What are the two sections of a gas turbine engine referred to?
* Cold section * Hot section
76
What is a major advantage of modular engine construction for manufacturers?
Fewer spare engines are needed in stock
77
What is a benefit of modular construction for engine operators?
Modules can be replaced with minimum disturbance to other nearby engine parts
78
What materials are commonly used in modern jet engines?
* Aluminium alloy * Ceramic material * Composite material * Cobalt base alloy * Nickel base alloy * Corrosion resistant steel alloy * Titanium base alloy
79
What material is mainly used for gearbox housings and fan stator casings?
Aluminium alloy
80
What is the benefit of using ceramic coatings in jet engines?
Heat and corrosion protection
81
What is the significance of nickel base alloys in jet engines?
They can withstand high centrifugal loads at high temperatures.

M15 B1 (22 decks)

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