15.01 FUNDAMENTALS Flashcards by anika brigoli

What is the unit of Force, Work, Power, Mass, Energy Weight, Velocity and Acceleration?

Newtons
Joules
Watts
Kg
Joules
Newtons
m/s
m/s^2

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What is ‘g’?

The acceleration due to gravity

9.8m/s^2

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What are the formulae for:
- Weight
- Force
- Work
- Power
- PE
And KE?

Weight = mass x acceleration due to gravity
Force = mass x acceleration
Work = Force x distance
Power = Work/Time
PE = mass x acceleration due to gravity x height
KE = 0.5 x mass x velocity^2

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What is Newtons 1st Law of motion?

An body will remain at rest or a constant state of motion unless acted on by an external force

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What is Newtons 1st Law of motion otherwise known as?

The Law of Inertia

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What is Newtons 2nd Law of motion?

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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Which law describes the production of thrust?

Newtons 2nd Law of motion

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What is Newtons 3rd Law of motion otherwise referred to as?

The Law of Action and Reaction

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What does Newtons 3rd Law of Motion state?

Every action has an equal and opposite reaction.

If object A exerts a force on object B then object B must exert an equal and opposite force on object A

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Which of Newton’s laws relate to Gas Turbine Engines?

Newtons 2nd and 3rd law

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What are the two forms of mechanical energy?

Potential Energy and Kinetic Energy

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What is the working fluid of a Gas Turbine Engine?

Air

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What does GTE stand for?

Gas Turbine Engine

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What must happen to the air in order to create thrust?

The air must be accelerated

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How is the air in an engine accelerated? (3)

pressure energy is increased
addition of heat energy
final conversion back to kinetic energy in the form of a high velocity jet efflux

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What is the Brayton Cycle?

Process of a GTE

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What are the processes of a GTE?

Induction
Compression
Combustion
Exhaust

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What is another name for a piston engine?

Reciprocating engine

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What is the difference between the Brayton cycle and the reciprocating engine?

The reciprocating engine processes are intermittent (one after the other) whereas in a GTE the processes occur continuously

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What is an advantage of the GTE working continuously compared to the reciprocating engine?

Carries out the processes simultaneously shich enables more fuel to be burnt over a shorter period of time which produces a greater power for a given size of engine

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What is heating at a constant pressure otherwise known as?

Isobaric heating

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What are the peak pressures of piston engines undergoing isobaric heating?

In excess of 1000psi

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When would piston engines be suitable?

For smaller aircraft at lower altitudes

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What type of engine uses higher octane fuels?

Piston engine

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Besides thrust, what do the aircraft engines also supply?

Hydraulic Power Electrical Power Bleed Air for Pneumatics

What are the two types of aircraft engines?

Piston engines | GTE

What type of aircraft is more fuel efficient?

Piston engine

What are the different types of GTE? (4)

Turbojet Turbofan Turboprop APU

What type of GTE is mainly used on modern aircraft?

Turbofan

What is a characteristic of the turbofan?

Higher aircraft speeds possible with good engine efficiency

What were the first types of gas turbine engines used on aircraft?

Turbojets

What is a disadvantage of the turbojet?

Can be very loud due to high exhaust gas velocities and require too much fuel

What are turboprops specificallt designed for?

To produce shaft horsepower only which is used to drive the propeller

What are turboprops usually installed on?

Small commuter aircraft

What is the APU used for?

To supply the aircraft with electric and pneumatic power if the main engines are not available

What is an advantage of the APU?

It is independent of airport equipment

What is Jet Propulsion?

The propelling force generated in the opposite direction to the flow of mass through the jet nozzle

What is an engine using jet propulsion otherwise known as?

Reaction engine

What law does jet propulsion relate to?

Newtons erd Law of motion

Which engine is likely to be more efficient, turbojet or turbofan?

Turbofan

How does a turbojet create thrust?

Accelerates a small quantity of ambient air to a high velocity

What is the purpose of a turbojet?

Designed to produce high velocity gases

How does a turboprop create thrust?

A small acceleration of a large quantity of air with a propeller

What is always required with a turboprop and why?

A reduction gear to reduce the high gas turbine engine rotation to speeds that the propeller can manage

What ar esome advantages of turboprops to turbo jets?

Easier to start | More efficient

What is a disadvantage of a turboprop?

Propellers do not permit high aircraft speeds

What is the difference between a turbo fan and a turboprop? (2)

- Instead of a prop, the turbo fan includes a fan enclosed in a casing - Turbofan does not require a reduction gear to reduce the speed of the fan

What is the fan always driven by in a turbofan engine?

The turbine via a drive shaft

How does a turbofan create thrust?

Fan accelerates a high airflow to a relatively low outlet velocity

What is the total thrust of a turbofan engine equal to?

The sum of the thurst developed by the core engine and the fan

How much more total thrust can a turbofan produce?

More than 80%

What is the increased total thrust by the fan primarily dependent on?

The bypass ratio

What produces the most thrust on a turbofan?

Fan

What is the bypass ratio?

The ratio thatbpasses through thr fan duct compared to the air that passes through the core engine

On modern fan engines what is the bypass ratio?

Between 4.1 and 9.1

Which type of GTE gives the most thrust?

Turbojet

What is an advantage of a prop-fan?

Using up to 20% less fuel than high bypass engines as they have a bypass ratio of 90:1

Why are prop-fans not used on modern jet aircraft?

Difficult to mount

What are the 2 types of constructions?

Modular | Non-modular

What does modular mean?

Built in modules

Turbofan engines are normally what type of construction?

Modular

What type of construction are modern engines?

Modular

What is an advantage of non-modular engines?

Saves weight with the same functions as a modular construction

What are modular engine constructions specifically designed to do?

Remove and be replaced easily

What does the number of modules depend on?

The manufacturer and the engine type

What are some advantages of a modular engine construction for the engine manufacturer? (4)

- the rotating module parts can be pre-balanced - less spare engines are needed in stock - more flexibility when changes are made to individual parts - main engine modules can be easily stored and transported

What are some advantages for the engine operator if modular engine constructions are being used? (4)

- modules can be removed and replaced with minimum disturbance to nearby engine parts - no re-balancing is required after a module change - most modules can be rellaced while the engine remains on the aircraft - less need for spare parts and the modules are easily transported

What are the major engine modules? (4)

Fan module Core module Accessory drive module Low pressure turbine module

What are the different types of materials used for different parts of the engine? (7)

- aluminium alloy - ceramic material - composite material - cobalt base alloy - nickel base alloy - CRES - titanium base alloy

What qualities should engine material have?

Strong enough for individual tasks but cheap and light enough

What parts of the engine are mainly made of Aluminium Alloy? (3)

Main gear box Fan exit case Fan case

What material is used to make the Flow Path Liner, outlet guide vanes and soinner cone?

Composite material

What parts of the engine are made of Ceramic material? (2)

Diffuser case and combuster | High pressure turbine

What material is the turbine exhaust case, N1 drive shaft and engine bearings made of?

CRES

Where can cobalt base alloys be found in the engine? (2)

Stators of the first stage high pressure turbine | Turbine nozzle

What parts of the engine is made of titanium base alloys? (3)

Fan Low pressure compressor High pressure compressor

What are nickel base alloys good at doing?

Withstanding high centrifugal loads at high temperatures

What parts of the engine are made of Nickel base alloys? (4)

HPC Diffuser case and combuster HPT LPT

What is the low pressure drive shaft otherwise known as?

What is titaniums advantages (1) and disadvantages (1)?

- lighter but has the same strength as steel | - more expensive