M15.01 Fundamentals Flashcards
Acceleration which is due to gravity is denoted by?
g
Earths gravitational speed is?
9.8m/s2
Weight is measured in?
Newtons
The unit of work is?
Joules (J)
1J = ?Nm
1Nm
What is Power?
The rate of doing work
What is the equation for power?
Power = work/ time (w)
Describe what potential energy is?
The energy a body has by virtue of its position
Explain what kinetic energy is?
The energy a body has by virtue of its motion
Equation of kinetic energy?
KE = 1/2mV2(squared)
Newton’s first law is called?
Law of inertia
What is Newton’s first law?
A body a rest remains at rest and a body remains in motion unless acted upon by an external force
What is newtons 2nd law?
Acceleration produced in a mass by a force acting in is directly proportional to the force and inversely proportional to the mass Force = mass x acceleration
Formula for force?( N)
Force = mass x acceleration
Newtons 3rd law?
Every action has an equal and an opposite
What does GTE stand for?
Gas turbine engine
The gas turbine engine is essentially?
A heat engine using air as a working fluid to provide thrust
What is the Brayton cycle?
The working cycle of a gas turbine engine
What’s the 4 processes of a engine?
. Induction
. Compression
. Combustion
. Exhaust
Piston engines have a peak pressure in excess of?
1000psi
Apart from thrust what else does an engine provide?
. Bleed air
. Hydraulic power
. Electrical power
What are the two different types of aircraft engines?
. Piston type engines
. Gas turbine engines
What are the 4 different types of turbine gas engines?
. Turbofan engine
. Turbojet engine
. Turboprop engine
. APU (auxiliary power unit)
An engine that uses jet propulsion is called?
A reaction engine
What newtons law does a reaction engine use?
Newton’s law of motion - every force has an equal and opposite reaction
Which engine is likely to be more efficient?
A turbofan has the highest efficiency (85%)
How does a turboprop create thrust?
By a small acceleration of a large mass of air
Pressure of air during combustion does what?
Doesn’t rise during combustion
The combustion process is known as?
. Heating at a constant pressure
. isobaric heating
What stroke is a piston engine?
One stroke
How many processes does a gas turbine engine do?
4 processes simultaneously
What’s the main function of an engine?
Create movement of the aircraft
Advantages of piston type engines?
. Simple design
. More fuel efficient
A disadvantage of a piston type engine?
. Performance decreases at high altitudes
. Too large
What aircraft are piston engines used on?
Very small aircraft
Gas turbine engines can operate at?
Very high altitudes
What’s the equation for force?
Force = mass x acceleration
What type of engine is used in modern aircraft?
Turbofan engine
Why do most modern aircraft use a turbofan engine?
As it makes high aircraft speeds possible with good engine efficiency
Why do turbojet engines not get used as much anymore?
. Very loud
. Requires too much fuel
What do turboprob engines drive?
Drives a propeller to produce shaft horse power only
What is the purpose of the APU?
Supply’s aircraft with electric and pneumatic power if main engines aren’t available
What two ways can you accelerate air (air pressure)?
. Mechanically by a compressor
. Thermally by increasing volume of air with fuel/heat is burned
Turboprop engines produce their thrust by?
A small acceleration of a large quantity of air with a propellor
What’s the main disadvantage of a turboprop engine?
Doesn’t permit high aircraft speeds
How many spools does a turbofan engine normally have?
Twin or triple spool
What’s required to reduce the high gas turbine engine rotation on a turboprop engine?
Reduction gear
Why are turboprop engines very efficient?
As they convert all of their gas energy to torque
A turbofan engine is similar to a turboprop engine, but instead of the propellor it has?
A fan enclosed in a casing
Where does the total thrust of the turbofan come from?
The sum of core engine and fan thrust
What does EGT mean?
Exhaust gas temperature
On a turbofan what % of total thrust comes from the fan?
80%
(Depending on the bypass ratio)
What is the bypass ratio?
The ratio of air that passes through the fan duct compared to the core engine
What modern turbofan engines what is the bypass ratio?
Between 4:1 and 9:1
What is the latest engine research about?
. Open rotor engines
. Propfans
What are the two different methods of engine construction design?
. Non modular
. Modular engine
Where is a non modular deign normally found?
. older engine construction
. Some APUs
What were the advatanges of a non modular engines?
. Saved weight
. Fully functional
What were the disadvantages of a non modular engine?
. Design was complicated
. Parts difficult to access
. Engine removed to access a single part
What are the main advantages of a modular construction?
. Whole engine split up into separate major modules
. Pre assembled and balanced
. Specially designed for removal and replace easily
What are the advantages for the manufacture for modular engines??
. Rotating parts can be pre balanced
. Less spare engines needed in stock
. More flexibility when changes made to engine parts
. Easily stored and transported
What is the main design aim fit the materials used within an engine?
. Cheap
. Strong
. Lightweight
Aluminium alloy is mainly used for?
. Gearbox housing
. Fan stator casings
. Low loaded parts
Where are ceramic coatings used??
In the combustion and high pressure turbine
Titanium alloys are as strong as steel but?
. weight half its amount
. Can take high centrifugal loads
. But expensive
Where are titanium materials used?
. Fan
. Low pressure compressor
. Front stages of HP compressor
Where are nickel base alloys used?
. HP compressor
. Combustion section
. High and low pressure turbine
What’s the main advantage of a cobalt material?
Highly heat resistant
