Chap 1- Engine Principles Flashcards
Newton’s third law
For every force acting on a body there is an equal and opposite reaction
What model was used in the history of jet propulsion
Aero themo dynamic duct
Modern day jet propulsion
Ram jet
How do Propel and jet produce thrust
Comes from thrusting backwards a large weight of air
What does a jet propulsion engine achieve
Accelerates a stream of air or gas and to expel at high velocity
What must the propeller engine be carefull off with regards to blade speed
It is kept below mach 1
What are the 5 types of jet engines
A. Rocket
B. Ram jet
C. Pulse jet
D. Tube jet/gas turbine engine
E. Turbo shaft
What jet engine is this :
Slef contained fuel/air mixture
When burnt exhaust is fed through an outlet nozzle no air needed
Rocket
What jet engine is this :
Consists of divergent entry or convergent
Or convergent/divergent exit
No rotating parts
Ram jet
What jet engine is this :
Similar to ATHODYD but with an added shutter system that help build pressure for combustion
Pulse jet
What jet engine is this :
Rotating components inside an ATHODYD that facilitates high pressure rise
Turbo jet/gas engine
What jet engine is this :
Gas turbine engine that is used to drive rotating component rather than being used for thrust
Turbo shaft
Look at the parts turbo jet engine
Basic layout photo of the gas turbine engine
What is a single spool and how does it work
Single shaft to the compressor
Number of turbine stages depends on power required to drive compressor
What is the highest amount of spool you can have
Triple spool
Multi spool what is it how does it work
For engines with more than one compressor
Spool require a separate turbine for each of the spools
Each spool named after the lvl of pressure:
LP - low pressure
IP - intermediate pressure
HP - high pressure
By pass what does it do
Allows a percentage of compressor air to flow around the outside the remainder of the engine
Designed to let over 50% = High by pass
Allow less than 50% = low by pass
What can the by pass assist in
Noise reduction
Reduce fuel consumption
What are the drive path configurations
Direct coupled turbo shaft
Free power turbine
What type of path configuration is this :
Similar to single spool
Direct coupled turbo shaft
What type of path configuration is this :
Engine compressor and turbines are separated from the turbine
Free power turbine
What engine is most suitable for high forward speeds and high altitudes
Pure jet
What engine is better at lower speed below 450 MPH
Propellor engine
What does the pure jet depend on largely
Forward speed
What is thermal efficency
The heat value or heat energy output of the engine, divided by the heat energy input ( fuel consumed )
When does thermal efficiency increase
As the turbine inlet temperature increases
When does combustion occur in gas turbine engine
Constant pressure
When does combustion occur in piston engines
Occurs at constant volume
What process is this :
Pressure of the air does not rise during combustion, like that of a piston engines, but it’s volume does increase
Heating at constant pressure
Brayton cycle
The working cycle
What is the relationships between pressure volume and temperature
The airflow or working fluid recieves and gives up heat changes P,V,T
Important understand photo
What are the advantages of a continuous working cycle
Smoother
More power for a given engine size
Use of lightweight combustion chambers and low octane fuels
What are the disadvantages of a continuous working cycle
High flame temperatures
Critical component - THE TURBINE ( must not exceed turbine temperature otherwise turbine will just melt )
What is standard notation
Consists of pressure temperature or velocity and a number to represent a given position in an engine
