Hot section π₯ Flashcards
(37 cards)
What does a swirl chamber do
Using holes or slots it converts pressure energy to kinetic energy
What speed does air leaving the compressor travel at
150m/s
What does flame stability rely on
Fuel air ratio and airflow speed
What percentage of air goes into the combustion chamber
20%. Of this 20%, 12% goes over swirl vanes and mixes with atomised fuel. The remaining 8% flows through a perforated flare and stabilises the flame
What does primary air do
Provides the high temperature for rapid combustion
What does secondary air do
It consists of 20% of the non bypass air and is Introduced to the combustion in stages to prevent a cold flame and slows the air down and Completes the combustion
What is tertiary air for
It is the remaining 60% of non bypass airflow and cools the air prior to entering the turbine section
What are the four types of combustion chambers
Multiple can
Can annular/turbo annular
Annular
Reverse flow annular
Multiple can combustion characteristics
Number of cans around engine interconnected to equalise pressure
Individual cans can be replaced
Strong
Can annular/tubo annular characteristics
Number of flame tubes fitted inside an air casing
Individual cans can be replaced
Easy to manufacture
Annular combustion characteristics
A single flame tube
75% smaller than other types and requires 15% less cooling
Even gas distribution
More efficient as lighter and less pressure loss
Easy to manufacture
Reverse flow annular combustion characteristics
Makes engines able to be smaller due to reversing airflow
Popular in turbo shafts and props
Usable on smaller aircraft
Purpose of the turbine
Extracts energy from the high pressure and high temperature gases from the combustion chamber.this energy turns the compressor and engine driven accessories
What are the two types of turbine
Axial flow turbine
Free power turbine
Axial flow turbine properties
It is turned on by the hot gases from the combustion chamber and is physically connected to the compressor
Fitted on single, dual and triple spooled engines
Free power turbine properties
Not physically connected to the compressor
Why must compressors and turbines be matched
To obtain max efficiency and performance of the engine
What is the casing or case assembly
A case enclosing the turbine, stator and rotor which is connected to the combustion at the front and the exhaust nozzle at the back end
What are NGVs
Nozzle guide vanes
Stationary vanes in front of first turbine wheel presenting air at the most efficient angle of attack
Allow expansion and acceleration of hot gases
Hollow for cooling
Have shrouds fitted at the top and bottom of the vane
ITT Meaning
Interstage turbine temperature
TIT meaning
Turbine inlet temperature
EGT meaning
Exhaust gas temperature
Turbine wheel properties
Itβs the rotating part of the turbine along with the turbine shaft
Each wheel increases in diameter and blade size towards the exhaust
Stator between each wheel
In a turbine what is a stage
A turbine wheel and a stator pairing
