jet prop 4
TRANSCRIPT
JET PROPULSION
Part 4
Types of Jet Engines
Turbo JetAvon, Olympus 593
Turbo Fan - Bypass Engines
SMALL BYPASS Spey, BR700MEDIUM BYPASS Pegasus, BR715, V2500LARGE BYPASS RB211, Trent Series
Turbo PropPROPELLER Dart, Tyne, BR715TP
Turbo Shaft
HELICOPTER Lycoming T55, GemRN SHIPS Marine SpeyPOWER GENERATION Industrial Spey & Trent
Engine Types
Flame almost goes out - no power – no thrust.
This is called: - COMPRESSOR SURGE
Rolls Royce Avon
Turbo Jet
17 Stage Compressor driven by a 3 stage turbine
With RPM (i.e. Thrust) changes, the airflow velocity does not change
in proportion to engine RPM
At low rpm the rear of the compressor cannot get rid of all the air from the front of the compressor
This can result in the rear end of compressor ‘choking’
So airblasts
forwards
Rolls Royce Avon
Turbo Jet
Air dumped overboard
Rear end of compressor ‘unchoked’
Rearward movement of air restored
Power restoredBUT
air dumped sideways out of the engine produces no thrust.
So a more efficient system was required
Rolls Royce Avon
Turbo Jet
‘Bleed’ valve
‘Excess’ air is dumped overboard through a valve
Turbo Jet
Single Shaft LayoutThe Olympus 593
driven byLow Pressure Compressor Low Pressure Turbine
driven byHigh Pressure Compressor High Pressure Turbine
The Two Shaft Layout
The Two Shaft Layout
Turbo JetThe Olympus 593
Compressor surges lessened
No wasted energy/thrust
Allows front end of compressor to slow down – move less airand
Allows rear end of compressor to speed up – move more air
Turbo Jet
The turbojet is the simplest and earliest form of gas turbine.
Used principally in high speed aircraft where its relatively low frontal area
and high jet velocity are advantages.
Examples are the Concorde supersonic transportand a variety of military aircraft including the Dominie/HS125.
Part of the air is compressed fullyand passes into the combustion chamber,
while the remainder is compressed to a lesser extent and ducted around the hot section.
Turbo FanLow Bypass Engine
Rolls Royce Spey Adour BR710 Series
Two shaft layout with Contra-rotating shafts
It has low pressure and high pressure AXIAL Flow Compressors
Turbo FanMedium Bypass Engine
Pegasus
Bypass flow to ‘Cold’ (front) Nozzles
Core flow to ‘Hot’(rear) Nozzles
Turbo FanHigh Bypass Engine
RB211 Series (Trent)
In service with RAF – Wide-body Tristar Tanker/Transport
Boeing 747 and later series, Airbus A330 and larger a/c
Three shaft layout – all rotate same direction
LP(Fan) Intermediate and HP AXIAL Flow Compressors
Turbo FanHigh Bypass Engine
RB211 Series (Trent)
Turbo FanTurbofan engines are loosely categorised by
the size of the bypass compared to the core flow. (The amount of air entering the core engine
compared to the bypass duct)which is called the Bypass Ratio.
The low bypass ratio is approximately 1:1.Half the air goes through the core or hot section,
the other half goes through the bypass.
Medium bypass engines have a 5:1 ratio,while high bypass have a ratio of 10:1 or more.
Turbo Fan
The turbofan (bypass) reduces overall jet velocity, giving better propulsive efficiency at lower speeds,
lower noise levels and improved specific fuel consumption,
features which make the turbofan ideal for both civil and military aircraft.
Examples are the Boeing 747 and 757, the Jaguar and Hawk, and the Tornado.
The Harrier has a variation of the turbofan.
Turbo PropRolls Royce Dart
Reduction Gearbox
Prop Shaft
Dart RDa6 = 2 stage turbine Dart RDa7 = 3 stage turbine
Turbine drives 2 stage CENTRIFUGAL Compressor and Propeller
Over 70 Marks of Engine – different power levels – 15 different aircraft
Fokker F27, Fairchild F27, Briguet Alize, (and P51 Mustang and Dakota!)
Turbo PropTyne
C160 Transall, Shorts Belfast, Brequet Atlantic, Avro Lincoln,Canadair CL44, Vickers Vanguard, Aeritalia 222.
1 Stage HP Turbine
9 Stage HP Compressor
3 Stage LP Turbine
6 Stage LP Compressor
Prop Shaft(via Reduction
Gearbox)
Reduction Gearbox
Turbo PropTyne
C160 Transall, Shorts Belfast, Brequet Atlantic, Avro Lincoln,Canadair CL44, Vickers Vanguard, Aeritalia 222.
1 Stage HP Turbine
9 Stage HP Compressor
3 Stage LP Turbine
6 Stage LP Compressor
Prop Shaft(via Reduction
Gearbox)
Reduction Gearbox
RR Allison T56-A-15
Turbo Prop
C130 Hercules
RR Allison T56-A-15
4 Stage Turbine
14 Stage HP Compressor
Turbine drives compressor and propeller
Output Shaft
Reduction Gearbox
Thrust Strut
Air Intake
Turbo Prop
The turboprop is basically a turbojetwith an extra turbine designed to absorb the energy
remaining in the gas stream after sufficient hasbeen removed to drive the compressor.
The turboprop is a very efficient power unit for relative low speed, low altitude aircraft.
Examples are the 748 and F27,and the Transall C-160 and Atlantic.
Turbo ShaftLycoming T55-GA-714
Boeing CH47 Chinook
Turboshaft with Free Power Turbine
Combining Transmission
Front Rotor Transmission
Rear Rotor Transmission
Turbo Shaft
The turboshaft is virtually a turboprop without a propeller.
The power turbine absorbs as much of the remaining gas energy as possible
and the residual thrust is very low.
The main use of the turboshaft is the helicopterand industrial and marine application, including power and pumping stations,
hovercraft and ships.
Examples are the Lynx, Chinook and the Sea King.
Which of these is a turbo jet engine?
Tyne
Spey
Pegasus
Olympus
Check Understanding
Which of the following features makes the turbofan ideal
for both civil and military aircraft?
The turbine absorbs as much of the gas energy as possible
Lower noise levels andimproved specific fuel consumption
Very efficient power unit for relative low speed, low altitude
It is ideal for high-speed,high-altitude aircraft
Check Understanding
Which of these is a turbo fan engine?
Tyne
Pegasus
Dart
Gem
Check Understanding
Which application or type of operation best suits the turbojet engine?
In low speed aircraftoperating at high altitudes
In high speed aircraft wherelow frontal area is an advantage
In low speed aircraft operating at low altitudes
In helicopters
Check Understanding
Which of these is a turbo prop engine?
Check Understanding
RB 211
Dart
Spey
Avon
Which of these statements applies to a turboprop engine?
It has one less turbinecompared to a turbojet
It has an extra turbinecompared to a turbojet
It is ideal for high-speed,high-altitude aircraft
It has a very highresidual thrust
Check Understanding
Which of these is a turbo shaft engine?
Tyne
Lycoming
RB 211
Trent
Check Understanding
JET PROPULSION
End of Presentation