Upload
shishir-dhone
View
235
Download
0
Embed Size (px)
Citation preview
7/29/2019 15186095 Turbofan Presentation
1/21
A SEMINAR ON
TURBOFANPresented by
Shishir Dhone
7/29/2019 15186095 Turbofan Presentation
2/21
AGENDA
Introduction
Propulsion, Thrust
Gas Turbines Turbofan engine working
Types of Turbofan
Parts of turbofan Turbofan benefits
7/29/2019 15186095 Turbofan Presentation
3/21
TURBOFAN
Powered by gas turbine
The combination of thrust
produced from the fan &
the exaust from the core
is more efficient
Efficient at subsonic speeds
Used in commercial jet
aircraft
7/29/2019 15186095 Turbofan Presentation
4/21
PROPULSION
Jet propulsion is the thrust imparting
forward motion to an object as a reaction
to the rearward expulsion of a high velocity
liquid or gaseous stream.
Based on Newtons third law.
For an aircraft to move, some kind of
propulsion system is required.
Turbofan engines serves the purpose
7/29/2019 15186095 Turbofan Presentation
5/21
THRUST
Equilibrium Reaction Action
7/29/2019 15186095 Turbofan Presentation
6/21
Thrust
Jet moves small mas of
gas at high velocity
Thrust is the force which
moves the Aircraft through
the air
Thrust is used to overcome
drag of an aeroplane
This is generated by the
aircraft through Some kind
of propulsion system
7/29/2019 15186095 Turbofan Presentation
7/21
HOW GAS TURBINE ENGINES
WORK?
Pressurised gas spins the turbine
7/29/2019 15186095 Turbofan Presentation
8/21
GAS TURBINE ADVANTAGES
Great power to weight ratio
Considerably smaller in size
Mechanical efficiency is high
Rotor blades operate at high speeds.
7/29/2019 15186095 Turbofan Presentation
9/21
GAS TURBINE
DISADVANTAGES Expensive
Operate at high speeds and high
temperature
Tend to use more fuel when they are idling
CHALLENGES
Vibration problems are severe.
The design of rotor blades is a complex
phenomenon
7/29/2019 15186095 Turbofan Presentation
10/21
PROPULSION DEVICES
7/29/2019 15186095 Turbofan Presentation
11/21
JET ENGINE BASIC
OPERATION
Air enters through the intake duct
Air compressed by passage through the compressor
Mixed with fuel in the combustion chamber
Fuel is ignited, pressure and temperature raised.
Some of the pressure used to turn a turbine.
Turbine shaft drives the compressor.
Hot high pressure air forced through a nozzle.
The reaction force is the engine thrust.
7/29/2019 15186095 Turbofan Presentation
12/21
GAS TURBINES-BRAYTON
CYCLE
7/29/2019 15186095 Turbofan Presentation
13/21
7/29/2019 15186095 Turbofan Presentation
14/21
Turbofan History
In early jet engines, high velocity jet
exhaust mixing with surrounding air is
major source of noise
In 1960s, low-bypass-ratio turbofans
introduced
In 1967, NASA initiates acoustically
treated nacelle program Engine ducts and inlets are lined with
acoustic treatments
7/29/2019 15186095 Turbofan Presentation
15/21
Flight tested on Boeing 707 and DC-8
Acoustic treatment proven effective and
feasible Even greater jet noise reduction is
achieved
With further reduction of jet noise, fannoise becomes major noise source
German Daimler-Benz, the very first
turbofan tested on April 1,1943 Improved materials and twin compressors
in the Pratt & Whitney JT3C engine
7/29/2019 15186095 Turbofan Presentation
16/21
How does turbofan engine work?
The incoming air is captured by the inlet
The incoming air is compressed by the
compressor
In the combustion chamber, the
Compressed air is mixed with fuel and
then ignited
The hot exhaust gases passes through
the Core, fan turbines & then out of the
nozzle
A turbofan gets thrust from both fan &the core
The ratio of air that goes around the engine
& To the air that goes through the core is
called BYPASS RATIO
7/29/2019 15186095 Turbofan Presentation
17/21
TYPES OF TURBOFAN
Low bypass turbofan
high bypass turbofan
Afterburning turbofan
7/29/2019 15186095 Turbofan Presentation
18/21
Low bypass turbofan
More fuel efficient than
basic turbojets
A bypass flow can be
introduced if the turbineinlet temperature is
allowed to increase
To compensate for a
Correspondingly smaller
core flowBetter specific fuel
consumption Can be
achieved
Normally used in military aircraft
7/29/2019 15186095 Turbofan Presentation
19/21
High bypass turbofan
A. Low pressure spool
B. High pressure spool
C. Stationary components
1. Nacelle
2. Fan
3. Low pressure compressor
4. High pressure compressor
5. Combustion chamber
6. High pressure turbine
7. Low pressure turbine
8. Core nozzle9. Fan nozzle
7/29/2019 15186095 Turbofan Presentation
20/21
Low specific thrust/high bypass ratio
turbofans primarily used in civilian
transport aircraft
Multistage fan replaced by single stage
unit
Reducing core flow increases bypass
ratio(5:1)
7/29/2019 15186095 Turbofan Presentation
21/21
AFTERBURNING TURBOFAN
An afterburner is a combustor
located downstream of the turbine
blades and directly upstream of the
nozzle, which burnsfuel from
afterburner-specific fuel injectorsRaises the temperature of exhaust gases
by a significant amount
Higher exhaust velocity
USED
-To give significant thrust boost
for take off- transonic acceleration
-combat maneuvers
Fuel intensive