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turbofan presentation

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A SEMINAR ON A SEMINAR ON TURBOFAN TURBOFAN Presented by PRADEEP A S
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Page 1: turbofan presentation

A SEMINAR ON A SEMINAR ON

TURBOFANTURBOFAN Presented by

PRADEEP A S

Page 2: turbofan presentation

AGENDAAGENDA

IntroductionIntroduction Propulsion, ThrustPropulsion, Thrust Gas TurbinesGas Turbines Turbofan engine workingTurbofan engine working Types of TurbofanTypes of Turbofan Parts of turbofanParts of turbofan Turbofan benefitsTurbofan benefits

Page 3: turbofan presentation

TURBOFANTURBOFAN

•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

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PROPULSIONPROPULSION

Jet propulsion is the thrust imparting Jet propulsion is the thrust imparting forward motion to an object as a reaction forward motion to an object as a reaction to the rearward expulsion of a high velocity to the rearward expulsion of a high velocity liquid or gaseous stream.liquid or gaseous stream.

Based on Newtons third law.Based on Newtons third law.For an aircraft to move, some kind of For an aircraft to move, some kind of

propulsion system is required.propulsion system is required.Turbofan engines serves the purposeTurbofan engines serves the purpose

Page 5: turbofan presentation

THRUSTTHRUST

Equilibrium Reaction Action

Page 6: turbofan presentation

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

Page 7: turbofan presentation

HOW GAS TURBINE ENGINES HOW GAS TURBINE ENGINES WORK?WORK?

Pressurised gas spins the turbine

Page 8: turbofan presentation

GAS TURBINE ADVANTAGESGAS TURBINE ADVANTAGES

Great power to weight ratioGreat power to weight ratio

Considerably smaller in sizeConsiderably smaller in size

Mechanical efficiency is highMechanical efficiency is high

Rotor blades operate at high speeds.Rotor blades operate at high speeds.

Page 9: turbofan presentation

GAS TURBINE GAS TURBINE DISADVANTAGESDISADVANTAGES

ExpensiveExpensiveOperate at high speeds and high Operate at high speeds and high

temperaturetemperatureTend to use more fuel when they are idlingTend to use more fuel when they are idling

CHALLENGES

•Vibration problems are severe.•The design of rotor blades is a complex phenomenon

Page 10: turbofan presentation

PROPULSION DEVICESPROPULSION DEVICES

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JET ENGINE BASIC JET ENGINE BASIC OPERATIONOPERATION

Air enters through the Air enters through the intake ductintake duct   Air compressed by passage through the Air compressed by passage through the compressorcompressor   Mixed with fuel in the Mixed with fuel in the combustion chambercombustion chamber

Fuel is ignited, pressure and temperature raised. Fuel is ignited, pressure and temperature raised.  Some of the pressure used to turn a Some of the pressure used to turn a turbine.turbine.   Turbine shaft drives the compressor.Turbine shaft drives the compressor.

Hot high pressure air forced through a Hot high pressure air forced through a nozzle.nozzle.   The reaction force is the engine thrust.The reaction force is the engine thrust.

Page 12: turbofan presentation

GAS TURBINES-BRAYTON GAS TURBINES-BRAYTON CYCLECYCLE

Page 13: turbofan presentation

BRAYTON CYCLEBRAYTON CYCLE

•1-2 Isentropic compression (in a compressor) •2-3 Constant pressure heat addition

•3-4 Isentropic expansion (in a turbine)

•4-1 Constant pressure heat rejection  

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Turbofan HistoryTurbofan History

In early jet engines, high velocity jet In early jet engines, high velocity jet exhaust mixing with surrounding air is exhaust mixing with surrounding air is major source of noisemajor source of noise

In 1960’s, low-bypass-ratio turbofans In 1960’s, low-bypass-ratio turbofans introducedintroduced

In 1967, NASA initiates acoustically In 1967, NASA initiates acoustically treated nacelle programtreated nacelle program

Engine ducts and inlets are lined with Engine ducts and inlets are lined with acoustic treatmentsacoustic treatments

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Flight tested on Boeing 707 and DC-8Flight tested on Boeing 707 and DC-8Acoustic treatment proven effective and Acoustic treatment proven effective and

feasiblefeasibleEven greater jet noise reduction is Even greater jet noise reduction is

achievedachievedWith further reduction of jet noise, fan With further reduction of jet noise, fan

noise becomes major noise sourcenoise becomes major noise sourceGerman Daimler-Benz, the very first German Daimler-Benz, the very first

turbofan tested on April 1,1943turbofan tested on April 1,1943 Improved materials and twin compressors Improved materials and twin compressors

in the Pratt & Whitney JT3C enginein the Pratt & Whitney JT3C engine

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How does turbofan engine work?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

Page 17: turbofan presentation

TYPES OF TURBOFANTYPES OF TURBOFAN

Low bypass turbofanLow bypass turbofan

high bypass turbofanhigh bypass turbofan

Afterburning turbofanAfterburning turbofan

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Low bypass turbofanLow bypass turbofan

• More fuel efficient than basic turbojets• A bypass flow can be introduced if the turbine inlet temperature is allowed to increase•To compensate for a Correspondingly smaller core flow•Better specific fuel consumption Can be achieved•Normally used in military aircraft

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High bypass turbofanHigh bypass turbofan

A. Low pressure spoolB. High pressure spoolC. Stationary components1. Nacelle2. Fan3. Low pressure compressor4. High pressure compressor5. Combustion chamber6. High pressure turbine7. Low pressure turbine8. Core nozzle9. Fan nozzle

Page 20: turbofan presentation

Low specific thrust/high bypass ratio Low specific thrust/high bypass ratio turbofans primarily used in civilian turbofans primarily used in civilian transport aircrafttransport aircraft

Multistage fan replaced by single stage Multistage fan replaced by single stage unitunit

Reducing core flow increases bypass Reducing core flow increases bypass ratio(5:1)ratio(5:1)

Page 21: turbofan presentation

AFTERBURNING TURBOFANAFTERBURNING TURBOFAN

•An afterburner is a combustor located downstream of the turbine blades and directly upstream of thenozzle, which burns fuel from afterburner-specific fuel injectors•Raises 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


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