TURBOFAN ENGINE

PRESENTED BY SHAMBU S ROLL NO. 55

MECH SNIT

CONTENTS

INTRODUCTIONTURBOFANTURBOFAN HISTORYPARTS OF TURBOFANTURBOFAN ENGINE WORKINGADVANTAGESDISADVANTAGES CONCLUSION REFERENCE

INTRODUCTIONThe turbofan or fanjet is a type of air breathing

jet engine that is widely used for aircraft propulsion.

The ‘turbo’ portion refers to a gas turbine engine which takes mechanical energy from combustion

The ‘fan’ uses the mechanical energy from the gas turbine to accelerate air rearwards

TURBOFAN•Powered by gas turbine

•The combination of thrust produced from the fan & the exhaust from the core is more efficient

•Efficient at subsonic speeds

•Used in commercial jet aircraft

TURBOFAN HISTORY In early jet engines, high velocity jet exhaust

mixing with surrounding air is major source of noise

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

In 1967, NASA initiates acoustically treated nacelle program

Engine ducts and inlets are lined with acoustic treatments

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, fan noise 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

German Daimler-Benz DB605

PARTS OF A TURBOFAN

A. LOW PRESSURE SPOOL

B. HIGH PRESSURE SPOOL

C. STATIONARY COMPONENTS

1. NACELLE2. FAN3. LOW PRESSURE COMPRESSOR4. HIGH PRESSURE COMPRESSOR5. COMBUSTION CHAMBER6. HIGH PRESSURE TURBINE7. LOW PRESSURE TURBINE8. CORE NOZZLE9. FAN NOZZLE

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

ADVANTAGES Since a fan is used, more amount of air is sucked

into the engine providing more thrust.

The fan is enclosed by the cowling and is thus protected and its aerodynamics can be easily controlled.

Due to presence of fan, the fuel consumption is increased only a little , the turbofan produces more thrust for same amount of fuel and is thus fuel efficient.

DISADVANTAGES It is the most efficient at subsonic speeds only.

It has a greater complexity due to addition of ducts and multiple shafts.

The engine diameter is increased.

SCOPE FOR THE FUTURE Considering the future applications of turbofan

engine,the most outstanding one is ‘The Geared Turbofan Concept’

In a geared turbofan, a (planetary) reduction gearbox between the fan and the LP shaft allows the latter to run at a higher rotational speed thus enabling fewer stages to be used in both the LP turbine increasing efficiency and reducing weight.

CONCLUSION A higher bypass ratio gives a low (actual) exhaust

speed. As a result, the thrust specific fuel consumption is reduced. A lower bypass ratio gives high exhaust speed, which is used to sustain supersonic speeds. Thus, one can conclude that a high bypass turbofan engine gives lower thrust specific fuel consumption.

A high bypass turbofan engine is used at subsonic speeds because of low exhaust speed it produces.

Turbofan engines gain better performance capabilities and better fuel efficiency

REFERENCE Aderson Jr., John D., 1995. McGraw Hill,

nInc.,“Computational Fluid Dynamics: The Basics with Applications” , New York, USA.

Ganesan, V., 2010. Ajay Shukla, Tata McGraw Hill Education Private

Advanced Control of Turbofan Engines - Hanz Richter

Gas Turbines: A Handbook of Air, Land and Sea Application - Claire Soares