Turbofan engine
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Transcript of Turbofan engine
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