Introduction to Gas Turbine Engines © 2015 SIM University. All rights reserved. Introduction • Gas Turbine Engine - Configurations © 2015 SIM University. All rights reserved. Gas Turbine Engine Gas Generator Compressor is driven Turbine is driven by the turbine through by heated air an interconnecting from the shaft combustor T u r b Compressor Combustor i n e Gas Generator – Heart of Gas Turbine (to supply high-temperature and high-pressure gas to the turbine) Adapted: “Elements of Propulsion: Gas Turbines and Rockets” by Jack D. Mattingly © 2015 SIM University. All rights reserved. Turbojet Exhaust Schematic of a Twin Spool Turbojet Adapted: “Elements of Propulsion: Gas Turbines and Rockets” by Jack D. Mattingly © 2015 SIM University. All rights reserved. Turbojet with Afterburner Schematic of Turbojet with Afterburner Adapted: “Elements of Propulsion: Gas Turbines and Rockets” by Jack D. Mattingly © 2015 SIM University. All rights reserved. Afterburning Turbojet (Concorde) Sources: http://www.concordesst.com/history/events/sia.html , © 2015 SIM University. All rights reserved. http://www.concordesst.com/model101/model101detail.html Turbojet • Additional turbine stages may be added to extract more gas energy into mechanical power – Less residual exhaust energy – Reduced thrust generated by core engine • Mechanical power directed to drive: – Shrouded fan >>> Turbofan – Propeller >>> Turboprop – Rotor blades >>> Turboshaft © 2015 SIM University. All rights reserved. Turbofan 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 nozzle Source: http://en.wikipedia.org/wiki/Turbofan Turbofans offer: • High efficiencies • Reduced noise levels © 2015 SIM University. All rights reserved. Rolls-Royce Trent XWB Bypass ratio ~ 9.3 Source: Airbus © 2015 SIM University. All rights reserved. F15, F16 P&W F100 Engine Bypass ratio ~ 0.36 Source: http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F100 © 2015 SIM University. All rights reserved. Twin Spool Turbofan Schematic of Unmixed Turbofan (Twin Spool) Adapted: “Elements of Propulsion: Gas Turbines and Rockets” by Jack D. Mattingly © 2015 SIM University. All rights reserved. Turbofan Station Numbering Schematic of Unmixed Turbofan (Twin Spool) Adapted: “Elements of Propulsion: Gas Turbines and Rockets” by Jack D. Mattingly © 2015 SIM University. All rights reserved. Turboprop & Turboshaft • Turbine, through reduction gear box, drives – A propeller - turboprop engine – Rotor blades – turboshaft engine (helicopters) • Exhaust gas is not a significant contributor to aircraft thrust • Power to drive the reduction gearbox can be extracted either from – the same turbine that drives the compressor or – from a separate, free-wheeling turbine (Power Turbine) Schematic of Turboprop Adapted: “Elements of Propulsion: Gas Turbines and Rockets” by Jack D. Mattingly © 2015 SIM University. All rights reserved. Turboprop & Turboshaft Schematic of Turboshaft with Power Shaft Driven by Free Power Turbine Source: http://en.wikipedia.org/wiki/Turboshaft © 2015 SIM University. All rights reserved. Turboprop • Propeller typically kept at constant rotational speed (rpm) • Propeller blade angle variable and controllable according to speed demands • Blade angle can be set to: – reverse pitch for reverse thrust – “Feather” to stop engine rotation Photo credit: Soon Kim Tat © 2015 SIM University. All rights reserved. Turboprop • Advantages and limitations of the turboprop are those of the propeller: – Excellent performance for low-speed flight and short-field take-off – High propulsive efficiency and high thrust at low subsonic speeds – Approaching the speed of sound, the propeller/rotor loses its aerodynamic efficiency due to compressibility effects Photo credit: Soon Kim Tat Watch video of C130 Turboprop take-off: http://www.youtube.com/watch?v=nwaWXrlZEIw © 2015 SIM University. All rights reserved. Turboshaft • Rotors kept at constant rpm • Rotor blade angle variable and controllable according to demands for lift (collective pitch), or speed and banking (cyclic pitch) Photo credit: Soon Kim Tat See video on how collective and cyclic pitch control works: http://www.youtube.com/watch?gl=SG&hl=en-GB&v=7HBziltI_t4 © 2015 SIM University. All rights reserved. Ramjet • Conceptually the simplest jet engine – Inlet – combustion chamber – nozzle • No rotating component • Compresses incoming air by decelerating it in the inlet Schematic of Ramjet • Requires forward motion to produce thrust Source: http://en.wikipedia.org/wiki/Ramjet © 2015 SIM University. All rights reserved. Turbo / Ram Jet Engine J58 Engine Source: Rolls-Royce, 1986, The jet engine, 5 th edition, Rolls-Royce plc © 2015 SIM University. All rights reserved. SCRAMJET • Supersonic Combustion RAMJET • Hypersonic flights (experimental) Source: Wikipedia http://commons.wikimedia.org/wiki/File:Scramjet_operation.png © 2015 SIM University. All rights reserved. Summary • The heart of the gas turbine engine – the gas generator • The different gas turbine configurations: – Turbojet (including with afterburner) – Turbofan or Bypass Engine – Turboprop and Turboshaft. • The operation of a Ramjet and Scramjet © 2015 SIM University. All rights reserved. Reflection Question • Explain the construction of a turbofan engine and elaborate on its advantages compared to a turbojet. © 2015 SIM University. All rights reserved..