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turbine engine intake


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this ppt is based on turbine engine of aircraft.

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turbine engine intake

  1. 1. TURBINE ENGINE  Aircraft Gas Turbine Power plants by Otis  FAA 12A  Aircraft Gas Turbine Engine Technology by Treager  Aircraft Power plant by Kroes& Wild  The Jet Engine by Rolls-Royce
  2. 2. TURBINE ENGINE  Gas turbine engine are considered to be of two types:- Gas turbine engine Torque Producing Engine Thrust Producing Engine Turbojet Engine Turbofan Engine Turboprop Engine Turbo shaft Engine
  4. 4. SECTIONS OF GAS TURBINE ENGINE  An aircraft gas turbine engine is divided into two sections:  Cold section Hot section  The cold section contains:   Air Inlet Duct Compressor Diffuser  The hot section contains:   Combustor Turbine Exhaust
  5. 5. ENGINE STATION DESIGNATION To standardize the locations in gas turbine engines, a numbering system has been devised that allows a person to identify a location by numbers.
  7. 7. NEED OF AIR INTAKE IN AN AIRCRAFT • A widely used method to increase the thrust generated by the aircraft engine is to increase the air flow rate in the air intake by using auxiliary air intake systems. • The air flow enters the intake and is required to reach the engine face with optimum levels of total pressure and flow uniformity hence need of an air intake system. • Deceleration of airflow at high flight mach numbers or aerodynamic compression with help of air intake.
  8. 8. AIR INTAKE DESIGN REQUIREMENTS • The air intake requires enormous effort properly to control • • • • • airflow to the engine. The intake must be designed to provide the appropriate amount of airflow required by the engine. Furthermore this flow when leaving the intake section to enter the compressor should be uniform stable and of high quality. Good air intake design is therefore a prerequisite if installed engine performance is to come close to performance figures obtained at the static test bench. The engine intake must be a low drag, light weight construction ,that is carefully and exactly manufactures. These above conditions must be met not only during all phases of flight but also on the ground with the aircraft at rest and the engine demand maximum, thrust prior to take off
  9. 9. THE COLD SECTION AIR INLET DUCTS  The air inlet duct is technically a part of the airframe, but it is so important in the development of thrust that it is included with the engine as a part of the clod section.  The air inlet duct must supply uniform flow of air to the compressor so that it can operate stall free.  It must produce as little drag as possible.  If taken only a small obstruction to the air flow inside the duct to cause a significant loss of efficiency.  Inlet cover must be installed to prevent damage or corrosion in this vital area.
  10. 10. THE COLD SECTION AIR INLET DUCTS Air Inlet Ducts Single Entrance Duct Divided Entrance Duct
  11. 11. AIR INLET DUCTS SINGLE ENTRANCE DUCT  Duct inlet is located directly ahead of the engine and aircraft in such a position that it scoops undisturbed air.  It is either straight configuration or with relatively genital curvatures.  Due to long shape there is a chance of pressure lost but that is offset by smooth airflow characteristic.  In multi engine installation a short straight duct results minimum pressure drop.
  13. 13. AIR INLET DUCTS DIVIDED ENTRANCE DUCT  It is used in high speed, single engine aircraft where pilot sits low in the fuselage and close to the nose.  This divided duct can be either a wing root inlet or a scoop at each side of fuselage.  Create huge amount of drag
  15. 15. THE COLD SECTION AIR INLET DUCTS Air Inlet Ducts Subsonic Inlet Duct Supersonic Inlet Duct
  16. 16. THE COLD SECTION SUBSONIC AIR INLET DUCTS  The inlet duct is used in the multiengine subsonic aircraft is a fix geometry duct whose diameter progressively increases from the front to back. It is diverging duct and is also called an inlet diffuser because of the effect, it has the effect on the pressure of the air entering the engine.  As air enters the inlet at ambient pressure it beguns to defuse, or spread out, and by the time it arrives at the inlet to the compressor its pressure is slightly higher than the ambient pressure.  Usually the air diffuses in the front portion the duct and than it progresses along at a fairly constant pressure passes the engine inlet fairing and then into the compressor. This allows the engine to receive the air with less turbulence and at a more uniform pressure.
  18. 18. THE COLD SECTION AIR INLET DUCTS Turbofan Engine
  19. 19. THE COLD SECTION AIR INLET DUCTS Turbofan Engine
  20. 20. AIR INLET DUCTS TURBOPROP ENGINE The propeller reduction gears are located at the front of the engine and thus interfere with a smooth flow of air entering the compressor. Generally 3 types of inlet duct is used:i) Ducted spinner inlet ii) Conical spinner inlet iii) Under scoop inlet
  23. 23. BELLMOUTH COMPRESSOR INLET  Bellmouth inlet are converging in shape, found primarily on helicopter.  It provides an inlet with very thin boundary layers and corresponding low pressure losses.  Actually duct lost is so slight that it is considered zero.
  24. 24. SUPERSONIC INLET DUCT  The air approaching the compressor inlet must always be at speed below the speed of sound.  when an aircraft is flying at supersonic speed, the inlet air must be slowed down to subsonic speed before it reaches the compressor. This is done by : Using a convergent-divergent or CD inlet duct  Raising a Wedge or Spike or Plug inlet
  25. 25. SUPERSONIC INLET DUCT Convergent-divergent or CD inlet duct
  26. 26. SUPERSONIC INLET DUCT Using movable wedge inlet
  27. 27. FLOW CONDITIONS OVER WEDGE AND CONE In the design of supersonic air intakes flow conditions over wedge and cone are of the greatest importance as these are simple geometric bodies and relatively easy to manufacture.
  28. 28. COMPARISON OF SUPERSONIC FLOW OVER CONE AND WEDGE The major advantage of a (supersonic) conical flow is a smaller total pressure loss (when compared to a wedge of the same half-angle), together with the fact that a conical shock sustains lower mach numbers until it becomes detached to form a high loss bow shock. A major disadvantage of conical flows is that it is less tolerant to asymmetric flow conditions which cause distortion to the intake flow. As combat aircraft are frequently required to maneuver at higher angles of attack, the flow inevitably gets asymmetric- hence a performance for the (horizontally arranged) wedge in all modern combat aircraft, despite its reduced efficiency.
  29. 29. SUPERSONIC INLET DUCT Using movable Plug inlet Using movable spike inlet
  30. 30. EXAMPLES OF USE OFF OBLIQUE SHOCK DIFFUSERS Mirage ||| fighter with side mounted obliqueshock diffuser Two dimensional oblique shock diffuser (Northrop F5 with vertical ramp)
  31. 31. SUPERSONIC STUDIES F-16 intake characteristics AIR INTAKE CASE
  32. 32. SUPERSONIC INLET DUCT  Inlet Buzz: The buzz is an airflow instability which occur when a shock wave is alternately slowed and irregular flow occur at the inlet.  In increasing condition it can cause violent fluctuations in pressure through the inlet, which occur when a shock wave is alternately swallowed and regulate by the inlet.  This condition also cause damage to the inlet structure or possibly to engine itself.  A suitable variable geometry duct is used to eliminate the buzz by increasing of airflow within the inlet duct.
  33. 33. INTAKE CONFIGURATION AND OPERATION Present-day turbine aero engines require subsonic flow at the entry to the compressor, even if the aircraft is flying at supersonic speed. The task of air intake is therefore to decelerate the supersonic external flow to a subsonic speed acceptable to the compressor. As intake discharge mach number are required to be in range of mach 0.4 to 0.7 great care must be exercised when decelerating the flow in order to keep total pressure losses to a minimum . Normal shock diffuser For aircraft operating at a maximum speed equivalent to mach 1.5 a normal shock diffuser is generally sufficient to decelerate the supersonic airflow efficiently to the speed needed by the compressor.
  34. 34. NACA SUBMERGED INLET IN A EURO FIGHTER The NACA submerged type intake is not very efficient for use with propulsion installations. However, they are frequently used as intakes of auxiliary systems (auxiliary power unit, heating and avionics bay cooling) as seen in Fig above
  35. 35. Various types of supersonic inlets
  36. 36. RAM RECOVERY  When a turbine engine is operated there is a negative pressure in the inlet because of the high velocity of the airflow. As the aircraft moves forward in the flight, air rams in to the inlet duct and ram recovery takes place. This ram pressure rise cancel the pressure drops due to friction inside the duct and the inlet pressure return to ambient. Ram recovery occur above about 160 miles/hrs or 0.1 mach to 0.2 mach in most of the aircraft.  From this point the pressure continue to increases with aircraft speed and additional thrust is created by the engine with less expenditure of fuel.
  38. 38. BLOW-IN -DOOR  It is used to prevent compressor stall.  It is installed in the side of inlet duct and are spring loaded to hold them closed.  But when the inlet pressure becomes a specified amount lower than that of the ambient air, the pressure differential forces then open and furnishes additional air to the compressor inlet.