Gas Turbine and Jet propulsion

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Gas Turbine and Jet propulsion

  1. 1. 
  2. 2. INDEX   Introduction  Objectives  Classification of Gas Turbine  Applications of Gas turbine  Methods to improve the thermal efficiency of gas turbine  Jet-propulsion  Types of jet engines  Rocket engine
  3. 3. INTRODUCTION  A gas turbine is a machine delivering mechanical power or thrust. It does this using a gaseous working fluid. The mechanical power generated can be used by, for example, an industrial device. The outgoing gaseous fluid can be used to generate thrust. In the gas turbine, there is a continuous flow of the working fluid.
  4. 4. Cont…  This working fluid is initially compressed in the compressor. It is then heated in the combustion chamber. Finally, it goes through the turbine. The turbine converts the energy of the gas into mechanical work. Part of this work is used to drive the compressor. The remaining part is known as the net work of the gas turbine.
  5. 5. Objectives   After this lesson students should be able to: – Define what a jet engine is – Describe how Newton’s laws apply to jet or rocket engines – List examples of jet engine applications – List some key points in the history of jet propulsion – List advantages and disadvantages of jet engines
  6. 6. Classification of Gas Turbine   Constant pressure type  Constant Volume type  According to thermodynamic cycle a) Brayton cycle b) Atkinson cycle (Constant volume) c) Ericsson cycle(Intercooler and repeaters)
  7. 7. Applications of Gas turbine   For supercharging of I.C. engines  Ship propulsion i.e. Marine engines  Industrial applications. Like Crude oil pumping, Refining processes.  Air craft engines.  Electric power generation.  For the turbojet and turbo propeller engines.
  8. 8. Open Cycle gas turbine  Fig. Open Cycle gas turbine
  9. 9. Closed gas cycle turbine  Fig. T-S & P-V Diagrams of closed cycle gas turbine 9
  10. 10. Basic Components 
  11. 11. Basic Components
  12. 12. Basic Components • Compressor • • Combustion Chamber • • Draws in air & compresses it Fuel pumped in and ignited to burn with compressed air Turbine • • Hot gases converted to work Can drive compressor & external load
  13. 13. Basic Components • Compressor • • Combustion Chamber • • Draws in air & compresses it Fuel pumped in and ignited to burn with compressed air Turbine • • Hot gases converted to work Can drive compressor & external load
  14. 14. Basic Components • Compressor • • Combustion Chamber • • Draws in air & compresses it Fuel pumped in and ignited to burn with compressed air Turbine • • Hot gases converted to work Can drive compressor & external load
  15. 15. Constant volume Gas turbine Exhaust Gas Load Feed Water To stack Boiler Valve V1 Motor Steam turbine Exhaust Valve V2 Air Valve V3 Compressor Fuel Tank
  16. 16. GAS TURBINE WITH REGENERATION CYCLE The thermal efficiency of the Brayton cycle increases as a result of regeneration since less fuel is used for the same work output. A gas-turbine engine with regenerator. T-s diagram of a Brayton cycle with regeneration. 16
  17. 17. Effectiveness of regenerator Effectiveness under coldair standard assumptions Under cold-air standard assumptions T-s diagram of a Brayton cycle with regeneration. 17
  18. 18. GAS TURBINE WITH INTERCOOLING CYCLE 
  19. 19. GAS TURBINE WITH REHEATING CYCLE
  20. 20. Brayton cycle with intercooling, reheating, and regeneration For minimizing work input to compressor and maximizing work output from turbine: A gas-turbine engine with two-stage compression with intercooling, two-stage expansion with reheating, and regeneration and its T-s diagram. 20
  21. 21. 21 Jet-propulsion   An engine that burns fuel and uses the expanding exhaust gases to turn a turbine and/or produce thrust  The concept of thrust is based on the principle of Newton’s Third Law In jet engines, the hightemperature and highpressure gases leaving the turbine are accelerated in a nozzle to provide thrust.
  22. 22. 4.4.1 Principles of jet propulsion   It is based on Newton's first and third law of motion.  A jet engine is an engine that discharges a fast moving jet of fluid to generate thrust in accordance with Newton's third law of motion.  An engine that burns fuel and uses the expanding exhaust gases to turn a turbine and/or produce thrust
  23. 23. Types Of Jet engines  •Turbo jets •Turbo fans •Ramjets •Rockets
  24. 24. Jet Engine 
  25. 25. Jet Engine 
  26. 26.
  27. 27. Turbo jet engines  Working principle jet engines are also called as gas turbines. The engine sucks air in at the front with a fan. A compressor raises the pressure of the air. The compressed air is then sprayed with fuel and an electric spark lights the mixture. The burning gases expand and blast out through the nozzle, at the back of the engine. As the jets of gas shoot backward, the engine and the aircraft are thrust forward.
  28. 28. Turboprop engine  Approximately 80 to 90% of the thrust is produced by the propeller and 10 to 20% of thrust is produced by jet exit of the exhaust gases
  29. 29. Turboprop engine 
  30. 30. Ram jet engine 
  31. 31. Rocket Principles  • Rocket thrust is the reaction force produced by expelling particles at high velocity from a nozzle opening. • High pressure/temperature/velocity exhaust gases provided through combustion and expansion through nozzle of suitable fuel and oxidizer mixture. • A rocket carries both the fuel and oxidizer onboard the vehicle whereas an air-breather engine takes in its oxygen supply from the atmosphere.
  32. 32. Solid propellant rocket engine   In the solid-chemical rocket, the fuel and oxidizer are intimately mixed together and cast into a solid mass, called a grain, in the combustion  The propellant grain is firmly cemented to the inside of the metal or plastic case, and is usually cast with a hole down the center. This hole, called the perforation, may be shaped in various ways, as star, gear, or other more unusual outlines, The perforation shape and dimension affects the burning rate or number of pounds of gas generated per second and, thereby, the thrust of the engine.  After being ignited by a pyrotechnic device, which is usually triggered by an electrical impulse, the propellant grain burns on the entire inside surface of the perforation. The hot combustion gases pass down the grain and are ejected through the nozzle to produce thrust.
  33. 33. Types of solid propellant  a) Restricted burning
  34. 34. a) Restricted burning  usually in the shape of a  A restricted-burning charge is solid cylinder.  It completely falls the combustion chamber and burns only on its end.  The thrust developed is proportional to the cross-sectional area of the charge  The restricted-burning charge provides a low thrust and long burning time.
  35. 35. Types of solid propellant b) Unrestricted burning   It is essentially free to burn on all surfaces at the same time  The restricted burning propellant delivers a small trust for a relatively long period while unrestricted type delivers relatively large thrust for short period.  It’s application is in aircraft rockets, antiaircraft rockets and boosters etc.
  36. 36. Liquid propellant rocket engine 
  37. 37. Liquid propellant rocket engine  • The common liquid rocket is bipropellant; it uses two separate propellants, a liquid fuel and liquid oxidizer • These are contained in separate tanks and are mixed only upon injection into the combustion chamber • They may be fed to the combustion chamber by pumps or by pressure in the tanks

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