Jet Propulsion: Recap, Intake, Types of compressor, and More


Published on

Jet Propulsion: Recap, Intake, Types of compressor: Axial flow compressor and Centrifugal flow compressor.
After Burners
Air distribution in the Combustion Chamber.
Reverse Thrust

Published in: Engineering
1 Like
  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Jet Propulsion: Recap, Intake, Types of compressor, and More

  1. 1. Jet Propulsion
  2. 2. Recap Quiz • What does the compressor do? • What is the difference between Rotor Blades and Stator Blades? • How is the Turbine driven? • Name the 3 types of Combustion Chambers? • Briefly explain what happens to the temperature and pressure as the air goes through the engine? • Name 2 different types of jet engines? • What is a Compressor Surge and how is it solved?
  3. 3. • What does the compressor do? The function of the compressor in a jet engine is to increase the pressure of airflow through the engine. • What is the difference between Rotor Blades and Stator Blades? Rotor blades push the air back to the Stator blades. These then compress the air increasing its pressure. • How is the Compressor driven? By the Turbine
  4. 4. • Name the 3 types of Combustion Chambers? Can, Cannular and Annular. • Briefly explain what happens to the temperature and pressure as the air goes through the engine Pressure: As the air goes through the compressors, it increases. Once it is ignited, the pressure drops and continues to drop as the air goes out the exhaust. Temperature: As the air goes through the compressors the temperature increases slowly. Once it is ignited in the combustion chamber, there is a rapid increase. IT then slowly decreases as it leaves the exhaust.
  5. 5. • Name 2 different types of jet engines? Turbojet, Turboshaft, Turboprop, Turbofan, • What is a Compressor Surge and how is it solved? A compressor surge (stall) is a situation of abnormal airflow resulting from a stall of the airfoil within the compressor of a jet engine. The compressors are unable to cope with the amount of air entering the engine. This is solved by having a bleed valve. A double shaft.
  6. 6. Intakes • An engine’s air inlet duct is normally considered an airframe part, and not a part of the engine. However, the duct, itself, is so important to engine performance.
  7. 7. The inlet duct has two engine functions: • It must be able to recover as much of the total pressure of the free air-stream as possible and deliver this pressure to the front of the engine with minimum loss. • The duct must deliver air to the compressor inlet under all flight conditions with as little turbulence and pressure variation as possible.
  8. 8. • Most inlet ducts on subsonic airplanes are of the divergent type. Air flowing into a divergent duct expands slightly and converts some of its velocity energy into pressure. • Rectangular inlets are designed to absorb the shockwaves produced.
  9. 9. Compressors Centrifugal flow • Centrifugal compressors were used on many of the earliest gas turbine engines because of their ruggedness, light weight and high pressure ratio for each stage of compression. • A typical centrifugal compressor consists of three components: the impeller, the diffuser, and the manifold.
  10. 10. Eye of the impeller Impeller Diffuser Manifold
  11. 11. • Air enters the eye of the fast-rotating impeller and is accelerated to a high velocity as it is slung to the outer edge by centrifugal force. The high-velocity air then flows into the diffuser, which fits closely around the outside edge of the impeller. • There it flows through divergent ducts where some of the velocity energy is changed into pressure energy. • The air, which has slowed down and has had its pressure increased, flows into the manifold through a series of turning vanes. • From the manifold, the air flows into the combustion section of the engine.
  12. 12. Axial flow compressor • Axial-flow are compressors in which the air passes axially or straight through the compressor. • They are heavier than a centrifugal compressor, but they are capable of a much higher overall compression ratio, and they have a smaller cross-sectional area, which makes them easier to streamline. • Axial-flow compressors have therefore become the standard for large gas turbine engines and are also used on many small engines.
  13. 13. • Axial-flow compressors are made up of a number of stages of rotor blades that are driven by the turbine, and that rotate between stages of fixed stator vanes. • Both the rotor blades and stator vanes have airfoil shapes and are mounted so that they form a series of divergent ducts through which the air flows.
  14. 14. Combustion Air distribution • Approximately 82% of the air from the compressor passes around the outside of the inner flame tube. • This air is then passes into the flame tube via a number of large and small ‘dilution’ holes into the inside of the flame tube where it is heated by the combustion flame
  15. 15. • Approximately 18% of the air passes immediately into the flame tube where it is split into another two main flows: - • A. Approximately half of the air passes around and through the end baffle plate and swirls into the flame tube. It can be seen that this air flow produces a forward flow right at the point where the fuel is sprayed in. • B. Approximately half the airflow passes through swirl vanes situated around the fuel jet. This swirl air hits the forward flow to produce what is known as a ‘Re-Circulating Vortex’.
  16. 16. Afterburners • An afterburner is an additional component on some jet engines. Its purpose is to provide an increase in thrust. • Afterburning is achieved by injecting additional fuel into the jet pipe downstream of the turbine. It is burnt using the remaining oxygen. • This heats and expands the exhaust gases further, and can increase the thrust of a jet engine by 50% or more.
  17. 17. Reverse Thrust • Modern aircraft are normally so heavy to land at such a high speed that the aircraft brakes cannot be depended upon for complete speed control. • Thrust reversal is the temporary diversion of an aircraft engine's exhaust so that the exhaust produced is directed forward, rather than rearwards. • This acts against the forward travel of the aircraft, providing deceleration