1. Turbine Engines & Oxygen Systems
AVIA 222
Turbine Engines & Oxygen Systems

2. Turbine Engines
GE90 Specifically designed for the Boeing 777, this is the world's most powerful turbofan, having demonstrated over 127,000 pounds of thrust. It is the exclusive power for long-range ER and -200LR twinjets.

3. F-18, each low bypass engine produces about 17,000lbs of thrust…
The business end of this Boeing 777 engine produces between 85,000 to 127,000 lbs of thrust!

4. Gas Turbine (jet) Engines
The Basics
There are five sections to a jet engine:
Inlet
Compressor
Combustor
Turbine
Nozzle

5. Inlet
The inlet takes large amounts of ram-air and converts it to static pressure. The inlet is considered part of the airframe/engine housing.

6. Compressor
The compressor is comprised of a series of rotating blades (airfoils), and fixed (immobile) “Stator Blades”. This section takes the ram air pressure and increases it to deliver high pressure air to the combustion chamber.

7. This is a pressure flow analysis of the compressor section of the GE90 turbofan.

8. Combustor
The combustor section is comprised of burner cans, or annular burners which take a portion (about 25%) of the compressed air, injects jet fuel (kerosene) and burns it to create thrust for the turbine blades. The remaining air is circulated around the burners for cooling.

9. Cross section of an annular burner.

10. Turbine
The turbine blades are downstream of the burners, and function similarly to a turbocharger, using the exhaust gases to produce a turning motion for the drive shaft, which in turn drives the compressor blades at the front of the engine.

11. Nozzle (exhaust)
The exhaust nozzle is the area where the hot gases exit the engine. This is where the higher pressure created by the compressed air/fuel burn is converted into thrust. If a second shaped chamber is added to the the nozzle then afterburning can be achieved by injecting a large amount of fuel into what is basically a large burner “can”. Very inefficient, but can pack quite a punch when extra acceleration is required.

12. Three Types of Jet Engines

13. Turbo-jet
This is the most basic of jet engines. It is still used on many aircraft, such as the older Boeing series…the really loud ones!

14. Turbo-Fan
This is an evolution of the turbojet engine in which the core jet engine is surrounded by a large fan that accelerates air around the outside. The outer fan produces a substantial amount of thrust as well as greatly reducing exhaust noise…B series, or the Airbus 319 are our Kelowna examples. This is a cutaway of a GE90.

15. Turbo Prop
This is a jet turbine system that instead of using the exhaust air flow as thrust, a propeller is turned via the drive shaft and transmission, or by a viscous coupling.
Free turbine: the power turbine, which turns the propeller, is mechanically free from the compressor turbine.
This model shows a fixed shaft turbine which has a shaft/gearbox system that does not have a viscous coupling.

16. NASA Web Site
This site contains full animations of all types of jet engines.

17. Turbine Engine Lingo
Axial Flow Compressor – most common type of engine design. Compressor stages can be added without increasing diameter of the engine. Older jets used a centrifugal type.
Compression Pressure Ratio (CPR) – the ratio between compressor discharge pressure and engine inlet pressure.

18. Centrifugal Compressor
The vanes at the far right are staged behind the axial flow compressor section. Advantage: Centrifugal sections create pressure much quicker (at lower rpm than axial flow).

19. Cold Stall is when only a few blades of the compressor stalls…
Engine/Exhaust Pressure Ratio (EPR) – The ratio of the compressor inlet pressure to the total exhaust turbine outlet pressure.
Compressor Stall – When airflow is turbulent over the compressor blades the airflow can stall thus dropping the compressor pressure
Turbulence, high angles of attack or sudden power reductions can all trigger compressor stall.
Cold Stall is when only a few blades of the compressor stalls…
Hot Stall is when the entire compressor face stalls preventing correct airflow. This type of stall can lead to reverse airflow resulting in severe engine damage (similar to a carburetor back fire).
Torquemeter – A gauge that measures shaft horsepower as a reflection of engine power output.

20. Compressor Bleed Air – the portion of compressed air that does not enter the combustion chambers but is diverted around for cooling and powering other systems such as pressurization systems, oil systems etc.
Inlet Guide Vanes – vanes at the front of the engine that regulate the amount of air available to the compressor
Compressor Bleeds - valves that regulate the pressure in the various stages of the compressor that open to bleed off excessive pressure build up during throttle adjustments.

21. Interstage Turbine Temperature (ITT) – An engine monitoring gauge that measures the exhaust turbine temperatures. This is the hottest part of the engine and requires close monitoring to keep within AFM operation range limits.
Temperature and Pressure – High air temperature and low pressure (high altitudes) reduce air density and thus reduce the performance of turbine engines.
Humidity and Moisture – Humidity and moisture (rain etc) have no measurable effect on the power production of a turbine.
Beta Range – The propeller position where the pitch and fuel flow are both controlled by the power lever for the purpose of taxing or reverse. Low pitch stops prevent operation of Beta range during cruise

22. Oxygen Systems
Supplemental Oxygen is required for all flights above 13,000 feet, or for over 30 minutes between 10,000 and 13,000 feet.
Pressurized a/c can maintain oxygen levels, but supplemental oxygen is still required for everyone aboard in case of depressurization
Oxygen can be useful to sharpen your sight at night. The A.I.M. (AIR 3.7) advises that if available oxygen should be used. Note your vision acuteness while on night IFR flights, especially near the end of the flight.
Hypoxia is the lack of oxygen in the blood. The most common first symptom is a sense of well being (euphoria), followed by confusion, nausea etc. Be aware when doing your IFR training!!! Watch for symptoms!!! A.I.M. AIR 3.2.1

23. Loss of Cabin Pressure…
Seat belts and oxygen masks….you never know when you will need them!

24. Constant Flow Oxygen Masks
A constant flow mask system provides a steady metered flow of oxygen into a face mask. Supply is from a oxygen bottle and low pressure line. A re-breather bag is attached below the mask to make more efficient use by recycling the breathed mixture.

25. Oxygen flow through the regulator may be manually adjusted, or automated to adjust flow dependant on pressure altitude.

26. A demand oxygen system has a valve system that only flows oxygen when inhaling. This system is more complex but eliminates the need for a rebreather bag.

27. Required Readings The Turbine Pilots Flight Manual Homework
Chapters 1-4 will be included in the material tested on the mid-term exam.
Homework
TPFM: ch3
ATPL prep section 2