Skip to main content

Gas Turbine Engines

Gas turbine engines are widely used in different fields for generate energy. They are commonly used in aircrafts. If you watch a huge passenger aircraft, you can see the gas turbine engines are either hanging on the wing section or tail section. Those power plants gives enough energy to generate thrust which finally result the aircraft fly.


Figure: An Airbus A340's 4 engines are situated on the wing, 2 in each side.

Figure: A Tupolev 154 Aircraft where engines situated on the empennage 
How does a gas turbine engine work?
There are several sections inside of an engine. First one is the air intake and fan which direct the air to inside of the engine, then the compressor, which compress the air to a very high pressure while reducing its speed. Then air meets the combustion chamber, where kerosene (fuel) is spread as small particles and burned in a high temperature.  Then this high speed, energized hot gas meets the turbine. Turbine rotates, using the kinetic energy from high speed gas.
  The most interesting thing is that the turbine is connected with the compressor via a valve. This means, the turbine makes the compressor rotate, obviously with a very high angular velocity.  This combination process results the thrust.


Figure: Simple Schematic view of a gas turbine engine
…->Rotation of the compressor-> compressed air-> combustion-> combusted air with high energy->Rotation of the turbine-> once again rotation of the compressor->…
Compressor and turbine consists of blades which has different functions which are called stators and rotors. They are usually fixed in to disks. Blades are situated in different stages which have different forms and sizes.

Figure: Variation of blade sizes
Figure: Opened engine, turbine blades
 A blade as a single element reminds a small scaled aircraft wing.  What I wanted to say, is that every blade has an aerodynamically designed profile.
Figure: Blades
Additionally the combustion chamber is one of the most important elements of a gas turbine engine.
Figure : A combustion chamber of a Gas turbine engine
 These elements can be destroyed or deteriorated by stone/ sand which engine may sucks during the departure or landing. Change of the aero dynamical shape of a blade can result fuel inefficiency and even a future failure of the engine during the flight.  So it is utmost important to inspect them frequently. Although opening up an engine is not profitable. That waste time and money. That is when NDT engineers use a borescope to inspect inside of an engine.
Labels:

Popular posts from this blog

Aircraft Visual Inspection

Figure: Boeing 777 aircraft Commercial aircrafts are frequently inspected visually. There is a primary inspection called "walk around check" both in the line and the base, transit checks, daily check, weekly check, A check, B check etc… Line is the more about the quick checks while aircraft is in the park or in between flights. Base is mostly the hanger, where hard checks, repairs take place. A qualified engineer walk around the aircraft and inspect structural items visually. Engine is also checked during the walk around checks. There engineer watches for oil leaks, structural damages in the engine, inlet of the engine for composite parts fixtures to the structure, fan/first stages of the compressor, last stages of the turbine for deterioration or damages , or any unusual changes of the engine. In this example shows how, engineer/Pilot carry on a walk around inspection of a Boeing 777 aircraft. Figure: Walk around inspection of a Boeing 777 1. Left Mid Fuselage...
Read more

Eddy current Theory

Eddy current theory is based on electromagnetic induction. That means, a variable magnetic field can induce an electric current on a conductor which is separate to the source of the magnetic field, and also vice versa, which is an electric current generates a magnetic field. Similar theory is used for the magnetic particles inspection as well. Electromagnetic induction is used in many applications such as, Transformers, Electric motors, Generators, etc...   In the field of Non destructive testing (NDT), we manipulate with this theory which I mentioned above, and try to find surface defects or/and shallow internal defects of ferromagnetic materials.
Read more

GKN A350 spar program update

"Automated fiber placement to replace established tape laying/drape forming process for the composite rear spars on the new midsize commercial passenger jet" Headquartered in Redditch, Worcestershire, U.K., GKN Plc’s Aerospace Division continues its strong growth, based to a large extent on its expertise in the production of composite structures. Even the 50 percent of the business that is not focused on composites is based primarily on materials technologies, such as complex titanium aero-engine components and cockpit canopies with vacuum-deposited surfaces to enhance stealth performance. This should not come as a surprise, because GKN’s first use of materials technology to gain market share was in the 1860s, when it dominated the railroad supply business by being the first company in the U.K. to make steel by the cost-effective Bessemer process. The company produced more than 56 million lb (25,400 metric tonnes) of steel per year by 1871. Fig. 1: The inner rear spar demo...
Read more