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Gas Turbine Aircraft Engine Design and Operation

Posted on March 3, 2023 by Peter Rogers

Conventional gas turbine jet engines, such as the turbofan, have been around for years. They electricity almost all commercial aircraft and are extremely reliable. Each time you board a commercial aircraft, this technology is providing safe and effective ability to get you to your destination.

A gas turbine engine varies greatly in design from the motor in your car. Air enters the front of the engine via the fan section, which runs on the N1 or low-pressure shaft. In large by-pass motors, which are the most effective, 4 times the air that continues into the center of the engine, or more, is directed around the motor generating thrust. Then the air going into the center of the engine reaches the compressor section. Here, the air is compressed in stages as it continues rearward. Since air doesn't like to flow from areas of low pressure to high pressure, turbine engines depend on the cascade effect. The compressor, running on the N2 shaft or high-pressure shaft, contains stages of rotor blades. These rotor blades are small titanium airfoils radiating in the shaft. The same as an aircraft wing moving through the air, these blades are positioned to make an area of low pressure on the top and higher pressure underneath.

Considering these blades are angled forward, the low pressure area is facing forward in the motor and the high pressure faces rearward. In between each pair of rotating rotor blades, there's a ring of stationary blades called the stator vanes. These are identical titanium airfoil shaped blades positioned opposite to the rotor blades. As the area of high pressure behind the rotor blades pass the area of low pressure before the stator blades, the air flows from the high pressure to low pressure. This can be continued through the compressor section until the strain is increased considerably greater than the external pressure.

When the air exits the compressor section of the turbine motor, it enters the combustion area. As a consequence of the increased pressure, the air is at higher temperature. Fuel is injected into this heated air and a spark is added to ignite the mixture. During combustion, the air rapidly heats and expands further. This increases the pressure in the combustion chamber forces the air rearward during the high-pressure compressor turbine. Here, energy in the expanding air is used to turn the turbine which transfers energy via the N2 shaft to power the compressor at the front of the engine. After passing through the compressor the air continues into the power turbine. This is where the majority of the energy in the air transfers throughout the N1 shaft to the fan producing the majority of the engines thrust. The remaining air exits the rear of the motor and provides the engine about twenty per cent of its total thrust.

The gas turbine engine basically uses the same intake, compression, power, and exhaust cycles as your automotive four stroke motor. Turbine engines just vary in operation from a four stroke motor. The simplicity of the engine has allowed it to remain the essential motor of commercial aviation.