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This site is an education resource for students interested in conventional gas turbines used for aircraft propulsion or industrial power. 

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Gas Turbine History

The word "turbine" is associated with spinning.  It is derived from the Latin word for a spinning top "turbines".

The turbine traces its history back to Hero of Alexandria who in AD 62 demonstrated a device he name Aeolipile.  It did not produce useful work bit it did demonstrate the result of accelerating a gaseous fluid thru nozzle causing the sphere to rotate.

The development of the gas turbine depended upon the prior development of many devices including smoke jacks (first described by Leonardo da Vinci), windmills, water wheels and steam turbines.  Of particular significance in the development of the gas turbine were those technologies associated with the development of efficient compressors and improved materials that could withstand the high temperatures required for gas turbines.

The first patent issued for a gas turbine was issued in 1791 to John Barber, an Englishman.  The principle of operation of this gas turbine required that air and fuel from a gas producer be compressed in different cylinders and then directed into a combustion chamber where the fuel was burned.  The products of combustion were then caused to flow through a nozzle onto a turbine wheel.  John Barber’s concept was sound, but given the technology of that day, it was not possible for the device to create sufficient power to both compress the air and the gas and to have power left over to provide useful work.  Nevertheless, the credit for the idea that leads to the modern gas turbine can clearly be given to John Barber. 

In spite of the fact that John Barber’s 1791 patent represented all of the important features of a successful gas turbine it wasn’t until the early part of the 20th century that engineers were able to produce a machine that was useful. 

 for more Gas Turbine History

 

Hero's Aeolipile, 75 AD
Greek

Barber's Patent, 1791
British

Whittle's Engine, 1937
British

Uninstalled Engine Thrust

A control volume is drawn around the engine and the forces acting on this space are added to determine the resulting net force.

Uninstalled engine thrust is the addition of:
1) The difference of the static pressure of the exit and inlet pressure multiplied by the exhaust area.
2) The difference of the mass flow momentum of the exit and inlet.

Engine ByPass Ratio

Most large commercial aircraft engines are high bypass ratio designs.  This means most of the air is not passed through the engine high pressure compressor but rather simply by passes the internal turbomachinery and exits through the fan nozzle.  Bypass ratio is calculated simply by dividing the fan mass flow by the compressor mass flow.  Engine bypass ratios for commercial regional jets (< 100 passengers) are typically 5 and large commercial jets can be up to 9.