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The propelling nozzle converts a gas turbine or gas generator into a jet engine. Power available in the gas turbine exhaust is converted into a high speed propelling jet by the nozzle. The power is defined by typical gauge pressure and temperature values for a turbojet of 20 psi (140 kPa) and 1,000 °F (538 °C). [18]
The type of jet engine used to explain the conversion of fuel into thrust is the ramjet.It is simpler than the turbojet which is, in turn, simpler than the turbofan.It is valid to use the ramjet example because the ramjet, turbojet and turbofan core all use the same principle to produce thrust which is to accelerate the air passing through them.
Early examples of different solutions to alleviate rotating stall in the front stages include the Rolls-Royce Avon with variable inlet guide vanes and interstage bleed, the General Electric J79 with variable inlet guide vanes and variable stators, the Bristol Olympus with split compressor and the Pratt & Whitney J57 with split compressor and intercompressor bleed.
Jet vanes must be made of a refractory material or actively cooled to prevent them from melting. Sapphire used solid copper vanes for copper's high heat capacity and thermal conductivity, and Nexo used graphite for its high melting point, but unless actively cooled, jet vanes will undergo significant erosion.
Diagram of a typical gas turbine jet engine Frank Whittle Hans von Ohain. The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and a turbine (that drives the ...
Modern high-bypass turbofan engines build on this principle by utilizing available bypass air to envelop the jet-core exhaust at the rear of the engine, reducing noise. Most hush kits make further modifications to the exhaust, including acoustically treated tailpipes, revised inlet nacelles and guide vanes. They reduce the forward propagating ...
Compressor stalls were a common problem on early jet engines with simple aerodynamics and manual or mechanical fuel control units, but they have been virtually eliminated by better design and the use of hydromechanical and electronic control systems such as full authority digital engine control. Modern compressors are carefully designed and ...
Aircraft engine performance refers to factors including thrust or shaft power for fuel consumed, weight, cost, outside dimensions and life. It includes meeting regulated environmental limits which apply to emissions of noise and chemical pollutants, and regulated safety aspects which require a design that can safely tolerate environmental hazards such as birds, rain, hail and icing conditions.