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Turboprop, turboshaft and turbofan engines have additional turbine stages to drive a propeller, bypass fan or helicopter rotor. In a free turbine the turbine driving the compressor rotates independently of that which powers the propeller or helicopter rotor. Cooling air, bled from the compressor, may be used to cool the turbine blades, vanes ...
A jet engine is a type of reaction engine, discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition may include rocket , water jet , and hybrid propulsion, the term jet engine typically refers to an internal combustion air-breathing jet engine such as a turbojet , turbofan ...
All practical airbreathing jet engines heat the air by burning fuel. [1] Alternatively a heat exchanger may be used, as in a nuclear-powered jet engine. [6] Most modern jet engines are turbofans, which are more fuel efficient than turbojets because the thrust supplied by the gas turbine is augmented by bypass air passing through a ducted fan. [4]
For jet engine forms of internal combustion engines, a propelling nozzle is present. This takes the high temperature, high pressure exhaust and expands and cools it. The exhaust leaves the nozzle going at much higher speed and provides thrust, as well as constricting the flow from the engine and raising the pressure in the rest of the engine ...
The next afterburning engine, the TF30 as installed in the F-111, used an airframe-mounted secondary nozzle with free-floating flaps similar to that used on the SR-71. [27] J58 emissions were measured as part of the NASA Stratospheric Wake Experiment, which looked at the environmental impact of using afterburning jet engines for supersonic ...
The Pratt & Whitney JT9D engine was the first high bypass ratio jet engine to power a wide-body airliner. [46] The lower the specific thrust of a turbofan, the lower the mean jet outlet velocity, which in turn translates into a high thrust lapse rate (i.e. decreasing thrust with increasing flight speed). See technical discussion below, item 2.
An airline worker killed in a Dec. 31 incident at an Alabama airport was exposed to multiple warnings about the dangers of being near running jet engines, the National Transportation Safety Board ...
Motorjet engines provide greater thrust than a propeller alone mounted on a piston engine; this has been successfully demonstrated in a number of different aircraft. A jet engine also can provide thrust at higher speeds where a propeller becomes less efficient or even ineffective; in fact, a jet engine gains efficiency as speed rises, while a ...