(LITERASI KELAS ) Jet engines

(LITERASI KELAS ) Jet engines

The gas  turbine engine  has  almost  completely replaced  the  reciprocating engine for aircraft propulsion. Jet engines derive thrust by ejecting the products of combustion in a jet at high speed. A turbine engine that passes all the air through the combustion chamber is called a turbojet. Because its basic design employs rotating rather than reciprocating parts, a turbojet is far simpler than a reciprocating engine of  equivalent  power, weighs  less,  is  more reliable, requires less maintenance, and has a far greater potential for generating power. It consumes fuel at a faster rate, but the fuel is less expensive.

In simplest terms, a jet engine ingests air, heats it, and ejects it at high speed. Thus in a turbojet, ambient air is taken in at the engine inlet (induction), compressed about 10 to 15 times in a compressor  consisting of rotor and  stator blades (compression), and introduced  into a combustion chamber where igniters ignite the injected fuel (combustion). The resulting combustion produces high temperatures (on the order of 1,400 to 1,900 °F [760 to 1,040 °C]). The expanding hot gases pass through a multistage turbine, which turns the air compressor through a coaxial shaft, and then into a discharge nozzle, thereby producing thrust from the high- velocity stream of gases being ejected to the rear (exhaust).

A turbofan is a turbine engine having a large low-pressure fan ahead of the compressor section; the low-pressure air is allowed to bypass the compressor and turbine, to mix with the jet stream, increasing the mass of accelerated air. This system of moving large volumes of air at a slower speed raises efficiency and cuts both fuel consumption and noise.

A turboprop is a turbine engine connected by a reduction gearbox to a propeller. Turboprop engines are typically smaller and lighter than a piston engine, produce more power, and burn more but cheaper fuel. Propfans, unducted fan jet engines, obtain ultrahigh bypass airflow using wide chord propellers driven by the jet engine. Rockets are purely reactive engines, which usually use a fuel and an oxidizing agent in combination. They are used primarily for research aircraft and for launching the space shuttle vehicles and satellites.

A ramjet is an air-breathing engine that, after being accelerated to high speeds, acts like a turbojet without the need for a compressor or turbine. A scramjet (supersonic combustion ramjet) is an engine designed for speeds beyond Mach 6, which mixes fuel into air flowing through it at supersonic speeds; it is intended for hypersonic aircraft.