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A fuel control unit is a control system for gas turbine engines.
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A fuel control unit is a control system for gas turbine engines.
Gas turbine engines are primarily controlled by the amount of fuel supplied to the combustion chambers. With this in mind we can say that, the very simplest fuel control for a turbine engine is a fuel valve operated by the pilot. Many pre-production models of early turbojet engines featured just that, but it was soon found that this kind of control was difficult and dangerous in actual use. Closing the valve too quickly while trying to reduce power output could cause a lean die-out, where the airflow through the engine blows the flame out of the combustion chamber and extinguishes it. Adding fuel too quickly to increase power can damage the turbines due to excessive heat, or the sudden rise in combustion chamber pressure may cause a compressor stall. Another danger of too much fuel is a rich blow-out, where soaking the fire with fuel displaces the oxygen and lowers the temperature enough to extinguish the flame. The excess fuel may then be heated on the hot tailpipe and ignite, possibly causing damage to the aircraft. [1] For an aircraft engine, changes in airspeed or altitude cause changes in air speed and density through the engine, which would then have to be manually adjusted for by the pilot.
A fuel control unit attempts to solve those problems by acting as an intermediary between the operator's controls and the fuel valve. The operator has a power lever which only controls the engine's potential, not the actual fuel flow. The fuel control unit acts as a computer to determine the amount of fuel needed to deliver the power requested by the operator.
A jet engine is a type of reaction engine discharging a fast-moving jet that generates thrust by jet propulsion. While this broad definition can include rocket, water jet, and hybrid propulsion, the term jet engine typically refers to an internal combustion airbreathing jet engine such as a turbojet, turbofan, ramjet, or pulse jet. In general, jet engines are internal combustion engines.
A ramjet, sometimes referred to as a flying stovepipe or an athodyd, is a form of airbreathing jet engine that uses the engine's forward motion to compress incoming air without an axial compressor or a centrifugal compressor. Because ramjets cannot produce thrust at zero airspeed, they cannot move an aircraft from a standstill. A ramjet-powered vehicle, therefore, requires an assisted take-off like a rocket assist to accelerate it to a speed where it begins to produce thrust. Ramjets work most efficiently at supersonic speeds around Mach 3. This type of engine can operate up to speeds of Mach 6.
A turbocharger, colloquially known as turbo, is a turbine-driven, forced induction device that increases an internal combustion engine's power output by forcing extra compressed air into the combustion chamber. This improvement over a naturally aspirated engine's power output is because the compressor can force more air—and proportionately more fuel—into the combustion chamber than atmospheric pressure alone.
The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the turbo portion refers to a gas turbine engine which achieves mechanical energy from combustion, and the fan, a ducted fan that uses the mechanical energy from the gas turbine to accelerate air rearwards. Thus, whereas all the air taken in by a turbojet passes through the combustion chamber and turbines, in a turbofan some of that air bypasses these components. A turbofan thus can be thought of as a turbojet being used to drive a ducted fan, with both of these contributing to the thrust.
A starter is a device used to rotate (crank) an internal-combustion engine so as to initiate the engine's operation under its own power. Starters can be electric, pneumatic, or hydraulic. The starter can also be another internal-combustion engine in the case, for instance, of very large engines, or diesel engines in agricultural or excavation applications.
The turbojet is an airbreathing jet engine, typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet, a compressor, a combustion chamber, and a turbine. The compressed air from the compressor is heated by burning fuel in the combustion chamber and then allowed to expand through the turbine. The turbine exhaust is then expanded in the propelling nozzle where it is accelerated to high speed to provide thrust. Two engineers, Frank Whittle in the United Kingdom and Hans von Ohain in Germany, developed the concept independently into practical engines during the late 1930s.
An air-start system is a power source used to provide the initial rotation to start large diesel and gas turbine engines.
The Brayton cycle is a thermodynamic cycle named after George Brayton that describes the workings of a constant-pressure heat engine. The original Brayton engines used a piston compressor and piston expander, but more modern gas turbine engines and airbreathing jet engines also follow the Brayton cycle. Although the cycle is usually run as an open system, it is conventionally assumed for the purposes of thermodynamic analysis that the exhaust gases are reused in the intake, enabling analysis as a closed system.
An afterburner is an additional combustion component used on some jet engines, mostly those on military supersonic aircraft. Its purpose is to increase thrust, usually for supersonic flight, takeoff, and combat. Afterburning injects additional fuel into a combustor in the jet pipe behind the turbine, "reheating" the exhaust gas. Afterburning significantly increases thrust as an alternative to using a bigger engine with its attendant weight penalty, but at the cost of very high fuel consumption which limits its use to short periods. This aircraft application of reheat contrasts with the meaning and implementation of reheat applicable to gas turbines driving electrical generators and which reduces fuel consumption.
A compressor map is a chart which shows the performance of a turbomachinery compressor. This type of compressor is used in gas turbine engines, for supercharging reciprocating engines and for industrial processes, where it is known as a dynamic compressor. A map is created from compressor rig test results or predicted by a special computer program. Alternatively the map of a similar compressor can be suitably scaled. This article is an overview of compressor maps and their different applications and also has detailed explanations of maps for a fan and intermediate and high-pressure compressors from a three-shaft aero-engine as specific examples.
The Heinkel HeS 40(HeS - Heinkel Strahltriebwerke) was an experimental constant-volume jet engine designed by Adoph Müller's team at Heinkel starting some time in 1940 or 41. It was based on the mechanical layout of the HeS 30, but replaced the conventional flame cans with oversized ones including large poppet valves that sealed off the chambers during firing. Constant-volume combustion, similar to the Otto cycle used in most piston engines, is considerably more fuel efficient than the constant-pressure combustion used in a typical jet engine.
Overspeed is a condition in which an engine is allowed or forced to turn beyond its design limit. The consequences of running an engine too fast vary by engine type and model and depend upon several factors, the most important of which are the duration of the overspeed and the speed attained. With some engines, a momentary overspeed can result in greatly reduced engine life or catastrophic failure. The speed of an engine is typically measured in revolutions per minute (rpm).
The air turborocket is a form of combined-cycle jet engine. The basic layout includes a gas generator, which produces high pressure gas, that drives a turbine/compressor assembly which compresses atmospheric air into a combustion chamber. This mixture is then combusted before leaving the device through a nozzle and creating thrust.
This article briefly describes the components and systems found in jet engines.
An airbreathing jet engine is a jet engine that emits a jet of hot exhaust gases formed from air that is forced into the engine by several stages of centrifugal, axial or ram compression, which is then heated and expanded through a nozzle. They are typically gas turbine engines. The majority of the mass flow through an airbreathing jet engine is provided by air taken from outside of the engine and heated internally, using energy stored in the form of fuel.
Internal combustion engines come in a wide variety of types, but have certain family resemblances, and thus share many common types of components.
The Pirna 014 was an axial turbojet designed in East Germany in the mid- to late 1950s by former Junkers engineers, who were repatriated to East Germany in 1954 after being held in custody in the Soviet Union following World War II.
Many variations of aircraft engine starting have been used since the Wright brothers made their first powered flight in 1903. The methods used have been designed for weight saving, simplicity of operation and reliability. Early piston engines were started by hand, with geared hand starting, electrical and cartridge-operated systems for larger engines being developed between the wars.
An internal combustion engine (ICE) is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is applied typically to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into useful work. This replaced the external combustion engine for applications where weight or size of the engine is important.
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. It is the end product that an engine company sells.