Today, aviation is almost 100% composed of machines that use a gas turbine type. power plant. In other words - gas turbine engines. However, despite the increasing popularity of air travel now, few people know how that buzzing and whistling container that hangs under the wing of an airliner works.

Principle of operation gas turbine engine.

A gas turbine engine, like a piston engine on any car, refers to engines internal combustion. Both of them convert the chemical energy of the fuel into heat, by burning, and then into useful, mechanical. However, how this happens is somewhat different. In both engines, 4 main processes take place - these are: intake, compression, expansion, exhaust. Those. in any case, air (from the atmosphere) and fuel (from tanks) first enter the engine, then the air is compressed and fuel is injected into it, after which the mixture ignites, due to which it expands significantly, and is eventually released into the atmosphere. Of all these actions, only expansion gives energy, all the rest are necessary to ensure this action.

Now what's the difference. In gas turbine engines, all these processes occur constantly and simultaneously, but in different parts of the engine, and in a piston engine, in one place, but at different times and in turn. In addition, the more compressed the air, the more energy can be obtained during combustion, and today the compression ratio of gas turbine engines has already reached 35-40:1, i.e. in the process of passing through the engine, the air decreases in volume, and accordingly increases its pressure by 35-40 times. For comparison, in piston engines, this figure does not exceed 8-9: 1, in the most modern and advanced models. Accordingly, having equal weight and dimensions, the gas turbine engine is much more powerful, and the coefficient useful action he is higher. This is the reason for such a widespread use of gas turbine engines in aviation today.

And now more about the design. The four processes listed above take place in the engine, which is shown in the simplified diagram under the numbers:

• air intake - 1 (air intake)
• compression - 2 (compressor)
• mixing and ignition - 3 (combustion chamber)
• exhaust - 5 (exhaust nozzle)
• The mysterious section at number 4 is called the turbine. This is an integral part of any gas turbine engine, its purpose is to obtain energy from gases that exit the combustion chamber at high speeds, and it is located on the same shaft as the compressor (2), which drives it.

Thus, a closed cycle is obtained. Air enters the engine, is compressed, mixed with fuel, ignited, directed to the turbine blades, which remove up to 80% of the gas power to rotate the compressor, all that is left determines the final engine power, which can be used in many ways.

Depending on the method of further use of this energy, gas turbine engines are divided into:

• turbojet
• turboprop
• turbofan
• turboshaft

The engine shown in the diagram above is turbojet. It can be said to be “clean” gas turbine, because after passing through the turbine, which rotates the compressor, the gases exit the engine through the exhaust nozzle at great speed and thus push the aircraft forward. Such engines are now used mainly in high-speed combat aircraft.

Turboprop engines differ from turbojet engines in that they have additional section turbine, also called a turbine low pressure, consisting of one or more rows of blades that take the energy left after the compressor turbine from the gases and thus rotate the propeller, which can be located both in front and behind the engine. After the second section of the turbine, the exhaust gases actually exit by gravity, having practically no energy, so they are simply used to remove them. exhaust pipes. Similar engines are used in low-speed, low-altitude aircraft.

Turbofans engines have a similar scheme with turboprops, only the second section of the turbine does not take all the energy from the exhaust gases, so these engines also have an exhaust nozzle. But the main difference is that the low-pressure turbine drives the fan, which is enclosed in a casing. Therefore, such an engine is also called a dual-circuit engine, because the air passes through the internal circuit (the engine itself) and the external one, which is necessary only to direct the air stream that pushes the engine forward. Because they have a rather "chubby" shape. It is these engines that are used on most modern airliners, since they are the most economical at speeds approaching the speed of sound and efficient when flying at altitudes above 7000-8000m and up to 12000-13000m.

Turboshaft the engines are almost identical in design to turboprops, except that the shaft that is connected to the low-pressure turbine comes out of the engine and can power absolutely anything. Such engines are used in helicopters, where two or three engines drive a single main rotor and a compensating tail propeller. Even tanks, the T-80 and the American Abrams, now have similar power plants.

Gas turbine engines are also classified according to other signs:

• by input device type (adjustable, unregulated)
• by compressor type (axial, centrifugal, axial-centrifugal)
• according to the type of air-gas path (straight-through, loop)
• by turbine type (number of stages, number of rotors, etc.)
• by type of jet nozzle (adjustable, unregulated), etc.

Turbojet engine with axial compressor received wide application. When running engine is coming continuous process. The air passes through the diffuser, slows down and enters the compressor. Then it enters the combustion chamber. Fuel is also supplied to the chamber through the nozzles, the mixture is burned, the combustion products move through the turbine. The products of combustion in the turbine blades expand and cause it to rotate. Further, gases from the turbine with reduced pressure enter the jet nozzle and break out at great speed, creating thrust. The maximum temperature also occurs in the water of the combustion chamber.

The compressor and turbine are located on the same shaft. To cool the products of combustion, cold air. In modern jet engines working temperature can exceed the melting point of rotor blade alloys by about 1000 °C. The cooling system for turbine parts and the choice of heat-resistant and heat-resistant engine parts are one of the main problems in the design of jet engines of all types, including turbojet ones.

A feature of turbojet engines with a centrifugal compressor is the design of the compressors. The principle of operation of such engines is similar to engines with an axial compressor.

Gas turbine engine. Video.

Useful related articles.

Jet engine

Jet engine

an engine whose thrust is created by the reaction (recoil) of the jet of the working fluid flowing from it. The working fluid in relation to engines is understood as a substance (gas, liquid, solid body), with the help of which the heat released during the combustion of fuel is converted into useful mechanical work. The basis of a jet engine is where it is burned (source of primary energy) and generated - hot gases (fuel combustion products).

According to the method of generating the working fluid, jet engines are divided into air-jet (AJ) and rocket engines(RD). In jet engines, the fuel burns in the air stream (is oxidized by atmospheric oxygen), turning into the thermal energy of hot gases, which in turn is converted into the kinetic energy of the jet stream. Depending on the method of supplying air to the combustion chamber, turbocompressor, ramjet and pulse jet engines are distinguished.

In a turbocharged engine, air is forced into the combustion chamber by a compressor. Such engines are the main type of aircraft engine. They are divided into turboprop, turbojet and pulse jet engines.

Turboprop engine (TVD) - turbocompressor, in which thrust is mainly created by a propeller driven into rotation gas turbine, and partly by direct reaction of the flow of gases flowing from the jet nozzle.

1 - air; 2 - compressor; 3 - gas; 4 - nozzle; 5 - hot gases; 6 - combustion chamber; 7 - liquid fuel; 8 - nozzles

Turbo jet engine(TRD) - a turbocompressor engine in which thrust is created by the direct reaction of a stream of compressed gases flowing from a nozzle. Pulsating jet engine - a jet engine in which air periodically entering the combustion chamber is compressed under the action of velocity pressure. Has little traction used mainly on subsonic aircraft. A ramjet engine (ramjet) is a jet engine in which the air continuously entering the combustion chamber is compressed under the action of a velocity pressure. It has great thrust at supersonic flight speeds; there is no static thrust, so a forced start is necessary for the ramjet.

Encyclopedia "Technology". - M.: Rosman. 2006 .

Jet engine

direct reaction engine, - code name big class engines for aircraft for various purposes. Unlike a power plant with a reciprocating internal combustion engine and a propeller, where the traction force is created as a result of the interaction of the propeller with the external environment, the R. engine creates a driving force, called reactive force or thrust, as a result of the expiration of a working fluid jet from it, which has kinetic energy. This force is directed opposite to the outflow of the working fluid. In this case, the propeller itself is the prime mover. The primary energy necessary for the operation of the propellant, as a rule, is contained in the working fluid itself (the chemical energy of the combusted fuel, the potential energy of the compressed gas).
R. d. are divided into two main groups. The first group consists of rocket engines - engines that create traction only due to the working fluid stored on board the aircraft. These include liquid rocket engines, solid fuel rocket engines, electric rocket engines, etc. They are used in rockets for various purposes, including powerful boosters that serve to output spaceships into orbit.
The second group includes jet engines, in which the main component of the working fluid is air taken into the engine from environment. In rocket engines - turbojet engines, ramjet engines, pulse jet engines - all propulsion is generated by direct reaction. According to the working process and design features, some aircraft gas turbine engines of indirect reaction are adjacent to air-rocket engines - turboprop engines and their varieties (turbopropfan engines and turboshaft engines), in which the share of thrust due to direct reaction is insignificant or it is practically absent. Turbojet dual circuit engines with different bypass ratios occupy an intermediate position in this sense between turbojet engines and turboprop engines. Air-rocket engines are used mainly in aviation as part of the power plant of military and civil purpose. Using ambient air as an oxidizing agent, air-rocket engines provide a significantly greater fuel efficiency than rocket engines, since only fuel is needed on board the aircraft. At the same time, the possibility of carrying out a working process using ambient air limits the scope of use of air-rocket engines to the atmosphere.
The main advantage of a rocket engine over an air-rocket engine is its ability to operate at any speed and flight altitude (the thrust of a rocket engine does not depend on flight speed and increases with altitude). In some cases, combined engines are used that combine the features of rocket and air-rocket engines. AT combined engines to improve efficiency, air is used at the initial stage of acceleration with the transition to rocket mode at high flight altitudes.

Aviation: Encyclopedia. - M.: Great Russian Encyclopedia. Chief editor G.P. Svishchev. 1994 .

See what a "jet engine" is in other dictionaries:

JET ENGINE, an engine that provides propulsion by quickly releasing a jet of liquid or gas in a direction opposite to the direction of movement. To create a high-speed flow of gases, fuel in a jet engine ... ... Scientific and technical encyclopedic dictionary

An engine that creates the traction force necessary for movement by converting the initial energy into the kinetic energy of the jet stream of the working fluid; as a result of the expiration of the working fluid from the engine nozzle, ... ... Great Soviet Encyclopedia

- (direct reaction engine) an engine whose thrust is created by the reaction (recoil) of the working fluid flowing from it. Subdivided into air jet and rocket engines ... Big Encyclopedic Dictionary

An engine that converts any type of primary energy into the kinetic energy of the working fluid (jet stream), which creates jet thrust. In a jet engine, the engine itself and the propulsion unit are combined. The main part of any ... ... Marine dictionary

JET engine, an engine whose thrust is created by direct reaction (recoil) of the working fluid flowing out of it (for example, combustion products of chemical fuel). They are divided into rocket engines (if stocks of the working fluid are placed ... ... Modern Encyclopedia

Jet engine- JET ENGINE, an engine whose thrust is created by direct reaction (recoil) of the working fluid flowing out of it (for example, combustion products of chemical fuel). They are divided into rocket engines (if stocks of the working fluid are placed ... ... Illustrated Encyclopedic Dictionary

JET ENGINE- a direct reaction engine, the reactive (see) of which is created by the return of the jet of the working fluid flowing from it. There are air-jet and rocket (see) ... Great Polytechnic Encyclopedia

jet engine- — Topics oil and gas industry EN jet engine … Technical Translator's Handbook

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- (direct reaction engine), an engine whose thrust is created by the reaction (recoil) of the working fluid flowing from it. They are divided into air jet and rocket engines. * * * JET ENGINE JET ENGINE (direct motor… … encyclopedic Dictionary

Books

• Aircraft model pulsating air-jet engine , V. A. Borodin , The book covers the design, operation and elementary theory of a pulsating WFD. The book is illustrated with diagrams of jet aircraft models. Reproduced in the original… Category: Agricultural machines Publisher: YoYo Media, Manufacturer:

ESSAY

ON THIS TOPIC:

Jet Engines .

WRITTEN: Kiselev A.V.

KALININGRAD

Introduction

Jet engine, an engine that creates the traction force necessary for movement by converting the initial energy into the kinetic energy of the jet stream of the working fluid; as a result of the expiration of the working fluid from the nozzle of the engine, a reactive force is formed in the form of a reaction (recoil) of the jet, which moves the engine and the apparatus structurally associated with it in the direction opposite to the outflow of the jet. The kinetic (speed) energy of a jet stream can be converted into R. j. different kinds energy (chemical, nuclear, electrical, solar). R. d. (direct reaction engine) combines the actual engine with the mover, i.e., provides its own movement without participation intermediate mechanisms.

For creating jet thrust used by R. d., you need:

the source of the initial (primary) energy, which is converted into the kinetic energy of the jet;

the working fluid, which is ejected from the R. d. in the form of a jet stream;

R. D. himself is an energy converter.

The initial energy is stored on board an aircraft or other apparatus equipped with RD (chemical fuel, nuclear fuel), or (in principle) it can come from outside (solar energy). To obtain a working fluid in R. d., a substance taken from the environment (for example, air or water) can be used;

the substance which is in tanks of the device or directly in the R.'s chamber of d.; a mixture of substances coming from the environment and stored on board the vehicle.

In modern R. d., chemical is most often used as the primary

Missile firing tests

engine Space Shuttle

Turbojet engines AL-31F aircraft Su-30MK. belong to the class jet engines

energy. In this case, the working fluid is incandescent gases - combustion products of chemical fuel. During the operation of a rocket engine, the chemical energy of the burning substances is converted into the thermal energy of the combustion products, and the thermal energy of the hot gases is converted into the mechanical energy of the translational motion of the jet stream and, consequently, the apparatus on which the engine is installed. The main part of any R. d. is the combustion chamber in which the working fluid is generated. The end part of the chamber, which serves to accelerate the working fluid and obtain a jet stream, is called a jet nozzle.

Depending on whether the environment is used or not during the operation of rocket engines, they are divided into 2 main classes - air-jet engines (WRD) and rocket engines (RD). All WFDs are heat engines, the working fluid of which is formed by the oxidation reaction of a combustible substance with atmospheric oxygen. The air coming from the atmosphere makes up the bulk of the working fluid of the WFD. Thus, an apparatus with a WFD carries a source of energy (fuel) on board, and draws most of the working fluid from the environment. Unlike the WFD, all components of the working fluid of the RD are on board the apparatus equipped with the RD. The absence of a propulsor interacting with the environment and the presence of all components of the working fluid on board the apparatus make the RD the only one suitable for work in space. There are also combined rocket engines, which are, as it were, a combination of both main types.

History of jet engines

The principle of jet propulsion has been known for a very long time. Heron's ball can be considered the ancestor of R. d. Solid rocket engines - powder rockets appeared in China in the 10th century. n. e. For hundreds of years, such missiles were used first in the East, and then in Europe as fireworks, signal, combat. In 1903, K. E. Tsiolkovsky, in his work "Investigation of World Spaces with Reactive Devices", was the first in the world to put forward the main provisions of the theory of liquid-propellant rocket engines and proposed the main elements of a liquid-propellant rocket engine. The first Soviet liquid rocket engines - ORM, ORM-1, ORM-2 were designed by V. P. Glushko and created under his leadership in 1930-31 at the Gas Dynamics Laboratory (GDL). In 1926, R. Goddard launched a rocket using liquid fuel. For the first time, an electrothermal RD was created and tested by Glushko at the GDL in 1929-33.

In 1939, missiles with ramjet engines designed by I. A. Merkulov were tested in the USSR. First scheme turbojet engine? was proposed by the Russian engineer N. Gerasimov in 1909.

In 1939, the construction of turbojet engines designed by A. M. Lyulka began at the Kirov Plant in Leningrad. The tests of the created engine were prevented by the Great Patriotic War of 1941-45. In 1941, a turbojet engine designed by F. Whittle (Great Britain) was first installed on an aircraft and tested. The theoretical works of the Russian scientists S. S. Nezhdanovsky, I. V. Meshchersky, and N. E. Zhukovsky, the works of the French scientist R. Enot-Peltri, and the German scientist G. Oberth were of great importance for the creation of R. D.. An important contribution to the creation of the VRD was the work of the Soviet scientist B. S. Stechkin "Theory of an air-breathing engine", published in 1929.

R. d. have a different purpose and the scope of their application is constantly expanding.

R. d. are most widely used on various types of aircraft.

Turbojet engines and dual-circuit turbojet engines are equipped with most military and civil aircraft around the world, they are used in helicopters. These rocket engines are suitable for flights at both subsonic and supersonic speeds; they are also installed on projectile aircraft; supersonic turbojet engines can be used in the first stages of aerospace aircraft. Ramjet engines are installed on anti-aircraft guided missiles, cruise missiles, supersonic fighter-interceptors. Subsonic direct-flow motors used on helicopters (installed at the ends of the main rotor blades). Pulsating jet engines have little thrust and are intended only for aircraft at subsonic speeds. During the 2nd World War of 1939-45, these engines were equipped with V-1 projectiles.

RD in most cases are used on high-speed aircraft.

Liquid-propellant rocket engines are used on launch vehicles of spacecraft and spacecraft as marching, braking and control engines, as well as on guided ballistic missiles. Solid-propellant rocket engines are used in ballistic, anti-aircraft, anti-tank, and other military missiles, as well as on launch vehicles and spacecraft. Small solid propellant engines are used as boosters for aircraft takeoff. Electric rocket engines and nuclear rocket engines can be used in spacecraft.

However, this mighty trunk, the principle of direct reaction, gave life to a huge crown of the "family tree" of the family of jet engines. To get acquainted with the main branches of its crown, crowning the "trunk" of the direct reaction. Soon, as can be seen from the figure (see below), this trunk is divided into two parts, as if split by a lightning strike. Both new trunks are equally decorated with mighty crowns. This division occurred due to the fact that all "chemical" jet engines are divided into two classes, depending on whether they use ambient air for their work or not.

One of the newly formed trunks is the class of air-breathing engines (VRD). As the name suggests, they cannot operate outside of the atmosphere. That's why these engines are the backbone of modern aviation, both manned and unmanned. WFD use atmospheric oxygen for the combustion of fuel, without it, the combustion reaction in the engine will not go. But still, turbojet engines are currently the most widely used.

(TRD), installed on almost all modern aircraft without exception. Like all engines that use atmospheric air, turbojet engines need special device to compress air before it enters the combustion chamber. After all, if the pressure in the combustion chamber does not significantly exceed atmospheric pressure, then the gases will not flow out of the engine at a higher speed - it is the pressure that pushes them out. But at a low exhaust velocity, the thrust of the engine will be small, and the engine will consume a lot of fuel, such an engine will not find application. In a turbojet engine, a compressor is used to compress the air, and the design of the engine largely depends on the type of compressor. There are engines with axial and centrifugal compressors, axial compressors can have fewer or more compression stages thanks to using our system, be one-two-stage, etc. To drive the compressor, the turbojet engine has a gas turbine, which gave the name to the engine. Due to the compressor and turbine, the design of the engine is very complex.

Air-jet engines without compressors are much simpler in design, in which the necessary pressure increase is carried out in other ways, which have names: pulsating and ramjet engines.

In a pulsating engine, this is usually done by a valve grill installed at the engine inlet, when a new portion of the fuel-air mixture fills the combustion chamber and a flash occurs in it, the valves close, isolating the combustion chamber from the engine inlet. As a result, the pressure in the chamber rises, and the gases rush out through the jet nozzle, after which the whole process is repeated.

In a compressorless engine of another type, a ramjet, there is not even this valve grid and the pressure in the combustion chamber rises as a result of dynamic pressure, i.e. deceleration of the oncoming air flow entering the engine in flight. It is clear that such an engine is able to work only when the aircraft is already flying at a sufficiently high speed, it will not develop thrust in the parking lot. But at a very high speed, 4-5 times more speed sound, a ramjet engine develops very high traction and consumes less fuel than any other "chemical" jet engine under these conditions. That's why ramjet motors.

The peculiarity of the aerodynamic scheme of supersonic aircraft with ramjet engines (ramjet engines) is due to the presence of special accelerating engines that provide the speed necessary to start stable operation of the ramjet. This makes the tail part of the structure heavier and requires the installation of stabilizers to ensure the necessary stability.

The principle of operation of a jet engine.

At the heart of modern powerful jet engines of various types is the principle of direct reaction, i.e. principle of creation driving force(or thrust) in the form of a reaction (recoil) of a jet of "working substance" flowing out of the engine, usually hot gases.

In all engines, there are two processes of energy conversion. First, the chemical energy of the fuel is converted into thermal energy of the combustion products, and then the thermal energy is used to perform mechanical work. These engines include piston engines cars, diesel locomotives, steam and gas turbines of power plants, etc.

Consider this process in relation to jet engines. Let's start with the combustion chamber of the engine, in which a combustible mixture has already been created in one way or another, depending on the type of engine and the type of fuel. This may be, for example, a mixture of air and kerosene, as in a modern turbojet engine. jet aircraft, or a mixture of liquid oxygen with alcohol, as in some liquid rocket engines, or, finally, some kind of solid propellant for powder rockets. The combustible mixture can burn, i.e. enter into a chemical reaction with a rapid release of energy in the form of heat. The ability to release energy chemical reaction, and is the potential chemical energy of the molecules of the mixture. The chemical energy of molecules is related to the features of their structure, more precisely, the structure of their electron shells, i.e. the electron cloud that surrounds the nuclei of the atoms that make up the molecule. As a result of a chemical reaction, in which some molecules are destroyed, while others are formed, a rearrangement of the electron shells naturally occurs. In this restructuring, it is the source of released chemical energy. It can be seen that only substances that, during a chemical reaction in the engine (combustion), emit a sufficiently large amount of heat, and also form a large amount of gases, can serve as fuels for jet engines. All these processes take place in the combustion chamber, but let's dwell on the reaction not at the molecular level (this has already been discussed above), but at the "phases" of work. Until combustion has begun, the mixture has a large supply of potential chemical energy. But then the flame engulfed the mixture, another moment - and the chemical reaction is over. Now, instead of the molecules of the combustible mixture, the chamber is filled with molecules of combustion products, more densely "packed". The excess binding energy, which is the chemical energy of the combustion reaction that has taken place, has been released. Molecules possessing this excess energy almost instantly transferred it to other molecules and atoms as a result of frequent collisions with them. All molecules and atoms in the combustion chamber began to randomly, chaotically move at a much higher speed, the temperature of the gases increased. So there was a transition of the potential chemical energy of the fuel into the thermal energy of the combustion products.

A similar transition was carried out in all other heat engines, but jet engines fundamentally differ from them in relation to the further fate of hot combustion products.

After hot gases have formed in the heat engine, containing large thermal energy, this energy must be converted into mechanical energy. After all, the purpose of the engines is to perform mechanical work, to "move" something, to put it into action, it doesn't matter whether it is a dynamo at the request to supplement the drawings of a power plant, a diesel locomotive, a car or an airplane.

In order for the thermal energy of gases to be converted into mechanical energy, their volume must increase. With such an expansion, the gases do the work for which their internal and thermal energy is expended.

In the case of a piston engine, expanding gases press on a piston moving inside the cylinder, the piston pushes the connecting rod, which already rotates the crankshaft of the engine. The shaft is connected to the rotor of a dynamo, the driving axles of a diesel locomotive or car, or the propeller of an aircraft - the engine performs useful work. AT steam engine, or a gas turbine, gases, expanding, force the wheel connected to the turbine shaft to rotate - there is no need for a transmission crank mechanism, which is one of the great advantages of the turbine

Gases expand, of course, in a jet engine, because without it they do not do work. But the expansion work in that case is not spent on the rotation of the shaft. Associated with the drive mechanism, as in other heat engines. The purpose of a jet engine is different - to create jet thrust, and for this it is necessary that a jet of gases - combustion products flow out of the engine at a high speed: the reaction force of this jet is the thrust of the engine. Consequently, the work of expanding the gaseous products of fuel combustion in the engine must be spent on accelerating the gases themselves. This means that the thermal energy of gases in a jet engine must be converted into their kinetic energy - the random chaotic thermal motion of molecules must be replaced by their organized flow in one direction common to all.

For this purpose, one of the most important parts of the engine, the so-called jet nozzle, serves. No matter what type a particular jet engine belongs to, it is necessarily equipped with a nozzle through which hot gases flow out of the engine at great speed - the products of fuel combustion in the engine. In some engines, gases enter the nozzle immediately after the combustion chamber, for example, in rocket or ramjet engines. In others, turbojets, the gases first pass through a turbine, to which they give up part of their thermal energy. It consumes in this case to drive the compressor, which serves to compress the air in front of the combustion chamber. But anyway, the nozzle is the last part of the engine - gases flow through it before leaving the engine.

The jet nozzle may have various forms, and, moreover, a different design depending on the type of engine. The main thing is the speed with which the gases flow out of the engine. If this outflow velocity does not exceed the speed with which sound waves propagate in the outflowing gases, then the nozzle is a simple cylindrical or narrowing pipe section. If the outflow velocity must exceed the speed of sound, then the nozzle is given the shape of an expanding pipe or, first, narrowing, and then expanding (Love's nozzle). Only in a tube of such a shape, as theory and experience show, is it possible to disperse the gas to supersonic speeds, to step over the "sonic barrier".

Jet engine diagram

The turbofan engine is the most widely used jet engine in civil aviation.

The fuel entering the engine (1) is mixed with compressed air and burned in the combustion chamber (2). The expanding gases rotate high-speed (3) and low-speed) turbines, which, in turn, drive the compressor (5), pushing air into the combustion chamber, and fans (6), driving air through this chamber and directing it to the exhaust pipe. By displacing air, fans provide additional thrust. An engine of this type is capable of developing thrust up to 13,600 kg.

Conclusion

The jet engine has many remarkable features, but the main one is as follows. A rocket does not need land, water, or air to move, as it moves as a result of interaction with gases formed during the combustion of fuel. Therefore, the rocket can move in airless space.

K. E. Tsiolkovsky is the founder of the theory of space flights. Scientific proof of the possibility of using a rocket for flights into outer space, beyond the earth's atmosphere and to other planets of the solar system was given for the first time by the Russian scientist and inventor Konstantin Eduardovich Tsiolkovsky

Bibliography

Encyclopedic Dictionary of the Young Technician.

Thermal Phenomena in Technology.

Materials from the site http://goldref.ru/;

1. jet movement (2)

   Abstract >> Physics

   Which is in the form reactive jet is ejected from reactive engine; myself reactive engine- an energy converter ... with which reactive engine affects a device equipped with this reactive engine. thrust reactive engine depends on...

2. jet movement in nature and technology

   Abstract >> Physics

   Salp forward. Of greatest interest is reactive engine squid. The squid is the most...i.e. apparatus with reactive engine using fuel and oxidizer located on the apparatus itself. Reactive engine- this is engine transforming...

3. Reactive multiple launch rocket system BM-13 Katyusha

   Abstract >> Historical figures

   head and gunpowder reactive engine. The head part in its own way ... a fuse and an additional detonator. Reactive engine has a combustion chamber, in ... a sharp increase in fire capabilities reactive

Have you ever wondered how a jet engine works? The jet thrust that powers it has been known since ancient times. But they were only able to put it into practice at the beginning of the last century, as a result of the arms race between England and Germany.

The principle of operation of a jet aircraft engine is quite simple, but it has some nuances that are strictly observed in their production. In order for the plane to be able to stay in the air reliably, they must work perfectly. After all, the lives and safety of all who are on board the aircraft depend on it.

It is driven by jet thrust. It needs some kind of fluid pushed out from the back of the system and giving it forward motion. Works here Newton's third law which says: "For every action there is an equal and opposite reaction."

At the jet engine air instead of liquid. It creates a force that provides movement.

It uses hot gases and a mixture of air with combustible fuel. This mixture comes out of it at high speed and pushes the plane forward, allowing it to fly.

If we talk about the device of a jet aircraft engine, then it is combination of the four important details:

• compressor;
• combustion chambers;
• turbines;
• exhaust.

The compressor consists from several turbines, which suck in air and compress it as it passes through the angled blades. When compressed, the temperature and pressure of the air increase. Part compressed air enters the combustion chamber, where it is mixed with fuel and ignited. It increases thermal energy of the air.

Jet engine.

hot mix on high speed exits the chamber and expands. There she goes through yet one turbine with blades that rotate due to the energy of the gas.

The turbine is connected to the compressor at the front of the engine., and thus sets it in motion. Hot air exits through the exhaust. At this point, the temperature of the mixture is very high. And it keeps growing thanks to throttling effect. After that, the air comes out of it.

Development of jet-powered aircraft has begun in the 30s of the last century. The British and Germans began to develop similar models. This race was won by German scientists. Therefore, the first aircraft with a jet engine was "Swallow" in the Luftwaffe. "Gloucester Meteor" took to the air a little later. The first aircraft with such engines are described in detail

The engine of a supersonic aircraft is also jet, but in a completely different modification.

How does a turbojet engine work?

Jet engines are used everywhere, and turbojet engines are installed large. Their difference is that the first carries with it a supply of fuel and oxidizer, and the design ensures their supply from the tanks.

aircraft turbojet engine carries with it only fuel, and the oxidizing agent - air - is forced by the turbine from the atmosphere. Otherwise, the principle of its operation is the same as that of the reactive one.

One of their most important details is This is the turbine blade. It depends on the power of the engine.

Scheme of a turbojet engine.

It is they who develop the traction forces necessary for the aircraft. Each of the blades produces 10 times more energy than a typical car engine. They are installed behind the combustion chamber, in the part of the engine where the most high pressure, and the temperature reaches up to 1400 degrees Celsius.

During the production of blades, they pass through the process of monocrystallization which gives them strength and durability.

Each engine is tested for full thrust before being installed on an aircraft. He must pass certification by the European Safety Council and the company that produced it. One of the most large firms their production is Rolls-Royce.

What is a nuclear powered aircraft?

During the Cold War attempts were made to create a jet engine not on a chemical reaction, but on the heat that would be produced by a nuclear reactor. It was put in place of the combustion chamber.

Air passes through the reactor core, lowering its temperature and raising its own. It expands and flows out of the nozzle at a speed greater than the flight speed.

Combined turbo-nuclear engine.

In the USSR, it was tested based on TU-95. In the USA, too, they did not lag behind scientists in the Soviet Union.

In the 60s studies in both sides gradually ceased. The main three problems that hindered the development were:

• safety of pilots during the flight;
• release of radioactive particles into the atmosphere;
• in the event of a plane crash, a radioactive reactor can explode, causing irreparable harm to all living things.

How are jet engines for model airplanes made?

Their production for aircraft models takes about 6 hours. Turned first aluminum base plate to which all other parts are attached. It is the same size as a hockey puck.

Attached to it is a cylinder., so it turns out something like a tin can. it future engine internal combustion. Next, the supply system is installed. To fix it, screws are screwed into the main plate, previously lowered into a special sealant.

Aircraft model engine.

Starter channels are mounted on the other side of the chamber to redirect gas emissions to the turbine wheel. Installed in the hole on the side of the combustion chamber incandescent spiral. It ignites the fuel inside the engine.

Then they put the turbine and the central axis of the cylinder. They put on it compressor wheel which forces air into the combustion chamber. It is checked with a computer before the launcher is fixed.

The finished engine is once again checked for power. Its sound is slightly different from the sound of an aircraft engine. He, of course, of lesser strength, but completely resembles him, giving more similarity to the model.

JET ENGINE, an engine that creates the traction force necessary for movement by converting potential energy into kinetic energy of the jet stream of the working fluid. Under the working fluid m, in relation to engines, is understood a substance (gas, liquid, solid), with the help of which the thermal energy released during the combustion of fuel is converted into useful mechanical work. As a result of the expiration of the working fluid from the engine nozzle, a reactive force is formed in the form of a reaction (recoil) of a jet directed in space in the direction opposite to the outflow of the jet. Various types of energy (chemical, nuclear, electrical, solar) can be converted into the kinetic (speed) energy of a jet stream in a jet engine.

A jet engine (direct reaction engine) combines the engine itself with a propeller, that is, it provides its own movement without the participation of intermediate mechanisms. To create jet thrust (engine thrust) used by a jet engine, you need: a source of initial (primary) energy, which is converted into the kinetic energy of the jet stream; the working fluid, which is ejected from the jet engine in the form of a jet stream; the jet engine itself is an energy converter. Engine thrust - this is a reactive force, which is the result of gas-dynamic forces of pressure and friction applied to the internal and external surfaces of the engine. Distinguish between internal thrust (reactive thrust) - the resultant of all gas-dynamic forces applied to the engine, without taking into account external resistance and effective thrust, taking into account the external resistance of the power plant. The initial energy is stored on board an aircraft or other apparatus equipped with a jet engine (chemical fuel, nuclear fuel), or (in principle) can come from outside (solar energy).

To obtain a working fluid in a jet engine, a substance taken from the environment (for example, air or water) can be used; a substance located in the tanks of the apparatus or directly in the chamber of a jet engine; a mixture of substances coming from the environment and stored on board the vehicle. Modern jet engines most often use chemical energy as primary energy. In this case, the working fluid is incandescent gases - combustion products of chemical fuel. During the operation of a jet engine, the chemical energy of the burning substances is converted into the thermal energy of the combustion products, and the thermal energy of the hot gases is converted into the mechanical energy of the forward motion of the jet and, consequently, the apparatus on which the engine is installed.

The principle of operation of a jet engine

In a jet engine (Fig. 1), a jet of air enters the engine, meets with turbines rotating at great speed compressor , which sucks in air from the external environment (using a built-in fan). Thus, two tasks are solved - the primary air intake and the cooling of the entire engine as a whole. Compressor turbine blades compress the air by about 30 times or more and "push" it (inject) into the combustion chamber (the working fluid is generated), which is the main part of any jet engine. The combustion chamber also acts as a carburetor, mixing fuel with air. This can be, for example, a mixture of air and kerosene, as in a turbojet engine of a modern jet aircraft, or a mixture of liquid oxygen and alcohol, as in some liquid rocket engines, or some kind of solid propellant for powder rockets. After education fuel-air mixture it is ignited and energy is released in the form of heat, i.e., jet engines can only be fueled by substances that, during a chemical reaction in the engine (combustion), release a lot of heat, and also form a large amount of gases.

In the process of ignition, there is a significant heating of the mixture and surrounding parts, as well as volumetric expansion. In fact, the jet engine uses a controlled explosion for propulsion. The combustion chamber of a jet engine is one of its hottest parts (the temperature in it reaches 2700 ° C), it must be constantly cooled intensively. The jet engine is equipped with a nozzle through which hot gases, the products of fuel combustion in the engine, flow out of the engine at great speed. In some engines, gases enter the nozzle immediately after the combustion chamber, for example, in rocket or ramjet engines. In turbojet engines, the gases after the combustion chamber first pass through turbine , which is given part of its thermal energy to drive a compressor that compresses air in front of the combustion chamber. But anyway, the nozzle is the last part of the engine - gases flow through it before leaving the engine. It creates directly jet stream. Cold air is directed into the nozzle, pumped by the compressor for cooling internal details engine. The jet nozzle may have various shapes and designs depending on the type of engine. If the outflow velocity must exceed the speed of sound, then the nozzle is given the shape of an expanding pipe, or first narrowing and then expanding (Laval nozzle). Only in a pipe of this shape can gas be accelerated to supersonic speeds, to step over the "sonic barrier".

Depending on whether or not the environment is used during the operation of a jet engine, they are divided into two main classes - jet engines(WFD) and rocket engines(RD). All WFD - heat engines, the working fluid of which is formed during the oxidation reaction of a combustible substance with atmospheric oxygen. The air coming from the atmosphere makes up the bulk of the working fluid of the WFD. Thus, an apparatus with a WFD carries a source of energy (fuel) on board, and draws most of the working fluid from the environment. These include turbojet engine (TRD), ramjet engine (ramjet), pulsed jet engine (PuVRD), hypersonic ramjet engine (scramjet). Unlike the WFD, all components of the working fluid of the RD are on board the vehicle equipped with the RD. The absence of a propeller interacting with the environment and the presence of all components of the working fluid on board the vehicle make the RD suitable for space operation. There are also combined rocket engines, which are, as it were, a combination of both main types.

Main characteristics of jet engines

Main technical parameter characterizing a jet engine is thrust - the force that develops the engine in the direction of movement of the device, specific impulse - the ratio of engine thrust to the mass of rocket fuel (working fluid) consumed in 1 s, or an identical characteristic - specific consumption fuel (the amount of fuel consumed in 1 s per 1 N of thrust developed by a jet engine), engine specific gravity (mass of a jet engine in working condition per unit of thrust developed by it). For many types of jet engines important characteristics are dimensions and resource. Specific impulse is an indicator of the degree of perfection or quality of the engine. The above diagram (Fig. 2) graphically presents the upper values ​​of this indicator for different types jet engines depending on the flight speed, expressed in the form of a Mach number, which allows you to see the scope of each type of engine. This indicator is also a measure of the efficiency of the engine.

Thrust - the force with which a jet engine acts on a device equipped with this engine - is determined by the formula: $$P = mW_c + F_c (p_c - p_n),$$ where $m$ is mass flow(mass consumption) of the working fluid for 1 s; $W_c$ is the speed of the working fluid in the nozzle section; $F_c$ is the area of ​​the outlet section of the nozzle; $p_c$ – gas pressure in the nozzle section; $p_n$ – ambient pressure (usually atmospheric pressure). As can be seen from the formula, the thrust of a jet engine depends on the ambient pressure. It is greatest in emptiness and least of all in the densest layers of the atmosphere, i.e., it varies depending on the flight altitude of an apparatus equipped with a jet engine above sea level, if flight in the Earth’s atmosphere is considered. The specific impulse of a jet engine is directly proportional to the speed of the outflow of the working fluid from the nozzle. The outflow rate increases with an increase in the temperature of the outgoing working fluid and a decrease in the molecular weight of the fuel (the lower the molecular weight of the fuel, the greater the volume of gases formed during its combustion, and, consequently, the rate of their outflow). Since the rate of exhaust of combustion products (working fluid) is determined by the physicochemical properties of the fuel components and design features engine, being a constant value at not very big changes mode of operation of a jet engine, then the magnitude of the reactive force is determined mainly by the mass per second fuel consumption and varies over a very wide range (a minimum for electric ones - a maximum for liquid and solid rocket engines). Low-thrust jet engines are mainly used in aircraft stabilization and control systems. In space, where gravitational forces are felt weakly and there is practically no medium, the resistance of which would have to be overcome, they can also be used for overclocking. RD with maximum thrust is necessary for launching rockets at long ranges and altitudes, and especially for launching aircraft into space, i.e., for accelerating them to first space velocity. Such engines consume a very large amount of fuel; they usually work for a very short time, accelerating the rockets to a given speed.

WFDs use ambient air as the main component of the working fluid, which is much more economical. WJDs can operate continuously for many hours, making them suitable for aviation use. Different schemes allowed them to be used for aircraft operated on different modes flight. Turbojet engines (TRDs) are widely used, which are installed on almost all modern aircraft without exception. Like all engines that use atmospheric air, turbojet engines need a special device to compress the air before it enters the combustion chamber. In a turbojet engine, a compressor is used to compress the air, and the design of the engine largely depends on the type of compressor. Uncompressor jet engines are much simpler in design, in which the necessary pressure increase is carried out in other ways; these are pulsating and direct-flow motors. In a pulsating jet engine(PuVRD) this is usually done by a valve grill installed at the engine inlet, when a new portion of the fuel-air mixture fills the combustion chamber and a flash occurs in it, the valves close, isolating the combustion chamber from the engine inlet. As a result, the pressure in the chamber rises, and the gases rush out through the jet nozzle, after which the whole process is repeated. In a compressorless engine of another type, a ramjet, there is not even this valve grid and atmospheric air, entering the engine inlet at a speed equal speed flight, is compressed due to the velocity pressure and enters the combustion chamber. The injected fuel burns, the heat content of the flow increases, which flows out through the jet nozzle at a speed greater than the flight speed. Due to this, the jet thrust of the ramjet is created. The main disadvantage of the ramjet is the inability to independently provide takeoff and acceleration of the aircraft (LA). It is required first to accelerate the aircraft to a speed at which the ramjet is launched and its stable operation is ensured. The peculiarity of the aerodynamic scheme of supersonic aircraft with ramjet engines (ramjet engines) is due to the presence of special accelerating engines that provide the speed necessary to start stable operation of the ramjet. This makes the tail part of the structure heavier and requires the installation of stabilizers to ensure the necessary stability.

History reference

The principle of jet propulsion has been known for a long time. Heron's ball can be considered the ancestor of the jet engine. Solid rocket motors(RDTT - solid fuel rocket engine) - powder rockets appeared in China in the 10th century. n. e. For hundreds of years, such missiles were used first in the East, and then in Europe as fireworks, signal, combat. An important stage in the development of the idea of ​​jet propulsion was the idea of ​​using a rocket as an engine for an aircraft. It was first formulated by the Russian revolutionary Narodnaya Volya N. I. Kibalchich, who in March 1881, shortly before his execution, proposed a scheme for an aircraft (rocket plane) using jet propulsion from explosive powder gases. Solid propellant rocket engines are used in all classes of military missiles (ballistic, anti-aircraft, anti-tank, etc.), in space (for example, as starting and sustainer engines) and aviation technology (aircraft take-off boosters, in systems ejection), etc. Small solid propellant engines are used as boosters for aircraft takeoff. Electric rocket engines and nuclear rocket engines can be used in spacecraft.

Turbojet engines and dual-circuit turbojet engines are equipped with most military and civil aircraft around the world, they are used in helicopters. These jet engines are suitable for flights at both subsonic and supersonic speeds; they are also installed on projectile aircraft, supersonic turbojet engines can be used in the first stages aerospace aircraft, rocket and space technology, etc.

Of great importance for the creation of jet engines were the theoretical works of Russian scientists S. S. Nezhdanovsky, I. V. Meshchersky, N. E. Zhukovsky, the works of the French scientist R. Enot-Peltri, the German scientist G. Oberth. An important contribution to the creation of the VRD was the work of the Soviet scientist B. S. Stechkin, The Theory of an Air Jet Engine, published in 1929. Practically more than 99% of aircraft use a jet engine to one degree or another.