Where is the jet engine used? How an airplane jet engine works. American polar icebreaker USCGC Polar-Class Icereaker

ESSAY

ON THIS TOPIC:

Jet Engines .

WRITTEN: A. V. Kiselev

KALININGRAD

Introduction

A 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 outflow of the working fluid from the nozzle of the engine, a reactive force is generated in the form of a reaction (recoil) of the jet, which moves the engine and the apparatus structurally connected to it in space in the direction opposite to the outflow of the jet. Various types of energy (chemical, nuclear, electric, solar) can be converted into kinetic (high-speed) energy of a jet stream in a rocket engine. R. d. (The engine of direct reaction) combines the engine itself with the mover, i.e., it provides its own motion without the participation of intermediate mechanisms.

For creating jet thrust, used by R. d., are necessary:

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

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

the R. d. itself is an energy converter.

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

the substance located in the tanks of the apparatus or directly in the chamber of R. d .; a mixture of substances coming from the environment and stored on board the vehicle.

In modern R. d. As primary is most often used chemical

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 hot gases - products of combustion of chemical fuel. During the operation of a rocket engine, the chemical energy of combustible substances is converted into thermal energy of combustion products, and the thermal energy of hot gases is converted into mechanical energy of the translational motion of the jet stream and, consequently, of the apparatus on which the engine is installed. The main part of any combustion chamber is a combustion chamber in which a 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 or not the environment is used in the operation of a rocket engine, they are subdivided into two main classes — air-breathing engines (WFM) and rocket engines (RD). All WFDs are heat engines, the working fluid of which is formed during the oxidation reaction of a combustible substance with atmospheric oxygen. Air coming from the atmosphere makes up the bulk of the WFD working fluid. Thus, an apparatus with a WFD carries an energy source (fuel) on board, and draws most of the working fluid from the environment. In contrast to the WFD, all the components of the working fluid of the taxiway are on board the vehicle equipped with the taxiway. The absence of a propeller interacting with the environment and the presence of all the components of the working fluid on board the vehicle make the RD the only one suitable for operation in space. There are also combined rocket engines, which are, as it were, a combination of both basic types.

History of jet engines

The principle of jet propulsion has been known for a very long time. The ancestor of R. d. Can be considered the ball of Heron. Solid-propellant 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, and combat missiles. In 1903, K.E. Tsiolkovsky, in his work "Investigation of World Spaces by Reactive Devices", was the first in the world to put forward the basic principles of the theory of liquid-propellant rocket engines and proposed the main elements of a liquid-propellant rocket engine. The first Soviet liquid-propellant rocket engines - ORM, ORM-1, ORM-2 were designed by V.P. Glushko and created under his leadership in 1930-31 at the Gas Dynamic Laboratory (GDL). In 1926, R. Goddard launched a liquid-fueled rocket. For the first time, an electrothermal RD was created and tested by Glushko at the GDL in 1929-33.

In 1939, the USSR tested rockets with ramjet engines designed by I.A.Merkulov. The first scheme of a 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 Great Patriotic War of 1941-45 interfered with the tests of the created engine. In 1941, a turbojet engine designed by F. Whittle (Great Britain) was first installed on an aircraft and tested. The theoretical work of the Russian scientists S.S. Nezhdanovsky, I.V. An important contribution to the creation of an air-jet engine was the work of the Soviet scientist BS Stechkin, "The Theory of an Air-Jet Engine", published in 1929.

R. d. Have different purposes and the area of ​​their application is constantly expanding.

The most widely used aircrafts are used on aircraft of various types.

Most military and civil aircraft all over the world are equipped with turbojet engines and bypass turbojet engines, they are used in helicopters. These rocket launchers 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. The ramjet engines are installed on anti-aircraft guided missiles, cruise missiles, and supersonic interceptor fighters. Subsonic ramjet engines are used in helicopters (installed at the ends of the rotor blades). Pulsating jet engines have low thrust and are intended only for subsonic aircraft. During World War II, 1939-45, these engines were equipped with FAU-1 projectile aircraft.

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

Liquid-propellant rocket engines are used on launch vehicles for spacecraft and spacecraft as propulsion, brake 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 in launch vehicles and spacecraft. Small solid-fuel engines are used as accelerators 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 birth to a huge crown of the "family tree" of the jet engine family. To get acquainted with the main branches of its crown, crowning the "trunk" of a direct reaction. Soon, as you can see from the picture (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 was due to the fact that all "chemical" jet engines are divided into two classes, depending on what they use for their work. ambient air or not.

One of the newly formed barrels is the class of air-jet engines (WFD). As the name suggests, they cannot work outside of the atmosphere. That is why these engines are the backbone of modern aviation, both manned and unmanned. WFDs use atmospheric oxygen to burn fuel; without it, the combustion reaction in the engine will not go. But still, turbojet engines are currently the most widely used.

(Turbojet engine), installed on almost all modern aircraft without exception. Like all engines that use atmospheric air, turbojet engines require a special device to compress the air before it is fed into the combustion chamber. After all, if the pressure in the combustion chamber does not significantly exceed atmospheric, then the gases will not flow out of the engine from more speed- it is the pressure that pushes them out. But at a low flow rate, the engine thrust will be low, and the engine will consume a lot of fuel, such an engine will not find application. In a turbojet engine, a compressor serves to compress air, and the design of the engine largely depends on the type of compressor. There are motors with axial and centrifugal compressors, axial compressors can have, thanks to using our system, fewer or more compression stages, be one-two-stage, etc. To drive the compressor into rotation, 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.

Much simpler in design is non-compressor air-jet engines, in which the necessary pressure increase is carried out in other ways, which have the names: pulsating and ramjet engines.

In a pulsating engine, this is usually done by a valve grate 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 non-compressor engine of another type, a ramjet, there is not even this valve lattice and the pressure in the combustion chamber rises as a result of the high-speed pressure, i.e. braking the oncoming air flow entering the engine in flight. It is clear that such an engine is capable of operating only when the aircraft is already flying at a sufficiently high speed; it will not develop thrust in the parking lot. But on the other hand, with a very high speed, 4-5 times the speed of sound, a ramjet engine develops a very high thrust and consumes less fuel than any other "chemical" jet engine under these conditions. This is why ramjet engines.

The peculiarity of the aerodynamic design of supersonic aircraft with ramjet engines (ramjet engines) is due to the presence of special accelerating engines that provide the speed required for the start of stable operation of the ramjet engine. This makes the tail section heavier and requires the installation of stabilizers to provide the necessary stability.

The principle of operation of a jet engine.

Modern powerful jet engines of various types are based on 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 incandescent gases.

All motors have two energy conversion processes. First, the chemical energy of the fuel is converted into thermal energy of 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.

Let's 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. It can be, for example, a mixture of air with kerosene, as in a turbojet engine of a modern jet aircraft, or a mixture of liquid oxygen with alcohol, as in some liquid propellant rocket engines, or, finally, some solid fuel for powder rockets. The combustible mixture can burn, i.e. enter into a chemical reaction with a violent release of energy in the form of heat. The ability to release energy during a chemical reaction is the potential chemical energy of the molecules in the mixture. The chemical energy of molecules is associated with the peculiarities of their structure, more precisely, the structure of their electronic shells, i.e. of 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 arise, there naturally occurs a rearrangement of the electron shells. This restructuring is a source of released chemical energy. It can be seen that the only substances that can serve as fuels for jet engines are those that, during a chemical reaction in the engine (combustion), release a lot of heat, and also form a large amount of gases. 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 store of potential chemical energy. But then the flame engulfed the mixture, another moment - and the chemical reaction is over. Now, instead of 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 past combustion reaction, is released. The molecules possessing this excess energy transferred it almost instantly to other molecules and atoms as a result of frequent collisions with them. All molecules and atoms in the combustion chamber began to move randomly, chaotically at a much higher speed, the temperature of the gases increased. This is how the potential chemical energy of the fuel was transformed into the thermal energy of combustion products.

A similar transition was carried out in all other heat engines, but jet engines are fundamentally different from them with regard to the further fate of incandescent combustion products.

After hot gases have formed in a heat engine, containing a large thermal energy, this energy must be converted into mechanical energy. After all, the engines are used to perform mechanical work, to "move" something, to put it into action, it does not matter whether it is a dynamo machine on request to add drawings to a power plant, a diesel locomotive, a car or an airplane.

In order for the thermal energy of gases to pass into mechanical energy, their volume must increase. With this expansion, the gases do the work, which consumes their internal and thermal energy.

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

Gases expand, of course, in a jet engine, because without this they do not perform work. But the work of expansion 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 from 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. Whichever type everything in there really belongs to this or that jet engine, it is necessarily equipped with a nozzle through which hot gases - products of fuel combustion in the engine - flow out of the engine at a high speed. 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 off 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, one way or another, the nozzle is the last part of the engine - gases flow through it before leaving the engine.

The jet nozzle can have different shapes, and, moreover, different designs depending on the type of engine. The main thing is the speed at which the gases flow out of the engine. If this outflow velocity does not exceed the velocity with which sound waves propagate in the outgoing gases, then the nozzle is a simple cylindrical or narrowing pipe segment. 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 (Lovely nozzle). Only in a pipe of this shape, as theory and experience show, can the gas be accelerated to supersonic speeds, and the "sound barrier" can be stepped over.

Jet engine diagram

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

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

Conclusion

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

K.E. Tsiolkovsky - the founder of the theory of space flight. 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. Reactive movement (2)

   Abstract >> Physics

   Which in the form reactive jet is ejected from reactive engine; myself reactive engine- energy converter ... with which reactive engine affects the apparatus equipped with this reactive engine... Thrust reactive engine depends on...

2. Reactive 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- it engine transforming ...

3. Reactive multiple launch rocket system BM-13 Katyusha

   Abstract >> Historical figures

   Head and powder reactive engine... The head part is ... a fuse and an additional detonator. Reactive engine has a combustion chamber, in ... a sharp increase in firepower reactive

Reactive motion is a process in which one of its parts is separated from a certain body at a certain speed. The force that arises in this case works by itself, without the slightest contact with external bodies. Jet propulsion was the impetus for the creation of a jet engine. Its principle of operation is based precisely on this force. How does such an engine work? Let's try to figure it out.

Historical facts

The idea of ​​using jet thrust, which would make it possible to overcome the gravitational force of the Earth, was put forward in 1903 by the phenomenon of Russian science - Tsiolkovsky. He published an entire study on the subject, but it was not taken seriously. Konstantin Eduardovich, having survived the change of the political system, spent years of work to prove to everyone that he was right.

Today there are a lot of rumors that the first in this matter was the revolutionary Kibalchich. But the will of this man by the time of publication of Tsiolkovsky's works was buried together with Kibalchich. In addition, it was not a full-fledged work, but only sketches and sketches - the revolutionary could not provide a reliable basis for theoretical calculations in his works.

How does reactive force work?

To understand how a jet engine works, you need to understand how this force works.

So, let's imagine a shot from any firearm. This illustrative example action of reactive force. A jet of hot gas, which was formed during the combustion of the charge in the cartridge, pushes the weapon back. The more powerful the charge, the stronger the recoil will be.

Now imagine the process of ignition of a combustible mixture: it takes place gradually and continuously. This is how the principle of operation of a ramjet engine looks like. A rocket with a solid-propellant jet engine works in a similar way - this is the simplest of its variations. Even novice rocket modelers are familiar with it.

At first, black powder was used as fuel for jet engines. Jet engines, the principle of which was already more advanced, required fuel with a base of nitrocellulose, which was dissolved in nitroglycerin. In large units that launch rockets that launch shuttles into orbit, today they use a special mixture of polymer fuel with ammonium perchlorate as an oxidizing agent.

Operating principle of taxiway

Now it's worth understanding the principle of operation of a jet engine. For this, you can consider the classics - liquid engines, which have practically not changed since the time of Tsiolkovsky. These units use fuel and an oxidizer.

As the latter, liquid oxygen or nitric acid is used. Kerosene is used as fuel. Modern cryogenic liquid engines consume liquid hydrogen. When oxidized with oxygen, it increases the specific impulse (by as much as 30 percent). The idea that hydrogen could be used was also born in Tsiolkovsky's head. However, at that time, due to the extreme explosiveness, it was necessary to look for another fuel.

The principle of operation is as follows. The components enter the combustion chamber from two separate tanks. After mixing, they turn into a mass, which, when burned, releases a huge amount of heat and tens of thousands of atmospheres of pressure. The oxidant is fed into the combustion chamber. Fuel mixture cools these elements as it passes between the double walls of the chamber and the nozzle. Further, the fuel, heated by the walls, will enter the ignition zone through a huge number of nozzles. The jet, which is formed by the nozzle, escapes outward. Due to this, the pushing moment is provided.

Briefly, the principle of operation of a jet engine can be compared to a blowtorch. However, the latter is much simpler. In the scheme of her work, there are no different support systems engine. And these are the compressors needed to create injection pressure, turbines, valves, and other elements, without which a jet engine is simply impossible.

Despite the fact that liquid-propellant engines consume a lot of fuel (fuel consumption is approximately 1000 grams per 200 kilograms of cargo), they are still used as propulsion units for launch vehicles and shunting units for orbital stations, as well as other space vehicles.

Device

A typical jet engine is arranged as follows. Its main nodes are:

Compressor;

Combustion chamber;

Turbines;

Exhaust system.

Let's consider these elements in more detail. The compressor consists of several turbines. Their job is to suck in and compress air as it passes through the blades. The compression process increases the temperature and pressure of the air. Part of this compressed air fed into the combustion chamber. It mixes air with fuel and ignites. This process further increases the thermal energy.

The mixture leaves the combustion chamber for high speed and then expands. Then it follows through another turbine, the blades of which rotate due to the action of gases. This turbine connects to the compressor at the front of the unit and sets it in motion. Air heated to high temperatures, exits through exhaust system... The temperature, already high enough, continues to rise due to the throttling effect. Then the air comes out completely.

Airplane engine

Airplanes also use these engines. So, for example, turbojet units are installed in huge passenger liners. They differ from the usual ones by the presence of two tanks. One contains fuel, and the other contains an oxidizer. While the turbojet engine carries only fuel, and the air is used as an oxidizer, forced from the atmosphere.

Turbojet engine

The principle of operation of an aircraft jet engine is based on the same jet force and the same laws of physics. The most important part is the turbine blades. The final power depends on the size of the blade.

It is thanks to the turbines that the thrust is generated, which is necessary to accelerate the aircraft. Each of the blades is ten times more powerful than ordinary automobile internal combustion engine... The turbines are installed after the combustion chamber where the pressure is highest. And the temperature here can reach one and a half thousand degrees.

Double-circuit taxiway

These units have many advantages over turbojets. For example, significantly lower fuel consumption for the same power.

But the engine itself is more complex and heavier.

And the principle of operation of a two-circuit jet engine is slightly different. The air entrained by the turbine is partially compressed and supplied to the first circuit for the compressor and on the second circuit - to the fixed blades. At the same time, the turbine works as a compressor. low pressure... In the first circuit of the engine, air is compressed and heated, and then by means of a compressor high pressure fed into the combustion chamber. This is where the mixture with fuel and ignition takes place. Gases are formed, which are fed to the high-pressure turbine, due to which the turbine blades rotate, which, in turn, supply rotary motion to the high-pressure compressor. The gases then pass through a low pressure turbine. The latter drives the fan and, finally, the gases enter the outside, creating thrust.

Synchronous taxiways

These are electric motors. The principle of operation of a synchronous reluctance motor is similar to that of a stepper unit. Alternating current is fed to the stator and creates a magnetic field around the rotor. The latter rotates due to the fact that it tries to minimize the magnetic resistance. These motors are not related to space exploration and launching shuttles.

Jet engines are such devices that create the traction force necessary for the movement process by converting the internal energy of the fuel into the kinetic energy of the jet jets in the working medium. The working fluid rapidly flows from the engine, and according to the law of conservation of momentum, a reactive force is formed, which pushes the engine in the opposite direction. To accelerate the working fluid, it can be used as an expansion of gases heated in a variety of ways to high temperatures, as well as other physical processes, in particular, the acceleration of charged particles in an electrostatic field.

Jet engines combine actual engines with propellers. It means that they create tractive effort exclusively by interaction with working bodies, without supports, or by contacts with other bodies. That is, they ensure their own progress, while intermediate mechanisms do not take any part. As a result, they are mainly used to propel aircraft, rockets and, of course, spacecraft.

What is engine thrust?

The thrust of the engines is called the reactive force, which is manifested by gas-dynamic forces, pressure and friction applied to the internal and outside parties engine.

The rods differ in:

• Internal (jet thrust), when external resistance is not taken into account;
• Effective, taking into account the external resistance of power plants.

The starting energy is stored on board aircraft or other vehicles equipped with jet engines (chemical fuel, nuclear fuel), or can be supplied from outside (for example, solar energy).

How is jet thrust formed?

To generate jet thrust (engine thrust), which is used by jet engines, you will need:

• Sources of initial energy, which are converted into kinetic energy of jet jets;
• Working fluids that will be ejected from jet engines as jet streams;
• The jet engine itself as an energy converter.

How to get a working body?

To purchase a working fluid in jet engines, the following can be used:

• Substances taken from the environment (for example, water or air);
• Substances in the tanks of apparatus or in the chambers of jet engines;
• Mixed substances coming from the environment and stored on board the vehicles.

Modern jet engines mainly use chemical energy. Working fluids are a mixture of incandescent gases, which are products of combustion of chemical fuels. When a jet engine is running, the chemical energy from the combustion materials is converted into heat energy from the combustion products. At the same time, thermal energy from hot gases is converted into mechanical energy from translational movements jet streams and apparatus on which engines are installed.

In jet engines, the jets of air that enter the engines meet the turbines of the compressors rotating at tremendous speed, which draw in air from the environment (using built-in fans). Therefore, two tasks are being solved:

• Primary air intake;
• Cooling of the whole engine.

The turbine blades of the compressors compress the air approximately 30 or more times, push it (injection) into the combustion chamber (the working fluid is generated). In general, combustion chambers also play the role of carburetors, mixing fuel with air.

It can be, in particular, a mixture of air and kerosene, as in turbojet engines modern jet aircraft, or a mixture of liquid oxygen and alcohol, such are the properties of some liquid-propellant rocket engines, or some other solid fuel in powder rockets. As soon as the fuel-air mixture is formed, it ignites with the release of energy in the form of heat. Thus, the fuel in jet engines can be only those substances that, as a result of chemical reactions in the engines (during combustion), generate heat, while forming a lot of gases.

In the event of a fire, a significant heating of the mixture and parts around it occurs with volumetric expansion. As a matter of fact, jet engines are used for propelling controlled explosions. Combustion chambers in jet engines are some of the hottest elements ( temperature regime in them it can reach up to 2700 ° C), and they require constant intensive cooling.

Jet engines are equipped with nozzles through which hot gases, which are products of fuel combustion, flow out from them at a high speed. In some engines, gases end up in the nozzles immediately after the combustion chambers. This applies, for example, to rocket or ramjet engines.

Turbojet engines function somewhat differently. So, the gases, after the combustion chambers, first pass through the turbines, to which they give their thermal energy. This is done in order to drive the compressors, which will serve to compress the air in front of the combustion chamber. In any case, the nozzles remain the last parts of the engines through which gases can flow. Actually, they form the jet stream directly.

The nozzles are directed cold air which is pumped by compressors to cool the internal parts of the engines. Jet nozzles can be of different configurations and designs based on the variety of engines. So, when the velocity of the outflow should be higher than the speed of sound, then the nozzles are given the shape of expanding pipes or, at first, narrowing, and then expanding (the so-called Laval nozzles). Only with tubes of this configuration, gases are accelerated to supersonic speeds, with the help of which jet planes step over the "sound barriers".

Based on whether the environment is involved in the operation of jet engines, they are subdivided into the main classes of air-breathing engines (WFM) and rocket engines (RD). All WFDs are heat engines, the working bodies of which are formed when the oxidation reaction of combustible substances with oxygen of the air masses occurs. Air flows coming from the atmosphere form the basis of the WFD working bodies. Thus, vehicles with WFD carry energy sources (fuel) on board, but most of the working bodies are drawn from the environment.

The WFD devices include:

• Turbojet engines (TRD);
• Ramjet engines (ramjet);
• Pulsating air-jet engines (PuVRD);
• Hypersonic ramjet engines (scramjet engines).

In contrast to air-jet engines, all components of the working fluids of the taxiway are on board vehicles equipped with rocket engines. The absence of propellers interacting with the environment, as well as the presence of all constituent working bodies on board the vehicles, make rocket engines suitable for functioning in outer space. There is also a combination of rocket engines, which is a kind of combination of the two main varieties.

Briefly about the history of the jet engine

It is believed that the jet engine was invented by Hans von Ohain and the outstanding German design engineer Frank Whittle. The first patent for a working gas turbine engine was received by Frank Whittle in 1930. However, the first working model was assembled by Ohain himself. At the end of the summer of 1939, the first jet aircraft appeared in the sky - the He-178 (Heinkel-178), which was equipped with the HeS 3 engine developed by Ohain.

How does a jet engine work?

The structure of jet engines is quite simple and at the same time extremely complex. It is simple in principle. So, outboard air (in rocket engines- liquid oxygen) is sucked into the turbine. After which it begins to mix with fuel and burn there. At the edge of the turbine, a so-called "working fluid" (previously mentioned jet stream) is formed, which propels the aircraft or spacecraft.

For all its simplicity, in fact, this is a whole science, because in the middle of such engines the operating temperature can reach more than a thousand degrees Celsius. One of the most important problems in turbojet engine building is the creation of non-melting metal parts that themselves melt.

At the beginning, in front of each turbine, there is always a fan that sucks air masses from the environment into the turbines. The fans have a large area, as well as a colossal number of blades of special configurations, the material for which is titanium. Immediately behind the fans are powerful compressors, which are necessary to force air under enormous pressure into the combustion chambers. After combustion chambers burning air-fuel mixture are sent to the turbine itself.

Turbines consist of a plurality of blades, which are pressurized by jet streams, which drive the turbines into rotation. Further, the turbines rotate the shafts on which the fans and compressors are "mounted". Actually, the system becomes closed and needs only the supply of fuel and air masses.

Following the turbines, the flows are directed to the nozzles. Jet engine nozzles are the last, but not the least important, parts in jet engines. They form direct jet streams. Cold air masses are directed into the nozzles, which are forced by fans to cool the "insides" of the engines. These streams restrict the nozzle collars from superheated jet streams and prevent them from melting.

Deflected thrust vector

Jet engines have a wide variety of nozzle configurations. The most advanced are considered to be movable nozzles located on engines that have a deflected thrust vector. They can squeeze and expand, as well as deviate at significant angles - this is how the jet streams are regulated and directed directly. Thanks to this, aircraft with engines having a deflected thrust vector become extremely maneuverable, because the maneuvering processes occur not only due to the actions of the wing mechanisms, but also directly by the engines themselves.

Jet engine types

There are several main types of jet engines. So, the classic jet engine can be called an aircraft engine in the F-15 aircraft. Most of these engines are used primarily in various types of fighters.

Two-blade turboprop engines

In this variety turboprop engines the power of the turbines is directed through reduction gears to rotate the classic propellers. The presence of such engines allows large aircraft to fly at maximum acceptable speeds while using less aviation fuel. The normal cruising speed for turboprop aircraft can be 600-800 km / h.

Turbofan jet engines

This type of engine is more economical in the classic engine family. The main distinctive characteristic in them is that large-diameter fans are placed at the inlet, which supply air flows not only for the turbines, but also create rather powerful flows outside them. As a consequence, it is possible to achieve increased efficiency by improving the efficiency. They are used on liners and large aircraft.

Ramjet engines

This type of engine functions in such a way that it does not need moving parts. Air masses are forced into the combustion chamber in a relaxed way, thanks to the braking of the flows about the fairings of the inlets. In the future, everything is done as in ordinary jet engines, namely, air flows are mixed with fuel and come out like jet jets from nozzles. Direct-flow jet engines are used in trains, in aircraft, in "drones", in rockets, in addition, they can be installed on bicycles or scooters.

Jet engines are now widely used in connection with the exploration of outer space. They are also used for meteorological and military rockets of various ranges. In addition, all modern high-speed aircraft are equipped with jet engines.

It is impossible to use any other engines besides jet engines in outer space: there is no support (solid liquid or gaseous), starting from which spaceship could get a boost. The use of jet engines for aircraft and rockets that do not leave the atmosphere is associated withwhat exactly jet engines can provide maximum speed flight.

Jet engine device.

Simply by the principle of operation: outboard air (in rocket engines - liquid oxygen) is sucked intoturbine, there it mixes with fuel and burns, at the end of the turbine forms the so-called. "Working fluid" (jet stream), which moves the machine.

At the beginning of the turbine stands fan that sucks in air from external environment into the turbines. There are two main tasks- primary air intake and cooling of only twothe engine as a whole, by pumping air between the outer shell of the engine and the internal parts. This cools the mixing and combustion chambers and prevents them from collapsing.

There is a powerful fan behind the fan compressor, which pushes air under high pressure into the combustion chamber.

The combustion chamber mixes fuel with air. After the formation of fuel air mixture, it is set on fire. In the process of ignition, significant heating of the mixture and surrounding parts occurs, as well as volumetric expansion. Actually, the jet engine uses a controlled explosion for propulsion. The combustion chamber of a jet engine is one of the hottest parts of it. She needs constant intensive cooling... But this is not enough either. The temperature in it reaches 2700 degrees, so it is often made of ceramics.

After the combustion chamber, burning air-fuel mixture goes directly to turbine. The turbine consists of hundreds of blades, which are pressed by the jet stream, driving the turbine into rotation. The turbine, in turn, rotates shaft on which there are ventilator and compressor... Thus, the system is closed and only requires supply fuel and air for its functioning.

There are two main classes of jet propulsion tellers:

Air-jet engines- a jet engine in which atmospheric air is used as the main working fluid in the thermodynamic cycle, as well as when creating the jet thrust of the engine. Such engines use the energy of oxidation of combustible oxygen in the air taken from the atmosphere. The working fluid of these engines is a mixture of productscombustion with the rest of the intake air.

Rocket engines- contain all the components of the working fluid on board and able to work in any environment, including in an airless space.

Types of jet engines.

- Classic jet engine- is used mainly on fighters in various modifications.