What is a jet engine? Jet engine: modern versions.

In a jet engine, the thrust force necessary for movement is created by converting the initial energy into the kinetic energy of the working fluid. As a result of the expiration of the working fluid from the engine nozzle, a reactive force is formed in the form of recoil (jet). The recoil moves the engine and the device structurally connected with it in space. The movement occurs in the direction opposite to the outflow of the jet. Various types of energy can be converted into the kinetic energy of a jet stream: chemical, nuclear, electrical, solar. The jet engine provides its own movement without the participation of intermediate mechanisms.

To create jet thrust, you need a source of initial energy, which is converted into the kinetic energy of a jet stream, a working fluid ejected from the engine in the form of a jet stream, and the jet engine itself, which converts the first type of energy into the second.

The main part of a jet engine is the combustion chamber, in which the working fluid is created.

All jet engines are divided into two main classes, depending on whether they use the environment in their work or not.

The first class is air jet engines (WFD). All of them are thermal, in which the working fluid is formed during the oxidation reaction of a combustible substance with oxygen from the surrounding air. The main mass of the working fluid is atmospheric air.

In a rocket engine, all components of the working fluid are on board the apparatus equipped with it.

There are also combined engines that combine both of the above types.

For the first time, jet propulsion was used in Heron's ball, the prototype of a steam turbine. Solid fuel jet engines appeared in China in the 10th century. n. e. Such rockets were used in the East, and then in Europe for fireworks, signaling, and then as combat ones.

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 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.

N. E. Zhukovsky in his works “On the reaction of outflowing and inflowing fluid” (1880s) and “On the theory of ships set in motion by the reaction force of outflowing water” (1908) first developed the main issues of the theory of a jet engine.

Interesting work on the study of rocket flight also belongs to the famous Russian scientist I. V. Meshchersky, in particular in the field of the general theory of the motion of bodies of variable mass.

In 1903, K. E. Tsiolkovsky, in his work “Investigation of the World Spaces with Reactive Devices,” gave a theoretical justification for the flight of a rocket, as well as a schematic diagram of a rocket engine, which anticipated many of the fundamental and design features of modern liquid-propellant rocket engines (LRE). So, Tsiolkovsky provided for the use of liquid fuel for a jet engine and its supply to the engine with special pumps. He proposed to control the flight of the rocket by means of gas rudders - special plates placed in the jet of gases emitted from the nozzle.

A feature of a liquid-propellant engine is that, unlike other jet engines, it carries with it the entire supply of oxidizer along with the fuel, and does not take the oxygen-containing air necessary for burning fuel from the atmosphere. This is the only engine that can be used for ultra-high-altitude flight outside the earth's atmosphere.

The world's first rocket with a liquid-propellant rocket engine was created and launched on March 16, 1926 by the American R. Goddard. It weighed about 5 kilograms, and its length reached 3 m. Goddard's rocket was fueled by gasoline and liquid oxygen. The flight of this rocket lasted 2.5 seconds, during which it flew 56 m.

Systematic experimental work on these engines began in the 1930s.

The first Soviet rocket engines were designed and built in 1930–1931. in the Leningrad Gas Dynamic Laboratory (GDL) under the guidance of the future academician V.P. Glushko. This series was called ORM - an experienced rocket motor. Glushko applied some novelties, for example, cooling the engine with one of the fuel components.

In parallel, the development of rocket engines was carried out in Moscow by the Jet Propulsion Study Group (GIRD). Its ideological inspirer was F. A. Zander, and the organizer was the young S. P. Korolev. Korolev's goal was to build a new rocket apparatus - a rocket plane.

In 1933, F. A. Zander built and successfully tested the OR? 1 rocket engine, which ran on gasoline and compressed air, and in 1932-1933. - engine OR? 2, on gasoline and liquid oxygen. This engine was designed to be installed on a glider that was supposed to fly as a rocket plane.

In 1933, the first Soviet liquid-fuel rocket was created and tested at GIRD.

Developing the work begun, Soviet engineers subsequently continued to work on the creation of liquid-propellant jet engines. In total, from 1932 to 1941, 118 designs of liquid-propellant jet engines were developed in the USSR.

In Germany in 1931, rockets were tested by I. Winkler, Riedel, and others.

The first flight on an airplane? rocket plane with a liquid-propellant engine was made in the Soviet Union in February 1940. An LRE was used as the power plant of the aircraft. In 1941, under the leadership of the Soviet designer VF Bolkhovitinov, the first jet aircraft was built - a fighter with a liquid-propellant rocket engine. His tests were carried out in May 1942 by pilot G. Ya. Bakhchivadzhi.

At the same time, the first flight of a German fighter with such an engine took place. In 1943, the first American jet aircraft was tested in the United States, on which a liquid-propellant engine was installed. In Germany, in 1944, several fighters with these Messerschmitt-designed engines were built and in the same year they were used in a combat situation on the Western Front.

In addition, liquid propellant rocket engines were used on German V-2 rockets, created under the direction of W. von Braun.

In the 1950s, liquid-propellant rocket engines were installed on ballistic missiles, and then on artificial satellites of the Earth, the Sun, the Moon and Mars, automatic interplanetary stations.

The rocket engine consists of a combustion chamber with a nozzle, a turbopump unit, a gas generator or a steam-gas generator, an automation system, control elements, an ignition system and auxiliary units (heat exchangers, mixers, drives).

The idea of ​​air jet engines has been put forward more than once in different countries. The most important and original works in this respect are the studies carried out in 1908–1913. French scientist R. Loren, who, in particular, in 1911 proposed a number of schemes for ramjet engines. These engines use atmospheric air as an oxidizer, and the air in the combustion chamber is compressed by dynamic air pressure.

In May 1939, for the first time in the USSR, a rocket with a ramjet engine designed by P. A. Merkulov was tested. It was a two-stage rocket (the first stage was a powder rocket) with a take-off weight of 7.07 kg, and the weight of fuel for the second stage of a ramjet engine was only 2 kg. During the test, the rocket reached a height of 2 km.

In 1939–1940 for the first time in the world in the Soviet Union, summer tests of air-jet engines installed as additional engines on an aircraft designed by N.P. Polikarpov were carried out. In 1942, ramjet engines designed by E. Senger were tested in Germany.

The air-jet engine consists of a diffuser in which air is compressed due to the kinetic energy of the oncoming air flow. Fuel is injected into the combustion chamber through the nozzle and the mixture ignites. The jet stream exits through the nozzle.

The operation of the WFD is continuous, so there is no starting thrust in them. In this regard, at flight speeds less than half the speed of sound, jet engines are not used. The use of WFD is most effective at supersonic speeds and high altitudes. The takeoff of an aircraft with an air-jet engine occurs with the help of rocket engines on solid or liquid fuel.

Another group of air-jet engines, turbocompressor engines, has received more development. They are divided into turbojet, in which the thrust is created by a jet of gases flowing from the jet nozzle, and turboprop, in which the main thrust is created by the propeller.

In 1909, the design of a turbojet engine was developed by engineer N. Gerasimov. In 1914, Lieutenant of the Russian Navy M.N. Nikolskoy designed and built a model of a turboprop aircraft engine. The gaseous combustion products of a mixture of turpentine and nitric acid served as the working fluid for driving the three-stage turbine. The turbine worked not only on the propeller: the exhaust gaseous products of combustion directed into the tail (jet) nozzle created jet thrust in addition to the propeller thrust.

In 1924, V. I. Bazarov developed the design of an aircraft turbocompressor jet engine, which consisted of three elements: a combustion chamber, a gas turbine, and a compressor. For the first time, the compressed air flow here was divided into two branches: the smaller part went into the combustion chamber (to the burner), and the larger part was mixed with the working gases to lower their temperature in front of the turbine. This ensured the safety of the turbine blades. The power of the multistage turbine was used to drive the centrifugal compressor of the engine itself and partly to rotate the propeller. In addition to the propeller, thrust was created by the reaction of a jet of gases passed through the tail nozzle.

In 1939, the construction of turbojet engines designed by A. M. Lyulka began at the Kirov Plant in Leningrad. His trials were interrupted by the war.

In 1941, in England, the first flight was made on an experimental fighter aircraft equipped with a turbojet engine designed by F. Whittle. It was equipped with a gas turbine engine that drove a centrifugal compressor that supplied air to the combustion chamber. Combustion products were used to create jet thrust.

In a turbojet engine, air entering during flight is compressed first in the air intake and then in the turbocharger. Compressed air is fed into the combustion chamber, where liquid fuel (most often aviation kerosene) is injected. Partial expansion of the gases formed during combustion occurs in the turbine that rotates the compressor, and the final expansion occurs in the jet nozzle. An afterburner can be installed between the turbine and the jet engine, designed for additional combustion of fuel.

Today, most military and civil aircraft, as well as some helicopters, are equipped with turbojet engines.

In a turboprop engine, the main thrust is created by a propeller, and an additional (about 10%) - by a jet of gases flowing from a jet nozzle. The principle of operation of a turboprop engine is similar to a turbojet engine, with the difference that the turbine rotates not only the compressor, but also the propeller. These engines are used in subsonic aircraft and helicopters, as well as for the movement of high-speed ships and cars.

The earliest solid propellant jet engines were used in combat missiles. Their widespread use began in the 19th century, when missile units appeared in many armies. At the end of the XIX century. the first smokeless powders were created, with more stable combustion and greater efficiency.

In the 1920s–1930s, work was underway to create jet weapons. This led to the appearance of rocket launchers - "Katyusha" in the Soviet Union, six-barreled rocket mortars in Germany.

Obtaining new types of gunpowder made it possible to use solid-propellant jet engines in combat missiles, including ballistic ones. In addition, they are used in aviation and astronautics as the engines of the first stages of launch vehicles, starting engines for aircraft with ramjet engines and brake engines of spacecraft.

A solid propellant jet engine consists of a body (combustion chamber) in which the entire supply of fuel and a jet nozzle are located. The body is made of steel or fiberglass. Nozzle - made of graphite, refractory alloys, graphite.

The fuel is ignited by an igniter.

Thrust is controlled by changing the combustion surface of the charge or the area of ​​the critical section of the nozzle, as well as by injecting liquid into the combustion chamber.

The direction of thrust can be changed by gas rudders, a deflecting nozzle (deflector), auxiliary control engines, etc.

Jet solid propellant engines are very reliable, can be stored for a long time, and therefore, are constantly ready for launch.

Great Definition

Incomplete definition ↓

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, understand the 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 propulsion unit, 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 apparatus. 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 (push it) 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 the formation of the fuel-air mixture, it is ignited and energy is released in the form of heat, i.e., only substances that, during a chemical reaction in the engine (combustion), release a lot of heat, and also form a large amount of gases, can serve as fuel for jet engines .

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 forms a direct jet stream. The cold air forced by the compressor is directed into the nozzle to cool the internal parts of the 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 a turbojet engine (TRD), a ramjet engine (ramjet), a pulsed jet engine (PuVRD), a 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

The main technical parameter that characterizes 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 fuel consumption (quantity 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, size and resource are important characteristics. 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 of 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 the mass flow rate (mass flow rate) 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 altitude of the flight 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 the combustion products (working fluid) is determined by the physicochemical properties of the fuel components and the design features of the engine, being a constant value for not very large changes in the operating mode of the jet engine, the magnitude of the reactive force is determined mainly by the mass per second fuel consumption and varies over a very wide range. limits (minimum for electric - 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 in different flight modes. 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 array and atmospheric air, entering the engine inlet at a speed equal to the flight speed, 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 design of supersonic aircraft with ramjet engines (ramjet engines) is due to the presence of special accelerator 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.

Jet aircraft engines in the second half of the 20th century opened up new opportunities in aviation: flights at speeds exceeding the speed of sound, the creation of aircraft with a high payload, made mass travel over long distances possible. The turbojet engine is rightfully considered one of the most important mechanisms of the past century, despite the simple principle of operation.

Story

The Wright Brothers' first aircraft to take off from Earth on its own in 1903 was powered by a piston internal combustion engine. And for forty years this type of engine remained the main one in aircraft construction. But during World War II, it became clear that traditional piston-propeller aviation had reached its technological limit, both in terms of power and speed. One alternative was the air-jet engine.

The idea of ​​using jet thrust to overcome gravity was first brought to practical feasibility by Konstantin Tsiolkovsky. As early as 1903, when the Wright brothers were launching their first Flyer-1 aircraft, the Russian scientist published his work Exploring the Spaces of the World with Jet Instruments, in which he developed the fundamentals of the theory of jet propulsion. An article published in the Scientific Review established his reputation as a dreamer and was not taken seriously. It took Tsiolkovsky years of work and a change in the political system to prove his case.

Su-11 jet aircraft with TR-1 engines, developed by Lyulka Design Bureau

Nevertheless, a completely different country, Germany, was destined to become the birthplace of a serial turbojet engine. The creation of a turbojet engine in the late 1930s was a kind of hobby of German companies. In this area, almost all currently known brands were noted: Heinkel, BMW, Daimler-Benz and even Porsche. The main laurels went to Junkers and its world's first serial turbojet 109-004, installed on the world's first Me 262 turbojet.

Despite an incredibly successful start in first-generation jet aviation, German solutions were not further developed anywhere in the world, including in the Soviet Union.

In the USSR, the development of turbojet engines was most successfully carried out by the legendary aircraft designer Arkhip Lyulka. Back in April 1940, he patented his own scheme for a bypass turbojet engine, which later received worldwide recognition. Arkhip Lyulka did not find support from the country's leadership. With the outbreak of war, he was generally offered to switch to tank engines. And only when the Germans had aircraft with turbojet engines, Lyulka was ordered to urgently resume work on the domestic TR-1 turbojet engine.

Already in February 1947, the engine passed the first tests, and on May 28, the Su-11 jet aircraft with the first domestic TR-1 engines, developed by A.M. Design Bureau, made its first flight. Lyulka, now a branch of the Ufa engine-building software, part of the United Engine Corporation (UEC).

Principle of operation

A turbojet engine (TRD) operates on the principle of a conventional heat engine. Without delving into the laws of thermodynamics, a heat engine can be defined as a machine for converting energy into mechanical work. This energy is possessed by the so-called working fluid - the gas or steam used inside the machine. When compressed in a machine, the working fluid receives energy, and when it is subsequently expanded, we have useful mechanical work.

At the same time, it is clear that the work expended on compressing the gas must always be less than the work that the gas can do when expanding. Otherwise, there will be no useful “product”. Therefore, the gas must also be heated before expansion or during it, and cooled before compression. As a result, due to preheating, the expansion energy will increase significantly and its excess will appear, which can be used to obtain the mechanical work we need. That's actually the whole principle of operation of a turbojet engine.

Thus, any heat engine must have a compression device, a heater, an expansion device and a cooling device. The turbojet engine has all this, respectively: a compressor, a combustion chamber, a turbine, and the atmosphere acts as a refrigerator.

Next, the air enters the combustion chamber, where it is heated and mixed with combustion products (kerosene). The combustion chamber encircles the engine rotor after the compressor with a continuous ring, or in the form of separate pipes, which are called flame pipes. Aviation kerosene is fed into the flame tubes through special nozzles.

From the combustion chamber, the heated working fluid enters the turbine. It is similar to a compressor, but works, so to speak, in the opposite direction. It spins the hot gas on the same principle as the air propeller toy. The turbine has few stages, usually from one to three or four. This is the most loaded node in the engine. The turbojet engine has a very high speed - up to 30 thousand revolutions per minute. The torch from the combustion chamber reaches a temperature of 1100 to 1500 degrees Celsius. The air expands here, setting the turbine in motion and giving it some of its energy.

After the turbine - a jet nozzle, where the working fluid accelerates and expires at a speed greater than the speed of the oncoming flow, which creates jet thrust.

Generations of turbojet engines

Despite the fact that in principle there is no exact classification of generations of turbojet engines, it is possible to describe in general terms the main types at various stages of the development of engine building.

The first generation engines include German and British engines from the Second World War, as well as the Soviet VK-1, which was installed on the famous MIG-15 fighter, as well as on the IL-28 and TU-14 aircraft.

Fighter MiG-15

TRDs of the second generation are already distinguished by the possible presence of an axial compressor, an afterburner and an adjustable air intake. Among the Soviet examples is the R-11F2S-300 engine for the MiG-21 aircraft.

Engines of the third generation are characterized by an increased compression ratio, which was achieved by increasing the stages of the compressor and turbines, and the appearance of bypass. Technically, these are the most complex engines.

The emergence of new materials that can significantly raise operating temperatures has led to the creation of fourth-generation engines. Among these engines is the domestic AL-31 developed by the UEC for the Su-27 fighter.

Today, the production of fifth-generation aircraft engines is starting at the Ufa enterprise UEC. The new units will be installed on the T-50 fighter (PAK FA), which is replacing the Su-27. The new power plant on the T-50 with increased power will make the aircraft even more maneuverable, and most importantly, it will open a new era in the domestic aircraft industry.

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 connection of the four most 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 of the compressed air enters the combustion chamber, where it is mixed with fuel and ignited. It increases thermal energy of the air.

Jet engine.

The hot mixture exits the chamber at high speed 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 that part of the engine where the pressure is highest 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 largest companies in 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. This is the future internal combustion engine. 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 engines are currently widely used in connection with the exploration of outer space. They are also used for meteorological and military missiles of various ranges. In addition, all modern high-speed aircraft are equipped with jet engines.

In outer space, it is impossible to use any other engines, except for jet engines: there is no support (solid liquid or gaseous), starting from which the spacecraft could get acceleration. The use of jet engines for aircraft and rockets that do not go beyond the atmosphere is connected with thethat it is jet engines that can provide the maximum flight speed.

Jet engine device.

Simply according to 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 body” (jet stream), which moves the car.

At the beginning of the turbine is fan, which sucks air from the external environment into the turbine. Two main tasks- primary air intake and cooling of the entire engineengine as a whole, by pumping air between the outer shell of the engine and internal parts. This cools the mixing and combustion chambers and prevents them from collapsing.

Behind the fan is a powerful compressor which forces air at high pressure into the combustion chamber.

The combustion chamber mixes fuel with air. After the formation of the fuel-air mixture, it is ignited. In the process of ignition, there is a significant heating of the mixture and surrounding parts, as well as volumetric expansion. Actually, a jet engine uses a controlled explosion to propel itself. The combustion chamber of a jet engine is one of the hottest parts of it. She needs constant intensive cooling.. But even this is not enough. The temperature in it reaches 2700 degrees, so it is often made of ceramics.

After the combustion chamber, the burning fuel-air mixture is sent directly to turbine. The turbine consists of hundreds of blades, which are pressed by the jet stream, causing the turbine to rotate. The turbine, in turn, rotates shaft on which are fan and compressor. Thus, the system is closed and requires only a supply fuel and air for its functioning.

There are two main classes of jet engines bodies:

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

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

Types of jet engines.

- classic jet engine- used mainly on fighters in various modifications.