Sinusitis

Diagram of jet engine operation. Jet engine: operating principle (briefly)

Pushing the engine in the opposite direction. To accelerate the working fluid, it can be used as an expansion of gas heated in one way or another to high temperature(so-called thermal jet engines), as well as other physical principles, for example, the acceleration of charged particles in an electrostatic field (see ion engine).

A jet engine combines the engine itself with a propulsion device, that is, it creates traction force only through interaction with the working fluid, without support or contact with other bodies. For this reason, it is most often used to propel aircraft, rockets and spacecraft.

Jet engine classes

There are two main classes of jet engines:

Jet engines- heat engines that use the energy of oxidation of fuel with oxygen from air taken from the atmosphere. The working fluid of these engines is a mixture of combustion products with the remaining components of the intake air.
Rocket engines- contain all components of the working fluid on board and are capable of operating in any environment, including in airless space.

Components of a jet engine

Any jet engine must have at least two components:

Combustion chamber (“chemical reactor”) - it is where the chemical energy of the fuel is released and converted into thermal energy of gases.
Jet nozzle (“gas tunnel”) - in which thermal energy gases are converted into their kinetic energy when gases flow out of the nozzle at high speed, thereby creating jet thrust.

Main technical parameters of a jet engine

Main technical parameter characterizing a jet engine is traction(otherwise known as traction force) is the force that the engine develops in the direction of movement of the vehicle.

In addition to thrust, rocket engines are characterized by specific impulse, which is an indicator of the degree of sophistication or quality of the engine. This indicator is also a measure of engine efficiency. The chart below shows in graphical form the top values of this indicator for different types jet engines, depending on the flight speed, expressed in the form of Mach number, which allows you to see the range of applicability of each type of engine.

Story

The jet engine was invented by Dr. Hans von Ohain, a prominent German design engineer, and Sir Frank Whittle. The first patent for a working gas turbine engine was obtained in 1930 by Frank Whittle. However, it was Ohain who assembled the first working model.

On August 2, 1939, the first jet aircraft, the Heinkel He 178, equipped with an engine, took off in Germany HeS 3, developed by Ohain.

What is engine thrust?

Engine thrust is called reactive force, which is manifested by gas-dynamic forces, pressure and friction applied to internal and external parties engine.

The thrusts differ in:

Internal (jet thrust), when external resistance is not taken into account;
Efficient, 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 flow 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 that are converted into kinetic energy of jet streams;
Working fluids that will be ejected from jet engines as jet streams;
The jet engine itself acts as an energy converter.

How to obtain a working fluid?

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

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

Modern jet engines primarily use chemical energy. The working fluids are a mixture of hot gases, which are products of the combustion of chemical fuels. When a jet engine operates, chemical energy from combustion materials is converted into thermal energy from combustion products. At the same time, thermal energy from hot gases is converted into mechanical energy from the translational movements of jet streams and devices on which engines are installed.

In jet engines, the jets of air that enter the engines meet compressor turbines spinning at tremendous speed, which suck in air from the environment (using built-in fans). Consequently, two problems are solved:

Primary air intake;
Cooling of the entire engine as a whole.

The blades of compressor turbines compress air approximately 30 times or more, “pushing” it (pumping) into the combustion chamber (generating a working fluid). In general, combustion chambers also serve as carburetors, mixing fuel with air.

These can be, in particular, mixtures of air and kerosene, as in the turbojet engines of modern jet aircraft, or mixtures of liquid oxygen and alcohol, such as some liquid rocket engines, or some other solid fuel in powder rockets. Once the fuel-air mixture has formed, it ignites, releasing energy in the form of heat. Thus, fuel in jet engines can only be substances that, as a result, chemical reactions in engines (when ignited) they release heat, while forming many gases.

When ignited, a significant heating of the mixture and parts around occurs with volumetric expansion. In fact, jet engines use controlled explosions to propel themselves. The combustion chambers in jet engines are some of the hottest elements ( temperature regime they 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 of them at great 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 operate somewhat differently. Thus, gases, after the combustion chambers, first pass through turbines, to which they give off their thermal energy. This is done in order to set in motion the compressors, which will serve to compress the air in front of the combustion chamber. In any case, the nozzles are the last parts of the engines through which gases will flow. Actually, they directly form the jet stream.

Cold air is directed into the nozzles, which is forced by compressors to cool the internal parts of the engines. Jet nozzles can have different configurations and designs based on the types of engines. So, when the flow velocity must be higher than the speed of sound, then the nozzles are shaped like expanding pipes or first narrowing and then expanding (the so-called Laval nozzles). Only with pipes of this configuration gases are accelerated to supersonic speeds, with the help of which jet aircraft cross the “sound barriers”.

Based on whether the environment is involved in the operation of jet engines, they are divided into the main classes of air-breathing engines (WRE) and rocket engines(RD). All jet engines are heat engines, the working fluids of which are formed when the oxidation reaction of flammable substances with oxygen in the air masses occurs. Coming from the atmosphere air currents form the basis of the working fluids of the jet engines. Thus, devices with a propellant engine carry energy sources (fuel) on board, but most of the working fluids are drawn from the environment.

VRD devices include:

Turbojet engines (TRD);
Ramjet engines (ramjet engines);
Pulse air jet engines (PvRE);
Hypersonic ramjet engines (scramjet engines).

In contrast to air-breathing engines, all components of the working fluids of the rocket engines are located on board vehicles equipped with rocket engines. Lack of movers interacting with environment, as well as the presence of all the components of the working fluids on board the vehicles make rocket engines suitable for operation in outer space. There is also a combination of rocket engines, which are a kind of combination of two main types.

Brief history of the jet engine

The jet engine is believed to have been invented by Hans von Ohain and the eminent German design engineer Frank Wittle. 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. Thus, outside air (in rocket engines - liquid oxygen) is sucked into the turbine. After which it begins to mix with fuel and burn. At the edge of the turbine, a so-called “working fluid” (the previously mentioned jet stream) is formed, which propels the aircraft or spacecraft.

Despite all its simplicity, this is actually 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 construction is the creation of non-consumable parts from metals that themselves can be melted.

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 pump air under enormous pressure into the combustion chambers. After the combustion chambers, the burning air-fuel mixtures are sent to the turbine itself.

Turbines consist of many blades that are pressurized by jet streams, which cause the turbines to rotate. Next, the turbines rotate the shafts on which fans and compressors are mounted. Actually, the system becomes closed and requires only the supply of fuel and air masses.

Following the turbines, the flows are directed into the nozzles. Jet engine nozzles are the last but not the least important part in a jet engine. They form direct jet streams. Cold air masses are directed into the nozzles, pumped by fans to cool the “insides” of the engines. These flows restrict the nozzle cuffs from super-hot jet streams and prevent them from melting.

Deflectable thrust vector

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

Types of jet engines

There are several main types of jet engines. Thus, a classic jet engine can be called an aircraft engine in an F-15 aircraft. Most of these engines are used primarily on fighter aircraft of a wide variety of modifications.

Two-blade turboprop engines

In this type of turboprop engine, the power of the turbines is directed through reduction gearboxes to rotate the classic propellers. The presence of such engines allows large aircraft to fly at the maximum acceptable speeds and at the same time consume less aviation fuel. Normal cruising speed for turboprop aircraft can be 600-800 km/h.

Turbofan jet engines

This type of engine is more economical in the engine family classical types. Home distinctive characteristic The difference between them is that large-diameter fans are installed at the inlet, which supply air flows not only for the turbines, but also create quite powerful flows outside them. As a result, increased efficiency can be achieved by improving efficiency. They are used on airliners and large aircraft.

Ramjet engines

This type of engine functions in such a way that it does not require moving parts. Air masses are forced into the combustion chamber in a relaxed way, thanks to the braking of the flows against the fairings of the inlet openings. Subsequently, the same thing happens as in ordinary jet engines, namely, air flows are mixed with fuel and come out as jet streams from the nozzles. Ramjet engines are used in trains, aircraft, drones, rockets, and can also be installed on bicycles or scooters.

Jet engines. History of jet engines.

Jet engines.

A jet engine is a device whose design makes it possible to obtain jet thrust by converting the internal energy of the fuel supply into the kinetic energy of the jet stream of the working fluid.

The working fluid of the object flows out of the jet engine at high speed, and, in accordance with the law of conservation of momentum, a reactive force is generated, pushing the engine in the opposite direction. To accelerate the working fluid, both the expansion of a gas heated in one way or another to a high temperature (thermal jet engines) and other physical principles, for example, the acceleration of charged particles in an electrostatic field (ion engine), can be used.

A jet engine allows you to create traction force only due to the interaction of the jet stream with the working fluid, without support or contact with other bodies. In this regard, the jet engine found wide application in aviation and astronautics.

History of jet engines.

The Chinese were the first to learn how to use jet propulsion; rockets with solid fuel appeared in China in the 10th century AD. e. Such missiles were used in the East and then in Europe for fireworks, signaling, and as combat missiles.

Rockets of ancient China.

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 design 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 driven by the reaction force of outflowing water” (1908), first developed the basic issues of the theory of a jet engine.

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

In 1903, K. E. Tsiolkovsky, in his work “Exploration of World Spaces with Jet Instruments,” gave a theoretical justification for the flight of a rocket, as well as a schematic diagram of a rocket engine, which anticipated many fundamental and design features modern liquid rocket engines (LPRE). Thus, Tsiolkovsky envisaged 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 using gas rudders - special plates placed in a stream of gases escaping from the nozzle.

The peculiarity of a liquid-jet 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 air containing oxygen necessary for burning the 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 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. The fuel in Goddard’s rocket was 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 liquid-propellant rocket engines were developed and created in 1930-1931 at the Leningrad Gas Dynamics Laboratory (GDL) under the leadership of the future academician V.P. Glushko. This series was called ORM - experimental rocket motor. Glushko used some new innovations, 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 Research Group (GIRD). Its ideological inspirer was F.A. Tsander, and its organizer was the young S.P. Korolev. Korolev's goal was to build a new rocket vehicle - a rocket plane.

In 1933, F.A. Zander built and successfully tested the OR1 rocket engine, running on gasoline and compressed air, and in 1932-1933, the OR2 engine, running on gasoline and liquid oxygen. This engine was designed to be installed on a glider that was intended to fly as a rocket plane.

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

In Germany in 1931, tests of missiles by I. Winkler, Riedel and others took place.

The first flight of a rocket-propelled aircraft with a liquid-propellant engine was made in the Soviet Union in February 1940. A liquid propellant rocket engine was used as the aircraft's power plant. In 1941, under the leadership of the Soviet designer V.F. Bolkhovitinov, the first jet fighter aircraft with a liquid-propellant engine was built. Its 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 United States tested the first American jet aircraft to use a liquid-propellant jet engine. In Germany in 1944, several fighter aircraft were built with these Messerschmitt-designed engines.

In addition, liquid rocket engines were used on German V2 rockets, created under the leadership of V. von Braun.

In the 1950s, liquid-propellant engines were installed on ballistic missiles and then on space rockets, artificial satellites, automatic interplanetary stations.

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

The idea of air-breathing engines (WRE) has been put forward more than once in different countries. The most important and original works in this regard are the studies carried out in 1908-1913 by the French scientist Renault Laurent, who proposed a number of designs for ramjet engines (ramjet engines). These engines use atmospheric air as an oxidizer, and air compression in the combustion chamber is ensured by dynamic air pressure.

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

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

An air-breathing 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 a nozzle and the mixture ignites. The jet stream exits through the nozzle.

The process of operation of the jet engines is continuous, so they do not have starting thrust. In this regard, at flight speeds less than half the speed of sound, air-breathing engines are not used. The most effective use of jet engines is at supersonic speeds and high altitudes. An aircraft powered by a jet engine takes off using rocket engines running on solid or liquid fuel.

Another group of air-breathing engines - turbocompressor engines - has received greater development. They are divided into turbojet, in which the thrust is created by a stream 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 working fluid for driving the three-stage turbine was the gaseous combustion products of a mixture of turpentine and nitric acid. The turbine worked not only on the propeller: the exhaust gaseous combustion products directed into the tail (jet) nozzle created jet thrust in addition to the thrust force of the propeller.

In 1924, V.I. Bazarov developed the design of an aviation turbocompressor jet engine, which consisted of three elements: a combustion chamber, a gas turbine, and a compressor. Here, for the first time, the compressed air flow 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 multi-stage turbine was spent on driving the centrifugal compressor of the engine itself and partly on rotating the propeller. In addition to the propeller, thrust was created due to the reaction of a stream 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 carried out on an experimental fighter aircraft equipped with a turbojet engine designed by F. Whittle. It was equipped with an engine with a gas turbine, which drove a centrifugal compressor that supplied air to the combustion chamber. Combustion products were used to create jet thrust.

By the end of World War II it became clear that further effective development aviation is possible only with the introduction of engines that use the principles of jet propulsion in whole or in part.

The first aircraft with jet engines were created in Nazi Germany, Great Britain, the USA and the USSR.

In the USSR, the first fighter project, with a jet engine developed by A. M. Lyulka, was proposed in March 1943 by the head of OKB-301, M. I. Gudkov. The plane was called Gu-VRD. The project was rejected by experts due to a lack of faith in the relevance and advantages of WFD compared to piston aircraft engines.

German designers and scientists working in this and related fields (rocket science) found themselves in a more advantageous position. The Third Reich planned a war, and hoped to win it due to technical superiority in weapons. Therefore, in Germany, new developments that could strengthen the army in the field of aviation and rocket technology were subsidized more generously than in other countries.

The first aircraft equipped with a HeS 3 turbojet engine designed by von Ohain was the He 178 (Heinkel Germany). This happened on August 27, 1939. This aircraft exceeded the piston fighters of its time in speed (700 km/h), maximum speed which did not exceed 650 km/h, but was less economical and, as a result, had a shorter range. In addition, it had high takeoff and landing speeds compared to piston aircraft, which is why it required a longer runway with high-quality pavement.

Work on this topic continued almost until the end of the war, when the Third Reich, having lost its former advantage in the air, made an unsuccessful attempt to restore it by supplying jet aircraft to military aviation.

Since August 1944, the Messerschmitt Me.262 jet fighter-bomber, equipped with two Jumo-004 turbojet engines manufactured by Junkers, began to be mass-produced. The Messerschmitt Me.262 aircraft was significantly superior to all its “contemporaries” in speed and climb rate.

Since November 1944, the first jet bomber Arado Ar 234 Blitz with the same engines began to be produced.

The only Allied jet aircraft anti-Hitler coalition, which formally took part in the Second World War, was the Gloucester Meteor (Great Britain) with a Rolls-Royce Derwent 8 turbojet engine designed by F. Whittle.

After the war, intensive development in the field of air-breathing engines began in all countries that had an aviation industry. Jet engine construction has opened up new opportunities in aviation: flights at speeds exceeding the speed of sound, and the creation of aircraft with a payload capacity many times greater than that of piston aircraft, as a result of the higher power density of gas turbine engines compared to piston engines.

The first domestic production jet aircraft was the Yak-15 fighter (1946), developed in record time on the basis of the Yak-3 airframe and an adaptation of the captured Jumo-004 engine, made at the engine-building design bureau of V. Ya. Klimov.

And a year later, the first, completely original, domestic turbojet engine TR-1, developed at the A. M. Lyulka Design Bureau, passed state tests. Such a rapid pace of development of a completely new area of engine building has an explanation: A. M. Lyulka’s group has been working on this issue since pre-war times, but the “green light” for these developments was given only when the country’s leadership suddenly discovered that the USSR was lagging behind in this area.

The first domestic jet passenger airliner was the Tu-104 (1955), equipped with two RD-3M-500 (AM-3M-500) turbojet engines developed at the A. A. Mikulin Design Bureau. By this time, the USSR was already among the world leaders in the field of aircraft engine building.

The ramjet engine (ramjet engine), invented in 1913, also began to be actively improved. Since the 1950s, a number of experimental aircraft and production aircraft have been created in the USA. cruise missiles different purposes with this type of engine.

Having a number of disadvantages for use on manned aircraft (zero thrust at a standstill, low efficiency at low flight speeds), the ramjet has become the preferred type of ramjet for unmanned disposable projectiles and cruise missiles, due to its simplicity, and, consequently, low cost and reliability.

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

Nowadays, most military and civil aircraft, as well as some helicopters, are equipped with turbojet engines (TRDs).

In a turboprop engine, the main thrust is generated by the propeller, and additional thrust (about 10%) is generated by a stream of gases flowing from the jet nozzle. The operating principle of a turboprop engine is similar to a turbojet (TR), 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 propulsion of high-speed ships and cars.

The earliest solid rocket motors (SRM) were used in combat missiles. Their widespread use began in the 19th century, when rocket units appeared in many armies. IN late XIX centuries, the first smokeless gunpowder was created, with more stable combustion and greater efficiency.

In the 1920-1930s, work was carried out to create jet weapons. This led to the appearance of rocket-propelled mortars - Katyushas in the Soviet Union, six-barreled rocket-propelled mortars in Germany.

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

A solid fuel jet engine (SFRE) consists of a housing (combustion chamber), which contains the entire fuel supply and a jet nozzle. The body is made of steel or fiberglass. The nozzle is made of graphite or refractory alloys. The fuel is ignited by an ignition device. Thrust can be adjusted by changing the combustion surface of the charge or the critical cross-sectional area of the nozzle, as well as by injecting liquid into the combustion chamber. The direction of thrust can be changed by gas rudders, a deflector (deflector), auxiliary control motors, etc.

Solid fuel jet engines are very reliable, do not require complex maintenance, can be stored for a long time, and are always ready to start.

Types of jet engines.

Nowadays, jet engines of various designs are used quite widely.

Jet engines can be divided into two categories: rocket jet engines and air-breathing engines.

Solid propellant rocket engine (SRM) - a solid fuel rocket engine - an engine running on solid fuel, most often used in rocket artillery and much less often in astronautics. It is the oldest of the heat engines.

Liquid rocket engine (LPRE) is a chemical rocket engine that uses liquids, including liquefied gases, as rocket fuel. Based on the number of components used, one-, two-, and three-component liquid propellant engines differ.

Ramjet;

Pulse air jet;

Turbojet;

Turboprop.

Modern jet engines.

The photograph shows an aircraft jet engine during testing.

The photo shows the process of assembling rocket engines.

Jet engines. History of jet engines. Types of jet engines.

ABSTRACT

ON TOPIC:

Jet Engines .

WRITTEN BY: 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 outflow of the working fluid from the engine nozzle, a reactive force is generated in the form of a reaction (recoil) of the jet, moving 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, electrical, solar) can be converted into the kinetic (velocity) energy of a jet stream in a rocket jet. A direct reaction engine (direct reaction engine) combines the engine itself with a propulsion device, i.e., it provides its own movement without the participation of intermediate mechanisms.

To create the jet thrust used by R.D., it is necessary:

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

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

The R.D. itself is an energy converter.

The initial energy is stored on board an aircraft or other vehicle equipped with a rocket engine (chemical fuel, nuclear fuel), or (in principle) can come from outside (solar energy). To obtain a working fluid in a liquid propellant, 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 R.D. chamber; a mixture of substances coming from the environment and stored on board the vehicle.

In modern R.D., chemical is most often used as a primary

Missile fire tests

engine Space Shuttle

Turbojet engines AL-31F airplane Su-30MK. Belong to class air-breathing engines

energy. In this case, the working fluid is hot gases - products of combustion of chemical fuels. During the operation of a jet engine, the chemical energy of combustion 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, the apparatus on which the engine is installed. The main part of any combustion engine is the combustion chamber in which the working fluid is generated. The final part of the chamber, which serves to accelerate the working fluid and produce a jet stream, is called a jet nozzle.

Depending on whether or not the environment is used during the operation of rocket engines, they are divided into 2 main classes - air-breathing engines (ARE) and rocket engines (RE). All VRDs are 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 WRD. Thus, a device with a propellant engine carries an energy source (fuel) on board, and draws most of the working fluid from the environment. In contrast to the VRD, all components of the working fluid of the thruster are located on board the apparatus equipped with the thruster. The absence of a propulsion device interacting with the environment and the presence of all components of the working fluid on board the device make the rocket launcher the only one suitable for operation in space. There are also combined rocket engines, which are a combination of both main 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 “Exploration of World Spaces with Jet Instruments,” was the first in the world to put forward the basic principles of the theory of liquid rocket engines and proposed the basic elements of a liquid-fuel rocket engine design. The first Soviet liquid rocket engines - ORM, ORM-1, ORM-2 were designed by V.P. Glushko and, under his leadership, created in 1930-31 at the Gas Dynamics Laboratory (GDL). In 1926, R. Goddard launched a rocket using liquid fuel. The first electrothermal RD was created and tested by Glushko at the GDL in 1929-33.

In 1939, the USSR tested missiles with ramjet engines designed by I. A. Merkulov. The first turbojet engine diagram? 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 testing of the created engine was 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. Great value The creation of R.D. was based on the theoretical works of Russian scientists S. S. Nezhdanovsky, I. V. Meshchersky, N. E. Zhukovsky, the works of the French scientist R. Hainault-Peltry, and the German scientist G. Oberth. An important contribution to the creation of the WRD was the work of the Soviet scientist B. S. Stechkin, “The Theory of an Air-Jet Engine,” published in 1929.

R.D. have various purposes and the scope of their application is constantly expanding.

Radar drives are most widely used on aircraft of various types.

Most military and civil aircraft around the world are equipped with turbojet engines and bypass turbojet engines, and they are used on helicopters. These radar 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, and supersonic interceptor fighters. Subsonic ramjet engines are used on helicopters (installed at the ends of the main rotor blades). Pulse jet engines have low thrust and are intended only for aircraft at subsonic speeds. During the 2nd World War 1939-45, these engines were equipped with V-1 projectile aircraft.

Taxiways are mostly used on high-speed aircraft.

Liquid rocket engines are used on launch vehicles of spacecraft and spacecraft as propulsion, 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 take-off. Electric rocket motors and nuclear rocket motors can be used on 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 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 powerful crowns. This division occurred because all “chemical” jet engines are divided into two classes depending on whether they use ambient air for their operation or not.

One of the newly formed trunks is the class of air-breathing engines (WRE). As the name itself indicates, they cannot operate outside the atmosphere. That's why these engines are the basis of modern aviation, both manned and unmanned. WRDs use atmospheric oxygen to burn fuel; without it, the combustion reaction in the engine will not proceed. But still, turbojet engines are currently most widely used.

(turbojet engines), 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 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 speed, 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 is used to compress air, and the design of the engine largely depends on the type of compressor. There are engines with axial and centrifugal compressors, axial compressors may have less or less thanks for using our system larger number compression stages, be one or two cascade, etc. To drive the compressor, the turbojet engine has a gas turbine, which gives the engine its name. Because of the compressor and turbine, the engine design is quite complex.

Non-compressor air-breathing engines are much simpler in design, in which the necessary increase in pressure is achieved by other methods, which have names: pulsating and ramjet engines.

In a pulsating engine, this is usually done by a valve grid 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 increases, and gases rush out through the jet nozzle, after which the whole process is repeated.

In a non-compressor engine of another type, direct-flow, there is not even this valve grid and the pressure in the combustion chamber increases 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 aircraft It's already flying at a fairly high speed; it won't develop any thrust while parked. But at a very high speed, 4-5 times the speed of sound, a ramjet engine develops very high thrust and consumes less fuel than any other “chemical” jet engine under these conditions. That's why ramjet engines.

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 begin stable operation of the ramjet engine. This makes the tail section 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 various types lies the principle of direct reaction, i.e. the principle of creating a driving force (or thrust) in the form of a reaction (recoil) of a stream of “working substance” flowing from the engine, usually hot gases.

In all engines there are 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. Such engines include piston engines of 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 type of fuel. This could be, for example, a mixture of air and kerosene, as in the turbojet engine of a modern jet aircraft, or a mixture of liquid oxygen and alcohol, as in some liquid rocket engines, or, finally, some kind of solid fuel for powder rockets. The flammable mixture can burn, i.e. enter into a chemical reaction with the rapid 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 of the mixture. The chemical energy of molecules is associated with the features of their structure, more precisely, the structure of their electronic shells, i.e. that 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 and others are created, a restructuring of the electron shells naturally occurs. In this restructuring there is a source of released chemical energy. It can be seen that jet engine fuels can only be those substances that, during a chemical reaction in the engine (combustion), release quite a lot of heat and also form a large amount of gases. All these processes occur in the combustion chamber, but let’s focus 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 was over. Now, instead of molecules of the combustible mixture, the chamber is filled with molecules of combustion products, more densely “packed”. Excess binding energy, which is the chemical energy of the combustion reaction that has taken place, is released. The 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 move randomly, chaotically at a significantly higher speed, and the temperature of the gases increased. This is how the potential chemical energy of the fuel was converted into 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 the hot combustion products.

After hot gases containing large thermal energy have been generated in a heat engine, this energy must be converted into mechanical energy. After all, engines serve to perform mechanical work, to “move” something, to put it into action, it doesn’t matter whether it’s a dynamo, please add drawings of a power plant, a diesel locomotive, a car or an airplane.

In order for the thermal energy of gases to transform into mechanical energy, their volume must increase. With such expansion, gases perform 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 then 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 an airplane propeller - the engine performs useful work. In a steam engine or gas turbine, the gases, expanding, force the wheel connected to the turbine shaft to rotate - here there is no need for a transmission crank mechanism, which is one of the great advantages of the turbine

Gases, of course, also expand in a jet engine, because without this they do not do work. But the expansion work in that case is not spent on shaft rotation. Associated with a 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 stream of gases - combustion products - flow out of the engine at high speed: the reaction force of this stream is the thrust of the engine. Consequently, the work of expansion of 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 movement of molecules must be replaced by their organized flow in one direction common to all.

One of the most important parts of the engine, the so-called jet nozzle, serves this purpose. No matter what type this or that jet engine belongs to, it is necessarily 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 others, turbojet engines, the gases first pass through a turbine, to which they give off part of their thermal energy. In this case, it is used to drive the compressor, which compresses 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 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 tapered section of pipe. If the outflow velocity should exceed the speed of sound, then the nozzle is shaped like an expanding pipe or first narrowing and then expanding (Lavl nozzle). Only in a pipe of this shape, as theory and experience show, is it possible to accelerate gas to supersonic speeds and step over the “sound barrier.”

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). The expanding gases rotate high-speed (3) and low-speed) turbines, which, in turn, drive the compressor (5), which pushes air into the combustion chamber, and fans (6), driving air through this chamber and directing it into 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 wonderful features, but the main one is this. A rocket does not need earth, water, or air to move, since 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 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 Russian scientist and inventor Konstantin Eduardovich Tsiolkovsky

References

Encyclopedic Dictionary of Young Technicians.

Thermal Phenomena in Technology.

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

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Creation ideas heat engine, which includes the jet engine, have been known to man since ancient times. Thus, in the treatise of Heron of Alexandria entitled “Pneumatics” there is a description of Aeolipile - the ball “Aeolus”. This design was nothing more than a steam turbine, in which steam was supplied through tubes into a bronze sphere and, escaping from it, spun this sphere. Most likely, the device was used for entertainment.

Ball “Aeolus” The Chinese advanced somewhat further, creating in the 13th century a kind of “rockets”. Initially used as fireworks, the new product was soon adopted and used for combat purposes. The great Leonardo did not ignore the idea either, intending to use hot air supplied to the blades to rotate a spit for frying. The idea of a gas turbine engine was first proposed in 1791 by the English inventor J. Barber: his gas turbine engine design was equipped with a gas generator, a piston compressor, a combustion chamber and a gas turbine. He used a heat engine and A.F. as a power plant for his aircraft, developed in 1878. Mozhaisky: two steam engines drove the propellers of the machine. Due to low efficiency, the desired effect could not be achieved. Another Russian engineer – P.D. Kuzminsky - in 1892, developed the idea of a gas turbine engine in which fuel burned at constant pressure. Having started the project in 1900, he decided to install a gas turbine engine with a multi-stage gas turbine on a small boat. However, the death of the designer prevented him from finishing what he started. They began to create a jet engine more intensively only in the 20th century: first theoretically, and a few years later – practically. In 1903, in the work “Exploration of World Spaces by Reactive Instruments” K.E. Tsiolkovsky were developed theoretical foundations liquid rocket engines (LPRE) with a description of the main elements of a jet engine using liquid fuel. The idea of creating an air-breathing engine (WRE) belongs to R. Lorin, who patented the project in 1908. When trying to create an engine, after the drawings of the device were made public in 1913, the inventor failed: the speed required for the operation of the jet engine could not be achieved. Attempts to create gas turbine engines continued further. So, in 1906, Russian engineer V.V. Karavodin developed and, two years later, built a compressor-free gas turbine engine with four intermittent combustion chambers and a gas turbine. However, the power developed by the device, even at 10,000 rpm, did not exceed 1.2 kW (1.6 hp). The intermittent combustion gas turbine engine was also created by the German designer H. Holwarth. Having built a gas turbine engine in 1908, by 1933, after many years of work to improve it, he had brought Engine efficiency up to 24%. However, the idea has not found widespread use.

V.P. Glushko The idea of a turbojet engine was voiced in 1909 by Russian engineer N.V. Gerasimov, who received a patent for a gas turbine engine for creating jet thrust. Work on the implementation of this idea did not stop in Russia and subsequently: in 1913 M.N. Nikolskoy designs a gas turbine engine with a power of 120 kW (160 hp) with a three-stage gas turbine; in 1923 V.I. Bazarov proposes a schematic diagram of a gas turbine engine, similar in design to modern turboprop engines; in 1930 V.V. Uvarov together with N.R. Briling designs and in 1936 implements a gas turbine engine with a centrifugal compressor. A huge contribution to the creation of the theory of the jet engine was made by the work of Russian scientists S.S. Nezhdanovsky, I.V. Meshchersky, N.E. Zhukovsky. French scientist R. Hainault-Peltry, German scientist G. Oberth. The creation of an air-breathing engine was also influenced by the work of the famous Soviet scientist B.S. Stechkin, who published his work “The Theory of an Air-Jet Engine” in 1929. Work on the creation of a liquid jet engine did not stop: in 1926, the American scientist R. Goddard launched a rocket using liquid fuel. Work on this topic also took place in the Soviet Union: from 1929 to 1933 V.P. Glushko developed and tested an electrothermal jet engine at the Gas Dynamics Laboratory. During this period, he also created the first domestic liquid jet engines - ORM, ORM-1, ORM-2. The greatest contribution to the practical implementation of the jet engine was made by German designers and scientists. Having support and funding from the state, which hoped to achieve technical superiority in this way the coming war, engineering corps of the III Reich with maximum efficiency and in short terms approached the creation of combat systems based on the ideas of jet propulsion. Concentrating attention on the aviation component, we can say that already on August 27, 1939, the Heinkel test pilot, flag-captain E. Varsitz, took into the air the He.178 - a jet aircraft, the technological developments of which were subsequently used in the creation of the Heinkel He.280 and Messerschmitt Me.262 Schwalbe. The Heinkel Strahltriebwerke HeS 3 engine installed on the Heinkel He.178, designed by H.-I. von Ohaina, although he did not have high power, managed to open the era of jet flights of military aircraft. The maximum speed of 700 km/h achieved by the He.178 using an engine whose power did not exceed 500 kgf spoke volumes. Limitless possibilities lay ahead, which deprived piston engines of a future. A whole series of jet engines created in Germany, for example, Jumo-004 produced by Junkers, allowed it to have serial jet fighters and bombers, ahead of other countries in this direction by several years. After the defeat of the Third Reich, it was German technology that gave impetus to the development of jet aircraft in many countries around the world. The only country that managed to answer the German challenge was Great Britain: the Rolls-Royce Derwent 8 turbojet engine created by F. Whittle was installed on the Gloster Meteor fighter.

Captured Jumo 004 The world's first turboprop engine was the Hungarian Jendrassik Cs-1 engine designed by D. Jendrasik, who built it in 1937 at the Ganz plant in Budapest. Despite the problems that arose during implementation, the engine was supposed to be installed on the Hungarian twin-engine attack aircraft Varga RMI-1 X/H, specially designed for this purpose by aircraft designer L. Vargo. However, the Hungarian specialists were unable to complete the work - the enterprise was redirected to the production of German Daimler-Benz DB 605 engines, selected for installation on the Hungarian Messerschmitt Me.210. Before the start of the war, work continued in the USSR on the creation of various types of jet engines. So, in 1939, rockets were tested, powered by ramjet engines designed by I.A. Merkulova. In the same year, work began at the Leningrad Kirov Plant on the construction of the first domestic turbojet engine designed by A.M. Cradles. However, the outbreak of war stopped experimental work on the engine, directing all production power to the needs of the front. The real era of jet engines began after the end of World War II, when in a short period of time not only the sound barrier, but also gravity was conquered, which made it possible to take humanity into outer space.