Electric rocket engine operating principle and design. Electric jet engine (EPE). Calculation of electricity costs for private clients
Many metals.
Continuing the conversation we started, we learn what is an electric jet engine, what are the principles of its operation and scope of application, and we will even get an answer to the question of whether a flight is possible in the near future...
First let's go back to impact explosions of metals. The most important condition for this process is the speed of the metal.
If the critical speed for uranium is 1,500 m/s, for iron it exceeds 4,000 m/s.
Therefore, from some meteorites falling to the ground at the same or even greater speed, not a trace remains. They turn into the thinnest...
This feature was noticed back in 1929 by the famous creator of our engines and rockets, Valentin Petrovich Glushko.
Photo 1. Academician Valentin Petrovich Glushko
He wrote an article under the very intriguing title “Metal as an Explosive.”
In its very first lines, the author said that we are not talking about using metal as an explosive, but that when a sufficiently strong pulse of electric current is passed through a metal wire, an explosion can occur.
The temperature rises to 300,000 degrees. The energy of such an explosion is many times greater than the energy of the explosion of the most powerful explosive taken in an amount equal to the mass of the wire.
In this case, the energy itself exceeds the energy of the current pulse that caused it.
Electric jet engine
The energy of such an explosion was used by V.P. Glushko in miniature electric jet engine (EPE), developed in the early 1930s.
The engine fit easily in the palm of your hand.
A metal wire was fed into it and electrical impulses were given, turning it into steam.
Photo 2. Electric jet engine (EPE), created by V.P. Glushko in 1929-1933.
This steam came out through a special nozzle at a speed of several tens of thousands of meters per second.
In order to reach a speed of 30 km/s in 4 months, the engine must consume power... 300 W.
Not so much, 3 times less power of the iron! But the iron has an outlet, and where can I get an outlet?
As a source of energy for a rocket equipped with an electric propulsion engine, V.P. Glushko proposed using photocells.
A rocket equipped with such engines cannot go into space on its own. To start, a different engine must be used.
But after entering outer space, a “solar” rocket equipped with an electric propulsion engine could, within a few days, reach a speed that is inaccessible to any other type of rocket.
A similar flight scheme to Mars is currently being considered in the Russian project for landing cosmonauts on the Red Planet.
A complex consisting of a set of electric propulsion engines, a working fluid storage and supply system (SHiP), an automatic control system (ACS), and a power supply system (SPS) is called electric propulsion system (EPS).
The idea of using electrical energy in jet engines for acceleration arose almost at the beginning of the development of rocket technology. It is known that such an idea was expressed by K. E. Tsiolkovsky. In -1917, R. Goddard conducted the first experiments, and in the 30s of the 20th century in the USSR, under the leadership of V.P. Glushko, one of the first operating electric propulsion engines was created.
From the very beginning, it was assumed that the separation of the energy source and the accelerated substance would provide a high speed of exhaust of the working fluid (PT), as well as a lower mass of the spacecraft (SC) due to a decrease in the mass of the stored working fluid. Indeed, in comparison with other rocket engines, electric propulsion engines make it possible to significantly increase the active lifetime (AS) of a spacecraft, while significantly reducing the mass of the propulsion system (PS), which, accordingly, makes it possible to increase the payload or improve the weight-dimensional characteristics of the spacecraft itself.
Calculations show that the use of electric propulsion will reduce the duration of flights to distant planets (in some cases even make such flights possible) or, with the same flight duration, increase the payload.
Classification of electric rocket engines accepted in Russian-language literature
ETDs, in turn, are divided into electric heating (END) and electric arc (EDA) engines.
Electrostatic engines are divided into ion (including colloidal) engines (ID, CD) - particle accelerators in a unipolar beam, and particle accelerators in a quasineutral plasma. The latter include accelerators with closed electron drift and an extended (UZDP) or shortened (UZDU) acceleration zone. The first ones are usually called stationary plasma engines (SPD), and the name also appears (increasingly less often) - linear Hall engine (LHD), in Western literature it is called a Hall engine. Ultrasonic motors are usually called anode-accelerated motors (LAMs).
These include motors with their own magnetic field and motors with an external magnetic field (for example, an end-mounted Hall motor - THD).
Pulse engines use the kinetic energy of gases produced by the evaporation of a solid in an electrical discharge.
Any liquids and gases, as well as their mixtures, can be used as a working fluid in electric propulsion engines. However, for each type of engine there are working fluids, the use of which allows you to achieve the best results. Ammonia is traditionally used for ETD, xenon for electrostatic, lithium for high-current, and fluoroplastic for pulsed.
The disadvantage of xenon is its cost, due to its small annual production (less than 10 tons per year worldwide), which forces researchers to look for other RTs with similar characteristics, but less expensive. Argon is being considered as the main candidate for replacement. It is also an inert gas, but, unlike xenon, it has higher ionization energy with a lower atomic mass. The energy spent on ionization per unit of accelerated mass is one of the sources of efficiency losses.
Electric propulsion engines are characterized by a low RT mass flow rate and a high outflow velocity of an accelerated particle flow. The lower limit of the exhaust velocity approximately coincides with the upper limit of the exhaust velocity of a chemical engine jet and is about 3,000 m/s. The upper limit is theoretically unlimited (within the speed of light), however, for promising engine models, a speed not exceeding 200,000 m/s is considered. Currently, for engines of various types, the optimal exhaust velocity is considered to be from 16,000 to 60,000 m/s.
Due to the fact that the acceleration process in an electric propulsion engine takes place at low pressure in the accelerating channel (particle concentration does not exceed 10 20 particles/m³), the thrust density is quite low, which limits the use of electric propulsion engines: the external pressure should not exceed the pressure in the accelerating channel, and the acceleration of the spacecraft is very small (tenths or even hundredths g ). An exception to this rule may be EDD on small spacecraft.
The electrical power of electric propulsion engines ranges from hundreds of watts to megawatts. Electric propulsion engines currently used on spacecraft have a power from 800 to 2,000 W.
Electric jet engine in the Polytechnic Museum, Moscow. Created in 1971 at the Institute of Atomic Energy named after. I. V. Kurchatova
In 1964, in the attitude control system of the Soviet Zond-2 spacecraft, 6 erosive pulse thrusters operating on fluoroplastic operated for 70 minutes; the resulting plasma clots had a temperature of ~ 30,000 K and flowed out at a speed of up to 16 km/s (the capacitor bank had a capacity of 100 μ, the operating voltage was ~ 1 kV). In the USA, similar tests were carried out in 1968 on the LES-6 spacecraft. In 1961, a pinch pulse taxiway of the American company Republic Aviation developed a thrust of 45 mN on the stand at an exhaust speed of 10-70 km/s.
On October 1, 1966, the Yantar-1 automatic ionospheric laboratory was launched to an altitude of 400 km by a three-stage geophysical rocket 1YA2TA to study the interaction of the jet stream of an electric rocket engine (ERE), running on argon, with ionospheric plasma. The experimental plasma-ion electric propulsion engine was first turned on at an altitude of 160 km, and during the subsequent flight 11 cycles of its operation were carried out. A jet stream velocity of about 40 km/s was achieved. The Yantar laboratory reached a specified flight altitude of 400 km, the flight lasted 10 minutes, the electric propulsion engine operated steadily and developed a design thrust of five grams of force. The scientific community learned about the achievement of Soviet science from a TASS report.
In the second series of experiments, nitrogen was used. The exhaust speed was increased to 120 km/s. In 1971, four similar devices were launched (according to other sources, before 1970 there were six devices).
In the fall of 1970, a ramjet electric propulsion system successfully passed tests in real flight. In October 1970, at the XXI Congress of the International Astronomical Federation, Soviet scientists - Professor G. Grodzovsky, Candidates of Technical Sciences Yu. Danilov and N. Kravtsov, Candidates of Physical and Mathematical Sciences M. Marov and V. Nikitin, Doctor of Technical Sciences V. Utkin - reported on testing of an air propulsion system. The recorded jet speed reached 140 km/s.
In 1971, the correction system of the Soviet meteorological satellite “Meteor” operated two stationary plasma engines developed by the Fakel Design Bureau, each of which, with a power supply of ~ 0.4 kW, developed a thrust of 18-23 mN and an exhaust velocity of over 8 km/s. The RDs had a size of 108×114×190 mm, a mass of 32.5 kg and a reserve of Xenon (compressed xenon) of 2.4 kg. During one of the starts, one of the engines worked continuously for 140 hours. This electric propulsion system is shown in the figure.
Electric rocket engines are also used in the Dawn mission. Planned use in the BepiColombo project.
Although electric rocket engines have low thrust compared to liquid-fuel rockets, they are capable of operating for long periods of time and capable of slow flight over long distances.
This broad class of engines combines various types of engines that are currently being developed very intensively. The working fluid is accelerated to a certain exhaust velocity using electrical energy. The energy is obtained from a nuclear or solar power plant located on board the spacecraft (in principle, even from a chemical battery). Numerous types of onboard propulsion systems are conceivable.
The designs of the electric motors being developed are extremely diverse. We will look at three main groups of electric motors, differing in the way in which the working fluid is ejected from the rocket. (However, other ways of classifying electric motors are possible
Electrothermal engines. These engines, like all those we have considered so far, are thermal engines. The working fluid (hydrogen) heated to a high temperature turns into plasma - an electrically neutral mixture
positive ions and electrons. Electrical heating methods can be different: heating in an electric arc (Fig. 10), using tungsten heating elements, through an electric discharge and others
Rice. 10. Electric arc motor diagram
During laboratory tests of electric arc engines, an exhaust velocity of the order of magnitude was achieved. If it is possible to magnetically isolate the plasma from the walls of the thrust chamber, the plasma temperature can be very high and the exhaust velocity is brought to Reactive accelerations in electrothermal engines will be of the order of .
The world's first electrothermal engine was developed in 1929-1933. in the Soviet Union under the leadership of V.P. Glushko in the famous Gas Dynamics Laboratory.
Electrostatic (ion) engines. In these engines, for the first time we are faced with “cold” acceleration of the working fluid. Particles of the working fluid (pairs of easily ionized metals, such as rubidium or cesium) lose their electrons in the ionizer and are accelerated to high speed in an electric field. So that the electric charge of the jet of charged particles behind the apparatus does not interfere with further outflow, this jet is neutralized outside it by the ejection of electrons taken from the atoms (Fig. 11).
Rice. 11. Schematic diagram of the engine
There are no temperature restrictions in an ion engine. Therefore, in principle, it is possible to achieve arbitrarily high exhaust velocities, up to those approaching the speed of light. However, too high exhaust velocities must be excluded from consideration, since they would require enormous power from the power plant on board the ship.
Rice. 12. Scheme of the formation of moving plasmoids in a “pulse” plasma engine 11.18].
In this case, the mass of the propulsion system would increase much more than the thrust, and as a result, the reactive acceleration would be greatly reduced. The purpose of the space flight, its duration, and the quality of the power plant determine the best, optimal exhaust velocity for a given task. It is, according to some authors, within the limits, and according to others, , . Ion engines will be capable of delivering jet acceleration of the order of .
Some experts place great hopes on a special type of electrostatic motor - colloidal motor. These engines accelerate large charged molecules and even groups of molecules or dust particles with a diameter of about 1 micron.
Rice. 13. Diagram of a magnetohydrodynamic engine with crossed fields.
Magnetohydrodynamic (electrodynamic, electromagnetic, magnet-plasma, “plasma”) engines. This group of engines combines a huge variety of schemes in which the plasma is accelerated to a certain outflow velocity by changing the magnetic field or by the interaction of electric and magnetic fields. Specific methods for accelerating plasma, as well as obtaining it, are very different. In a plasma engine (Fig. 12), a plasma clot (“plasmoid”) is accelerated by magnetic pressure. In the “engine with crossed electric and magnetic fields” (Fig. 13) through plasma,
placed in a magnetic field, an electric current is passed (plasma is a good conductor), and as a result, the plasma acquires speed (like a wire frame with current placed in a magnetic field). The optimal exhaust velocity for magnetohydrodynamic engines is likely to be on the order of jet acceleration
In laboratory tests of magnetohydrodynamic engines, exhaust velocities of up to .
It should be noted that in many cases it is difficult to classify an engine into one class or another.
Electric motors with intake of working fluid from the upper atmosphere. An aircraft moving in the upper atmosphere can use the rarefied external environment as a working fluid for an electric motor. Such an electric motor is similar to an air-breathing engine in the class of chemical engines. The gas entering through the air intake can be used as a working fluid either directly or after accumulation (and possibly liquefaction) in tanks. It is also possible that the working fluid will be accumulated in the tanks of one aircraft and then pumped into the tanks of another aircraft.
An important advantage of all types of electric motors is the ease of traction adjustment. A serious difficulty is the need to get rid of excess heat generated by a nuclear reactor. This excess is not carried away by the working fluid and is not given to the environment, which is practically absent in the world space. You can get rid of it only with the help of radiators with a large surface.
In 1964, the United States conducted the first successful test for 31 minutes of an ion engine mounted on a container launched on a ballistic trajectory. In real space conditions, ion and plasma engines were first tested on the Soviet ship Voskhod-1 and the Soviet station Zond-2, launched in 1964 (“Zond-2” - towards Mars); Along with conventional ones, they were used in orientation systems. In April 1965, a liquid cesium ion engine was tested together with the Snap-10A nuclear reactor on the American Earth satellite, developing thrust (instead of Cesium ion engines with calculated adjustable thrust and electrothermal engines using liquid ammonia as a working fluid and developing thrust were previously tested with varying success on a series of satellites launched in the United States since 1966.
Electric rocket motor (ERD)
The limited use of electric propulsion engines is associated with the need for high power consumption (10-100 kW by 1 n traction). Due to the presence of an on-board power plant (and other auxiliary systems), as well as due to the low thrust density, a device with an electric propulsion engine has low acceleration. Therefore, electric propulsion engines can only be used in spacecraft flying either in conditions of weak gravitational fields or in near-planetary orbits. They are used for orientation, correction of spacecraft orbits and other operations that do not require large amounts of energy. Electrostatic, plasma Hall and other electric propulsion systems are considered promising as the main engines of spacecraft. Due to the small ejected mass of the RT, the continuous operation time of such electric propulsion engines will be measured in months and years; their use instead of existing chemical taxiways will increase the payload mass of the spacecraft. The idea of using electrical energy to generate thrust was put forward by K. E. Tsiolkovsky and other pioneers of astronautics. In 1916-17, R. Goddard (USA) confirmed the reality of this idea with experiments. In 1929-33, V. P. Glushko (USSR) created an experimental electric propulsion engine. In 1964 in the USSR, plasma pulsed thrusters were tested on the Zond-type spacecraft, in 1966-71 on the Yantar spacecraft - ion thrusters, in 1972 on the Meteor spacecraft - plasma quasi-stationary thrusters. Various types of electric propulsion systems have been tested since 1964 in the USA: in ballistic flight, and then in space flight (on ATS, CERT-2, etc.). Work in this area is also being carried out in Great Britain, France, Germany, and Japan. Lit.: Corliss W.R., Rocket engines for space flights, trans. from English, M., 1962; Stuhlinger E., Ion engines for space flights, trans. from English. M., 1966; Gilzin K. A., Electric interplanetary ships, 2nd ed., M., 1970; Gurov A.F., Sevruk D.D., Surnov D.N., Design and strength calculation of space electric rocket engines, M., 1970; Favorsky O. N., Fishgoit V, V., Yantovsky E. I., Fundamentals of the theory of space electric propulsion systems, M., 1970; Grishin S. D., Leskov L. V., Kozlov N. P., Electric rocket engines, M., 1975. Yu. M. Trushin.
Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .
See what “Electric rocket engine” is in other dictionaries:
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Electric rocket motor
An electric rocket engine is a rocket engine whose operating principle is based on the use of electrical energy received from a power plant on board the spacecraft to create thrust. The main area of application is minor trajectory correction, as well as space orientation of spacecraft. A complex consisting of an electric rocket engine, a working fluid supply and storage system, an automatic control system and a power supply system is called an electric rocket propulsion system.
Mention of the possibility of using electric energy in rocket engines to create thrust is found in the works of K. E. Tsiolkovsky. In 1916-1917 The first experiments were carried out by R. Goddard, and already in the 30s. XX century under the leadership of V.P. Glushko, one of the first electric rocket engines was created.
In comparison with other rocket engines, electric ones make it possible to increase the lifespan of a spacecraft, and at the same time the weight of the propulsion system is significantly reduced, which makes it possible to increase the payload and obtain the most complete weight and size characteristics. Using electric rocket engines, it is possible to shorten the duration of flights to distant planets, and also make flights to any planet possible.
In the mid-60s. XX century Electric rocket engines were actively tested in the USSR and the USA, and already in the 1970s. they were used as standard propulsion systems.
In Russia, classification is based on the mechanism of particle acceleration. The following types of engines can be distinguished: electrothermal (electric heating, electric arc), electrostatic (ionic, including colloidal, stationary plasma engines with acceleration in the anode layer), high-current (electromagnetic, magnetodynamic) and pulse engines.
Any liquids and gases, as well as their mixtures, can be used as a working fluid. For each type of electric motor, it is necessary to use the appropriate working fluids to achieve the best results. Ammonia is traditionally used for electrothermal motors, xenon is used for electrostatic motors, lithium is used for high-current motors, and fluoroplastic is the most effective working fluid for pulse motors.
One of the main sources of losses is the energy spent on ionization per unit of accelerated mass. The advantage of electric rocket engines is the low mass flow of the working fluid, as well as the high speed of the accelerated flow of particles. The upper limit of the outflow velocity is theoretically within the speed of light.
Currently, for various types of engines, the exhaust velocity ranges from 16 to 60 km/s, although promising models will be able to give an exhaust velocity of the particle flow of up to 200 km/s.
The disadvantage is the very low thrust density; it should also be noted that the external pressure should not exceed the pressure in the acceleration channel. The electrical power of modern electric rocket engines used on spacecraft ranges from 800 to 2000 W, although theoretical power can reach megawatts. The efficiency of electric rocket engines is low and varies from 30 to 60%.
In the next decade, this type of engine will mainly perform tasks for correcting the orbit of spacecraft located in both geostationary and low-Earth orbits, as well as for delivering spacecraft from the reference low-Earth orbit to higher ones, such as geostationary orbit.
Replacing a liquid rocket engine, which serves as an orbit corrector, with an electric one will reduce the mass of a typical satellite by 15%, and if the period of its active stay in orbit is increased, then by 40%.
One of the most promising areas for the development of electric rocket engines is their improvement in the direction of increasing power to hundreds of megawatts and specific thrust impulse, and it is also necessary to achieve stable and reliable operation of the engine using cheaper substances, such as argon, lithium, nitrogen.
From the book Great Soviet Encyclopedia (AN) by the author TSB From the book Great Soviet Encyclopedia (DV) by the author TSB From the book Great Soviet Encyclopedia (RA) by the author TSB From the book Great Soviet Encyclopedia (SB) by the author TSB From the book Great Soviet Encyclopedia (SU) by the author TSB From the book Great Soviet Encyclopedia (EL) by the author TSB From the book Great Encyclopedia of Technology author Team of authors From the author's book From the author's bookAviation rocket engine An aviation rocket engine is a direct reaction engine that converts some type of primary energy into the kinetic energy of the working fluid and creates jet thrust. The thrust force is applied directly to the rocket body
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