The exploration of outer space is involuntarily associated with spaceships. The heart of any launch vehicle is its engine. It must develop the first cosmic velocity - about 7.9 km / s in order to deliver the astronauts into orbit, and the second cosmic velocity in order to overcome the planet's gravitational field.
This is not easy to achieve, but scientists are constantly looking for new ways to solve this problem. Designers from Russia stepped even further and managed to develop a detonation rocket engine, whose trials were successful. This achievement can be called a real breakthrough in the field of space engineering.
New opportunities
Why are there high hopes for detonation engines? According to scientists, their power will be 10 thousand times greater than the power of existing rocket engines. At the same time, they will consume much less fuel, and their production is characterized by low cost and profitability. What is it connected with?
It's all about the oxidation of fuel. If modern rockets use the deflagration process - slow (subsonic) combustion of fuel at constant pressure, then the detonation rocket engine functions due to an explosion, detonation combustible mixture. It burns at supersonic speed with the release of a huge amount of thermal energy simultaneously with the propagation of the shock wave.
The development and testing of the Russian version of the detonation engine was carried out by the specialized laboratory "Detonation LRE" as part of the Energomash production complex.
Superiority of new engines
The world's leading scientists have been studying and developing detonation engines for 70 years. The main reason preventing the creation of this type of engine is the uncontrolled spontaneous combustion of fuel. In addition, the tasks of efficient mixing of fuel and oxidizer, as well as the integration of the nozzle and air intake, were on the agenda.
Having solved these problems, it will be possible to create a detonation rocket engine, which, in its own way, technical specifications overtakes time. At the same time, scientists call its following advantages:
- The ability to develop speeds in the subsonic and hypersonic ranges.
- Exception from the design of many moving parts.
- Lower weight and cost power plant.
- High thermodynamic efficiency.
Serially given type the engine was not produced. It was first tested on low-flying aircraft in 2008. The detonation engine for launch vehicles was tested for the first time by Russian scientists. That is why this event is of such great importance.
Working principle: pulse and continuous
Currently, scientists are developing installations with a pulsed and continuous workflow. The principle of operation of a detonation rocket engine with impulse circuit The work is based on the cyclic filling of the combustion chamber with a combustible mixture, its sequential ignition and the release of combustion products into the environment.
Accordingly, in a continuous operating process, fuel is continuously supplied to the combustion chamber, the fuel burns in one or more detonation waves that continuously circulate across the flow. The advantages of such engines are:
- Single ignition of fuel.
- Relatively simple design.
- Small dimensions and mass of installations.
- More efficient use of the combustible mixture.
- Low level of produced noise, vibration and harmful emissions.
In the future, using these advantages, a detonation liquid-propellant rocket engine of a continuous operation scheme will replace all existing installations due to its weight, size and cost characteristics.
Detonation engine tests
The first tests of the domestic detonation plant were carried out as part of a project established by the Ministry of Education and Science. presented as a prototype small engine with a combustion chamber with a diameter of 100 mm and an annular channel width of 5 mm. The tests were carried out on a special stand, indicators were recorded when working on various types combustible mixture - hydrogen-oxygen, natural gas-oxygen, propane-butane-oxygen.
Tests of an oxygen-hydrogen detonation rocket engine proved that the thermodynamic cycle of these units is 7% more efficient than that of other units. In addition, it was experimentally confirmed that with an increase in the amount of fuel supplied, the thrust increases, as well as the number of detonation waves and the rotational speed.
Analogues in other countries
The development of detonation engines is carried out by scientists from leading countries of the world. Designers from the USA have achieved the greatest success in this direction. In their models, they implemented a continuous mode of operation, or rotational. The US military plans to use these installations to equip surface ships. Due to their lighter weight and small size with high output power, they will help increase the effectiveness of combat boats.
A stoichiometric mixture of hydrogen and oxygen is used for its work by an American detonation rocket engine. The advantages of such an energy source are primarily economic - oxygen burns exactly as much as is required to oxidize hydrogen. Now the US government is spending several billion dollars to provide warships with carbon fuel. Stoichiometric fuel will reduce costs by several times.
Further directions of development and prospects
New data obtained as a result of testing detonation engines determined the use of fundamentally new methods for constructing a scheme for operating on liquid fuel. But for functioning, such engines must have high heat resistance due to the large amount of thermal energy released. At the moment, a special coating is being developed that will ensure the operability of the combustion chamber under high-temperature exposure.
A special place in further research is occupied by the creation of mixing heads, with the help of which it will be possible to obtain drops of combustible material of a given size, concentration and composition. To address these issues, a new detonation liquid-propellant rocket engine will be created, which will become the basis of a new class of launch vehicles.
At the end of January, there were reports of new successes in Russian science and technology. It became known from official sources that one of the domestic projects of a promising detonation-type jet engine has already passed the testing stage. This brings the moment of complete completion of all the required work, as a result of which Russian-made space or military rockets will be able to receive new power plants with improved performance. Moreover, the new principles of engine operation can be applied not only in the field of rockets, but also in other areas.
In the last days of January, Deputy Prime Minister Dmitry Rogozin told the domestic press about the latest successes of research organizations. Among other topics, he touched on the process of creating jet engines using new operating principles. A promising engine with detonation combustion has already been brought to the test. According to the Deputy Prime Minister, the use of new principles of operation of the power plant makes it possible to obtain a significant increase in performance. In comparison with the designs of traditional architecture, there is an increase in thrust of about 30%.
Diagram of a detonation rocket engine
Modern rocket engines different classes and types operated in various areas use the so-called. isobaric cycle or deflagration combustion. In their combustion chambers, a constant pressure is maintained, at which the fuel burns slowly. An engine based on deflagration principles does not need particularly strong units, but is limited in maximum performance. Increasing the main characteristics, starting from a certain level, turns out to be unreasonably difficult.
An alternative to an isobaric cycle engine in the context of performance enhancement is a system with a so-called. detonation combustion. In this case, the fuel oxidation reaction occurs behind the shock wave, with high speed moving through the combustion chamber. This places special demands on the design of the engine, but at the same time offers obvious advantages. In terms of fuel combustion efficiency, detonation combustion is 25% better than deflagration combustion. It also differs from combustion with constant pressure by an increased heat release rate per unit surface area of the reaction front. In theory, it is possible to increase this parameter by three to four orders of magnitude. Consequently, the speed of reactive gases can be increased by 20-25 times.
Thus, the detonation engine, differing increased coefficient useful action, capable of developing greater traction with less fuel consumption. Its advantages over traditional designs are obvious, but until recently, progress in this area left much to be desired. The principles of a detonation jet engine were formulated as early as 1940 by the Soviet physicist Ya.B. Zeldovich, but finished products of this kind have not yet reached operation. The main reasons for the lack of real success are problems with creating a sufficiently strong structure, as well as the difficulty of launching and subsequently maintaining a shock wave using existing fuels.
One of the latest domestic projects in the field of detonation rocket engines was launched in 2014 and is being developed at NPO Energomash named after V.I. Academician V.P. Glushko. According to the available data, the purpose of the project with the Ifrit cipher was to study the basic principles new technology with the subsequent creation of a liquid rocket engine using kerosene and gaseous oxygen. The new engine, named after the fire demons from Arab folklore, was based on the principle of spin detonation combustion. Thus, in accordance with the main idea of the project, the shock wave must continuously move in a circle inside the combustion chamber.
The lead developer of the new project was NPO Energomash, or rather, a special laboratory created on its basis. In addition, several other research and design organizations were involved in the work. The program received support from the Advanced Research Foundation. By joint efforts, all participants in the Ifrit project were able to form the optimal look of a promising engine, as well as create a model combustion chamber with new operating principles.
To study the prospects of the whole direction and new ideas, a so-called. a model detonation combustion chamber that meets the requirements of the project. Such an experimental engine with a reduced configuration was supposed to use liquid kerosene as a fuel. Gaseous hydrogen was proposed as the oxidizing agent. In August 2016, testing of the experimental chamber began. Important, that for the first time in history, a project of this kind was brought to the stage of bench tests. Previously, domestic and foreign detonation rocket engines were developed, but not tested.
During the tests of the model sample, it was possible to obtain very interesting results showing the correctness of the approaches used. So, by using the right materials and technologies turned out to bring the pressure inside the combustion chamber to 40 atmospheres. The thrust of the experimental product reached 2 tons.
Model camera on the test bench
Within the framework of the Ifrit project, certain results were obtained, but the domestic liquid-fuel detonation engine is still far from full-fledged practical application. Before introducing such equipment into new technology projects, designers and scientists will have to decide whole line the most serious tasks. Only after that, the rocket and space industry or the defense industry will be able to start realizing the potential of new technology in practice.
In the middle of January Russian newspaper”published an interview with the chief designer of NPO Energomash, Petr Levochkin, the topic of which was the current state of affairs and the prospects for detonation engines. The representative of the enterprise-developer recalled the main provisions of the project, and also touched upon the topic of the successes achieved. In addition, he spoke about the possible areas of application of Ifrit and similar structures.
Eg, detonation engines can be used in hypersonic aircraft. P. Levochkin recalled that the engines now proposed for use in such equipment use subsonic combustion. At the hypersonic speed of the flight apparatus, the air entering the engine must be slowed down to sound mode. However, the braking energy must lead to additional thermal loads on the airframe. In detonation engines, the fuel burning rate reaches at least M=2.5. This makes it possible to increase the flight speed of the aircraft. Such a machine with a knock-type engine would be able to accelerate to speeds eight times the speed of sound.
However, the real prospects for detonation-type rocket engines are not too great yet. According to P. Levochkin, we "have just opened the door to the area of detonation combustion." Scientists and designers will have to study many issues, and only after that it will be possible to create structures with practical potential. Because of this, the space industry will have to use traditional liquid-propellant engines for a long time, which, however, does not negate the possibility of their further improvement.
An interesting fact is that detonation principle combustion finds application not only in the field of rocket engines. Already exists domestic project aviation system with a detonation-type combustion chamber operating on the impulse principle. A prototype of this kind was brought to the test, and in the future it may give rise to a new direction. New engines with detonation combustion can find application in the most different areas and partially replace gas turbine or turbojet engines of traditional designs.
The domestic project of a detonation aircraft engine is being developed at the OKB. A.M. Cradles. Information about this project was first presented at last year's international military-technical forum "Army-2017". At the stand of the enterprise-developer there were materials on various engines, both serial and under development. Among the latter was a promising detonation sample.
The essence of the new proposal is the use of a non-standard combustion chamber capable of carrying out pulsed detonation combustion of fuel in an air atmosphere. In this case, the frequency of "explosions" inside the engine should reach 15-20 kHz. In the future, an additional increase in this parameter is possible, as a result of which the engine noise will go beyond the range perceived by the human ear. Such features of the engine may be of particular interest.
The first launch of the Ifrit prototype
However, the main advantages of the new power plant are associated with improved performance. Bench tests of experimental products showed that they are about 30% superior to traditional gas turbine engines in terms of specific performance. By the time of the first public demonstration of materials on the OKB engine. A.M. Cradles could get and quite high performance characteristics. An experimental engine of a new type was able to work for 10 minutes without interruption. The total operating time of this product at the stand at that time exceeded 100 hours.
Representatives of the developer indicated that it is already possible to create a new detonation engine with a thrust of 2-2.5 tons, suitable for installation on light aircraft or unmanned aerial vehicles. In the design of such an engine, it is proposed to use the so-called. resonators responsible for right move fuel combustion. An important advantage new project is the fundamental possibility of installing such devices anywhere in the airframe.
Specialists of OKB im. A.M. The cradles are working on aircraft engines with pulsed detonation combustion for more than three decades, but so far the project has not left the research stage and has no real prospects. main reason– lack of order and necessary financing. If the project receives the necessary support, then in the foreseeable future a sample engine suitable for use on various vehicles can be created.
To date, Russian scientists and designers have managed to show very remarkable results in the field of jet engines using new operating principles. There are several projects at once suitable for use in the rocket-space and hypersonic fields. In addition, new engines can be used in "traditional" aviation. Some projects are still in their early stages and not yet ready for inspections and other work, while in other areas the most remarkable results have already been obtained.
Exploring the subject of jet engines with detonation combustion, Russian specialists were able to create a bench model of a combustion chamber with the desired characteristics. The Ifrit prototype has already been tested, during which a large amount of various information was collected. With the help of the received data, the development of the direction will continue.
Mastering a new direction and translating ideas into a practically applicable form will take a lot of time, and for this reason, in the foreseeable future, space and army rockets in the foreseeable future will be equipped only with traditional liquid engines. Nevertheless, the work has already left the purely theoretical stage, and now each test run of an experimental engine brings closer the moment of building full-fledged missiles with new power plants.
According to the websites:
http://engine.space/
http://fpi.gov.ru/
https://rg.ru/
https://utro.ru/
http://tass.ru/
http://svpressa.ru/
Ecology of consumption. Science and technology: At the end of August 2016, the world news agencies spread the news: at one of the stands of NPO Energomash in Khimki near Moscow, the world's first full-size liquid-propellant rocket engine (LRE) using detonation combustion of fuel was launched.
At the end of August 2016, the news spread around the world news agencies: at one of the stands of NPO Energomash in Khimki near Moscow, the world's first full-size liquid-propellant rocket engine (LRE) using detonation combustion of fuel was launched. Domestic science and technology has been going to this event for 70 years.
The idea of a detonation engine was proposed by the Soviet physicist Ya. B. Zeldovich in the article “On the Energy Use of Detonation Combustion”, published in the Journal of Technical Physics back in 1940. Since then, research and experiments have been carried out around the world on the practical implementation of advanced technology. In this race of minds, Germany, then the USA, then the USSR pulled ahead. And now Russia secured an important priority in the world history of technology. IN last years something like our country can not boast often.
On the crest of a wave
What are the advantages of a detonation engine? In traditional rocket engines, as, indeed, in conventional piston or turbojet aircraft engines uses the energy that is released when the fuel is burned. In this case, a stationary flame front is formed in the LRE combustion chamber, combustion in which occurs at a constant pressure. This process of normal combustion is called deflagration. As a result of the interaction of the fuel and the oxidizer, the temperature of the gas mixture rises sharply and a fiery column of combustion products escapes from the nozzle, which form the jet thrust.
Detonation is also combustion, but it occurs 100 times faster than with conventional fuel combustion. This process is so fast that detonation is often confused with an explosion, especially since so much energy is released in this case that, for example, car motor when this phenomenon occurs in its cylinders, it can actually collapse. However, detonation is not an explosion, but a type of burning so rapid that the reaction products do not even have time to expand, so this process, unlike deflagration, takes place at a constant volume and a sharply increasing pressure.
In practice, it looks like this: instead of a stationary flame front in the fuel mixture inside the combustion chamber, a detonation wave is formed, which moves at supersonic speed. In this compression wave, the detonation of the mixture of fuel and oxidizer occurs, and from a thermodynamic point of view, this process is much more efficient than conventional fuel combustion. The efficiency of detonation combustion is 25–30% higher, i.e., when the same amount of fuel is burned, more thrust is obtained, and due to the compactness of the combustion zone, the detonation engine in terms of power removed per unit volume theoretically exceeds conventional rocket engines by an order of magnitude.
This alone was enough to draw the closest attention of specialists to this idea. After all, the stagnation that has now arisen in the development of world cosmonautics, which has been stuck in near-Earth orbit for half a century, is primarily associated with the crisis of rocket engine building. By the way, aviation is also in crisis, unable to cross the threshold of three speeds of sound. This crisis can be compared to the situation in piston aviation in the late 1930s. Screw and motor internal combustion have exhausted their potential, and only the advent of jet engines made it possible to reach a qualitatively new level altitude, speed and range.
The designs of classical rocket engines over the past decades have been licked to perfection and have practically come to the limit of their capabilities. It is possible to increase their specific characteristics in the future only within very small limits - by a few percent. Therefore, world cosmonautics is forced to follow an extensive path of development: for manned flights to the Moon, giant launch vehicles have to be built, and this is very difficult and insanely expensive, at least for Russia. An attempt to overcome the crisis with the help of nuclear engines stumbled upon environmental problems. It may be too early to compare the appearance of detonation rocket engines with the transition of aviation to jet propulsion, but they are quite capable of accelerating the process of space exploration. Moreover, this type of jet engines has another very important advantage.
GRES in miniature
An ordinary LRE is, in principle, a large burner. To increase its thrust and specific characteristics, it is necessary to raise the pressure in the combustion chamber. In this case, the fuel that is injected into the chamber through the nozzles must be supplied at a higher pressure than is realized during the combustion process, otherwise the fuel jet simply cannot penetrate into the chamber. Therefore, the most difficult and expensive unit in the LRE is not a chamber with a nozzle, which is in plain sight, but a fuel turbopump unit (TNA), hidden in the depths of the rocket among the intricacies of pipelines.
For example, the most powerful RD-170 liquid-propellant rocket engine in the world, created for the first stage of the Soviet super-heavy launch vehicle Energia by the same NPO Energia, has a pressure in the combustion chamber of 250 atmospheres. This is a lot. But the pressure at the outlet of the oxygen pump pumping the oxidizer into the combustion chamber reaches 600 atm. This pump is powered by a 189 MW turbine! Just imagine this: a turbine wheel with a diameter of 0.4 m develops four times more power than the nuclear icebreaker Arktika with two nuclear reactors! At the same time, TNA is a complex mechanical device, the shaft of which makes 230 revolutions per second, and it has to work in an environment of liquid oxygen, where the slightest not even a spark, but a grain of sand in the pipeline leads to an explosion. The technology for creating such a TNA is the main know-how of Energomash, the possession of which allows the Russian company to sell its engines for installation on American Atlas V and Antares launch vehicles today. Alternatives Russian engines not yet in the US.
For a detonation engine, such difficulties are not needed, since detonation itself provides pressure for more efficient combustion, which is a compression wave running in the fuel mixture. During detonation, the pressure increases by 18–20 times without any TNA.
In order to obtain conditions in the combustion chamber of a detonation engine equivalent, for example, to the conditions in the combustion chamber of an LRE of the American Shuttle (200 atm), it is enough to supply fuel at a pressure of ... 10 atm. The unit required for this, in comparison with the TNA of a classic rocket engine, is like a bicycle pump near the Sayano-Shushenskaya State District Power Plant.
That is, a detonation engine will not only be more powerful and more economical than a conventional rocket engine, but also an order of magnitude simpler and cheaper. So why was this simplicity not given to designers for 70 years?
The main problem that confronted the engineers was how to cope with the detonation wave. The point is not only to make the engine stronger so that it can withstand increased loads. Detonation is not just a blast wave, but something more subtle. The blast wave propagates at the speed of sound, and the detonation wave propagates at supersonic speed - up to 2500 m/s. It does not form a stable flame front, so the operation of such an engine is pulsating: after each detonation, it is necessary to renew the fuel mixture, and then start a new wave in it.
Attempts to create a pulsating jet engine were made long before the idea of \u200b\u200bdetonation. It was in the use of pulsating jet engines that they tried to find an alternative piston engines in the 1930s. Simplicity again attracted: in contrast to aviation turbine for a pulse jet engine (PUJE) neither a compressor rotating at a speed of 40,000 revolutions per minute was needed to force air into the insatiable belly of the combustion chamber, nor a turbine operating at a gas temperature of over 1000 ° C. In the PuVRD, the pressure in the combustion chamber created pulsations in the combustion of the fuel.
The first patents for a pulsating jet engine were obtained independently in 1865 by Charles de Louvrier (France) and in 1867 by Nikolai Afanasyevich Teleshov (Russia). The first workable design of the PuVRD was patented in 1906 by the Russian engineer V.V. Karavodin, who built a model plant a year later. Due to a number of shortcomings, the Karavodin installation has not found application in practice. The first PUVRD to operate on a real aircraft was the German Argus As 014, based on a 1931 patent by the Munich inventor Paul Schmidt. Argus was created for the "weapon of retaliation" - the V-1 winged bomb. A similar development was created in 1942 by the Soviet designer Vladimir Chelomey for the first Soviet 10X cruise missile.
Of course, these engines were not yet detonation engines, since they used conventional combustion pulses. The frequency of these pulsations was low, which gave rise to a characteristic machine-gun sound during operation. Specific characteristics of PUVRD due to intermittent mode work on average was low, and after designers coped with the difficulties of creating compressors, pumps and turbines by the end of the 1940s, turbojet engines and rocket engines became the kings of the sky, and PUVRD remained on the periphery of technical progress.
It is curious that the German and Soviet designers created the first PuVRD independently of each other. By the way, the idea of a detonation engine in 1940 came to mind not only to Zeldovich. At the same time, the same thoughts were expressed by Von Neumann (USA) and Werner Döring (Germany), so that in international science the model for using detonation combustion was called ZND.
The idea to combine a PUVRD with detonation combustion was very tempting. But the front of an ordinary flame propagates at a speed of 60–100 m/s, and the frequency of its pulsations in a PUVRD does not exceed 250 per second. And the detonation front moves at a speed of 1500‒2500 m/s, so the frequency of pulsations should be thousands per second. It was difficult to implement such a rate of mixture renewal and detonation initiation in practice.
Nevertheless, attempts to create workable pulsating detonation engines continued. The work of the US Air Force specialists in this direction culminated in the creation of a demonstrator engine, which on January 31, 2008 for the first time took to the skies on an experimental Long-EZ aircraft. In the historical flight, the engine worked for... 10 seconds at a height of 30 meters. However, the priority this case remained with the United States, and the aircraft rightfully took its place in the National Museum of the US Air Force.
Meanwhile, another, much more promising scheme has long been devised.
Like a squirrel in a wheel
The idea to loop the detonation wave and make it run in the combustion chamber like a squirrel in a wheel was born by scientists in the early 1960s. The phenomenon of spin (rotating) detonation was theoretically predicted by the Soviet physicist from Novosibirsk B. V. Voitsekhovsky in 1960. Almost simultaneously with him, in 1961, the same idea was expressed by the American J. Nicholls from the University of Michigan.
Rotary, or spin, detonation engine is structurally an annular combustion chamber, fuel is supplied to which by means of radially arranged nozzles. The detonation wave inside the chamber does not move in an axial direction, as in a PuVRD, but in a circle, compressing and burning the fuel mixture in front of it and, in the end, pushing the combustion products out of the nozzle in the same way as a meat grinder screw pushes minced meat out. Instead of the pulsation frequency, we get the frequency of rotation of the detonation wave, which can reach several thousand per second, that is, in practice, the engine does not operate as a pulsating engine, but as a conventional liquid-propellant rocket engine with stationary combustion, but much more efficiently, since in fact it detonates the fuel mixture .
In the USSR, as well as in the USA, work on a rotary detonation engine has been going on since the beginning of the 1960s, but again, despite the seeming simplicity of the idea, its implementation required the solution of puzzling theoretical issues. How to organize the process so that the wave does not die out? It was necessary to understand the most complex physical and chemical processes occurring in a gaseous medium. Here, the calculation was no longer carried out at the molecular, but at the atomic level, at the junction of chemistry and quantum physics. These processes are more complex than those that occur during the generation of a laser beam. That is why the laser has been working for a long time, but the detonation engine has not. To understand these processes, it was necessary to create a new fundamental science - physicochemical kinetics, which did not exist 50 years ago. And for the practical calculation of the conditions under which the detonation wave will not fade, but will become self-sustaining, powerful computers were required, which appeared only in recent years. This is the foundation that had to be laid in the basis of practical success in taming detonation.
Active work in this direction is being carried out in the United States. These studies are carried out by Pratt & Whitney, General Electric, NASA. For example, the US Naval Research Laboratory is developing spin detonation gas turbines for the fleet. The US Navy uses 430 gas turbine plants on 129 ships, they consume fuel worth three billion dollars a year. The introduction of more economical detonation gas turbine engines(GTE) will save huge funds.
In Russia, dozens of research institutes and design bureaus have worked and continue to work on detonation engines. Among them is NPO Energomash, the leading engine-building company in the Russian space industry, with many of whose enterprises VTB Bank cooperates. The development of a detonation rocket engine was carried out for more than one year, but in order for the tip of the iceberg of this work to sparkle under the sun in the form of a successful test, it took the organizational and financial participation of the notorious Advanced Research Foundation (FPI). It was the FPI that allocated necessary funds to create in 2014 a specialized laboratory "Detonation rocket engines". After all, despite 70 years of research, this technology is still “too promising” in Russia to be funded by customers like the Ministry of Defense, who, as a rule, need a guaranteed practical result. And it's still very far away.
The Taming of the Shrew
I would like to believe that after all that has been said above, the titanic work that peeps between the lines of a brief message about the tests that took place at Energomash in Khimki in July - August 2016 becomes clear: “For the first time in the world, a steady state mode of continuous spin detonation of transverse detonation waves with a frequency of about 20 kHz (wave rotation frequency - 8 thousand revolutions per second) on the fuel pair "oxygen - kerosene". It was possible to obtain several detonation waves that balanced the vibration and shock loads of each other. Heat-shielding coatings specially developed at the Keldysh Center helped to cope with high temperature loads. The engine withstood several starts under conditions of extreme vibration loads and ultra-high temperatures in the absence of cooling of the near-wall layer. A special role in this success was played by the creation of mathematical models and fuel injectors, which made it possible to obtain a mixture of the consistency necessary for the occurrence of detonation.
Of course, the significance of the success achieved should not be exaggerated. Only a demonstrator engine was created, which worked for a relatively short time, and about it real characteristics nothing is reported. According to NPO Energomash, a detonation rocket engine will increase thrust by 10% while burning the same amount of fuel as in a conventional engine, and the specific thrust impulse should increase by 10–15%.
But the main result is that the possibility of organizing detonation combustion in a liquid-propellant rocket engine has been practically confirmed. However, the way to use this technology as part of real aircraft there is still a long way to go. Another important aspect is that another world priority in the field of high technologies is now assigned to our country: for the first time in the world, a full-size detonation rocket engine was launched in Russia, and this fact will remain in the history of science and technology. published
While all progressive humanity from the NATO countries is preparing to start testing a detonation engine (tests can happen in 2019 (but rather much later)), backward Russia announced the completion of testing such an engine.
They announced it quite calmly and without frightening anyone. But in the West, as expected, they got scared and a hysterical howl began - we will be left behind for the rest of our lives. Work on a detonation engine (DD) is being carried out in the USA, Germany, France and China. In general, there are reasons to believe that Iraq is interested in solving the problem and North Korea- a very promising development, which actually means new stage in rocket science. And in general in engine building.
The idea of a detonation engine was first voiced in 1940 by the Soviet physicist Ya.B. Zel'dovich. And the creation of such an engine promised huge benefits. For a rocket engine, for example:
- The power is increased by 10,000 times compared to a conventional rocket engine. In this case, we are talking about the power received per unit volume of the engine;
- 10 times less fuel per unit of power;
- DD is simply significantly (many times) cheaper than a standard rocket engine.
A liquid propellant rocket engine is such a big and very expensive burner. And expensive because a large number of mechanical, hydraulic, electronic and other mechanisms are required to maintain stable combustion. A very complex production. So complicated that the United States has been unable to create its own liquid-propellant rocket engine for many years and are forced to purchase RD-180 in Russia.
Russia will very soon receive a serial reliable inexpensive light rocket engine. With all the ensuing consequences:
a rocket can carry many times more payload- the engine itself weighs significantly less, fuel is needed 10 times less for the declared flight range. And you can simply increase this range by 10 times;
the cost of the rocket is reduced by a multiple. This is a good answer for those who like to organize an arms race with Russia.
And there is also deep space… Simply fantastic prospects for its development are opening up.
However, the Americans are right and now there is no time for space - packages of sanctions are already being prepared so that a detonation engine does not happen in Russia. They will interfere with all their might - our scientists have made a painfully serious claim for leadership.
07 Feb 2018 Tags: 2311Discussion: 3 comments
* 10,000 times more power compared to a conventional rocket engine. In this case, we are talking about the power received per unit volume of the engine;
10 times less fuel per unit of power;
—————
somehow does not fit with other posts:
“Depending on the design, it can exceed the original LRE in terms of efficiency from 23-27% for a typical design with an expanding nozzle, up to 36-37% increase in KVRD (wedge-air rocket engines)
They are able to change the pressure of the outflowing gas jet depending on atmospheric pressure, and save up to 8-12% of fuel throughout the entire structure launch site (The main savings occur at low altitudes, where it reaches 25-30%).»
The problem of development of rotary detonation engines is considered. The main types of such engines are presented: the Nichols rotary detonation engine, the Wojciechowski engine. The main directions and trends in the development of the design of detonation engines are considered. It is shown that modern concepts of a rotary detonation engine cannot, in principle, lead to the creation of a workable design that surpasses the existing jet engines in terms of its characteristics. The reason is the desire of designers to combine wave generation, fuel combustion, and fuel and oxidizer ejection into one mechanism. As a result of self-organization of shock-wave structures, detonation combustion is carried out in a minimum rather than maximum volume. The result actually achieved today is detonation combustion in a volume not exceeding 15% of the volume of the combustion chamber. The way out is seen in a different approach - first, an optimal configuration of shock waves is created, and only then fuel components are fed into this system and optimal detonation combustion is organized in a large volume.
detonation engine
rotary detonation engine
Wojciechowski engine
circular detonation
spin detonation
impulse detonation engine
1. B. V. Voitsekhovsky, V. V. Mitrofanov, and M. E. Topchiyan, Structure of the detonation front in gases. - Novosibirsk: Publishing House of the USSR Academy of Sciences, 1963.
2. Uskov V.N., Bulat P.V. On the problem of designing an ideal diffuser for compressing a supersonic flow // Fundamental Research. - 2012. - No. 6 (part 1). - S. 178-184.
3. Uskov V.N., Bulat P.V., Prodan N.V. The history of the study of irregular reflection of a shock wave from the symmetry axis of a supersonic jet with the formation of a Mach disk // Fundamental Research. - 2012. - No. 9 (part 2). - S. 414-420.
4. Uskov V.N., Bulat P.V., Prodan N.V. Justification of the application of the stationary Mach configuration model to the calculation of the Mach disk in a supersonic jet // Fundamental research. - 2012. - No. 11 (part 1). – S. 168–175.
5. Shchelkin K.I. Instability of combustion and detonation of gases // Uspekhi fizicheskikh nauk. - 1965. - T. 87, no. 2.– S. 273–302.
6. Nichols J.A., Wilkmson H.R., Morrison R.B. Intermittent Detonation as a Trust-Producing Mechanism // Jet Propulsion. - 1957. - No. 21. - P. 534–541.
Rotary detonation engines
All types of rotary detonation engines (RDE) have in common that the fuel supply system is combined with the fuel combustion system in the detonation wave, but then everything works like in a conventional jet engine - a flame tube and a nozzle. It was this fact that initiated such activity in the field of modernization of gas turbine engines (GTE). It seems attractive to replace only the mixing head and the mixture ignition system in the gas turbine engine. To do this, it is necessary to ensure the continuity of detonation combustion, for example, by launching a detonation wave in a circle. Nichols was one of the first to propose such a scheme in 1957, and then developed it and conducted a series of experiments with a rotating detonation wave in the mid-1960s (Fig. 1).
By adjusting the diameter of the chamber and the thickness of the annular gap, for each type of fuel mixture, it is possible to choose such a geometry that detonation will be stable. In practice, the relationship between the gap and the diameter of the engine turns out to be unacceptable, and it is necessary to control the speed of wave propagation by controlling the fuel supply, as discussed below.
As with pulse detonation engines, the circular detonation wave is capable of ejecting oxidizer, allowing RDE to be used at zero speeds. This fact led to a flurry of experimental and computational studies of RDE with an annular combustion chamber and spontaneous ejection. fuel-air mixture, to list here which does not make any sense. All of them are built approximately according to the same scheme (Fig. 2), reminiscent of the Nichols engine scheme (Fig. 1).
Rice. 1. Scheme of organization of continuous circular detonation in the annular gap: 1 - detonation wave; 2 - a layer of "fresh" fuel mixture; 3 - contact gap; 4 - an oblique shock wave propagating downstream; D is the direction of the detonation wave
Rice. 2. A typical RDE scheme: V is the free flow velocity; V4 - flow rate at the outlet of the nozzle; a - fresh fuel assemblies, b - detonation wave front; c - attached oblique shock wave; d - combustion products; p(r) - pressure distribution on the channel wall
A reasonable alternative to the Nichols scheme could be the installation of a plurality of fuel-oxidation injectors that would inject a fuel-air mixture into the region immediately before the detonation wave according to a certain law with a given pressure (Fig. 3). By adjusting the pressure and the rate of fuel supply to the combustion region behind the detonation wave, it is possible to influence the rate of its propagation upstream. This direction is promising, but the main problem in the design of such RDEs is that the widely used simplified model of the flow in the detonation combustion front does not correspond to reality at all.
Rice. 3. RDE with controlled fuel supply to the combustion area. Wojciechowski rotary engine
The main hopes in the world are associated with detonation engines operating according to the scheme rotary engine Voitsekhovsky. In 1963 B.V. Voitsekhovsky, by analogy with spin detonation, developed a scheme for continuous combustion of gas behind a triple configuration of shock waves circulating in an annular channel (Fig. 4).
Rice. Fig. 4. Scheme of the Wojciechowski continuous combustion of gas behind a triple configuration of shock waves circulating in the annular channel: 1 - fresh mixture; 2 - doubly compressed mixture behind a triple configuration of shock waves, detonation area
In this case, the stationary hydrodynamic process with gas combustion behind the shock wave differs from the detonation scheme of Chapman-Jouguet and Zel'dovich-Neumann. Such a process is quite stable, its duration is determined by the reserve of the fuel mixture and, in well-known experiments, is several tens of seconds.
The scheme of Wojciechowski's detonation engine served as a prototype for numerous studies of rotational and spin detonation engines̆ initiated in the last 5 years. This scheme accounts for more than 85% of all studies. All of them have one organic drawback - the detonation zone occupies too little of the total combustion zone, usually no more than 15%. As a result, the specific performance of engines is worse than that of engines of traditional design.
On the causes of failures with the implementation of the Wojciechowski scheme
Most of the work on engines with continuous detonation is associated with the development of the Wojciechowski concept. Despite the more than 40-year history of research, the results actually remained at the level of 1964. The share of detonation combustion does not exceed 15% of the volume of the combustion chamber. The rest is slow combustion under conditions that are far from optimal.
One of the reasons for this state of affairs is the lack of a workable calculation methodology. Since the flow is three-dimensional, and the calculation takes into account only the laws of conservation of momentum on the shock wave in the direction perpendicular to the model detonation front, the results of calculating the inclination of shock waves to the flow of combustion products differ from those observed experimentally by more than 30%. The result is that, despite many years of research various systems fuel supply and experiments on changing the ratio of fuel components, all that has been done is to create models in which detonation combustion occurs and is maintained for 10-15 s. There is no talk of increasing efficiency, or of advantages over existing liquid-propellant and gas-turbine engines.
The analysis of the available RDE schemes carried out by the authors of the project showed that all the RDE schemes offered today are inoperative in principle. Detonation combustion occurs and is successfully maintained, but only to a limited extent. In the rest of the volume, we are dealing with the usual slow combustion, moreover, behind a non-optimal system of shock waves, which leads to significant losses full pressure. In addition, the pressure is also several times lower than necessary for ideal combustion conditions with a stoichiometric ratio of the fuel mixture components. As a result specific consumption fuel per unit of thrust is 30-40% higher than that of conventional engines.
But most main problem is the very principle of organizing continuous detonation. As shown by studies of continuous circular detonation, carried out back in the 60s, the detonation combustion front is a complex shock wave structure consisting of at least two triple configurations (about triple configurations of shock waves. Such a structure with an attached detonation zone, like any thermodynamic feedback system, left alone, tends to assume a position corresponding to the minimum energy level.As a result, the triple configurations and the detonation combustion region are adjusted to each other so that the detonation front moves through the annular gap with the minimum amount of detonation combustion possible for this. This is directly opposite to the goal that engine designers set for detonation combustion.
For creating efficient engine RDE needs to solve the problem of creating an optimal triple configuration of shock waves and organizing a detonation combustion zone in it. Optimal shock-wave structures must be able to create in a variety of technical devices, for example, in optimal diffusers of supersonic air intakes. The main task is the maximum possible increase in the share of detonation combustion in the volume of the combustion chamber from today's unacceptable 15% to at least 85%. Existing engine designs based on the schemes of Nichols and Wojciechowski cannot provide this task.
Reviewers:Uskov V.N., Doctor of Technical Sciences, Professor of the Department of Hydroaeromechanics of St. Petersburg State University, Faculty of Mathematics and Mechanics, St. Petersburg;
Emelyanov V.N., Doctor of Technical Sciences, Professor, Head of the Department of Plasma Gas Dynamics and Heat Engineering, BSTU "VOENMEH" named after A.I. D.F. Ustinov, St. Petersburg.
The work was received by the editors on October 14, 2013.
Bibliographic link
Bulat P.V., Prodan N.V. REVIEW OF PROJECTS OF DETONATING ENGINES. ROTARY DETONATING ENGINES // Fundamental Research. - 2013. - No. 10-8. - S. 1672-1675;URL: http://fundamental-research.ru/ru/article/view?id=32642 (date of access: 07/29/2019). We bring to your attention the journals published by the publishing house "Academy of Natural History"
