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 // Basic 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 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. Typical circuit RDE: V - 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 Wojciechowski rotary engine scheme. 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.
Wojciechowski's detonation engine scheme served as a prototype numerous studies̆ 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 organization 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 system with feedback, left alone, tends to take a position corresponding to the minimum level of energy. As a result, the triple configurations and the area of detonation combustion are adjusted to each other so that the detonation front moves along the annular gap with the minimum possible volume of detonation combustion 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: 03/14/2019). We bring to your attention the journals published by the publishing house "Academy of Natural History"
Detonation engines will replace the core of gas turbines / Photo: finobzor.ru
In reality, instead of a constant frontal flame in the combustion zone, a detonation wave is formed, rushing at supersonic speed. In such a compression wave, fuel and oxidizer are detonated, this process, from the point of view of thermodynamics, increases Engine efficiency by an order of magnitude, due to the compactness of the combustion zone.
Interestingly, back in 1940, the Soviet physicist Ya.B. Zel'dovich proposed the idea of a detonation engine in the article "On the energy use detonation combustion". Since then, many scientists from different countries, then the United States, then Germany, then our compatriots came forward.
In the summer, in August 2016, Russian scientists managed to create the world's first full-size liquid-propellant jet engine operating on the principle of detonation combustion of fuel. Our country has finally established a world priority in the development of the latest technology for many post-perestroika years.
Why is it so good new engine? A jet engine uses the energy released by burning a mixture at constant pressure and a constant flame front. During combustion, the gas mixture of fuel and oxidizer sharply increases the temperature and the flame column escaping from the nozzle creates jet thrust.
detonation engine/ Photo: sdelanounas.ru
During detonation combustion, the reaction products do not have time to collapse, because this process is 100 times faster than deflagration and the pressure increases rapidly, while the volume remains unchanged. The allocation of such a large number energy can actually destroy a car engine, which is why such a process is often associated with an explosion.
In reality, instead of a constant frontal flame in the combustion zone, a detonation wave is formed, rushing at supersonic speed. In such a compression wave, fuel and oxidizer are detonated, this process, from the point of view of thermodynamics, increases the efficiency of the engine by an order of magnitude, due to the compactness of the combustion zone. Therefore, experts so zealously set about developing this idea. In a conventional rocket engine, which is essentially a large burner, the main thing is not the combustion chamber and nozzle, but the fuel turbopump unit (TNA), which creates such pressure that fuel penetrates into the chamber. For example, in the Russian RD-170 rocket engine for Energia launch vehicles, the pressure in the combustion chamber is 250 atm and the pump that supplies the oxidizer to the combustion zone has to create a pressure of 600 atm.
In a detonation engine, pressure is created by detonation itself, which represents a traveling compression wave in the fuel mixture, in which the pressure without any TNA is already 20 times greater and turbopump units are superfluous. To make it clear, the American Shuttle has a pressure in the combustion chamber of 200 atm, and the detonation engine in such conditions needs only 10 atm to supply the mixture - this is like a bicycle pump and the Sayano-Shushenskaya hydroelectric power station.
In this case, a detonation-based engine is not only simpler and cheaper by an order of magnitude, but much more powerful and economical than a conventional rocket engine. The problem of co-control with a detonation wave arose on the way to implementing the detonation engine project. This phenomenon is not just a blast wave, which has the speed of sound, but a detonation wave propagating at a speed of 2500 m / s, there is no stabilization of the flame front in it, for each pulsation the mixture is updated and the wave starts again.
Previously, Russian and French engineers developed and built pulsating jet engines, but not on the principle of detonation, but on the basis of ordinary combustion pulsation. The characteristics of such PUVRDs were low, and when engine builders developed pumps, turbines and compressors, the age came jet engines and LRE, and pulsating remained on the sidelines of progress. The bright heads of science tried to combine detonation combustion with a PUVRD, but the frequency of pulsations of a conventional combustion front is no more than 250 per second, and the detonation front has a speed of up to 2500 m/s and its pulsation frequency reaches several thousand per second. It seemed impossible to put into practice such a rate of mixture renewal and at the same time initiate detonation.
In the USA, it was possible to build such a detonation pulsating engine and test it in the air, however, it worked for only 10 seconds, but the priority remained with the American designers. But already in the 60s of the last century, the Soviet scientist B.V. Voitsekhovsky and, almost at the same time, an American from the University of Michigan, J. Nichols, came up with the idea to loop a detonation wave in the combustion chamber.
Image: sdelanounas.ru
How a detonation rocket engine works
Such rotary engine consisted of an annular combustion chamber with nozzles placed along its radius to supply fuel. The detonation wave runs around like a squirrel in a wheel, fuel mixture shrinks and burns out, pushing the products of combustion through the nozzle. In a spin engine, we obtain a wave rotation frequency of several thousand per second, its operation is similar to the working process in a rocket engine, only more efficiently, due to the detonation of the fuel mixture.
In the USSR and the USA, and later in Russia, work is underway to create a rotary detonation engine with a continuous wave, to understand the processes occurring inside, for which a whole science of physical and chemical kinetics was created. To calculate the conditions of an undamped wave, powerful computers were needed, which were created only recently.
In Russia, many research institutes and design bureaus are working on the project of such a spin engine, including the engine building company of the space industry. The Advanced Research Foundation came to help in the development of such an engine, because it is impossible to obtain funding from the Ministry of Defense - they only need a guaranteed result.
Nevertheless, during tests in Khimki at Energomash, a steady state of continuous spin detonation was recorded - 8 thousand revolutions per second on an oxygen-kerosene mixture. At the same time, detonation waves balanced vibration waves, and heat-shielding coatings withstood high temperatures.
But do not flatter yourself, because this is only a demonstrator engine that has worked for a very short time and nothing has yet been said about its characteristics. But the main thing is that the possibility of creating detonation combustion has been proven and a full-size spin engine it is in Russia that will remain in the history of science forever.
MOSCOW, edition "Made by us"
12
Detonation engine tests
FPI_RUSSIA / Vimeo
The specialized laboratory "Detonation LRE" of the Research and Production Association "Energomash" tested the world's first full-size detonation liquid propellant technology demonstrators. rocket engine. According to TASS, the new power plants run on an oxygen-kerosene fuel pair.
The new engine, unlike other power plants operating on the principle internal combustion, operates due to the detonation of the fuel. Detonation is the supersonic combustion of a substance, in this case a fuel mixture. In this case, a shock wave propagates through the mixture, followed by a chemical reaction with the release of a large amount of heat.
The study of the principles of operation and the development of detonation engines has been carried out in some countries of the world for more than 70 years. The first such work began in Germany in the 1940s. True, the researchers failed to create a working prototype of a detonation engine at that time, but pulsating jet engines were developed and mass-produced. They were placed on V-1 rockets.
In pulsating jet engines, fuel burned at subsonic speeds. This combustion is called deflagration. The engine is called pulsating because fuel and oxidizer were fed into its combustion chamber in small portions at regular intervals.
Pressure map in the combustion chamber of a rotary detonation engine. A - detonation wave; B - trailing front of the shock wave; C - mixing zone of fresh and old combustion products; D - fuel mixture filling area; E is the region of the non-knocking burnt fuel mixture; F - expansion zone with detonated burnt fuel mixture
Detonation engines today are divided into two main types: impulse and rotary. The latter are also called spin. Principle of operation pulse engines similar to that of pulse jet engines. The main difference lies in the detonation combustion of the fuel mixture in the combustion chamber.
Rotary detonation engines use an annular combustion chamber in which the fuel mixture is fed sequentially through radial valves. In such power plants, detonation does not fade - the detonation wave “runs around” the annular combustion chamber, the fuel mixture behind it has time to be updated. The rotary engine was first studied in the USSR in the 1950s.
Detonation engines are capable of operating in a wide range of flight speeds - from zero to five Mach numbers (0-6.2 thousand kilometers per hour). It is believed that such power plants can produce more power, consuming less fuel than conventional jet engines. At the same time, the design of detonation engines is relatively simple: they lack a compressor and many moving parts.
All detonation engines tested so far have been developed for experimental aircraft. Tested in Russia power point is the first designed to be mounted on a rocket. What type of detonation engine was tested is not specified.
The publication "Military-Industrial Courier" reports great news from the field of breakthrough missile technologies. A detonation rocket engine has been tested in Russia, Deputy Prime Minister Dmitry Rogozin said on his Facebook page on Friday.
“The so-called detonation rocket engines developed under the program of the Advanced Research Foundation have been successfully tested,” Interfax-AVN quotes the Deputy Prime Minister.
It is believed that a detonation rocket engine is one of the ways to implement the concept of the so-called motor hypersound, that is, the creation of hypersonic aircraft capable of own engine reach speeds of 4 - 6 Machs (Max - the speed of sound).
The russia-reborn.ru portal provides an interview with one of the leading specialized engine engineers in Russia about detonation rocket engines.
Interview with Petr Levochkin, chief designer of NPO Energomash im. Academician V.P. Glushko.
Engines for hypersonic missiles of the future are being created
Successful tests of the so-called detonation rocket engines were carried out, which gave very interesting results. Development work in this direction will be continued.
Detonation is an explosion. Can it be made manageable? Is it possible to create hypersonic weapons on the basis of such engines? What rocket engines will take uninhabited and manned vehicles into near space? This is our conversation with the Deputy General Director - Chief Designer of NPO Energomash im. Academician V.P. Glushko" by Petr Levochkin.
Petr Sergeevich, what opportunities do new engines open up?
Petr Levochkin: If we talk about the short term, today we are working on engines for such rockets as the Angara A5V and Soyuz-5, as well as others that are at the pre-design stage and are unknown to the general public. In general, our engines are designed to lift a rocket from the surface of a celestial body. And it can be any - terrestrial, lunar, Martian. So, if the lunar or Martian programs are implemented, we will definitely take part in them.
What is the efficiency of modern rocket engines and are there ways to improve them?
Petr Levochkin: If we talk about energy and thermodynamic parameters engines, it can be said that ours, as well as the best foreign chemical rocket engines today, have reached a certain perfection. For example, the completeness of fuel combustion reaches 98.5 percent. That is, almost all the chemical energy of the fuel in the engine is converted into thermal energy of the outgoing gas jet from the nozzle.
Engines can be improved in many ways. This includes the use of more energy-intensive fuel components, the introduction of new circuit designs, and an increase in pressure in the combustion chamber. Another direction is the use of new, including additive, technologies in order to reduce labor intensity and, as a result, reduce the cost of a rocket engine. All this leads to a decrease in the cost of the output payload.
However, upon closer examination, it becomes clear that increasing the energy characteristics of engines in the traditional way is ineffective.
Using a controlled propellant explosion could give a rocket a speed eight times the speed of sound
Why?
Petr Levochkin: Increasing pressure and fuel consumption in the combustion chamber will naturally increase engine thrust. But this will require an increase in the thickness of the walls of the chamber and pumps. As a result, the complexity of the structure and its mass increase, and the energy gain turns out to be not so great. The game will not cost the candle.
That is, rocket engines have exhausted the resource of their development?
Petr Levochkin: Not really. Speaking technical language, they can be improved by increasing the efficiency of intra-motor processes. There are cycles of thermodynamic conversion of chemical energy into the energy of an outflowing jet, which are much more efficient than the classical combustion of rocket fuel. This is the detonation combustion cycle and the Humphrey cycle close to it.
The very effect of fuel detonation was discovered by our compatriot - later Academician Yakov Borisovich Zeldovich back in 1940. Realization of this effect in practice promised very great prospects in rocket science. It is not surprising that the Germans in those same years actively investigated the detonation process of combustion. But not quite further successful experiments they didn't make any progress.
Theoretical calculations have shown that detonation combustion is 25 percent more efficient than the isobaric cycle, which corresponds to fuel combustion at constant pressure, which is implemented in the chambers of modern liquid-propellant engines.
And what provides the advantages of detonation combustion in comparison with the classical one?
Petr Levochkin: The classic combustion process is subsonic. Detonation - supersonic. The speed of the reaction in a small volume leads to a huge heat release - it is several thousand times higher than in subsonic combustion, implemented in classical rocket engines with the same mass of burning fuel. And for us engine engineers, this means that with a much smaller detonation engine and with a small mass of fuel, you can get the same thrust as in modern huge liquid rocket engines.
It is no secret that engines with detonation combustion of fuel are also being developed abroad. What are our positions? We yield, we go at their level or we are in the lead?
Petr Levochkin: We are not inferior, that's for sure. But I can’t say that we are in the lead either. The topic is fairly closed. One of the main technological secrets is how to ensure that the fuel and oxidizer of a rocket engine does not burn, but explodes, without destroying the combustion chamber. That is, in fact, to make a real explosion controllable and manageable. For reference: detonation is the combustion of fuel in the front of a supersonic shock wave. There are pulsed detonation, when the shock wave moves along the axis of the chamber and one replaces the other, as well as continuous (spin) detonation, when the shock waves in the chamber move in a circle.
As far as we know, experimental studies of detonation combustion have been carried out with the participation of your specialists. What results have been obtained?
Petr Levochkin: Work was done to create a model chamber for a liquid detonation rocket engine. Under the patronage of the Foundation for Advanced Study, a large cooperation of leading scientific centers Russia. Among them, the Institute of Hydrodynamics. M.A. Lavrentiev, MAI, "Keldysh Center", Central Institute of Aviation Motors named after A.I. P.I. Baranov, Faculty of Mechanics and Mathematics, Moscow State University. We proposed to use kerosene as a fuel, and gaseous oxygen as an oxidizing agent. In the process of theoretical and experimental studies, the possibility of creating a detonation rocket engine based on such components was confirmed. Based on the data obtained, we have developed, manufactured and successfully tested a model detonation chamber with a thrust of 2 tons and a pressure in the combustion chamber of about 40 atm.
This task was solved for the first time not only in Russia, but also in the world. So, of course, there were problems. Firstly, they are connected with the provision of stable detonation of oxygen with kerosene, and secondly, with the provision of reliable cooling of the fire wall of the chamber without curtain cooling and a host of other problems, the essence of which is clear only to specialists.
In reality, instead of a constant frontal flame in the combustion zone, a detonation wave is formed, rushing at supersonic speed. In such a compression wave, fuel and oxidizer are detonated, this process, from the point of view of thermodynamics, increases the efficiency of the engine by an order of magnitude, due to the compactness of the combustion zone.
Interestingly, back in 1940, the Soviet physicist Ya.B. Zel'dovich proposed the idea of a detonation engine in the article "On the Energy Use of Detonation Combustion". Since then, many scientists from different countries have been working on a promising idea, either the United States, then Germany, or our compatriots have come forward.
In the summer, in August 2016, Russian scientists managed to create the world's first full-size liquid-propellant jet engine operating on the principle of detonation combustion of fuel. Our country has finally established a world priority in the development of the latest technology for many post-perestroika years.
Why is the new engine so good? A jet engine uses the energy released by burning a mixture at constant pressure and a constant flame front. During combustion, the gas mixture of fuel and oxidizer sharply increases the temperature and the flame column escaping from the nozzle creates jet thrust.
During detonation combustion, the reaction products do not have time to collapse, because this process is 100 times faster than deflagration and the pressure increases rapidly, while the volume remains unchanged. The release of such a large amount of energy can actually destroy a car engine, which is why such a process is often associated with an explosion.
In reality, instead of a constant frontal flame in the combustion zone, a detonation wave is formed, rushing at supersonic speed. In such a compression wave, fuel and oxidizer are detonated, this process, from the point of view of thermodynamics, increases the efficiency of the engine by an order of magnitude, due to the compactness of the combustion zone. Therefore, experts so zealously began to develop this idea.
In a conventional LRE, which is in fact a large burner, the main thing is not the combustion chamber and nozzle, but the fuel turbopump unit (FPU), which creates such pressure that the fuel penetrates into the chamber. For example, in the Russian RD-170 rocket engine for Energia launch vehicles, the pressure in the combustion chamber is 250 atm and the pump that supplies the oxidizer to the combustion zone has to create a pressure of 600 atm.
In a detonation engine, pressure is created by detonation itself, which represents a traveling compression wave in the fuel mixture, in which the pressure without any TNA is already 20 times greater and turbopump units are superfluous. To make it clear, the American Shuttle has a pressure in the combustion chamber of 200 atm, and the detonation engine in such conditions needs only 10 atm to supply the mixture - this is like a bicycle pump and the Sayano-Shushenskaya hydroelectric power station.
In this case, a detonation-based engine is not only simpler and cheaper by an order of magnitude, but much more powerful and economical than a conventional rocket engine.
On the way to the implementation of the detonation engine project, the problem of co-ownership with the detonation wave arose. This phenomenon is not just a blast wave, which has the speed of sound, but a detonation wave propagating at a speed of 2500 m / s, there is no stabilization of the flame front in it, for each pulsation the mixture is updated and the wave starts again.
Previously, Russian and French engineers developed and built pulsating jet engines, but not on the principle of detonation, but on the basis of ordinary combustion pulsation. The characteristics of such PUVRDs were low, and when engine builders developed pumps, turbines and compressors, the age of jet engines and LREs came, and pulsating ones remained on the sidelines of progress. The bright heads of science tried to combine detonation combustion with a PUVRD, but the frequency of pulsations of a conventional combustion front is no more than 250 per second, and the detonation front has a speed of up to 2500 m/s and its pulsation frequency reaches several thousand per second. It seemed impossible to put into practice such a rate of mixture renewal and at the same time initiate detonation.
In the USA, it was possible to build such a detonation pulsating engine and test it in the air, however, it worked for only 10 seconds, but the priority remained with the American designers. But already in the 60s of the last century, the Soviet scientist B.V. Voitsekhovsky and, almost at the same time, an American from the University of Michigan, J. Nichols, came up with the idea to loop a detonation wave in the combustion chamber.
How a detonation rocket engine works
Such a rotary engine consisted of an annular combustion chamber with nozzles placed along its radius to supply fuel. The detonation wave runs like a squirrel in a wheel around the circumference, the fuel mixture is compressed and burned out, pushing the combustion products through the nozzle. In a spin engine, we obtain a wave rotation frequency of several thousand per second, its operation is similar to the working process in a rocket engine, only more efficiently, due to the detonation of the fuel mixture.
In the USSR and the USA, and later in Russia, work is underway to create a rotary detonation engine with a continuous wave to understand the processes occurring inside, and for this a whole science was created - physical and chemical kinetics. To calculate the conditions of an undamped wave, powerful computers were needed, which were created only recently.
In Russia, many research institutes and design bureaus are working on the project of such a spin engine, including the engine-building company of the space industry NPO Energomash. The Advanced Research Foundation came to help in the development of such an engine, because it is impossible to obtain funding from the Ministry of Defense - they only need a guaranteed result.
Nevertheless, during tests in Khimki at Energomash, a steady state of continuous spin detonation was recorded - 8 thousand revolutions per second on an oxygen-kerosene mixture. At the same time, detonation waves balanced vibration waves, and heat-shielding coatings withstood high temperatures.
But do not flatter yourself, because this is only a demonstrator engine that has worked for a very short time and nothing has yet been said about its characteristics. But the main thing is that the possibility of creating detonation combustion has been proven and a full-sized spin engine has been created in Russia, which will remain in the history of science forever.
Video: Energomash was the first in the world to test a detonation liquid-propellant rocket engine
