The problem of development of impulse detonation engines is considered. The main research centers conducting research on new generation engines are listed. The main directions and trends in the development of the design of detonation engines are considered. The main types of such engines are presented: impulse, impulse multitube, impulse with a high-frequency resonator. The difference in the method of creating thrust is shown in comparison with a classic jet engine equipped with a Laval nozzle. The concept of a traction wall and a traction module is described. It is shown that impulse detonation engines are being improved in the direction of increasing the pulse repetition rate, and this direction has its right to life in the field of light and cheap unmanned aircraft, as well as in the development of various ejector thrust amplifiers. The main difficulties of a fundamental nature in modeling a detonation turbulent flow using computational packages based on the use of differential turbulence models and time averaging of the Navier–Stokes equations are shown.
detonation engine
impulse detonation engine
1. Bulat P.V., Zasukhin O.N., Prodan N.V. History of experimental studies of bottom pressure // Basic Research. - 2011. - No. 12 (3). - S. 670-674.
2. Bulat P.V., Zasukhin O.N., Prodan N.V. Bottom pressure fluctuations // Fundamental research. - 2012. - No. 3. - S. 204-207.
3. Bulat P.V., Zasukhin O.N., Prodan N.V. Peculiarities of application of turbulence models in the calculation of flows in supersonic paths of advanced air-jet engines // Engine. - 2012. - No. 1. - P. 20–23.
4. Bulat P.V., Zasukhin O.N., Uskov V.N. On the classification of flow regimes in a channel with sudden expansion // Thermophysics and Aeromechanics. - 2012. - No. 2. - S. 209–222.
5. Bulat P.V., Prodan N.V. On low-frequency flow oscillations of bottom pressure // Fundamental research. - 2013. - No. 4 (3). – S. 545–549.
6. Larionov S.Yu., Nechaev Yu.N., Mokhov A.A. Research and analysis of "cold" purges of the traction module of a high-frequency pulsating detonation engine // Bulletin of the MAI. - T.14. - No. 4 - M .: Publishing house MAI-Print, 2007. - S. 36–42.
7. Tarasov A.I., Shchipakov V.A. Prospects for the use of pulsed detonation technologies in turbojet engine. OAO NPO Saturn NTC im. A. Lyulki, Moscow, Russia. Moscow Aviation Institute (GTU). - Moscow, Russia. ISSN 1727-7337. Aerospace Engineering and Technology, 2011. - No. 9 (86).
Detonation projects in the US are included in the IHPTET advanced engine development program. The cooperation includes almost all research centers working in the field of engine building. NASA alone allocates up to $130 million a year for these purposes. This proves the relevance of research in this direction.
Overview of work in the field of detonation engines
The market strategy of the world's leading manufacturers is aimed not only at the development of new jet detonation engines, but also at the modernization of existing ones by replacing the traditional combustion chamber with a detonation one. In addition, detonation engines can become constituent element combined plants various types, for example, be used as an afterburner of a turbofan engine, as lifting ejector engines in VTOL aircraft (an example in Fig. 1 is a Boeing VTOL transport project).
In the United States, many research centers and universities are developing detonation engines: ASI, NPS, NRL, APRI, MURI, Stanford, USAF RL, NASA Glenn, DARPA-GE C&RD, Combustion Dynamics Ltd, Defense Research Establishments, Suffield and Valcartier, Uniyersite de Poitiers, University of Texas at Arlington, Uniyersite de Poitiers, McGill University, Pennsylvania State University, Princeton University.
The leading position in the development of detonation engines is occupied by the specialized center Seattle Aerosciences Center (SAC), bought out in 2001 by Pratt and Whitney from Adroit Systems. Most of the work of the center is funded by the Air Force and NASA from the budget of the interagency program Integrated High Payoff Rocket Propulsion Technology Program (IHPRPTP), aimed at creating new technologies for jet engines of various types.
Rice. 1. Patent US 6,793,174 B2 by Boeing, 2004
In total, since 1992, SAC specialists have carried out more than 500 bench tests of experimental samples. Work on pulsed detonation engines (PDE) with the consumption of atmospheric oxygen is carried out by the SAC Center on the order of the US Navy. Given the complexity of the program, the Navy specialists involved almost all organizations involved in detonation engines in its implementation. In addition to Pratt and Whitney, the United Technologies Research Center (UTRC) and Boeing Phantom Works are participating in the work.
Currently in our country over this topical issue theoretically, the following universities and institutes of the Russian Academy of Sciences (RAS) operate: Institute of Chemical Physics RAS (ICP), Institute of Mechanical Engineering RAS, Institute for High Temperatures RAS (IVTAN), Novosibirsk Institute of Hydrodynamics. Lavrentiev (ISIL), Institute for Theoretical and applied mechanics them. Khristianovich (ITMP), Physico-Technical Institute. Ioffe, Moscow State University (MGU), Moscow State Aviation Institute (MAI), Novosibirsk State University, Cheboksary State University, Saratov State University, etc.
Directions of work on pulse detonation engines
Direction No. 1 - Classic pulse detonation engine (PDE). The combustion chamber of a typical jet engine consists of nozzles for mixing fuel with an oxidizer, an ignition device fuel mixture and the flame tube itself, in which redox reactions (combustion) take place. The flame tube ends with a nozzle. As a rule, this is a Laval nozzle, which has a tapering part, a minimum critical section in which the velocity of the combustion products is equal to the local speed of sound, an expanding part in which the static pressure of the combustion products is reduced to a pressure of environment, as much as possible. It is very rough to estimate the thrust of the engine as the area of the critical section of the nozzle, multiplied by the pressure difference in the combustion chamber and the environment. Therefore, the thrust is higher, the higher the pressure in the combustion chamber.
The thrust of a pulse detonation engine is determined by other factors - the transfer of an impulse by a detonation wave to the thrust wall. Nozzle in this case is not needed at all. Pulse detonation engines have their own niche - cheap and disposable aircraft. In this niche, they are successfully developing in the direction of increasing the pulse repetition rate.
The classic appearance of the IDD is a cylindrical combustion chamber, which has a flat or specially profiled wall, called the “draft wall” (Fig. 2). The simplicity of the IDD device is its undeniable advantage. As the analysis of available publications shows, despite the variety of proposed schemes of PDE, all of them are characterized by the use of detonation tubes of considerable length as resonant devices and the use of valves that provide periodic supply of the working fluid.
It should be noted that the PDE, created on the basis of traditional detonation tubes, despite the high thermodynamic efficiency in a single pulsation, has the disadvantages characteristic of classical pulsating air-jet engines, namely:
Low frequency (up to 10 Hz) of pulsations, which determines the relatively low level of average traction efficiency;
High thermal and vibration loads.
Rice. 2. circuit diagram pulse detonation engine (PDE)
Direction No. 2 - Multipipe IDD. The main trend in the development of IDD is the transition to a multi-pipe scheme (Fig. 3). In such engines, the frequency of operation of a single tube remains low, but due to the alternation of pulses in different tubes, the developers hope to obtain acceptable specific characteristics. Such a scheme seems to be quite workable if the problem of vibrations and asymmetry of thrust is solved, as well as the problem of bottom pressure, in particular, possible low-frequency oscillations in the bottom region between the pipes.
Rice. 3. Pulse detonation engine (PDE) of the traditional scheme with a package of detonation tubes as resonators
Direction No. 3 - IDD with a high-frequency resonator. There is also an alternative direction - a recently widely advertised scheme with traction modules (Fig. 4) having a specially profiled high-frequency resonator. Work in this direction is being carried out at the NTC im. A. Lyulka and in MAI. The scheme is distinguished by the absence of any mechanical valves and intermittent ignition devices.
The traction module of the IDD of the proposed scheme consists of a reactor and a resonator. The reactor serves to prepare fuel-air mixture to detonation combustion, decomposing the molecules of the combustible mixture into chemically active components. A schematic diagram of one cycle of operation of such an engine is clearly shown in fig. 5.
Interacting with the bottom surface of the resonator as with an obstacle, the detonation wave in the process of collision transfers to it an impulse from the overpressure forces.
IDD with high-frequency resonators have the right to success. In particular, they can claim to modernize afterburners and refine simple turbojet engines, again designed for cheap UAVs. An example is the attempts of the MAI and CIAM to modernize the MD-120 turbojet engine in this way by replacing the combustion chamber with a fuel mixture activation reactor and installing traction modules with high-frequency resonators behind the turbine. So far, it has not been possible to create a workable design, because. when profiling resonators, the authors use the linear theory of compression waves, i.e. calculations are carried out in the acoustic approximation. The dynamics of detonation waves and compression waves is described by a completely different mathematical apparatus. The use of standard numerical packages for the calculation of high-frequency resonators has a fundamental limitation. All modern models turbulences are based on averaging the Navier-Stokes equations (the basic equations of gas dynamics) over time. In addition, Boussinesq's assumption is introduced that the turbulent friction stress tensor is proportional to the velocity gradient. Both assumptions are not satisfied in turbulent flows with shock waves if the characteristic frequencies are comparable with the frequency of turbulent pulsation. Unfortunately, we are dealing with just such a case, so here it is necessary either to build a model more high level, or direct numerical simulation based on the full Navier-Stokes equations without the use of turbulence models (a task that is unbearable at the present stage).
Rice. 4. Scheme of PDD with a high-frequency resonator
Rice. Fig. 5. Scheme of PDE with a high-frequency resonator: SZS - supersonic jet; SW - shock wave; Ф - resonator focus; DW - detonation wave; VR - rarefaction wave; SHW - reflected shock wave
IDD are being improved in the direction of increasing the pulse repetition rate. This direction has its right to life in the field of light and cheap unmanned aerial vehicles, as well as in the development of various ejector thrust boosters.
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. PULSE ENGINES // Fundamental research. - 2013. - No. 10-8. - S. 1667-1671;URL: http://fundamental-research.ru/ru/article/view?id=32641 (date of access: 03/05/2019). We bring to your attention the journals published by the publishing house "Academy of Natural History"
Detonation engines are called engines in the normal mode of which detonation combustion of fuel is used. The engine itself can be (theoretically) anything - internal combustion engine, jet, or even steam. In theory. However, until now, all known commercially acceptable engines of such fuel combustion modes, commonly referred to as "explosion", have not been used due to their ... mmm .... commercial unacceptability ..
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What is the use of detonation combustion in engines? Grossly simplifying and generalizing, something like this:
Advantages
1. Replacing conventional combustion with detonation due to the features of the gas dynamics of the shock wave front increases the theoretical maximum achievable completeness of combustion of the mixture, which makes it possible to increase engine efficiency and reduce consumption by about 5-20%. This is true for all types of engines, both internal combustion engines and jet engines.
2. The combustion rate of a portion of the fuel mixture increases by about 10-100 times, which means that it is theoretically possible to increase the liter power for an internal combustion engine (or specific thrust per kilogram of mass for jet engines) by about the same number of times. This factor is also relevant for all types of engines.
3. The factor is relevant only for jet engines of all types: since the combustion processes take place in the combustion chamber at supersonic speeds, and the temperatures and pressures in the combustion chamber increase many times, there is an excellent theoretical opportunity to multiply the jet flow rate from the nozzle. Which in turn leads to a proportional increase in thrust, specific impulse, efficiency, and / or a decrease in engine mass and required fuel.
All these three factors are very important, but they are not revolutionary, but, so to speak, evolutionary in nature. Revolutionary is the fourth and fifth factor, and it applies only to jet engines:
4. Only the use of detonation technologies makes it possible to create a direct-flow (and, therefore, on an atmospheric oxidizer!) universal jet engine of acceptable weight, size and thrust, for the practical and large-scale development of the range of up to, super-, and hypersonic speeds of 0-20 Mach.
5. Only detonation technologies make it possible to squeeze out of chemical rocket engines (fuel-oxidizer steam) speed parameters required for their wide application in interplanetary flights.
Items 4 and 5. theoretically reveal to us a) cheap road into near space, and b) the road to manned launches to the nearest planets, without the need to make monstrous super-heavy launch vehicles weighing over 3500 tons.
The disadvantages of detonation engines stem from their advantages:
Source:
1. The burning rate is so high that most often these engines can be made to work only cyclically: inlet-burn-out. Which at least three times reduces the maximum achievable liter power and / or thrust, sometimes depriving the idea itself of meaning.
2. Temperatures, pressures, and rates of their rise in the combustion chamber of detonation engines are such that they exclude the direct use of most of the materials known to us. All of them are too weak to build a simple, cheap and efficient engine. Either a whole family of fundamentally new materials is required, or the use of design tricks that have not yet been worked out. We do not have materials, and the complication of the design, again, often makes the whole idea meaningless.
However, there is an area in which detonation engines are indispensable. This is an economically viable atmospheric hypersound with a speed range of 2-20 Max. Therefore, the battle is on three fronts:
1. Creation of a scheme of an engine with continuous detonation in the combustion chamber. Which requires supercomputers and non-trivial theoretical approaches to calculate their hemodynamics. In this area, the damned quilted jackets, as always, took the lead, and for the first time in the world they theoretically showed that a continuous delegation is generally possible. Invention, discovery, patent - all things. And they began to make a practical structure from rusty pipes and kerosene.
2. Creation constructive solutions making possible applications classic materials. Curse the quilted jackets with drunken bears, and here they were the first to come up with and make a laboratory multi-chamber engine that has already been working for an arbitrarily long time. The thrust is like that of the Su27 engine, and the weight is such that 1 (one!) grandfather holds it in his hands. But since the vodka was scorched, the engine turned out to be pulsating for the time being. On the other hand, the bastard works so cleanly that it can even be turned on in the kitchen (where the quilted jackets actually washed it down between vodka and balalaika)
3. Creation of supermaterials for future engines. This area is the tightest and most secret. I have no information about breakthroughs in it.
Based on the above, consider the prospects for detonation, piston internal combustion engine. As is known, the increase in pressure in a combustion chamber of classical dimensions during detonation in an internal combustion engine occurs faster than the speed of sound. Remaining in the same design, there is no way to make a mechanical piston, and even with significant bound masses, move in a cylinder with approximately the same speeds. The timing of the classic layout also cannot operate at such speeds. Therefore, a direct conversion of a classic ICE to a detonation one is meaningless from a practical point of view. The engine needs to be redesigned. But as soon as we start doing this, it turns out that the piston in this design is just an extra detail. Therefore, IMHO, a piston detonation ICE is an anachronism.
1The 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 ones in terms of its characteristics. jet engines. 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 the 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 of the fuel-air mixture, which it makes no sense to list here. 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 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.
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 in the total 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, the specific fuel consumption 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 studies of continuous circular detonation performed back in the 60s showed, 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 take a position corresponding to the minimum energy level. As a result, triple configurations and the detonation combustion region adjust each other under 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.
To create an efficient RDE engine, it is necessary 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"
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 detonation engines assigned big hopes? 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 the explosion, detonation of the 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.
Development and testing Russian version the detonation engine was engaged in a specialized laboratory "Detonation LRE" as part of the production complex "Energomash".
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 of the 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 a pulsed operation scheme 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. A small engine with a combustion chamber 100 mm in diameter and an annular channel width of 5 mm was presented as a prototype. The tests were carried out on a special stand, indicators were recorded when working on various types of 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 operation, such engines must have high heat resistance due to a large number released thermal energy. 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.
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 vice-premier.
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 reaching speeds of Mach 4–6 (Mach is the speed of sound) due to their own engine.
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 named after 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 was our conversation with the Deputy General Director - Chief Designer of "NPO Energomash named after Academician V.P. Glushko" 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 missiles 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 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 they did not advance further than not entirely successful experiments.
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. A large cooperation of the leading scientific centers of Russia worked on the project under the patronage of the Foundation for Advanced Study. Among them, the Institute of Hydrodynamics. M.A. Lavrentiev, MAI, "Keldysh Center", Central Institute of Aviation Motors. 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.
Can a detonation engine be used in hypersonic missiles?
Petr Levochkin: It is both possible and necessary. If only because the combustion of fuel in it is supersonic. And in those engines on which they are now trying to create controlled hypersonic aircraft, the combustion is subsonic. And this creates a lot of problems. After all, if the combustion in the engine is subsonic, and the engine flies, say, at a speed of Mach 5 (one Mach is equal to the speed of sound), it is necessary to slow down the oncoming air flow to sound mode. Accordingly, all the energy of this deceleration is converted into heat, which leads to additional overheating of the structure.
And in a detonation engine, the combustion process occurs at a speed of at least two and a half times higher than the sound speed. And, accordingly, we can increase the speed of the aircraft by this amount. That is, we are already talking not about five, but about eight swings. This is the currently achievable speed of aircraft with hypersonic engines, which will use the principle of detonation combustion.
Petr Levochkin: This is complex issue. We have just opened the door to the area of detonation combustion. There is still a lot of unexplored left outside the brackets of our study. Today, together with RSC Energia, we are trying to determine how the engine as a whole can look in the future with detonation chamber in relation to booster blocks.
On what engines will a person fly to distant planets?
Petr Levochkin: In my opinion, we will be flying on traditional LRE for a long time, improving them. Although, of course, other types of rocket engines are also developing, for example, electric rocket engines (they are much more efficient than rocket engines - their specific impulse is 10 times higher). Alas, today's engines and launch vehicles do not allow us to talk about the reality of massive interplanetary, and even more so intergalactic flights. So far, everything is at the level of fantasy: photon engines, teleportation, levitation, gravitational waves. Although, on the other hand, just a little over a hundred years ago, the writings of Jules Verne were perceived as pure fantasy. Perhaps a revolutionary breakthrough in the area where we work is not far away. Including in the field of practical creation of rockets using the energy of an explosion.
Dossier "RG":
"Scientific and Production Association Energomash" was founded by Valentin Petrovich Glushko in 1929. It now bears his name. Here they develop and produce liquid rocket engines for the I, in some cases II stages of launch vehicles. The NPO has developed more than 60 different liquid-propellant jet engines. The first satellite was launched on Energomash engines, the first man flew into space, the first self-propelled vehicle Lunokhod-1 was launched. Today, more than ninety percent of launch vehicles in Russia take off on engines designed and manufactured by NPO Energomash.
