Pulsing air jet engine for models. Jet engine with your own hands. Design valve lattices

The Liaulka's experimental design bureau has developed and experienced an experimental sample of a pulsating resonator detonation engine with a two-stage kerosene-grain mixture. According to the average measured motor thrust made up about a hundred kilograms, and the duration of continuous operation ─ more than ten minutes. Until the end of this year, the OKB intends to make and experience a full-sized pulsating detonation engine.

According to the chief designer of the OKB named after Lulleka Alexander Tarasova, during the tests, modes of work characteristic of turbojet and directional engines. The measured values \u200b\u200bof the specific thrust and the specific fuel consumption were 30-50 percent better than that of ordinary air-jet engines. During the experiments, it was repeatedly turned on and off the new engine, as well as control of thrust.

Based on the studies obtained when testing data, as well as the scheme-design analysis of the Audley OKB, intends to offer the development of a whole family of pulsating detonation aircraft engines. In particular, engines with a short resource of work can be created for unmanned aircraft and rockets and aircraft engines with a cruising supersonic flight mode.

In the future, on the basis of new technologies, engines can be created for rocket-space systems and combined power plants of aircraft capable of performing flights in the atmosphere and beyond.

According to the design bureau, new engines will increase the plot of aircraft by 1.5-2 times. In addition, when using such power plants, the flight distance or mass of aviation lesions may increase by 30-50 percent. In this case, the share of new engines will be 1.5-2 times less than the same indicator of conventional reactive power plants.

The fact that in Russia work is underway to create a pulsating detonation engine, in March 2011. This was then stated by Ilya Fedorov, managing director of the Saturn Scientific and Production Association, which includes chalki OKB. What kind of type of detonation engine was speech, Fedorov did not specify.

Currently, three types of pulsating engines ─ valve, bauble and detonation are known. The principle of operation of these power plants lies in the periodic supply to the combustion chamber of fuel and the oxidizing agent, where the fuel mixture is ignited and the exhaust of combustion products from the nozzle with formation reactive traction. The difference from conventional jet engines is the detonation combustion of the fuel mixture, in which the burning front spreads faster than the sound speed.

The pulsating air-jet engine was invented at the end of the XIX century by the Swedish engineer Martin Viberg. The pulsating engine is considered simple and cheap in the manufacture, however, due to the peculiarities of the fuel combustion ─ low-tech. For the first time, the new type of engine was used serially during World War II on German Winged Rockets FAu-1. ARGUS-WERKEN company ARGUS AS-014 was installed on them.

Currently, several large defense firms of the world are engaged in research in the field of creating highly efficient pulsating jet engines. In particular, the works are conducted by the French company Snecma and American General Electric and Pratt & Whitney. In 2012, the US Navy Research Laboratory on the intention to develop a spin detonation engine, which will have to replace ordinary gas turbine power plants on the ships.

Spin detonation engines differ from pulsating the fact that the detonation burning of the fuel mixture in them is continuously ─ the combustion front moves in the ring combustion chamber in which fuel mixture constantly updated.

The PAUD scheme is presented in Fig.3.16.

Fig.3.16.Shem pulsating air-reactive engine:

diffuser, 2-valve device; 3-nozzles; 4 - Camera combustion; 5 - nozzle; 6- exhaust pipe.

The fuel is injected through the nozzles 3, forming the fuel mixture with air compressed in the diffuser 1.

The ignition of the fuel mixture is performed in the combustion chamber 4, from the electrical candle. The combustion of the fuel mixture is injected in certain quantities, lasts hundredths of a second. As soon as the pressure in the combustion chamber becomes more air pressure in front of the valve device, the placed valves are closed. With a sufficiently large volume of nozzle 5 and exhaust pipe 6, established specifically to increase the volume, a sub-center of gases in the combustion chamber is created. During the combustion of fuel, the change in the amount of gases in the amount behind the combustion chamber is negligible, therefore it is believed that the burning goes at a constant volume.

After combustion of the fuel portion, the pressure in the combustion chamber decreases so that the valves 2 open and admit a new portion of air from the diffuser.

Figure 3.17. Presents the perfect thermodynamic cycle of pulsating VD.

P
cycle roces:

1-2 - air compression in the diffuser;

2-3 - isochhore heat supply in the combustion chamber;

3-4 - adiabatic expansion of gases in the nozzle;

4-1 - the isobaric cooling of combustion products in the atmosphere with heat removal.

Fig.3.17. Cycle PUVD.

As follows from Fig. 3.17, the Pavdi cycle does not differ from the cycle of GTU with isochorous heat supply. Then, by analogy with (3.8.) You can immediately write down the formula for the thermal efficiency of PUVD

(3.20.)

The degree of additional increase in pressure in the combustion chamber;

- The degree of increase in pressure in the diffuser.

Thus, the thermal efficiency in the pulsating BPD is greater than that of PVRs due to the greater average integral temperature of the thermal vehicle.

The complication of the design of Pavds led to an increase in its mass compared to PVRS.

3.5.3. Compressor turbojet engines (TRD)

These engines got the greatest spread in aviation. Two-stage air compression (in the diffuser and in the compressor) and two-stage expansion of the combustion of the fuel mixture (in the gas turbine and in the nozzle) occurs in the TRP.

The TRD schematic diagram is presented in Figure 3.18.

Fig.3.18. Schematic scheme The TRD and the nature of the change in the working fluid parameters in the gas-air path:

1-diffuser; 2-axis compressor; 3-combustion chamber; 4- gas turbine; 5- nozzle.

The pressure of the incident air flow is first rising in the diffuser 1, and then in the compressor 2. The compressor drive is carried out from the gas turbine 4. The fuel is fed to the combustion chamber 3, where, together with the air, it forms a fuel mixture and combusts at a constant pressure. Combustion products first expand on gas turbine blades 4, and then in a nozzle. The expiration of gases from the nozzle with a greater speed creates the force of the thrust moving the aircraft.

The perfect thermodynamic Cycle of the TRD is similar to the PVR Cycle, but is complemented by processes in the compressor and turbine (Fig.3.19).

Fig.3.19. The perfect Cycle of TRD inP.- V. diagram

Cycle processes:

1-2 - adiabatic air compression in the diffuser;

2-3 - adiabatic air compression in the compressor;

3-4 - the isobaric rise of heat from the combustion of the fuel mixture in the combustion chamber;

4-5 - adiabatic expansion of combustion products on turbine blades;

5-6 - adiabatic expansion of combustion products in the nozzle;

6-1 - cooling of combustion products in the atmosphere at a constant pressure with recycling of heat.

Thermal efficiency is determined by Formula (3.19):

(3.21.)

- the resulting degree of increase in air pressure in the diffuser and compressor.

Due to the higher than that of the PVRS, the CDR compression degree has a higher thermal efficiency. Without any start-up accelerators, the TRD develops the necessary thrust for the start.

The pulsating air jet engine (PAUD) is one of the three main varieties of air-jet engines (VDD), the feature of which is a pulsating mode of operation. Pulsation creates a characteristic and very loud sound, which is easy to find out these motors. In contrast to other types power aggregates Pavda has the most simplified design and low weight.

Building and principle of action of PAUD

The pulsating air jet is a hollow channel, open from two sides. On the one hand, an air intake is installed at the entrance, behind it - a traction unit with valves, then there is one or more combustion chambers and nozzle through which the jet stream comes out. Since the operation of the engine is cyclical, it is possible to allocate its main tacts:

• inlet tact, during which the input valve opens, and the air is inserted into the combustion chamber under the action of discharge. At the same time, fuel is injected through the nozzles, as a result of which the fuel charge is formed;
• the resulting fuel charge flammives from the spark of the spark plug, gases are formed during the combustion high pressureunder the action of which the intake valve is closed;
• with the valve closed, the combustion products go through the nozzle, providing reactive traction. At the same time, in the combustion chamber at the exhaust of the exhaust gases, the discharge is formed, the input valve automatically opens and admits inside the new air portion.

The engine input valve may have different designs and appearance. Alternatively, it can be made in the form of blinds - rectangular plates fixed on the frame, which are opened and closed under the action of the pressure drop. Another design has a flower shape with metal "petals", located in a circle. The first option is more efficient, but the second is more compact and can be used on small-scale structures, for example, with aircodellize.

Fuel supply is carried out by nozzles that have a check valve. When the pressure in the combustion chamber decreases, a portion of fuel is supplied, when the pressure increases due to the combustion and expansion of gases, the fuel supply is stopped. In some cases, for example, on low-power motors from aircamodes, nozzles may not be, and the fuel supply system is reminded by a carburetor engine.

The ignition candle is located in the combustion chamber. It creates a series of discharges, and when the concentration of fuel in the mixture reaches the desired value, the fuel charge flames. Since the engine has a small size, its walls, made of steel, in the process of work are quickly heated and can fuel the fuel mixture is not worse than the candle.

It is not difficult to understand that for the launch of PUVD, you need an initial "push", in which the first portion of the air will fall into the combustion chamber, that is, such engines need pre-acceleration.

History of creation

The first officially registered development of PAUD refers to the second half of the XIX century. In the 1960s, two inventors immediately managed to get patents to a new engine type. Names of these inventors - Telshov N.A. And Charles de Lumury. At that time, their development was not widely used, but at the beginning of the twentieth century, when a replacement was found for aircraft piston enginesGerman designers drew attention to Pavdde. During World War II, the Germans were actively used by the FAU-1 aircraft, equipped with Pavda, which was explained by the simplicity of the construction of this power unit and its low cost, although on its working characteristics he was inferior to even piston engines. It was the first and only time in history when this type of engine was used in mass production aircraft.

After the end of the war, PUVD remained "in military affairs", where they found the use as a power unit for the air-surface type missiles. But here over time they have lost their positions due to speed limitations, the need for initial overclocking and low efficiency. Examples of using PUVD are Rockets FI-103, 10X, 14X, 16X, JB-2. IN last years There is a renewal of interest in these engines, new developments aimed at its improvement appear, so that in the near future, PUVD will again become in demand in military aviation. At the moment, the pulsating air-jet engine is returned to life in the field of modeling, thanks to the use of modern structural materials.

Features Pavd

The main feature of Pavdards, which distinguishes it from its "closest relatives" of turbojet (TRD) and direct-flow air-reactive motor (PVRD), is the presence of an intake valve in front of the combustion chamber. It is this valve that does not pass back the products of combustion, determining their direction of movement through the nozzle. In other types of motors, there is no need for valves - there air enters the combustion chamber under pressure due to pre-compression. This, at first glance, a minor nuance plays a huge role in the work of Pavds from the point of view of thermodynamics.

The second difference from the TRD is cyclicality. It is known that in the TRD, the process of burning fuel passes almost continuously, which provides even and uniform reactive traction. Pavdde works cyclically, creating oscillations inside the design. To achieve maximum amplitude, it is necessary to synchronize the oscillations of all elements, which can be achieved by selecting the desired nozzle length.

In contrast to the direct-flow air jet engine, the pulsating air jet engine can work even at low speeds and being in a fixed position, that is, when there is no oncoming air flow. True, his work in this mode is not able to provide the magnitude of the reactive thrust required for the start, therefore aircraft and rockets equipped with PUVDs need initial acceleration.

Small video launches and works Pavd.

Types of Pavd

In addition to the usual Pavdde in the form of a straight-line channel with an inlet valve, which was described above, there are also its varieties: bauble and detonation.

Bindless PUVD, as it is clear by his name, does not have an inlet valve. The reason for its appearance and use was the fact that the valve is a rather vulnerable part, which is very quickly fail. In the same version, the "weak link" is eliminated, therefore the service life is extended. The design of the balanced Pavdde has the shape of the letter U with the ends, directed back along the reactive thrust. One channel is longer, he "answers" for the craving; The second is shorter, it enters the air into the combustion chamber, and when combustion and expansion of working gases, part of them goes through this channel. This design allows the best ventilation of the combustion chamber, does not allow the fuel charge leakage through the inlet valve and creates an additional, albeit insignificant, craving.

without a clapping version of the execution of PUVD
without valve U-shaped PURVD

The detonation Pavda implies the burning of the fuel charge in the detonation mode. Detonation involves a sharp increase in the pressure of combustion products in the combustion chamber at a constant volume, and the volume itself increases already when the gas moves along the nozzle. In this case, the thermal increases Efficiency engine In comparison, not only with the usual PAUD, but also with any other engine. At the moment, this type of motors is not used, but is at the stage of development and research.

detonation PURVD

Advantages and disadvantages of Pavdde, scope of application

The main advantages of pulsating air jet engines can be considered their simple design, which pulls their low cost. It is these qualities that caused their use as force aggregates on military rockets, unmanned aircraft, flying targets, where there are not durability and ultra-speed, but the ability to install a simple, light and cheap motor capable of developing the desired speed and deliver an object to the target. The same qualities brought PUUL's popularity among aircraft carrier lovers. Lightweight and compact engines, which, if desired, can be made independently or buy at an affordable price, are well suited for aircraft models.

The disadvantages of the PAUD is a lot: an increased level of noise when working, uneconomic fuel consumption, incomplete combustion, limited speed, vulnerability of some structural elements, the same as the inlet valve. But, despite such an impressive list of minuses, PUVD is still indispensable in their consumer niche. They are the perfect option for "disposable" purposes, when there is no point in setting more efficient, powerful and economical power units.

Testing of the detonation engine

FPI_RUSSIA / VIMEO.

The Specialized Laboratory "Detonational Easpresentation" of the Energomash Scientific and Production Association conducted tests of the world's first full-size demonstrators of the technologies of the detonation liquid rocket engine. According to TASS, new power plants work on fuel pare. Oxygen-kerosene.

New engine, unlike other power plants working on the principle internal combustion, functions due to detonation of fuel. Detonation is the supersonic combustion of any substance, in this case of the fuel mixture. In this case, the mixture spreads the shock wave, followed by a chemical reaction with highlighting a large amount of heat.

The study of the principles of work and the development of detonation engines is carried out in some countries of the world for more than 70 years. The first such works began in Germany in the 1940s. True, then the working prototype of the detonation engine researchers failed to create, but the pulsating air-jet engines were developed and serially produced. They put on the Rockets "Fau-1".

In pulsating air-jet engines, fuel combed with a subsonic speed. Such burning is called a deflagration. A pulsating engine is called because in its combustion chamber, the fuel and oxidizer were fed into small portions at equal intervals.

Pressure map in the combustion chamber of the rotary detonation engine. A - detonation wave; B - the rear front of the shock wave; C is a mixture zone of fresh and old combustion products; D - filling area with fuel mixture; E is an area of \u200b\u200buncompaired burnt fuel mixture; F - Expansion zone with a downstream 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 those in pulsating air-jet engines. The main difference lies in the detonation combustion of the fuel mixture in the combustion chamber.

In rotary detonation engines, an annular combustion chamber is used, in which the fuel mixture is fed sequentially through the radially located valves. In such power plants, detonation does not fade - the detonation wave "cuts" the ring chamber of combustion, the fuel mixture has time to upgrade. The rotary engine was first started to study in the USSR in the 1950s.

Detonation engines are capable of working in a wide range of flight rates - from zero to five Maha numbers (0-6.2 thousand kilometers per hour). It is believed that such power plants can produce greater power, consuming fuel less than ordinary jet engines. At the same time, the design of detonation engines is relatively simple: there is no compressor and many moving parts.

All detonation engines experienced so far developed for experimental aircraft. Tested in Russia such a power plant is the first intended for installation on the rocket. What kind of type of detonation engine was tested, not specified.

At the end of January, reports of new successes of Russian science and technology appeared. From official sources it became known that one of the domestic projects of a promising jet engine of detonation type has already passed the test stage. This brings the moment of complete completion of all required works, based on the results of which cosmic or military rockets of Russian development will be able to obtain new power plants with increased characteristics. Moreover, new principles of engine operation can be used 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 Patriotic Press on the latest success of research organizations. Among the other, he touched upon the process of creating jet engines using new principles of work. A promising engine with detonation burning has already been brought to the test. According to the vice-premier, the application of new work principles power plant Allows you to get a significant increase in characteristics. In comparison with the constructs of traditional architecture, there is an increase in thrust of about 30%.

Scheme of detonation rocket engine

Modern rocket engines of different classes and types operated in various fields are used by the so-called. Isobaric cycle or deflagration burning. In their combustion chambers, constant pressure is maintained, in which slow fuel burning occurs. The engine on the deflagration principles does not need particularly durable units, but is limited in maximum indicators. Increasing the main characteristics, starting from a certain level, it turns out to be unreasonably complex.

An alternative to the engine with an isobaric cycle in the context of improving the characteristics - the system with the so-called. detonation burning. In this case, the fuel oxidation reaction occurs behind the shock wave, with a high speed moving along the combustion chamber. This makes special requirements for the engine design, but it gives obvious advantages. From the point of view of the efficiency of combustion of fuel, detonation burning is 25% better than the deflagration. Also differs from burning with a constant pressure of the increased power of heat dissipation from the unit of the surface of the reaction front. In theory, it is possible to increase this parameter by three or four orders. As a result, the speed of jet gases can be increased by 20-25 times.

Thus, the detonation engine, differing in an increased efficiency, is able to develop a large thrust with less fuel consumption. Its advantages over traditional designs are obvious, however, until recently, progress in this area left much to be desired. The principles of the detonation jet engine were formulated back in 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 the creation of a sufficiently strong design, as well as the complexity of the launch and subsequent maintenance of the shock wave when applying existing fuels.

One of the last domestic projects in the field of detonation rocket engines Started in 2014 and is being developed in NGO "Energomash" them. Academician V.P. Glush. According to the available data, the goal of the project with the "Iphret" cipher was to study the basic principles of new techniques, followed by the creation of a liquid rocket engine using kerosene and gas oxygen. The basis of the new engine called by the name of fiery demons from Arab Folklore, the principle of spin detonation burning was laid. Thus, in accordance with the main idea of \u200b\u200bthe project, the shock wave should continuously move in a circle inside the combustion chamber.

The head developer of the new project was NGO Energomash, and more precisely created on its base a special laboratory. In addition, several other research and design organizations were attracted to the work. The program has supported the promising research fund. All participants in the project "Iphret" were able to form the optimal look of a promising engine, as well as create a model combustion chamber with new principles of work.

To explore the prospects for the entire direction and new ideas a few years ago, the so-called was built. Model detonation combustion chamber corresponding to the project requirements. Such an experienced engine with an abbreviated package was supposed to be used as a fuel liquid kerosene. As an oxidant was offered gas oxygen. In August 2016, the test chamber began. It is important that for the first time in the project of this kind, it was possible to bring to the stage of poster checks. 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, through the use of the right materials and technologies, it turned out the pressure inside the combustion chamber to 40 atmospheres. The thrust of the experienced product reached 2 tons.

Model camera on a test bench

Within the framework of the "Iphret" project, certain results were obtained, but the domestic detonation engine on liquid fuel is still far from full-fledged practical application. Before introducing such equipment to new projects, designers and scientists have to solve a number of most serious tasks. Only after this, the rocket-space industry or defense industry will be able to begin the implementation of the potential of new techniques in practice.

In mid-January, the Russian Gazeta published an interview with the chief designer NPO "Energomash" by Peter Levochkin, the theme of which was the current state of affairs and the prospects for detonation engines. The representative of the developer's enterprise recalled the main provisions of the project, and also touched upon the topic of success achieved. In addition, he spoke about the possible areas of use of "Iphritis" and similar designs.

For example, detonation engines can be used in hypersonic aircraft. P. Levochkin reminded that the engines are now proposed for use on this technique, use subsonic combustion. With the hypersonic velocity of the flight apparatus, the air entering the engine must be braked to the sound mode. However, braking energy should lead to additional thermal loads on the glider. In detonation engines, the fuel combustion rate reaches at least m \u003d 2.5. Due to this, it becomes possible to increase the speed of the flight machine. A similar machine with a detonation type engine will be able to accelerate up to speeds, eight times higher than the speed of the sound.

However, the real perspectives of the detonation rocket engines are not too large. According to P. Levochka, we "only opened the door to the detonation burning area." Scientists and designers will have to study many questions, and only after that it will be possible to create structures with practical potential. Because of this space industry, the liquid engines of the traditional design will have long to be used, which, however, does not cancel the possibilities of their further improvement.

Interesting is the fact that the detonation principle of combustion finds the use of not only in the sphere of rocket engines. There is already a domestic project of the aviation system with a detonation combustion chamber operating on a pulse principle. An experienced sample of this kind was brought to the test, and in the future it can give a new direction. New detonation combustion engines can be used in a variety of spheres and partially replace gas turbine or turbojet engines of traditional designs.

The domestic project of the detonation aviation engine is developed in the OKB. A.M. Cradle. Information about this project was first presented at last year's International Military Technical Forum "Army 2017". At the booth of the company-developer, there were materials on various enginessuch as serial and under development. Among the latter was a promising detonation sample.

The essence of the new proposal is to apply a non-standard combustion chamber capable of carrying out the impulse detonation combustion of fuel in the 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 some interest.

First launch of an experienced product "Iphret"

However, the main advantages of the new power plant are associated with elevated characteristics. Bent tests of experienced products showed that they are about 30% superior to traditional gas turbine engines According to specific indicators. By the time of the first public demonstration of materials on the engine of the OKB. A.M. Cradles could get and high enough performance features. An experienced engine of a new type was able to work for 10 minutes without a break. The total operation of this product on the stand at that time exceeded 100 hours.

Representatives of the developer's enterprise pointed out that now you can create a new detonation engine with a 2-2.5 taway tape, 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. Resonator devices responsible for the correct fuel combustion course. An important advantage of the new project is the principal possible installation of such devices anywhere in the glider.

Specialists of the OKB. A.M. The crackers work on aircraft engines with impulse detonation burning of more than three decades, but while the project does not come out of the research stage and does not have real prospects. The main reason is the lack of order and the necessary funding. If the project gets the necessary support, then in the foreseeable future, an engine sample suitable for use on various techniques can be created.

To date, Russian scientists and designers have managed to show very remarkable results in the field of jet engines using new principles of operation. There are several projects suitable for use in rocket and space and hypersonic areas. In addition, new engines can be applied in the "traditional" aviation. Some projects are still in early stages and are not yet ready for checks and other work, while in other directions the most remarkable results were already obtained.

Exploring the subject of jet engines with detonation burning, Russian experts were able to create a stand model sample combustion chamber with the desired characteristics. The experienced product "Iphret" has already passed the test, during which a large number of diverse information was collected. Using the obtained data, the development of the direction will continue.

The development of the new direction and the translation of ideas in almost applicable form will take a lot of time, and for this reason, in the foreseeable future, space and army missiles in the foreseeable future will be equipped with only traditional liquid engines. Nevertheless, the work has already come out of a purely theoretical stage, and now each test launch of an experimental engine brings the moment of construction of full missile with new power plants.

According to the materials of sites:
http://engine.space/
http://fpi.gov.ru/
https://rg.ru/
https://utro.ru/
http://tass.ru/
http://svpressa.ru/