Hypersonic Detonation Engine -- E.-Y. JANG, et al. / Beijing Power Machinery Research Institute

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Zhang YINING, et al.
Hypersonic Detonation Engine

https://www.scmp.com/news/china/science/article/3246361/revolutionary-design-chinese-scientists-invent-most-powerful-detonation-engine-hypersonic-flight?module=inline&pgtype=article
‘Revolutionary’ design: Chinese scientists invent the most powerful detonation engine for hypersonic flight

Hypersonic weapons researchers say they have an unprecedented power solution for aerospace planes. Paper says design integrating rotational and straight-line detonation across a wide speed range is ‘world first’ and testament to Chinese ingenuity...

https://www.nextbigfuture.com/2023/12/china-makes-most-powerful-detonation-engine-for-hypersonic-flight.html
China Makes Most Powerful Detonation Engine for Hypersonic Flght
by Brian Wang

...The “revolutionary” air-breathing engine could lift an aircraft from a runway to more than 30km (18.6 miles) into the stratosphere and continuously accelerate it to 16 times the speed of sound. The longest intercontinental flights would take just one or two hours while consuming less fuel compared with conventional jet engines.

The engine blueprint was detailed in a peer-reviewed paper published in the Chinese Journal of Propulsion Technology in December by a team led by Zhang Yining with the Beijing Power Machinery Institute.

According to the China research paper, the engine operates in two distinct modes: below Mach 7 speed, it functions as a continuous rotating detonation engine.

Air from the outside mixes with fuel and is ignited, creating a shock wave that propagates in an annular, or ring-shaped, chamber. The shock wave ignites more fuel during rotation, providing a powerful and continuous thrust for the aircraft.

Above Mach 7, the shock wave stops rotating and focuses on a circular platform at the engine’s rear, maintaining thrust through a nearly straight-line oblique detonation format, according to the paper.

The fuel auto-detonates as it reaches the rear platform because of the very high speed of incoming air. Throughout its operation, the engine relies on detonation as its primary driving force.

Zhang and his colleagues did not disclose the efficiency of the engine in their paper. However, based on previous scientific estimates, the explosion of combustible gases can convert nearly 80 per cent of chemical energy into kinetic energy. Conventional turbofan engines, which rely on slow and gentle combustion, achieve 20-30 per cent efficiencies.

In 2021, University of Florida researchers also had a paper on ways to stabilize the detonation needed for hypersonic propulsion by creating a special hypersonic reaction chamber for jet engines. The system could allow for air travel at speeds of Mach 6 to 17, which is more than 4,600 to 13,000 miles per hour. The technology harnesses the power of an oblique detonation wave, which they formed by using an angled ramp inside the reaction chamber to create a detonation-inducing shock wave for propulsion. Unlike rotating detonation waves that spin, oblique detonation waves are stationary and stabilized.

Publicly available information indicates that the Beijing Power Machinery Institute is China’s largest manufacturer of ramjet engines, supplying propulsion systems for the country’s most advanced weapons, including hypersonic missiles.

The PLA’s 93160 unit, headquartered in Beijing and deeply involved in designing the new detonation engine, remains shrouded in secrecy with no publicly available information.

Zhang’s team said the new detonation engine transition was a challenge between the two operating modes: as the speed approached Mach 7, the rotating detonation mode became unsustainable, and the oblique detonation mode had to be ignited within a short time.

The authors said possible solutions to the problem include reducing the incoming air speed from Mach 7 to Mach 4 or lower to allow the fuel to heat sufficiently for auto-ignition.

Slight adjustments to the engine’s internal structure, such as the diameter of the circular platform and the angle of the shock wave tilt, could affect engine performance.

Overall, the engine was not too demanding on operating conditions and could work efficiently in most typical scenarios, they said.

However, the researchers said that relying solely on the paper was not sufficient to produce a practically usable product because they had omitted critical parameters for engineering applications, such as the limited space available for air flow path...

Patents

https://worldwide.espacenet.com/advancedSearch?locale=en_EP

CN116104664 (A) -- Combined detonation engine and design method [ PDF ]
Applicant: BEIJING POWER MACHINERY RES INST

The invention provides a combined detonation engine and a design method, the combined detonation engine comprises an inner column and a shell, an adjustable boss structure is arranged on the inner column, the adjustable boss structure is composed of at least two adjustable grading structures, the length of each adjustable grading structure is sequentially increased in the incoming flow direction, and in the rotating detonation combustion mode, the length of the adjustable grading structures is larger than that of the adjustable grading structures. The inclination angles of the adjustable grading structures are consistent, and the inclination angles of all the adjustable grading structures are sequentially reduced in the incoming flow direction in the inclined detonation combustion mode. A unique design thought is adopted, so that the combined detonation engine gives consideration to both a rotating detonation combustion mode and an inclined detonation combustion mode.
Technical field

The invention relates to a combined detonation engine and a design method, and belongs to the technical field of detonation engines.

Background technique

As humans further explore the space and space, it is an inevitable trend for future development for aircraft to achieve faster speeds, achieve more functions, and be used in more different fields.

However, the development of aircraft in the direction of "large airspace and wide speed domain" is restricted by the power system.

Although traditional rocket engines can achieve full-speed flight, they need to carry oxidizer, which greatly reduces the payload. For traditional turbine engines and ramjet engines, the combustion chamber is long, the engine size and structural mass are large, which greatly increases the internal flow channel. The loss of frictional resistance and the difficulty of large-area thermal protection greatly weaken the possibility of the aircraft flying to higher altitudes and faster speeds.

There are two forms of combustion waves in nature, namely slow combustion and detonation.

The more common one is slow-ignition combustion. The propagation of flame depends on the diffusion of mass and heat. The propagation speed is generally several meters to tens of meters per second.

At present, most aerospace power devices (turbine engines, ramjet engines) use an isobaric mode based on slow combustion to organize combustion. Detonation is a combustion method in which shock waves are strongly coupled with chemical reactions and propagate at supersonic speeds of the order of kilometers per second. It can complete the release of fuel chemical energy in a short time and space scale. It has the characteristics of supersonic propagation, self-pressurization and release. Features of fast heating speed. Compared with isobaric combustion, the use of detonation combustion can increase the thermal efficiency of the power system cycle by more than 30% and reduce the fuel consumption rate by more than 30%. It can greatly improve the fuel economy of the engine and is more suitable for use in air-breathing power efficient combustion organizations. At present, power devices based on detonation combustion mainly include pulse detonation engines, rotating detonation engines, and oblique detonation engines. Among them, rotating detonation engines have a wide range of working capabilities from Ma2.5 to Ma6.5+ and a specific impulse performance of Compared with traditional ramjet engines, it can be increased by 30% to 50%, with continuous air intake and compact structure. The oblique detonation engine has a wide operating capability of Ma6.5~Ma15+. Its combustion chamber has a low static temperature, leaving a larger temperature difference space for the release of fuel chemical energy. The engine can work in a wide range of oil-gas ratio, and the thrust adjustment range is large, and The small size of the oblique detonation engine combustion chamber can effectively reduce friction loss and thermal protection difficulty. In addition, due to the fast oblique detonation combustion rate, it can stationary combustion in hypersonic airflow, which provides a feasible way to realize the air-breathing power operation process and improve performance at higher Mach numbers. Judging from the current oblique detonation engine combustion chamber configuration, it mainly relies on binary physics oblique splitting to induce oblique detonation waves. In addition, there is also related research on the cone-induced "conical oblique detonation wave", but it is still far from engineering practice. Big gap.

For future aerospace power, combined engines can significantly expand the working range of traditional single-type engines, which is the development trend of power systems.

The current aerospace power combination schemes generally include parallel type and series type. The two flow channels of the parallel combination engine work independently and do not affect each other. However, it has many problems such as heavy structural weight and low engine thrust-to-weight ratio. For structural design brought additional burden. For the series combination engine, it can achieve mutual conversion of multiple modes in one flow channel. However, since different modes in the same flow channel are prone to mutual influence, the design is extremely difficult. Taken together, the current combined power solution has a complex structure and is difficult to achieve ultra-wide-area flight.

Detonation engines based on detonation combustion are the future development trend of aerospace power due to their high performance and small size. However, there is currently no combined power solution based entirely on detonation combustion for ultra-wide-area flight.

The reason is, first of all, the huge difference in the configuration of the combustion chamber flow channels between the two: the principle of the rotating detonation engine is that after the explosive mixture formed by the fuel and the oxidizer is detonated, a detonation wave is formed in the head of the combustion chamber that rotates and propagates in the circumferential direction. , so the combustion chamber of the rotating detonation engine must be an axisymmetric annular flow channel. The principle of the oblique detonation engine is mainly that the supersonic combustible mixture forms an oblique shock wave on the surface of the detonator and induces combustion. Then the combustion wave and the oblique shock wave quickly couple to form an oblique detonation wave and settle in the high-speed airflow. At present, most combustion chambers of oblique detonation engines use binary oblique splitting to induce oblique detonation waves. However, there has been no relevant research on whether oblique detonation combustion can be organized in the annular cavity and the oblique detonation waves can be stationary. The complex differences in flow channel structures have led to very slow progress in the current research on combined power solutions based entirely on high-efficiency detonation combustion. In addition, detonation combustion is supersonic combustion with extremely fast heat release rate. Different detonation combustion forms are applicable to very different incoming flow conditions. Under the "connection conditions" (Ma6~Ma7), two kinds of detonation combustion are achieved. Full coverage and successful conversion of modalities have become a major difficulty. For rotational detonation, the flight conditions of Ma6 to Ma7 correspond to high total temperature, total pressure, and high inflow velocity. At this time, the problem of self-sustained propagation of rotational detonation waves will be encountered: the propagation process of the detonation wave itself is unstable. , its velocity will fluctuate periodically, and due to the mixing of fuel and oxidizer and the uneven supersonic flow, it may also cause unstable propagation of detonation waves. For example, the number of wave heads and propagation direction change during the propagation process, the detonation wave is extinguished and Redetonation, etc. (Feng Zixuan, Wang Aifeng, Yao Xuanyu, etc., Research Progress of Detonation Engines [J], Gas Turbine Test and Research, 2018, 31(04): 46-52). The high inflow velocity will make it difficult for the inherently unstable rotational detonation wave to propagate self-sustainably in the annular cavity. For oblique detonation combustion, the fundamental reason for oblique detonation propulsion is that the high-speed incoming flow suppresses the uploading of the detonation wave, while the existence of the wedge surface in ordinary oblique detonation engines plays a role in continuous ignition and flame stabilization (Teng Hong Hui, Jiang Zonglin, Research progress on multi-wave structure and stability of oblique detonation [J], Progress in Mechanics, 2020, 50(00): 50-92). The flight conditions of Ma6~Ma7 are low Mach number conditions for oblique detonation, corresponding to low inflow velocity and total inflow temperature. After the intake air is compressed, the static temperature before oblique detonation is low and it is difficult to realize the detonation wave. Ignition and detonation; the low incoming flow velocity causes the chemically appropriate ratio of the flow velocity to be smaller than the CJ velocity of the mixture at this time. After detonation, the detonation wave will also propagate forward without being able to settle (Miao Shikun, oblique detonation shock wave in supersonic airflow Research on structure and stationary characteristics[D]. National University of Defense Technology, 2018). Therefore, in the connecting working condition, the oblique detonation mode will encounter the problem that the oblique detonation wave is difficult to detonate and is difficult to settle. Therefore, how to solve the transition and conversion of the two combustion modes under connecting working conditions has become the top priority of research work.

Contents of the invention

The purpose of the present invention is to overcome one of the shortcomings of the prior art and provide a combined detonation engine and a design method.

Technical solution of the present invention: a method for designing a combined detonation engine. The combined detonation engine includes an inner column and a casing. An annular flow channel is formed between the inner column and the casing. It is characterized in that: the rear part of the inner column is provided Adjustable boss structure, the design of adjustable boss structure includes the following steps,

Determine the structure and series of the adjustable boss structure,

The adjustable boss structure is composed of no less than two adjustable hierarchical structures. Along the incoming flow direction, the length of each adjustable hierarchical structure increases sequentially. In the rotating detonation combustion mode, each of the adjustable boss structures The inclination angles of the adjustable hierarchical structures are consistent, and a rotating detonation nozzle throat is formed between the end of the adjustable boss structure and the shell. In the oblique detonation combustion mode, the inclination angles of each adjustable hierarchical structure are adjusted along the incoming flow direction. , the inclination angle of each adjustable hierarchical structure decreases in turn;

Determine the initial values of the length and inclination angle of the adjustable hierarchical structures at each level;

At the second Mach number, numerical simulation of oblique detonation is performed to optimize the inclination angle and length of the adjustable hierarchical structure at each level, and obtain the optimal length of the adjustable hierarchical structure at each level and the optimal adjustable hierarchical structure at each level related to the Mach number. graded structure inclination;

At the first Mach number, according to the length of the adjustable hierarchical structure at each level, a numerical simulation of rotating detonation is performed to obtain the height of the nozzle throat in the rotating detonation combustion mode, thereby determining the inclination angle of the adjustable boss structure;

At the third Mach number, a numerical simulation of oblique detonation is performed to determine the inclination angles of the adjustable hierarchical structures at each level related to the Mach number in the oblique detonation combustion mode.

A combined detonation engine obtained using any of the above design methods.

The beneficial effects of the present invention compared with the prior art:

(1) The present invention adopts a unique design idea to enable the combined detonation engine to take into account both rotational detonation and oblique detonation combustion modes;

(2) The present invention not only obtains the structural parameters of the structure, but also obtains the adjustable boss structure under different detonation modes and the inclination change of the adjustable boss structure during the detonation mode conversion, which provides the basis for subsequent combined detonation engine work. Provide parameter support;

(3) The present invention utilizes the unique advantages of detonation combustion and combines the two modes of rotational detonation and oblique detonation to significantly broaden the speed and airspace of the engine, shorten the engine size, greatly increase the engine payload, and achieve coverage of ( Ma2.5～15+) ultra-wide-area flight;

(4) The present invention uses a power combination based on detonation combustion to make the combustion chamber compact in structure and small in size. In the flow channel, the adjustable boss is used to meet the requirements of the rotating detonation combustion mode Rafal nozzle, and is also used for For the triggering of oblique detonation combustion, the combination scheme design has a simple structure and does not require additional structures in the flow channel, effectively solving the problems of thermal protection and combustion resistance at high Mach numbers;

(5) The "truncated cone type" oblique detonation combustion organization scheme of the present invention can realize the adaptation and transition to the rotating detonation combustion chamber, realize two different detonation combustion modes in the same flow channel, and realize the rotating detonation combustion chamber. Mode conversion between shock and oblique detonation;

(6) The present invention adopts a multi-stage "truncated cone-shaped" detonation configuration, which solves the problem of difficulty in detonating and settling the oblique detonation wave at low Mach number, and can realize that both detonation combustion modes can be stable under transition conditions. work, while reducing the height of the flow channel, ensuring the feasibility of the rotating detonation flow channel and reducing the size of the engine.

Description of drawings

Figure 1 is a schematic diagram of the rotating detonation combustion mode flow channel of the present invention (the end of the inner column is a pointed cone structure), in which I is the compression section of the inlet, 1 is the inlet, 3 is the nozzle, 4 is the inner column, 5 is the shell, 2 is the rotating detonation mode combustion chamber, 21 is the fuel injection area, 22 is the annular combustion chamber section, and 23 is the area in front of the throat of the rotating detonation nozzle;

Figure 2 is a schematic diagram of the rotational detonation and oblique detonation transition and oblique detonation combustion mode combustion chamber of the present invention (partially, the end of the inner column is a truncated cone structure), in which 3 is the nozzle, 4 is the inner column, 5 is the outer shell, 21 is the fuel injection area, 22' is the oblique detonation fuel mixing section, and 23' is the oblique detonation induced detonation area (the flow channel here is the oblique detonation mode combustion chamber 2');

Figure 3 is a schematic diagram of the inner column structure in Figure 2 (removing the front rectifying cone), in which 42 is the middle cylindrical section, 43 is the adjustable boss structure, and 44 is the end contraction structure;

Figure 4 is a schematic diagram of the profile structure of the adjustable boss structure of the present invention (inner column structure form in Figure 2). Figure 4a shows the rotational detonation combustion mode, in which 44 is the end contraction structure and 43 is the adjustable boss structure ( There is no classification in the rotating detonation combustion mode, and all stages have the same inclination angle). Figure 4b shows the oblique detonation combustion mode, in which 44 is the terminal contraction structure, 431 and 432 are the first and second-stage adjustable classification structures. 431 and 432 constitute a two-stage detonation device in oblique detonation combustion mode;

Figure 5 shows the adjustment mechanism of the adjustable boss structure and the end contraction structure of the present invention;

Figure 6 shows the simulation calculation and verification results of downslope detonation combustion in a typical "connection working condition" (Ma6.5) verified by the embodiment of the present invention;

Figure 7 is a design flow chart of the present invention.

Detailed ways

The present invention will be described in detail below with reference to specific examples and drawings.

As shown in Figures 1 and 2, the present invention provides a combined detonation engine, which includes an inner column 4 and an outer shell 5. An annular flow channel is formed between the inner column 4 and the outer shell 5, including an intake passage, a combustion chamber and a nozzle. As the flight Mach number continues to increase, the combined detonation engine realizes the transition between the rotating detonation combustion mode and the oblique detonation combustion mode by adjusting the annular flow channel.

The combustion mode of the combined detonation engine of the present invention includes a rotating detonation combustion mode and an oblique detonation combustion mode.

The rotating detonation combustion mode is shown in Figure 1. The annular flow channel includes the intake passage 1, the rotating detonation mode combustion chamber 2 and the nozzle 3.

The rotating detonation mode combustion chamber 2 includes a fuel injection area 21, an annular combustion chamber section 22 and a rotating detonation nozzle throat front area 23.

The oblique detonation combustion mode is shown in Figure 2. The annular flow channel includes the inlet passage, the fuel injection area 21, and the oblique detonation fuel mixing section 22' (the annular combustion chamber section 22 in the rotating detonation combustion mode) and oblique detonation induced detonation area 23′ (oblique detonation mode combustion chamber 2′) and nozzle 3.

The present invention realizes the conversion of combustion mode by adjusting the structure of the rear section of the inner column and adjusting the annular flow channel.

As shown in Figures 1, 2, and 3, the inner column includes a front rectifying cone, a middle cylindrical structure 42, a rear adjustable boss structure 43, and an end contraction structure 44.

The adjustable boss structure 43 is composed of no less than two adjustable hierarchical structures. The inclination angle of each adjustable hierarchical structure is adjustable. Along the direction of flow, the length of each adjustable hierarchical structure increases sequentially. Each adjustable hierarchical structure has It is a circular cone structure.

Preferably, the adjustable boss structure is 2 to 3 levels.

Further preferably, the length of the first-level adjustable hierarchical structure ranges from 0.05D to 0.15D, and the length of the last-level adjustable hierarchical structure ranges from 0.3D to 0.5D. D is the diameter of the cylindrical structure 42 in the middle of the inner column.

As shown in Figure 4a, in the rotating detonation combustion mode, the adjustable boss structure 43 is a primary structure, that is, the inclination angles of all the adjustable hierarchical structures of the adjustable boss structure 43 are the same, and the adjustable boss structure 43 It is a circular cone structure, and a rotating detonation nozzle throat is formed with the housing 5 at the end of the adjustable boss structure 43.

In the transition stage from the rotating detonation combustion mode to the oblique detonation combustion mode, that is, the transition mode, the adjustable boss structure transforms from a one-level structure to a multi-level structure. The inclination angle is adjusted, and along the direction of the incoming flow, the inclination angle of each adjustable hierarchical structure decreases successively.

Further preferably, in the transition mode, the inclination angle range of the first-stage adjustable hierarchical structure is 40°~50°, the length range is 0.05D~0.15D, and the inclination angle range of the last-stage adjustable boss structure is 25°~35 °, the length range is 0.3D~0.5D, and D is the diameter of the cylindrical structure 42 in the middle of the inner column.

In the oblique detonation combustion mode, the adjustable boss structure is a multi-stage structure. Along the direction of the incoming flow, the length of each level of the adjustable hierarchical structure increases and the inclination angle decreases.

Preferably, the inclination angle range of the first-stage adjustable hierarchical structure is 30°-40°, and the length range is 0.05D-0.15D, and the inclination angle range of the last-stage adjustable boss structure is 15°-30°, and the length range is 0.3 D～0.5D.

The specific number of stages, inclination angles of each stage, length, etc. of the present invention are selected according to the requirements for detonation and settling of the oblique detonation wave in the annular combustion chamber.

Taking the two-stage adjustable boss structure as an example, as shown in Figure 1, when the flight Mach number is between Ma2.5 and Ma6, the engine is in the rotating detonation combustion mode, and the adjustable boss structure 43 of the inner column serves as a rotating The throat of the Rafal nozzle in the detonation combustion chamber is a one-stage structure with the same angle in both stages. The specific nozzle throat size can refer to the traditional sub-fuel ramjet engine nozzle design method.

As the flight Mach number gradually increases to the second Mach number (Ma6~Ma7), the engine is in the transition mode, and the engine is in the "truncated cone-shaped" oblique detonation combustion mode, and the adjustable boss structure serves as the detonator for oblique detonation combustion. The induction mechanism is an adjustable and variable structure.

As shown in Figure 2, the adjustable boss structure 43 of the inner column is composed of a first-level adjustable hierarchical structure 431 and a second-level adjustable hierarchical structure 432.

The 431 inclination angle of the first-stage adjustable hierarchical structure is increased, the 432 inclination angle of the second-stage adjustable hierarchical structure is reduced, and the nozzle expansion ratio is increased.

Preferably, the inclination angle α1 of the first-stage adjustable hierarchical structure is 40°-50°, and the length L1 is 0.05-0.15D. Its design requires that it can accelerate the detonation without causing the oblique detonation shock wave to directly escape the body.

The second-stage adjustable hierarchical structure adopts a boss with a smaller angle and a longer length, which can re-maintain the stationary oblique detonation wave that is slightly detached.

The inclination angle α2 of the second-stage adjustable hierarchical structure is 25°~35°, and the length L2 is 0.3~0.5D. Its design requires that it can maintain the detonation and stationary detonation of the detonation wave.

When the flight Mach number continues to increase to Ma7~Ma15, the engine is in the oblique detonation combustion mode, as shown in Figure 2. Since the incoming flow velocity is high at this time, the stationary interval of the oblique detonation wave is large, so the two-stage The adjustable range of the detonating device angle is also correspondingly larger.

Preferably, the inclination angle range of the first-level adjustable hierarchical structure is 30°-40°, and the inclination angle range of the second-level adjustable boss structure is 15°-30°.

The rear section of the inner column of the present invention adopts an adjustable boss structure with different angles and lengths. In different modes, the functions of the adjustable boss structure are different. In the rotational detonation mode, the adjustable boss structure serves as a rotating The contraction section of the Rafal nozzle after the detonation combustion chamber; in the oblique detonation mode, the adjustable boss structure serves as an oblique detonation wave-induced detonation device.

The present invention proposes to adopt a "large angle + small angle" design in the annular combustion chamber, and at the same time adjust the fuel injection equivalence ratio in a timely manner, which can realize the initiation and stationing of the oblique detonation wave in the annular combustion chamber, and achieve a multi-stage "truncated cone-shaped" oblique detonation wave. The effect of detonation overcomes the problem of oblique detonation combustion under transition working conditions (Ma6~7) due to low static temperature and low speed, making it difficult to detonate and settle.

The first-stage oblique detonation detonation device uses a boss with a larger angle and a shorter length, which can induce a stronger oblique shock wave and significantly increase the temperature and pressure behind the wave.

In the present invention, the "truncated cone type" oblique detonation refers to the oblique detonation induced by the boss in the axisymmetric annular flow channel.

Further, the present invention provides a driving mechanism (secondary level) as shown in Figure 5, which is installed in the inner column. Under the low Mach number of the connecting working condition, the first driving mechanism (adjusting the first-stage adjustable hierarchical structure) When it moves backward, the second drive mechanism (which adjusts the second-stage adjustable hierarchical structure) also moves backward, but its translation amplitude is smaller than that of the first drive mechanism, ensuring the formation of a "large angle + small angle" detonator configuration. .

At the same time, the third driving mechanism (adjusting the end contraction structure) controls the degree of expansion of the nozzle. When the third driving mechanism moves backward, the rear part of the end contraction structure (corresponding to the expansion of the flow channel) moves downward, allowing the nozzle to expand even more. to meet the thrust requirements of the aircraft.

The adjustable boss structure is followed by a smooth transition end shrinkage structure, which serves as the expanded inner wall surface of the nozzle for the two modes. Its structure is a well-known technology. It can adopt a pointed cone or truncated cone structure as shown in Figures 1 and 2. The specific design See also adjustable nozzle.

Those skilled in the art can design the driving structure according to the actual situation to realize the adjustment of the adjustable boss structure and the end contraction structure of the present invention, and are not limited to the structure shown in Figure 5.

The middle section of the inner column of the invention is a cylindrical configuration with a fixed diameter. According to the flow and thrust requirements of the aircraft, the range of the diameter D [Dmin, Dmax] of the middle section of the inner column of the engine is determined based on the rotational detonation principle.

In order to be more conducive to the detonation of oblique detonation waves, using a larger inner column diameter can effectively shorten the length of the induction zone of oblique detonation waves, accelerate detonation, and achieve oblique detonation wave detonation at a lower flow channel height.

Preferably, the present invention selects [DZ, Dmax] within the inner diameter range [Dmin, Dmax] as the diameter range of the middle cylindrical structure of the inner column of the present invention, where DZ>(Dmin+Dmax)/2.

Preferably, the height of the annular cavity between the outer wall of the inner column (middle cylindrical part) and the inner wall of the housing does not exceed 0.5D.

The front part of the inner column of the present invention has a rectifying cone structure, and the front end of the casing is adjustable. Through the adjustable front end of the casing, the intake compression degree is adjusted to adapt to the two combustion modes of rotational detonation and oblique detonation.

The specific structure is a well-known technology in the art, and please refer to the prior art adjustable inlet and rectifying cone designs.

As shown in Figure 1, in the rotating detonation combustion mode, the front rectifier cone annular intake air, while the front end of the housing can adjust the intake compression degree. After being compressed by the intake compression section I, the incoming flow enters the rotating detonation annular combustion Chamber 2, at the same time, fuel is injected from the head of the rotating detonation combustion chamber (fuel injection area 21), and after mixing with air, rotating detonation combustion is organized in the annular cavity.

The combustion products in the annular cavity are expanded and discharged through the Rafal nozzle to generate thrust.

As shown in Figure 2, in the oblique detonation combustion mode, the front air intake and compression are the same as those in the rotating detonation combustion mode. The degree of intake compression is adjusted to adapt to the operation of the oblique detonation engine.

After being compressed by the intake compression section I, the incoming flow enters the fuel injection area 21. At the same time, the fuel is injected from the head of the oblique detonation combustion chamber. In the oblique detonation fuel mixing section 22' (annular cavity, that is, rotating detonation combustion The annular combustion chamber section 22) in the mode is fully mixed, and the detonation area 23' (oblique detonation annular combustion chamber 2') is induced by oblique detonation to detonate, generating a "truncated cone-shaped" oblique detonation wave, and at the same time, it is injected through the tail expansion The tube expands to create thrust.

Further, as shown in Figures 1 and 2, the fuel injection area 21 of the present invention is provided at the head of the combustion chamber, and a plurality of circumferential fuel injection inlets are provided in the fuel injection area 21. The position and length LP of the fuel injection area are and the fuel injection inlet are designed based on the oblique detonation principle.

The injector configuration of the fuel injection inlet can be a small support plate injection or a small cantilever beam injection scheme to improve the penetration depth and uniformity of fuel distribution after the fuel is injected close to the annular outer wall. , so that the injected fuel and the compressed air can be fully mixed in the annular channel.

Further preferably, in order to better organize oblique detonation combustion, the length LC of the oblique detonation fuel mixing section 22' (annular combustion chamber section 22) used for fuel mixing is between 5D and 10D.

As shown in Figure 6, the simulation results of "truncated cone type" oblique detonation under typical "connection conditions" (incoming flow Ma6.5) are provided. The figure shows the pressure contour distribution of a certain section. The simulation results show that: two-stage detonation The device can realize the detonation and stationing of oblique detonation waves under "connected working conditions", which verifies the feasibility of the invention.

Further, the present invention provides a method for designing a combined detonation engine. The combined detonation engine includes an inner column and a casing. An annular flow channel is formed between the inner column and the casing. As shown in Figure 7, the design includes the following steps:

Shell design.

The casing is divided into an inlet section, a combustion chamber section and a nozzle section. The front end of the inlet section is adjustable, and the compression amount is controlled according to the Mach number and combustion mode. It is designed using the design principle of the rotating detonation engine casing, which is the best in this field. Well-known technology.

Inner column design.

An adjustable boss structure is set at the rear of the inner column, as shown in Figure 3. The inner column includes a rectifying cone at the front, a cylindrical structure in the middle, an adjustable boss structure at the rear, and an end contraction structure.

The front rectifying cone, the middle cylindrical structure and the end contraction structure are designed using the design principle of the inner column of the rotating detonation engine, which is a well-known technology in the field.

Furthermore, in this step, in order to facilitate the detonation of the oblique detonation wave, using a larger inner column diameter can effectively shorten the length of the induction zone of the oblique detonation wave, accelerate detonation, and achieve oblique detonation shock wave detonation at a lower flow channel height.

Preferably, the present invention selects [DZ, Dmax] within the inner column diameter range [Dmin, Dmax] as the diameter range of the middle cylindrical structure of the inner column of the present invention, where DZ>(Dmin+Dmax)/2 is the preferred inner column diameter. Range minimum.

The range of the diameter D of the middle section of the inner column [Dmin, Dmax] is designed according to the flow and thrust requirements of the aircraft and the design principle of the inner column of the rotating detonation engine, which is a well-known technology in the art.

More preferably, in order to further facilitate the detonation of oblique detonation waves, the length design of the middle cylindrical structure in this step adopts a rotating detonation inner column design principle that is different from the existing technology.

The central cylindrical structure includes a fuel injection area and an annular combustion chamber section in the rotating detonation combustion mode. In the oblique detonation combustion mode, the annular combustion chamber section is converted into an oblique detonation fuel mixing section.

Furthermore, at the second Mach number, based on the oblique detonation combustion chamber design principle, the position of the fuel injection area and the injector setting and the length of the oblique detonation fuel mixing section that satisfy oblique detonation combustion are obtained.

Furthermore, the terminal contraction structure is adjustable. By adjusting the terminal contraction structure, the nozzle expansion ratio is changed to meet the needs of detonation combustion.

The specific design can be found in the design of the adjustable tail nozzle, which is a well-known technology in the art.

The rear adjustable boss structure design, the specific design includes the following steps:

A1. Determine the structure and series of the adjustable boss structure.

The adjustable boss structure consists of no less than two adjustable hierarchical structures. The inclination angle of each adjustable hierarchical structure is adjustable. Along the direction of the inflow, the length of each adjustable hierarchical structure increases sequentially. Each adjustable hierarchical structure is Round cone structure.

In the rotating detonation combustion mode, the adjustable boss structure is a primary structure, that is, the inclination angles of each adjustable hierarchical structure are consistent, and a rotating detonation nozzle throat is formed between the end of the adjustable boss structure and the shell. In the oblique detonation combustion mode, the adjustable boss structure is a multi-stage structure, that is, the inclination angles of each adjustable hierarchical structure are different, and along the incoming flow direction, the inclination angles of each adjustable hierarchical structure decrease in sequence.

Preferably, the adjustable boss structure in this step is 2 to 3 levels.

A2. Determine the initial value of the length of the adjustable hierarchical structure at each level.

The initial value of the length of the adjustable hierarchical structure at each level is initially determined to meet the requirement that the length of each adjustable hierarchical structure increases sequentially along the incoming flow direction.

The design is limited by the total length of the inner column and the length of the front rectifying cone, the middle cylindrical structure and the end contraction structure.

Further preferably, the initial value of the length of the adjustable hierarchical structure at each level is set as follows: the initial value range of the length of the first-level adjustable hierarchical structure is 0.05D ~ 0.15D, and the initial value range of the length of the last-level adjustable hierarchical structure is 0.3 D～0.5D, the initial value of the length of the intermediate stage is selected between the first stage and the last stage, as long as it meets the requirement that the length of each adjustable hierarchical structure increases sequentially along the direction of the inflow, where D is the middle part of the inner column The diameter of the cylindrical structure.

A3. Determine the initial value of the inclination angle of the adjustable hierarchical structure at each level to meet the requirement that the inclination angle of each adjustable hierarchical structure decreases in sequence along the direction of the incoming flow.

Further preferably, the initial value of the inclination angle of the adjustable hierarchical structure at each level is set as follows. The initial value range of the inclination angle of the first-level adjustable hierarchical structure is 40°~50°, and the initial value range of the inclination angle of the last-level adjustable boss structure is 25°. °～35°, the initial value of the inclination angle of the intermediate stage is selected between the first stage and the last stage, as long as it meets the requirement that the inclination angle of each adjustable hierarchical structure decreases in sequence along the direction of the incoming flow.

A4. Under the second Mach number, perform numerical simulation of oblique detonation, optimize the inclination angle and length of the adjustable hierarchical structure at each level, and obtain the optimal length of the adjustable hierarchical structure at each level and the optimal each level related to the Mach number. Adjustable graded structure inclination.

In this step, the inclination angles of the adjustable hierarchical structures at each level obtained at the second Mach number are related to the Mach number, and a series of inclination angle values corresponding to different Mach numbers are obtained.

A5. According to the length of the adjustable hierarchical structure at each level, perform numerical simulation of rotational detonation at the first Mach number to obtain the inclination angle of the adjustable boss structure in the rotational detonation combustion mode.

In this step, at the first Mach number, the principle of rotating detonation combustion is used to design the nozzle throat to determine the inclination angle of the adjustable boss structure.

In this step, the height of the nozzle throat at the first Mach number is related to the Mach number, and what is obtained is the inclination value of a series of adjustable boss structures corresponding to different Mach numbers.

A6. At the third Mach number, perform a numerical simulation of oblique detonation to determine the inclination angles of the adjustable hierarchical structures at each level related to the Mach number in the oblique detonation combustion mode.

Furthermore, this step performs oblique detonation numerical simulation to determine the initial value of the inclination angle of each adjustable hierarchical structure in the oblique detonation combustion mode, so as to meet the requirement that the inclination angle of each adjustable hierarchical structure decreases in sequence along the incoming flow direction.

Further preferably, the initial value of the inclination angle of each level of the adjustable hierarchical structure in this step is set as follows. The initial value range of the inclination angle of the first-level adjustable hierarchical structure is 30° to 40°, and the initial value range of the inclination angle of the last-level adjustable boss structure is. It is 15°~30°, and the initial value of the inclination angle of the intermediate stage is selected between the first stage and the last stage, as long as it meets the requirement that the inclination angle of each adjustable hierarchical structure decreases in sequence along the direction of the incoming flow.

In this step, the inclination angle of the adjustable hierarchical structure at each level at the third Mach number is related to the Mach number, and a series of inclination angle values corresponding to different Mach numbers are obtained.

Through the design of the inner column in this step, not only the structural parameters of the inner column structure are obtained, but also the adjustable boss structure of the inner column under different detonation modes and the adjustable boss structure of the inner column during detonation mode conversion are obtained. The change in inclination angle provides parameter support for subsequent combined detonation engine operation.

In the present invention, the first Mach number is the rotational detonation working range, which generally refers to the range between Ma2.5 and Ma6.5+ in this field.

The second Mach number in this step is the "connection working condition", which generally refers to Ma6~Ma7.

Furthermore, the third Mach number is the oblique detonation operating range, which generally refers to the range between Ma6.5 and Ma15+ in this field.

Furthermore, the present invention also provides a combined detonation engine obtained by adopting the above design method.

The parts of the present invention that are not described in detail are well known to those skilled in the art.

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