An air intake structure for a gaseous fuel pulse detonation combustion chamber

Abstract

The invention discloses an air intake structure for a gaseous fuel pulse detonation combustion chamber, belonging to the field of combustion; the structure comprises a mainstream channel sleeve, an interlayer sleeve, an outer wall sleeve and a twisted plate section, wherein the interior of the mainstream channel sleeve is a convergent-divergent structure, and 12 to 32 fuel inlet holes are opened at the throat and downstream of the throat; the fuel inlet holes on the interlayer sleeve correspond one-to-one with the fuel inlet holes of the mainstream channel sleeve, and the tail is a contraction structure with anti-backflow holes; the head of the outer wall sleeve contains 2 to 4 fan-shaped cavities, connecting the fuel inlet holes of the interlayer sleeve and the main fuel inlet holes; the interior of the twisted plate section is a twisted plate structure composed of multiple groups of bent plates with different rotation bending angles, and the aspect ratio of the bent plates is 1 to 3. The present invention reduces the cross-sectional area of ​​the mainstream channel and increases the air flow velocity. The kidney-shaped vortex formed at the throat can enhance the mixing process of the explosive mixture. At the outlet of the contraction section of the interlayer sleeve, the cross-sectional area of ​​the channel increases suddenly, and the increased turbulence intensity further enhances the mixing effect, and finally flows through the orthogonally arranged curved plates to obtain a uniformly mixed explosive mixture. When the combustion chamber is working stably, the torsion plate section generates shock wave reflections that can effectively reduce the total backflow pressure, and a part of the backflow gas forms a radial air curtain through the anti-backflow hole to block the high-pressure gas, and changes the flow direction of the other part of the gas, thereby playing a better backflow isolation role.

Description

Technical Field

[0001] The invention belongs to the field of aviation engines, and in particular relates to an air intake structure for a gaseous fuel pulse detonation combustion chamber. Background Art

[0002] Pulse detonation combustion has the characteristics of fast propagation speed, self-pressurization and low entropy increase in the combustion process. It is a supersonic combustion technology that can produce periodic high-temperature and high-pressure gas. Due to its unique combustion characteristics, it has different degrees of application in industry, such as pulse detonation engine, which is a new type of engine that uses periodic high-temperature and high-pressure gas generated by detonation combustion to generate thrust. Compared with traditional aircraft engines, it has the advantages of low combustion entropy increase, high cycle thermal efficiency, high thrust-to-weight ratio and high specific impulse. Due to its self-pressurization characteristics, the pulse detonation engine can remove some rotor components, making the engine structure simple. It can be used as an independent propulsion device for aircraft such as drones and missiles, or as a booster propulsion device for traditional engines; such as high-temperature detonation spraying technology, through continuous high-temperature thermal shock, the material powder with high temperature resistance and wear resistance is sprayed on the surface of the component, eliminating the melting process; such as pulse detonation cleaning technology, the detonation wave is decoupled after it is transmitted from the combustion device, generating a shock wave with strong kinetic energy, sound energy and thermal energy, which continuously vibrates, impacts and washes the surface with dust to achieve the purpose of cleaning. In addition to the applications mentioned above, there are also a series of applications such as detonation combustion power generation and detonation combustion internal combustion engines.

[0003] The first prerequisite for the engineering application of pulse detonation combustion chamber is to obtain a fully developed detonation wave. To obtain a stable and fully developed detonation wave, the first problem is whether the fuel and oxidant are fully mixed. If no measures are taken to fully mix the two, only an incompletely developed detonation wave may be obtained or detonation combustion may not occur at all, that is, the detonation limit range is narrow and detonation is difficult. Reference 1 [Wang Zhiwu, Zheng Longxi, Yan Chuanjun, Fan Wei. Research on the mixing chamber of pulse detonation combustor [J]. Experimental Fluid Mechanics, 2008, 22(04):48-52.] Combustion Science and Technology, 2005(03):282-285.] designed four 1.5 different enhanced fuel and oxidant mixing structures, but some designs have problems such as uneven distribution of fuel and oxidant and large pressure loss; secondly, the gas pressure generated by detonation combustion will be much higher than the incoming flow pressure, and the high-pressure gas will be transmitted back to the head of the combustion chamber, causing the compression wave and the expansion wave to oscillate and reflect back and forth in the intake structure. The exhaust gas that has not been completely discharged in the previous cycle seriously hinders the filling of fuel in the next cycle, increasing the detonation cycle time, thereby reducing the working frequency of the detonation combustion chamber. Summary of the invention

[0004] Technical issues to be solved:

[0005] In order to solve the deficiencies of the prior art, the present invention proposes an intake structure for a gaseous fuel pulse detonation combustion chamber. The present invention reduces the area of ​​the mainstream channel to increase the oxidant flow rate. The throat flow area is minimized and the flow rate is maximized. The two are mixed under the action of the kidney-shaped vortex in the throat, and at the same time, part of the fuel is sprayed into the mainstream channel from the fuel inlet hole downstream of the throat to form an explosive mixture. When the explosive mixture flows out of the tail outlet of the sandwich sleeve, the flow space suddenly expands and the turbulence intensity increases to strengthen the mixing of the two. Finally, the turbulence is enhanced by the orthogonally arranged torsion plate structure, and the mixing effect of the two is further strengthened, so that the fuel is more evenly distributed in space, ensuring the fresh mixture in the detonation chamber. Explosiveness: When the pulse detonation combustion chamber is working stably, due to the self-pressurization effect, the gas pressure will be much higher than the incoming flow pressure, and the high-pressure gas will be transmitted back to the head of the combustion chamber, causing the compression wave and the expansion wave to oscillate and reflect back and forth in the intake structure, so that the exhaust gas that has not been completely discharged in the previous cycle seriously hinders the filling of fuel in the next cycle. The present invention makes the reflux pass through the torsion plate structure and the anti-backflow hole in sequence during the upstream transmission process, and the reverse flow resistance is significantly increased. The reverse shock wave hits the curved plate to generate shock wave reflection, which effectively reduces the total reverse pressure. When part of the reflux passes through the anti-backflow hole, a radial air curtain is formed to block the reverse transmission of the high-pressure gas, and part of the reflux is turned back to offset the reflux momentum, thereby playing a better reverse isolation role.

[0006] The technical solution of the present invention is: an air intake structure for a gaseous fuel pulse detonation combustion chamber, characterized in that it includes a mainstream channel sleeve, an interlayer sleeve, an outer wall sleeve and a torsion plate section, the mainstream channel sleeve is provided with a plurality of fuel inlet holes in the central throat area, after the fuel flows in, it is mixed with the mainstream oxidant, and the formed explosive mixed gas flows through the contraction section of the interlayer sleeve and the outer wall sleeve in turn, and finally enters the detonation combustion chamber through the torsion plate section.

[0007] A further technical solution of the present invention is that the internal space of the main channel sleeve is a structure that contracts first and then expands, and the flow area of ​​the throat is 6% to 25% of the flow area of ​​the outer wall sleeve;

[0008] A further technical solution of the present invention is: a total of 12 to 32 fuel inlet holes with a diameter of 1 to 2.5 mm are formed at the throat and downstream of the throat of the mainstream channel sleeve, and the fuel inlet holes form an angle of 60° to 90° with the central axis of the outer wall sleeve;

[0009] A further technical solution of the present invention is: the sandwich sleeve is provided with fuel inlet holes of the same number and direction as the mainstream channel sleeve, and its tail portion is a contraction structure with a plurality of anti-backflow holes, and the tail portion outlet area is 18% to 41% of the flow area of ​​the outer wall sleeve;

[0010] A further technical solution of the present invention is that: the anti-backflow holes are evenly arranged along the circumferential direction on the contraction section, and the angle between the central axis of the anti-backflow holes and the central axis of the outer wall sleeve is 30° to 90°;

[0011] A further technical solution of the present invention is: the outer wall sleeve head has 2 to 4 fan-shaped cavities evenly distributed along the circumferential direction, and each fan-shaped space is externally connected to a main fuel inlet hole;

[0012] A further technical solution of the present invention is that the difference between the outer diameter and the inner diameter of the sector-shaped space is 2 to 5 mm, the sector angle is about 30° to 90° to completely cover the fuel inlet holes connected to it on the interlayer sleeve, and each sector-shaped cavity corresponds to at least 6 fuel inlet holes;

[0013] A further technical solution of the present invention is that the interior of the torsion plate section is a torsion plate structure composed of multiple groups of bending plates rotating at different bending angles, the aspect ratio of the bending plates is 1 to 3, and different bending plates are connected end to end and arranged orthogonally or at a certain angle.

[0014] Beneficial Effects

[0015] The beneficial effects of the present invention are as follows: by reducing the area of ​​the mainstream channel of the oxidant to increase the flow velocity, the mixing of the fuel and the oxidant is enhanced, and when the explosive mixed gas flows out of the tail of the interlayer sleeve, the flow space suddenly expands, the increase in turbulence intensity strengthens the mixing of the two, and finally the orthogonally arranged torsion plate structure enhances the turbulence, further enhancing the mixing effect of the two, so that the fuel is more evenly distributed in space, ensuring the explosiveness of the fresh mixed gas in the detonation chamber; in the early stage of combustion, the axial projection of the torsion plate section can be approximately regarded as 100% closed, which plays the role of a thrust wall, so that the pressure in the combustion chamber rises rapidly, accelerates the DDT process, and then increases the working frequency; when the pulse detonation combustion chamber is working stably, the backflow is transmitted upstream through the torsion plate structure and the anti-backflow hole in turn, and the backflow shock wave is reflected by the shock wave when it hits the torsion bending plate, which effectively reduces the total backflow pressure, and a part of the backflow gas forms a radial air curtain through the anti-backflow hole to block the high-pressure gas, and changes the flow direction of the other part of the gas to offset the backflow momentum, thereby playing a better backflow isolation role. The present invention has a simple structure, good fuel and oxidant mixing effect, and better back-transmission isolation capability, and can be applied to a variety of gaseous fuel pulse detonation combustion chambers. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 : Structural diagram of the present invention:

[0017] Figure 2 : Structural diagram of the main flow channel sleeve of the present invention;

[0018] Figure 3 : Structural diagram of the sandwich sleeve of the present invention;

[0019] Figure 4 : The outer wall sleeve structure diagram of the present invention;

[0020] Figure 5 : The structure diagram of the torsion plate segment of the present invention;

[0021] Figure 6 : Schematic diagram of an embodiment of the present invention;

[0022] Explanation of the reference numerals: 1. Main channel sleeve, 2. Interlayer sleeve, 3. Outer wall sleeve, 4. Twisted plate section, 5. Bending plate, 6. Fuel inlet hole, 7. Main fuel inlet hole, 8. Anti-backflow hole, 9. Fan-shaped cavity, 10. Ignition chamber, 11. Ignition device, 12. Main combustion chamber, 13. Explosion-aiding obstacle. DETAILED DESCRIPTION

[0023] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0024] In the description of the present invention, it is necessary to understand that the orientations or positional relationships indicated by terms such as "central axis", "angle", "upstream", "downstream", "circumferential", and "orthogonal" are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0025] See also Figure 1 The present invention discloses an air intake structure for a gaseous fuel pulse detonation combustion chamber, comprising a mainstream channel sleeve 1, an interlayer sleeve 2, an outer wall sleeve 3 and a torsion plate segment 4.

[0026] See also Figure 2 The internal space of the mainstream channel sleeve 1 is a structure that contracts first and then expands, and the flow area of ​​the throat is 6% to 25% of the flow area of ​​the outer wall sleeve 3; a total of 12 to 32 1-2.5 mm fuel inlet holes 6 are opened in the middle throat and downstream of the throat, and the fuel inlet holes 6 form an angle of 60° to 90° with the central axis of the outer wall sleeve 3.

[0027] Please refer to Figure 3 The sandwich sleeve 2 is provided with fuel inlet holes 6 of the same number and direction as the mainstream channel sleeve 1, and its tail is a contraction structure with a plurality of anti-backflow holes 8, and the tail outlet area is 18% to 41% of the flow area of ​​the outer wall sleeve, wherein the anti-backflow holes 8 are evenly arranged along the circumferential direction on the contraction section, and the angle between the central axis of the anti-backflow holes and the central axis of the outer wall sleeve 3 is 30° to 90°.

[0028] Please refer to Figure 4 The head of the outer wall sleeve 3 has 2 to 4 cavities 9 evenly distributed along the circumferential direction, and the outer wall of each fan-shaped cavity 9 is connected to a main fuel inlet hole 7, wherein the difference between the outer diameter and the inner diameter of the fan-shaped cavity 9 is 2 to 5 mm, and the fan-shaped angle is about 30° to 90° to completely cover the fuel inlet holes 6 connected to it on the interlayer sleeve 2, and each fan-shaped cavity 9 corresponds to at least 6 fuel inlet holes 6.

[0029] Please refer to Figure 5 The torsion plate section 4 is internally provided with a torsion plate structure composed of a plurality of bending plates 5 rotating and bending at different angles, the aspect ratio of the bending plates 5 is 1 to 3, and different bending plates 5 are connected end to end and arranged orthogonally or at a certain angle.

[0030] Please refer to Figure 6 , the mainstream channel sleeve 1 is connected to the oxidant channel, the main fuel inlet hole 7 is connected to the gas pipeline, and the twisted plate section 4 is connected to the ignition chamber 10. After entering the fan-shaped space 9 of the outer wall sleeve 3, the fuel is sprayed into the mainstream channel sleeve 1 through the interlayer sleeve 2 and the gas inlet hole 6 of the mainstream channel sleeve 1 in turn, and mixed at its throat and downstream of the throat. Since the cross-sectional area of ​​the oxidant channel gradually decreases, the air flow velocity in the throat is fast, and the mixing effect is better, forming a preliminary mixed explosive gas mixture. When the explosive gas mixture flows out of the tail of the interlayer sleeve 2, the mixing effect of the two is enhanced due to the sudden expansion of the flow space and the increase of turbulence intensity. Finally, the mixing effect of the two is further enhanced through the orthogonally arranged curved plates 5, so that the fuel is more evenly distributed in space, ensuring the explosiveness of the fresh mixed gas in the detonation chamber.

[0031] The ignition device 11 installed on the ignition chamber 10 ignites the explosive mixture. In the initial stage of combustion, the axial projection of the torsion plate section 4 can be approximately regarded as 100% closed, which acts as a thrust wall, causing the pressure in the combustion chamber to rise rapidly, accelerating the DDT process; when the combustion chamber 12 is working stably, the self-pressurization effect of the detonation combustion causes the gas pressure to increase sharply, exceeding the incoming flow pressure, and the high-pressure gas will be transmitted back to the head of the combustion chamber, causing the compression wave and the expansion wave to oscillate and reflect back and forth in the intake structure, which is not conducive to the fuel filling of the combustion chamber. During the transmission of the reverse flow to the upstream, it passes through the curved plate 5 in the torsion plate section 4 and the anti-backflow hole 8 on the interlayer sleeve 2 in turn. The reverse shock wave is reflected when it hits the torsion curved plate 5, effectively reducing the total reverse pressure. When the backflow passes through the anti-backflow hole 8, a part of the reverse gas is ejected from the anti-backflow hole 8 to form an air curtain to block the backflow of the high-pressure gas, and a part of the backflow is turned back to offset the backflow momentum, which has a good isolation and backflow capability.

[0032] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. An air intake structure for a gaseous fuel pulse detonation combustion chamber, characterized in that: It includes a mainstream channel sleeve, an interlayer sleeve, an outer wall sleeve and a twisted plate section. The inner space of the mainstream channel sleeve is a structure of first contraction and then expansion. The mainstream channel sleeve is provided with a plurality of fuel inlet holes in the central throat area. After the fuel flows in, it is mixed with the mainstream oxidant. The formed explosive mixed gas flows through the contraction section of the interlayer sleeve and the outer wall sleeve in turn, and finally enters the detonation combustion chamber through the twisted plate section. The sandwich sleeve is provided with fuel inlet holes of the same number and direction as those of the mainstream channel sleeve, and its tail is a contraction structure with a plurality of anti-backflow holes, and the tail outlet area is 18% to 41% of the flow area of ​​the outer wall sleeve; the anti-backflow holes are evenly arranged along the circumference of the contraction section, and the angle between the center axis of the anti-backflow holes and the center axis of the outer wall sleeve is 30° to 90°; The outer wall sleeve head has 2 to 4 fan-shaped cavities evenly distributed along the circumferential direction. After the fuel enters the fan-shaped cavity of the outer wall sleeve, it is sprayed into the mainstream channel sleeve through the gas inlet holes of the interlayer sleeve and the mainstream channel sleeve in turn and mixed at the throat and downstream of the throat; The interior of the torsion plate section is a torsion plate structure composed of multiple groups of bending plates rotating and bending at different angles, the aspect ratio of the bending plates is 1-3, and different bending plates are connected end to end and arranged orthogonally.

2. The air intake structure for a gaseous fuel pulse detonation combustion chamber according to claim 1, characterized in that: The flow area of ​​the throat is 6% to 25% of the flow area of ​​the outer wall sleeve.

3. The air intake structure for a gaseous fuel pulse detonation combustion chamber according to claim 1, characterized in that: A total of 12 to 32 fuel inlet holes with a diameter of 1 to 2.5 mm are opened at the throat and downstream of the throat of the mainstream channel sleeve, and the fuel inlet holes form an angle of 60° to 90° with the central axis of the outer wall sleeve.

4. The air intake structure for a gaseous fuel pulse detonation combustion chamber according to claim 1, characterized in that: Each of the fan-shaped cavities is externally connected to a main fuel inlet hole.

5. The air intake structure for a gaseous fuel pulse detonation combustion chamber according to claim 4, characterized in that: The difference between the outer diameter and the inner diameter of the fan-shaped cavity is 2-5 mm, and the fan-shaped angle is 30°-90° to completely cover the fuel inlet holes connected to it on the interlayer sleeve, and each fan-shaped cavity corresponds to at least 6 fuel inlet holes.

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