A flame-stabilized ramjet combustion chamber, combustion method and engine thereof

Abstract

The present invention belongs to the field of engines, and specifically relates to a flame-stabilized ramjet engine combustion chamber, a combustion method and an engine thereof, wherein the flame-stabilized ramjet engine combustion chamber comprises a combustion chamber housing and a center body coaxially arranged in the combustion chamber housing, a combustion chamber is formed between the outer wall of the center body and the inner wall of the combustion chamber housing; the combustion chamber is a sudden expansion wall after the inlet, and a ring plate II is provided on the center body protruding outward, and the sudden expansion wall, the outer wall of the center body and the side wall of the ring plate II form an annular concave cavity structure; the upstream side of the annular concave cavity structure is provided with a ring plate I, the outer wall of the ring plate I and the inner wall of the combustion chamber housing have a gap I, the side of the ring plate I and the sudden expansion wall have a gap II, and the inner wall of the ring plate I and the inner wall of the center body have a gap III. The present invention has stable double trapped vortex flame stabilization without relying on the injection design of the combustion chamber wall, and has a simple structure and stable performance.

Description

Technical Field

[0001] The invention belongs to the field of engines, and in particular relates to a flame-stabilized ramjet engine combustion chamber, a combustion method and an engine thereof. Background Art

[0002] Ramjet engines are currently an important power unit for high-speed aircraft. At the same time, ramjet engines can be organically combined with other power sources to realize the application of ramjet engines in aerospace vehicles in the future. In recent years, with the continuous widening of the flight envelope of high-speed aircraft, previous research on single flight conditions can no longer meet the needs, and wide-range ramjet engines have become a new development direction. The wide range requires the combustion chamber to achieve stable ignition and combustion under lower Mach numbers and changing equivalence ratio conditions. The key to solving this problem lies in how to design a suitable flame stabilizer.

[0003] The cavity has gradually been regarded as an ideal flame stabilizer by researchers due to its integration of fuel injection, mixing enhancement, flame stabilization and other functions, as well as its advantages such as a wide flame stabilization range and small total pressure loss. A large number of studies have been carried out. The research is mainly carried out from two directions: one is the scramjet combustion chamber under supersonic inflow conditions, and the other is the aircraft engine trapped vortex combustion chamber under low-speed inflow conditions. In the scramjet combustion chamber, the cavity has been used as its flame stabilizer in a series of experiments and numerical simulation studies at home and abroad, and the flow characteristics, ignition and flame stabilization, fuel injection, combustion oscillation, parameter design, etc. of the cavity have been systematically and deeply studied. In addition, many flight verification scramjet engines such as X-51A, Hyshot, and HiFire II all use the cavity as a flame stabilizer. The trapped vortex combustion chamber (TVC) of an aircraft engine uses a concave cavity to change the recirculation zone from the large recirculation zone of the combustion chamber generated by the traditional swirl flow to a stable recirculation zone in the wall concave cavity that is not disturbed by the mainstream. This can remain stable even when the mainstream is very lean, thereby greatly widening the flame stabilization boundary and reducing emissions. TVC has undergone four generations of improvements since its development. The fourth generation of TVC can achieve a combustion efficiency of more than 99% between the equivalence ratio of 0.12 and 0.82, which is at least 40% wider than the traditional combustion chamber. In addition, the TVC double vortex structure can have a lower LBO limit and show higher combustion efficiency than the traditional flame stabilization method and single vortex structure at the lowest total equivalence ratio.

[0004] For sub-ramjet combustion chambers, the most widely used flame stabilizers are still blunt-body and sudden expansion flame stabilizers. However, the excessive blockage ratio of the blunt-body flame stabilizer leads to large flow losses and easy structural deformation, which may even cause dangerous combustion oscillations. Although the sudden expansion flame stabilizer does not have the above-mentioned disadvantages, its flame stabilization ability is greatly restricted by the structural design and is very sensitive to changes in working conditions. It can only be used in sub-ramjet combustion chambers with a small thrust change range. There are few studies on the application of double trapped vortex flame stabilizers in sub-ramjet combustion chambers, which are relatively scattered. Although the double trapped vortex structure in the cavity can have a wider range of flame stabilization capabilities, according to current research, the formation of a stable double vortex structure strongly depends on the design of the fuel injection scheme on the inner wall of the cavity. In addition, the double vortex structure formed by injection on the inner wall of the cavity is easily affected by changes in the incoming flow conditions and cannot be stabilized, resulting in a decrease in the combustion performance of the combustion chamber. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a ramjet combustion chamber, a combustion method and an engine thereof which have flame stabilization with stable double trapped vortex flame stabilization and are independent of the combustion chamber inner wall injection design.

[0006] The present invention provides a flame-stabilized ramjet engine combustion chamber, comprising a combustion chamber casing and a center body coaxially arranged in the combustion chamber casing, wherein a combustion chamber is formed between an outer wall of the center body and an inner wall of the combustion chamber casing;

[0007] The combustion chamber has a protruding wall behind the inlet, and a ring plate II is provided on the center body protruding outward, and the protruding wall, the center body outer wall and the side wall of the ring plate II form an annular concave cavity structure;

[0008] An annular plate I is arranged on the upstream side of the annular concave cavity structure, the outer wall of the annular plate I has a gap I with the inner wall of the combustion chamber shell, the side of the annular plate I has a gap II with the expanded wall, and the inner wall of the annular plate I has a gap III with the inner wall of the center body.

[0009] Furthermore, the outer wall of the ring plate I is located between the outer end of the expanded wall and the upstream wall of the annular concave cavity structure.

[0010] Furthermore, the upstream wall surface of the annular concave cavity structure includes a plane section, an arc transition section and a downwash wall surface arranged in sequence from upstream to downstream;

[0011] The downwash wall surface is a section of inclined straight wall surface, and the diameter of the downwash wall surface gradually decreases from the upstream to the downstream direction.

[0012] Furthermore, the downwash angle of the downwash wall is 20°-40°.

[0013] Furthermore, the downwash angle of the downwash wall is 30°.

[0014] Furthermore, the length-to-depth ratio of the annular cavity structure is between 0.71 and 0.73.

[0015] Furthermore, the outer wall diameter of the central body is 232 mm, the length of the annular cavity structure is 75 mm, and the depth is 104 mm;

[0016] The distance between the outer end of the protruding wall and the outer wall of the central body is 97 mm;

[0017] The distance between the outer wall and the inner wall of the ring plate I is 96 mm, the distance between the side wall of the ring plate I and the protruding wall is 5 mm, and the distance between the inner wall of the ring plate I and the outer wall of the center body is 3 mm;

[0018] The distance between the outer wall of the ring plate II and the outer wall of the center body is 85 mm.

[0019] Furthermore, a cyclone is provided in the inlet;

[0020] Alternatively, a fuel injection structure is provided on the annular cavity structure.

[0021] The present invention also provides a flame-stabilized ramjet combustion method, using the flame-stabilized ramjet combustion chamber, comprising the following steps:

[0022] The incoming flow flows from the inlet to the combustion chamber, and part of the low-speed fluid in the boundary layer of the upstream wall of the cavity flows into the inner side of the vortex region formed between the ring plates I and II through the intervals II and III, and is blocked by the ring plate II, rolling up toward the inner wall of the combustion chamber shell to form a lower vortex;

[0023] A part of the incoming flow forms a shear layer after passing through the outer end of the ring plate I, and a part of the fluid in the shear layer hits the outer end side wall of the ring plate II and enters the outside of the trapped vortex area;

[0024] The lower trapped vortex continues to move toward the inner wall of the combustion chamber shell and interacts with the fluid outside the shear layer entering the trapped vortex area to form an upper trapped vortex outside the trapped vortex area, and then a stable double trapped vortex is formed in the trapped vortex area for flame stabilization.

[0025] The present invention also provides an engine, comprising the above-mentioned flame-stabilized ramjet combustion chamber.

[0026] The beneficial effect of the present invention is that in the flame-stabilized ramjet combustion chamber provided by the present invention, the incoming flow flows from the inlet to the combustion chamber, and part of the low-speed fluid in the boundary layer of the upstream wall of the concave cavity flows into the inner side of the vortex region formed between the ring plates I and II through the guide channels I and II formed by the intervals II and III, and is obstructed by the ring plate II, and rolls up toward the inner wall of the combustion chamber shell to form a lower trapped vortex. The lower trapped vortex rolled up by part of the low-speed fluid can not only ensure the oxygen in the lower trapped vortex, but also promote uniform distribution of fuel. After ignition, the lower trapped vortex can be considered as a fixed ignition source, which stabilizes the flame. At the same time, part of the incoming flow forms a shear layer after passing through the outer end of the ring plate I. Part of the fluid in the shear layer will hit the outer end side wall of the ring plate II and enter the outside of the trapped vortex area, that is, part of the shear layer directly enters the downstream of the combustion chamber, and the other part will be rolled into the outside of the trapped vortex area from the outer end of the ring plate I; at this time, the lower trapped vortex continues to move toward the inner wall of the combustion chamber shell and interacts with the fluid entering the outside of the trapped vortex area to form an upper trapped vortex outside the trapped vortex area. The upper trapped vortex can enhance the mass exchange between the lower trapped vortex and the mainstream of the incoming flow, and can spread the high-temperature products generated by the lower trapped vortex to the mainstream of the incoming flow after ignition. Then a stable double trapped vortex is formed in the trapped vortex area for flame stabilization.

[0027] In addition, the present invention can change the conventional single trapped vortex structure into a double trapped vortex. Although the double trapped vortex with the ring plate I will cause a certain total pressure loss in the trapped vortex area, the reduction of the total pressure recovery coefficient caused by the ring plate I does not exceed 4%, which is much lower than the total pressure loss caused by the introduction of blunt body flame stabilization. Therefore, even under high subsonic incoming flow, the total pressure loss introduced by the ring plate I can be ignored. However, the flame stabilization effect it brings is significant.

[0028] In addition, the fluid flowing into the guide channel I is mainly the low-speed fluid in the boundary layer on the upstream wall of the cavity, which has little effect on the flow velocity and total pressure of the mainstream of the incoming flow.

[0029] That is, the present invention realizes the design of injection in the combustion chamber that is independent of the inner wall of the combustion chamber by setting the ring plate I. It only needs to guide a certain mass flow rate of boundary layer low-speed fluid from the incoming flow through the ring plate I to form a stable double vortex flame stabilization, which has a simple structure and stable performance. In addition, the flame stabilization structure of the present invention can also be combined with other forms of flame stabilizers, and double vortex flame stabilization with excellent combustion performance can still be achieved in a wider range of incoming flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Attached Figure 1 A schematic diagram of the structure of a ramjet combustion chamber for flame stabilization (the dashed line in the figure is the rotation centerline of the ramjet combustion chamber);

[0031] Attached Figure 2Schematic diagram of the vortex flow field of the ramjet combustion chamber with flame stabilization (the dashed line in the figure is the rotation centerline of the ramjet combustion chamber);

[0032] Attached Figure 3 A perspective schematic diagram of a ramjet combustion chamber with flame stabilization;

[0033] Attached Figure 4 The air cold flow streamline distribution diagram of the ramjet combustion chamber for flame stabilization;

[0034] Attached Figure 5 Comparison of the total pressure recovery coefficient along the combustion chamber for a ramjet engine combustion chamber with and without ring plate II for flame stabilization.

[0035] In the figure, 1-combustion chamber shell; 2-center body; 3-combustion chamber; 4-sudden expansion; 5-upstream wall of the cavity; 501-plane section; 502-arc transition section; 503-downwash wall; 6-ring plate I; 7-interval I; 8-interval II; 9-interval III; 10-ring plate II; 11-inlet; 12-annular cavity structure; 13-incoming flow; 14-part of low-speed fluid; 15-trapped vortex area; 16-lower trapped vortex; 17-shear layer; 18-upper trapped vortex; - Lower wash corner. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0039] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] As attached Figure 1 -Attached Figure 3 As shown, the present invention provides a flame-stabilized ramjet engine combustion chamber, comprising a combustion chamber casing 1 and a center body 2 coaxially arranged in the combustion chamber casing 1, the combustion chamber casing 1 and the center body 2 are both axially symmetrical rotational body structures, and the combustion chamber casing 1 is hollow inside, and a combustion chamber 3 is formed between the outer wall of the center body 2 and the inner wall of the combustion chamber casing 1;

[0042] The combustion chamber 3 is a wall surface of a sudden expansion 4 behind the inlet 11, that is, the inlet 11 is an annular structure inlet, the combustion chamber 3 is an annular structure cavity, the inlet 11 and the combustion chamber 3 share the inner wall of the combustion chamber shell 1, and the inner diameter of the inlet 11 is larger than the inner diameter of the combustion chamber 3 (the outer wall diameter of the center body 2), so that the volume of the inlet 11 is smaller than the volume of the combustion chamber 3, and the center body 2 is provided with a ring plate II 10 protruding outward, and the wall surface of the sudden expansion 4, the outer wall of the center body 2 and the side wall of the ring plate II 10 form an annular concave cavity structure 12;

[0043] The upstream side of the annular cavity structure 12 is provided with a ring plate Ⅰ6, and the outer wall of the ring plate Ⅰ6 and the inner wall of the combustion chamber shell 1 have a gap Ⅰ7, and the gap Ⅰ7 is used for most of the fluid at the inlet 11 to flow directly into the combustion chamber 3, and the side of the ring plate Ⅰ6 and the wall of the sudden expansion 4 have a gap Ⅱ8, and the gap Ⅱ8 is used to form a guide channel Ⅰ, which is used to introduce part of the low-speed fluid 14 in the boundary layer of the upstream wall 5 of the cavity, and the inner wall of the ring plate Ⅰ6 and the inner wall of the center body 2 have a gap Ⅲ9, and the gap Ⅲ9 is used to form a guide channel Ⅱ, which is used to guide part of the low-speed fluid 14 in the guide channel Ⅰ to the trapped vortex area 15. In addition, the trapped vortex area 15 is formed between the ring plate Ⅰ6 and the ring plate Ⅱ10, that is, the annular cavity structure 12 includes the trapped vortex area 15 and the guide channel Ⅰ. In addition, the ring plate I6 is provided so that part of the incoming flow 13 forms a shear layer 17 after passing through the outer end of the ring plate I6 , and part of the fluid in the shear layer 17 hits the outer end side wall of the ring plate II 10 and enters the outside of the trapped vortex area 15 .

[0044] In the flame-stabilized ramjet combustion chamber provided by the present invention, an incoming flow 13 flows from an inlet 11 to a combustion chamber 3, and a part of the low-speed fluid 14 in the boundary layer of the upstream wall surface 5 of the concave cavity flows into the inner side of the vortex region 15 formed between the ring plate 16 and the ring plate Ⅱ10 through the guide channel Ⅰ and the guide channel Ⅱ formed by the interval Ⅱ8 and the interval Ⅲ9, and is blocked by the ring plate Ⅱ10, and rolls up toward the inner wall of the combustion chamber shell 1 to form a lower vortex 16. The lower vortex 16 rolled up by the part of the low-speed fluid 14 can not only ensure the oxygen of the lower vortex 16, but also promote the uniform distribution of fuel. After ignition, the lower vortex 16 can be regarded as a fixed ignition source, which plays a role in stabilizing the flame; at the same time, part of the After the incoming flow 13 passes through the outer end of the ring plate Ⅰ6, a shear layer 17 is formed. Part of the fluid in the shear layer 17 will hit the outer end side wall of the ring plate Ⅱ10 and enter the outer side of the trapped vortex area 15, that is, part of the shear layer 17 directly enters the downstream of the combustion chamber 3, and the other part will be drawn into the outer side of the trapped vortex area 15 from the outer end of the ring plate Ⅰ6; at this time, the lower trapped vortex 16 continues to move toward the inner wall of the combustion chamber shell 1 and interacts with the fluid entering the outer side of the trapped vortex area 15 to form an upper trapped vortex 18 outside the trapped vortex area 15. The upper trapped vortex 18 can enhance the mass exchange between the lower trapped vortex 16 and the mainstream of the incoming flow 13, and can propagate the high-temperature products generated by the lower trapped vortex 16 to the mainstream of the incoming flow 13 after ignition. Then, a stable double trapped vortex is formed in the trapped vortex area 15 for flame stabilization.

[0045] In addition, the present invention can change the conventional single trapped vortex structure into a double trapped vortex. Although the double trapped vortex with the ring plate Ⅰ6 will cause a certain total pressure loss in the trapped vortex area 15, the reduction of the total pressure recovery coefficient caused by the ring plate Ⅰ6 does not exceed 4%, which is much lower than the total pressure loss caused by the introduction of blunt body flame stabilization. Therefore, even under high subsonic incoming flow, the total pressure loss introduced by the ring plate Ⅰ6 can be ignored. However, the flame stabilization effect it brings is significant.

[0046] In addition, the fluid flowing into the guide channel I is mainly the low-speed fluid in the boundary layer on the upstream wall 5 of the cavity, and has little effect on the flow velocity and total pressure of the mainstream of the incoming flow 13.

[0047] That is, the present invention realizes the design of injection in the combustion chamber 3 that is independent of the inner wall of the combustion chamber 3 by setting the ring plate Ⅰ6, and only needs to guide a certain mass flow rate of boundary layer low-speed fluid from the incoming flow 13 through the ring plate Ⅰ6 to form a stable double vortex flame stabilization, which has a simple structure and stable performance. In addition, the flame stabilization structure of the present invention can also be combined with other forms of flame stabilizers, and can still achieve double vortex flame stabilization with excellent combustion performance in a wider incoming flow range.

[0048] In one embodiment, the ring plate Ⅰ6 of the present invention can be fixedly arranged on the wall surface of the sudden expansion 4 by a plurality of connecting plates arranged in an annular array on the side wall, so as to achieve the fixation of the ring plate Ⅰ6. In this embodiment, the flow guide channel Ⅰ is a plurality of fan-shaped channels arranged in an annular array. Of course, the ring plate Ⅰ6 can also be fixedly arranged on the outer wall of the central body 2 by a plurality of connecting plates arranged in an annular array on the bottom wall, so as to achieve the fixation of the ring plate Ⅰ6. In this case, the flow guide channel Ⅱ is a plurality of fan-shaped channels arranged in an annular array.

[0049] In one embodiment, the outer wall of the ring plate Ⅰ6 is located between the outer end of the wall of the sudden expansion 4 and the upstream wall 5 of the concave cavity of the annular concave cavity structure 12. The upstream wall 5 of the concave cavity is the upstream wall of the outer end of the wall of the sudden expansion 4, and the upstream wall 5 of the concave cavity is located inside the inlet 11 to ensure the size of the interval Ⅰ7, provide enough space for the incoming flow 13 of the inlet 11 to enter the combustion chamber 3, and reduce the flow resistance to the incoming flow 13. That is, the ring plate Ⅰ6 does not invade the mainstream of the incoming flow 13, and the flow resistance and total pressure loss caused even under high subsonic incoming flow are relatively small compared with the combustion chamber 3 without the ring plate Ⅰ6.

[0050] In one embodiment, the upstream wall surface 5 of the annular concave cavity structure 12 includes a plane section 501, an arc transition section 502 and a downwash wall surface 503 arranged in sequence from upstream to downstream;

[0051] The downwash wall 503 is a straight inclined wall, and the diameter of the downwash wall 503 gradually decreases from upstream to downstream. The downwash wall 503 is used to guide the incoming flow of the boundary layer into the flow guide channel I, thereby increasing the incoming flow in the flow guide channel I, and the arc transition section 502 is used to smoothly transition the plane section 501 and the downwash wall 503 to prevent flow separation.

[0052] Preferably, the outer wall of the ring plate I6 is located between the outer end of the wall of the expansion 4 and the plane section 501.

[0053] In one embodiment, referring to the attached Figure 2 , attached Figure 2 In The downwash angle of the downwash wall 503 is 20°-40°. The angle will significantly affect the performance of the double trapped vortex. Too large a downwash angle will make it difficult to form a stable double trapped vortex, and too small a downwash angle will cause a large total pressure loss. Preferably, the downwash angle of the downwash wall 503 is 30°.

[0054] In one embodiment, the length-to-depth ratio of the annular cavity structure 12 is between 0.71 and 0.73. This length-to-depth ratio can form a stable double trapped vortex, while an inappropriate ratio can only form a single vortex. Preferably, the length-to-depth ratio of the annular cavity structure 12 is 0.72.

[0055] In one embodiment, the outer wall diameter of the central body 2 is 232 mm, the length of the annular cavity structure 12 is 75 mm, and the depth is 104 mm, wherein the length of the annular cavity structure 12 is the distance from the ring plate II 10 to the wall of the sudden expansion 4, and the depth of the annular cavity structure 12 is the distance from the outer wall of the central body 2 to the plane section 501;

[0056] The distance between the outer end of the wall of the protruding expansion 4 and the outer wall of the central body 2 is 97 mm;

[0057] The distance between the outer wall and the inner wall of the ring plate Ⅰ6 is 96 mm, the distance between the side wall of the ring plate Ⅰ6 and the wall of the expansion 4 is 5 mm, and the distance between the inner wall of the ring plate Ⅰ6 and the outer wall of the central body 2 is 3 mm;

[0058] The distance between the outer wall of the ring plate II 10 and the outer wall of the central body 2 is 85 mm.

[0059] Reference Figure 4 , attached Figure 4 : is the streamline distribution diagram in the combustion chamber 3 when calculating the size of the combustion chamber of the flame-stabilized ramjet engine in this embodiment. The Mach number of the incoming flow 13 at the inlet 11 is 0.9 and the total temperature is 300K. Figure 4It can be seen that a stable double vortex structure is formed in the trapped vortex region 15, which are a lower trapped vortex 16 located inside the trapped vortex region 15 and an upper trapped vortex 18 outside the trapped vortex region 15; the lower trapped vortex 16 is mainly caused by the guide flow at interval II8 at the ring plate I6, and part of the low-speed fluid 14 in the boundary layer of the upstream wall 5 of the concave cavity rolls up the lower trapped vortex 16, which can not only ensure the oxygen of the lower trapped vortex 16, but also promote the uniform distribution of fuel. After ignition, the lower trapped vortex 16 can be considered as a fixed ignition source, which plays a role in stabilizing the flame; the upper trapped vortex 18 outside the trapped vortex region 15 is formed by the lower trapped vortex 16 and the shear layer 17, which can enhance the mass exchange between the lower trapped vortex 16 and the mainstream of the incoming flow 13, and can propagate the high-temperature products generated by the lower trapped vortex 16 to the mainstream of the incoming flow 13 after ignition.

[0060] Reference Figure 5 , attached Figure 5 This is a comparison diagram of the total pressure recovery coefficient along the combustion chamber when calculating the size of the flame-stabilized ramjet engine combustion chamber in this embodiment with and without ring plate Ⅰ6. The Mach number of the incoming flow 13 at the inlet 11 is 0.9, and the total temperature is 300K. Without ring plate Ⅰ6, only a single trapped vortex can be formed in the trapped vortex area 15 without injection on the inner wall of the trapped vortex area 15. It can be seen that the double trapped vortex in the case of ring plate Ⅰ6 will cause a certain total pressure loss in the trapped vortex area 15, but the reduction in the total pressure recovery coefficient caused by ring plate Ⅰ6 does not exceed 4%, which is much lower than the total pressure loss caused by the introduction of blunt body flame stabilization. Therefore, even under high subsonic incoming flow, the total pressure loss introduced by ring plate Ⅰ6 can be ignored.

[0061] In one embodiment, a swirler is provided in the inlet 11; or a fuel injection structure is provided on the annular cavity structure 12. That is, the flame stabilization structure of the present invention can also be combined with a swirler provided on the inlet 11, or combined with fuel injection in the annular cavity structure 12, so that double trapped vortex flame stabilization with excellent combustion performance can still be achieved in a wider range of incoming flow.

[0062] The present invention also provides a flame-stabilized ramjet combustion method, using the flame-stabilized ramjet combustion chamber, comprising the following steps:

[0063] The incoming flow 13 flows from the inlet 11 to the combustion chamber 3, and part of the low-speed fluid 14 in the boundary layer of the upstream wall surface 5 of the cavity flows into the inner side of the vortex region 15 formed between the ring plate Ⅰ6 and the ring plate Ⅱ10 through the intervals Ⅱ8 and Ⅲ9, and is blocked by the ring plate Ⅱ10, and rolls up toward the inner wall of the combustion chamber shell 1 to form a lower vortex 16;

[0064] Part of the incoming flow 13 forms a shear layer 17 after passing through the outer end of the ring plate I6, and part of the fluid in the shear layer 17 hits the outer end side wall of the ring plate II 10 and enters the outside of the trapped vortex area 15;

[0065] The lower trapped vortex 16 continues to move toward the inner wall of the combustion chamber casing 1 and interacts with the fluid entering the shear layer 17 outside the trapped vortex region 15 to form an upper trapped vortex 18 outside the trapped vortex region 15, thereby forming a stable double trapped vortex in the trapped vortex region 15 for flame stabilization.

[0066] The present invention also provides an engine, comprising the above-mentioned flame-stabilized ramjet combustion chamber.

[0067] The above is only an embodiment and does not limit the present invention in any way. Any person skilled in the art can use the above disclosed technical contents to make many possible changes, modifications or modifications to the technical solutions of the present invention into equivalent embodiments of equivalent changes without departing from the scope of the technical solutions of the present invention. Therefore, any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A flame-stabilized ramjet combustion chamber, characterized in that: It comprises a combustion chamber casing (1) and a center body (2) coaxially arranged in the combustion chamber casing (1), wherein a combustion chamber (3) is formed between an outer wall of the center body (2) and an inner wall of the combustion chamber casing (1); The combustion chamber (3) has a wall surface of a sudden expansion (4) behind the inlet (11); a ring plate II (10) is provided on the center body (2) protruding outward; the wall surface of the sudden expansion (4), the outer wall of the center body (2) and the side wall of the ring plate II (10) form an annular concave cavity structure (12); An annular plate I (6) is provided on the upstream side of the annular cavity structure (12); an outer wall of the annular plate I (6) and an inner wall of the combustion chamber shell (1) have a gap I (7); a side edge of the annular plate I (6) and a wall surface of the expansion (4) have a gap II (8); and an inner wall of the annular plate I (6) and an inner wall of the center body (2) have a gap III (9).

2. The flame-stabilized ramjet combustion chamber of claim 1, wherein: The outer wall of the ring plate I (6) is located between the outer end of the wall surface of the sudden expansion (4) and the upstream wall surface (5) of the concave cavity of the annular concave cavity structure (12).

3. The flame-stabilized ramjet combustion chamber of claim 1, wherein: The upstream wall surface (5) of the annular concave cavity structure (12) comprises a plane section (501), a circular arc transition section (502) and a downwash wall surface (503) which are arranged in sequence from upstream to downstream. The downwash wall surface (503) is a section of inclined straight wall surface, and the diameter of the downwash wall surface (503) gradually decreases from the upstream to the downstream direction.

4. The flame-stabilized ramjet combustion chamber of claim 3, wherein: The downwash angle of the downwash wall (503) is 20°-40°.

5. The flame-stabilized ramjet combustion chamber of claim 4, wherein: The downwash angle of the downwash wall surface (503) is 30°.

6. The flame-stabilized ramjet combustion chamber of claim 1, wherein: The length-to-depth ratio of the annular cavity structure (12) is between 0.71 and 0.

73.

7. The flame-stabilized ramjet combustion chamber according to any one of claims 1 to 6, characterized in that: The outer wall diameter of the central body (2) is 232 mm, the annular cavity structure (12) is 75 mm in length and 104 mm in depth; The distance between the outer end of the wall of the sudden expansion (4) and the outer wall of the central body (2) is 97 mm; The distance between the outer wall and the inner wall of the ring plate I (6) is 96 mm, the distance between the side wall of the ring plate I (6) and the wall surface of the expansion (4) is 5 mm, and the distance between the inner wall of the ring plate I (6) and the outer wall of the central body (2) is 3 mm; The distance between the outer wall of the ring plate II (10) and the outer wall of the central body (2) is 85 mm.

8. The flame-stabilized ramjet combustion chamber according to any one of claims 1 to 6, characterized in that: A cyclone is provided in the inlet (11); Alternatively, a fuel injection structure is provided on the annular cavity structure (12).

9. A flame-stabilized ramjet combustion method, characterized in that: Using the flame-stabilized ramjet combustion chamber according to any one of claims 1 to 8 comprises the following steps: The incoming flow (13) flows from the inlet (11) to the combustion chamber (3), and a portion of the low-speed fluid (14) in the boundary layer of the upstream wall surface (5) of the concave cavity flows into the inner side of the trapped vortex region (15) formed between the ring plate I (6) and the ring plate II (10) through the interval II (8) and the interval III (9), and is obstructed by the ring plate II (10) and rolls up toward the inner wall of the combustion chamber casing (1) to form a lower trapped vortex (16); A portion of the incoming flow (13) forms a shear layer (17) after passing through the outer end of the ring plate I (6), and a portion of the fluid in the shear layer (17) hits the outer end side wall of the ring plate II (10) and enters the outer side of the trapped vortex region (15); The lower trapped vortex (16) continues to move toward the inner wall of the combustion chamber casing (1) and interacts with the fluid entering the shear layer (17) outside the trapped vortex region (15), thereby forming an upper trapped vortex (18) outside the trapped vortex region (15), thereby forming a stable double trapped vortex in the trapped vortex region (15) for flame stabilization.

10. An engine, characterized in that: A ramjet combustion chamber comprising the flame-stabilized ramjet combustion chamber according to any one of claims 1 to 8.

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