Fuel injection device of central staged combustion chamber

Abstract

Disclosed in the present invention is a fuel injection device of a central staged combustion chamber. The fuel injection device comprises a fuel injector body, wherein the fuel injector body is annular; a plurality of nozzles are uniformly provided on the fuel injector body in a circumferential direction, and a fuel leakage hole is formed between any two adjacent nozzles; and the fuel leakage hole is in communication with the two adjacent nozzles. The present invention enables the structural integration and machining implementation of a plurality of self-excited sweeping fuel nozzles with the head of a central staged main combustion chamber under the constraints of limited spatial dimensions, and increases a characteristic throat dimension by 50% or more.

Description

A fuel injection device for a central staged combustion chamber

[0001] This application claims priority to Chinese patent application No. 2024100056570 filed with the Patent Office of China on January 2, 2024, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of aviation engines, and in particular to an oil injection device for a central staged combustion chamber. Background Art

[0003] Patent US6253782 proposes a fluid oscillator structure without feedback channels, which contains two inlets, an outlet and a jet coupling cavity. When the fluid enters the coupling cavity through the two inlets at a stable flow rate, due to the instability of the jet inside the cavity, after the complex internal coupling effect and vortex system evolution, it can be ejected at the outlet in the form of high-frequency sweeping oscillation. When the working medium is a liquid, a sweeping liquid column or a fan-shaped liquid surface can be formed at the outlet. The inventor's related patent application CN113464982A is the first to use a dual-feedback channel self-excited sweeping liquid injection device for fuel injection in the central staged main combustion chamber of an aircraft engine. The high-frequency dynamic sweeping effect generated by this device is used to greatly improve the spatial distribution uniformity of the fuel in the incoming flow, thereby reducing the emission of pollutants such as NOx and carbon soot, improving the temperature distortion of the combustion chamber outlet, and ultimately achieving the purpose of improving engine performance. However, the structure disclosed in CN113464982A has the following problems in actual application:

[0004] The space within the main combustion stage is limited, and the space available for arranging the self-excited swept nozzle flow path is even more limited, placing extremely stringent restrictions on the size of the self-excited swept nozzle flow path. The difference in radius between the inner and outer sides of the base ring where the self-excited swept nozzle flow path is arranged is generally no more than 10mm. For example, the inner diameter is generally no less than 40mm, and the outer diameter is generally no more than 60mm. At the same time, 10 to 20 fuel nozzle flow paths need to be formed on this ring. Integrating the complex flow path structure within the dual-feedback self-excited swept fuel nozzle into such a compact main combustion stage of the combustion chamber head, while also ensuring that there is no interference with the pre-combustion stage oil and gas circuits, as well as the main combustion stage swirl gas circuits, and that the overall flow structure is comparable to the original structure, with parameters such as the injection flow rate and sweep frequency of each nozzle remaining consistent, undoubtedly poses a huge challenge to the design of the combustion chamber head coupled with the self-excited swept nozzle structure.

[0005] Taking the structure disclosed in CN 113464982 A as an example, it forms 12 self-excited swept nozzle flow channels on the base ring. The ring width is only 8mm, that is, the difference between the inner and outer diameters is 16mm. When using a dual-feedback self-excited swept fuel nozzle, the height of the nozzle flow channel itself (from the inlet section to the outlet section) is at least 12 times the throat width. The throat width, as the minimum internal dimension of the flow channel, generally cannot be less than 0.5mm. Therefore, its height H is at least greater than 6mm, and generally greater than 7mm. Considering that an oil leak hole with a diameter at least three times the throat width must be reserved at the inlet, a 1mm welding contact surface must be reserved on the side of the flow channel near the retaining ring. In other words, the ring width must be greater than 6+1.5+1=8.5mm to arrange a dual-feedback channel self-excited swept nozzle flow channel with a characteristic size of 0.5mm.

[0006] In order to highlight the advantages of the self-excited swept nozzle, the characteristic size of the inlet throat of the self-excited swept nozzle is generally designed to be larger, so as to reduce the number of nozzles while ensuring the atomization and dispersion effects. In addition, the larger the flow channel size of the self-excited swept nozzle, the higher the dimensional accuracy of the processing, the lower the cost, and the less likely it is to cause fuel coking and carbon deposition problems. In summary, how to significantly increase the throat size without increasing the overall size of the combustion chamber head structure, changing the position and size of the swirler, and changing the distribution of the injection holes is one of the important problems that need to be solved in this field.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a fuel injection device for a centrally staged combustion chamber to address the deficiencies in the prior art. It is capable of realizing the structural integration and processing of multiple self-excited swept fuel nozzles and the head of a centrally staged main combustion chamber under the constraints of limited space dimensions, and of increasing the characteristic throat size by more than 50%.

[0009] The present invention provides a fuel injection device for a central staged combustion chamber, which comprises: a fuel injector body;

[0010] The injector body is annular;

[0011] The injector body is evenly provided with a plurality of nozzles along the circumferential direction, and an oil leakage hole is provided between any two adjacent nozzles; the oil leakage hole is communicated with the two adjacent nozzles.

[0012] The fuel injection device of the central staged combustion chamber as described above, wherein, optionally, the fuel injector body includes a first base plate, a fuel injection plate and a second base plate;

[0013] The first bottom plate, the oil spray plate and the second bottom plate are coaxially arranged and fixedly connected in sequence;

[0014] The oil spray plate is provided with an oil channel, and the first bottom plate and the second bottom plate block the oil spray plate from both sides to form the nozzle and the oil leakage hole;

[0015] An annular mounting groove is provided on the first bottom plate, and the annular mounting groove is communicated with the oil leakage hole.

[0016] In the fuel injection device of the central staged combustion chamber as described above, optionally, the first base plate and the fuel injection plate are integrally formed, and the oil leakage hole is directly opposite to the annular mounting groove.

[0017] The fuel injection device of the centrally staged combustion chamber as described above, wherein optionally: the center of the oil leakage hole is located on the bisector of the angle formed by the center lines of two adjacent nozzles, and the diameter of the oil leakage hole is greater than 3 times the throat width of the nozzle.

[0018] In the fuel injection device of the central staged combustion chamber as described above, optionally, the minimum width of the channel connecting the oil leakage hole and the nozzle is greater than the throat width of the nozzle.

[0019] In the fuel injection device for the central staged combustion chamber as described above, optionally, the nozzle is a self-excited swept nozzle without a feedback channel or a self-excited swept nozzle with dual feedback channels.

[0020] As described above, in the fuel injection device of the central staged combustion chamber, optionally, when the nozzle is a self-excited sweep nozzle without a feedback channel, the width of the channel connecting the oil leakage hole and the nozzle gradually decreases in the direction approaching the nozzle.

[0021] In the fuel injection device for the central staged combustion chamber as described above, optionally, the width of the throat of the nozzle is 0.4 to 0.8 mm.

[0022] The fuel injection device of the central staged combustion chamber as described above, wherein, optionally, when the nozzle is a dual-feedback channel self-excited swept nozzle, the distance from the inlet of the nozzle to the inner wall of the oil channel is greater than 1.5 times the throat width of the nozzle.

[0023] The fuel injection device for the central staged combustion chamber as described above, wherein optionally, the number of the nozzles is 6 to 24.

[0024] Compared with existing technologies, the present invention can achieve the structural integration and processing of multiple self-excited swept fuel nozzles and a centrally staged main combustion chamber head within the constraints of spaced dimensions. By spacing the nozzles and oil leakage holes—that is, by changing the radial arrangement of the nozzles and corresponding oil leakage holes from the existing radial arrangement to a circumferential arrangement of the nozzles and oil leakage holes—the nozzle size can be proportionally enlarged, while the injection device size remains the same, increasing the characteristic throat size by more than 50%. In some preferred solutions, the characteristic throat size can be increased by 75%. The increase in characteristic throat size can significantly reduce nozzle processing costs and improve the nozzle flow path forming precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is a schematic diagram of the installation structure of the oil spray plate and the first base plate proposed by the present invention;

[0026] FIG2 is a schematic diagram of the structure in FIG1 from another perspective;

[0027] FIG3 is a cross-sectional view of the fuel injector body proposed by the present invention;

[0028] FIG4 is a schematic diagram of the nozzle distribution structure proposed in Example 1 of the present invention;

[0029] FIG5 is a schematic diagram showing a comparison of the flow channel and oil leakage hole dimensions of the self-excited swept nozzle in Example 1 and the prior art under the same size constraints;

[0030] FIG6 is a schematic diagram of the fuel flow direction of the oil leakage hole and the self-excited sweep nozzle flow channel in Example 1;

[0031] FIG7 is a schematic diagram of a fuel injector with a self-excited swept nozzle structure without a feedback channel proposed in Example 2;

[0032] Figure 8 shows the bottom plate annular flow channel structure of self-excited swept nozzles with different sizes and no feedback structure under the same constraint size;

[0033] FIG9 is a comparison of characteristic dimensions of the existing coupling scheme of the self-excited swept nozzle and the coupling scheme of this patent;

[0034] FIG10 is a schematic diagram of the structure of a parameterized self-excited sweep nozzle without feedback channel proposed in Example 2 of the present invention.

[0035] Explanation of the reference numerals: 1-injector body, 2-nozzle, 3-leakage hole; 11-first base plate, 12-injection plate, 13-second base plate; 111-annular mounting groove. DETAILED DESCRIPTION

[0036] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0037] Example 1

[0038] 1 to 6 , this embodiment provides a fuel injection device for a central staged combustion chamber, which includes a fuel injector body 1. The fuel injector body 1 is used to connect to an external fuel channel and inject fuel into the combustion chamber.

[0039] In this embodiment, the injector body 1 is annular. In a specific implementation, the injector body 1 takes in oil from one end surface and sprays oil from the outer side surface.

[0040] Specifically, the injector body 1 is uniformly arranged with multiple nozzles 2 along the circumference. An oil leakage hole 3 is located between any two adjacent nozzles 2; each oil leakage hole 3 communicates with both adjacent nozzles 2. Referring to Figures 5 and 6, the nozzles 2 and oil leakage holes 3 are spaced apart on the injector body 1. This shift from the conventional radial arrangement of the nozzles 2 and oil leakage holes 3 to a circumferential arrangement saves radial space and allows the nozzles 2 to be proportionally enlarged, thereby increasing the characteristic throat size. In one model, the throat size of the nozzle 2 can be increased from 0.4 mm in the prior art to 0.7 mm, a more than 75% increase in nozzle throat size. This significantly reduces nozzle manufacturing costs and improves nozzle flow path molding precision. Furthermore, the size of the oil leakage holes 3 can be increased.

[0041] Changing the position of the oil leakage hole 3 to between the nozzles 2 also moves the position of the oil leakage hole 3 radially outward. The change in the position of the oil leakage hole 3 in the radial direction can also increase the area of ​​the oil leakage hole 3, which is beneficial to reducing the resistance of the oil leakage hole 3 itself to the oil. On the other hand, moving the position of the oil leakage hole 3 radially outward can reserve enough space on the inner and outer sides of the oil leakage hole 3 in the radial direction to connect to the main combustion stage oil collection chamber. It can avoid designing a step surface in the main combustion stage oil collection chamber to accommodate the oil leakage hole 3, and can make the processing of the main combustion stage oil collection chamber more convenient.

[0042] In the specific design, in order to facilitate processing and manufacturing, the injector body 1 includes a first base plate 11, a fuel injection plate 12, and a second base plate 13. That is, the injector body 1 is formed into corresponding shapes by the first base plate 11, the fuel injection plate 12, and the second base plate 13, and then welded together to form a whole.

[0043] The first base plate 11, the fuel injection plate 12, and the second base plate 13 are coaxially arranged and fixedly connected in sequence. The fuel injection plate 12 is provided with an oil passage. The first base plate 11 and the second base plate 13 block the fuel injection plate 12 from both sides to form the nozzle 2 and the oil leakage hole 3. The first base plate 11 is provided with an annular mounting groove 111, which is connected to the oil leakage hole 3. Specifically, the first annular mounting groove 111 is provided on the side away from the fuel injection plate 12, and a through hole is provided at the bottom of the first annular mounting groove 111. The side of the first base plate 11 close to the fuel injection plate 12 is provided with a raised retaining ring, which is used to block the oil passage from the inside when mated with the fuel injection plate 12. Fuel enters the annular main combustion stage oil collection chamber through the main combustion stage oil inlet pipe, passes through the oil leakage hole 3 on the first base plate 11, and enters the two adjacent nozzles. Due to the restriction of the retaining ring, the fuel can only be sprayed into the main combustion stage airflow channel through the nozzle outlet. The first base plate 11 and retaining ring can be machined and formed separately, then welded together and assembled before being assembled with the oil collection chamber and other components. In practice, the second base plate 13 can be a separate annular plate or the end surface of another component. That is, rather than separately machining the second base plate 13, the first base plate 11 and the fuel injection plate 12 are welded together and then connected to the end surfaces of other components to form the injector body.

[0044] The oil spray plate 12 is processed into a structure with a nozzle and an oil channel outline. When welded with the first base plate 11 and the second base plate 13, a nozzle, an oil leakage hole and a channel connecting the nozzle and the oil leakage hole are formed.

[0045] In a specific implementation, the first bottom plate 11 and the oil spray plate 12 are integrally formed, and the oil leakage hole 3 is directly opposite to the annular mounting groove 111. That is, the oil leakage hole 3 is directly connected to the annular mounting groove 111.

[0046] The circumferential surface with a larger inner diameter of the annular mounting groove 111 is used to position the outer ring of the oil collecting chamber, and the circumferential surface with a smaller inner diameter of the annular mounting groove 111 is used to position the inner ring of the oil collecting chamber. In a specific implementation, the second base plate 13 is located on the leeward side of the injector body 1. This design has the following advantages: first, the side surfaces are all flat, the structure is compact, and it is easy to process; second, compared with the outward convex positioning method, the positioning method through the annular mounting groove 111 saves more space and weight; third, after the annular mounting groove 111 is positioned and installed with the oil collecting chamber, it is easier to fix the connection by welding; fourth, the space between the oil collecting chamber retaining ring and the outer ring is directly connected to the oil leakage hole, so that the fuel entering each oil leakage hole is more uniform.

[0047] In practice, the center of the leak hole 3 lies on the line bisector of the angle formed by the centerlines of two adjacent nozzles 2. The plane passing through the centerline of the leak hole 3 and the centerline of the injector body 1 serves as the plane of symmetry, and the channels on either side of the leak hole 3 are symmetrical. After the fuel enters the leak hole, its flow direction becomes perpendicular to the plane of the nozzle's flow path. This change in flow direction results in a loss of dynamic head, so the velocity of the fuel within the leak hole 3 should be minimized. Assuming the inlet throat has a width of T and a depth of S = T, and the required flow rate corresponds to a fuel velocity of U, the flow velocity within the leak hole is UT2 / 0.785D2, completely losing all kinetic energy. To this end, the diameter of the leak hole 3 is set to be greater than three times the width of the nozzle 2's throat. If D > 3T, the flow loss caused by the leak hole corresponds to a flow velocity less than 1 / 7 of the nozzle throat's flow velocity, and the pressure loss is less than 1 / 49 of the ideal pressure, effectively negating the effect. In the traditional self-excited sweep nozzle, the fuel needs to flow in from the lower inlet and then be ejected through the outlet at the top, so an oil leakage hole is generally constructed at the inlet. By constructing an oil leakage hole in the middle of adjacent nozzles and then entering the nozzle inlet through a drainage channel, not only can the size of the oil leakage hole be greatly increased, the pressure loss caused by the change in flow direction can be significantly reduced, and the space required can be significantly saved. Taking the structure disclosed in CN113464982 A as an example, under the condition that the diameter of the oil leakage hole is greater than 4T, the characteristic size of the nozzle can be increased from 0.4mm to 0.5mm by simply arranging the oil leakage hole in the middle, which is an increase of 25%. In order to further increase the characteristic size of the nozzle, a self-excited sweep nozzle without a feedback channel can be further selected. This will be further explained in Implementation 2. This embodiment adopts a self-excited sweep nozzle with dual feedback channels.

[0048] Referring to Figures 5 and 6 , to ensure ease of machining and welding, the distances W1 and W2 between the main flow channel and the outer and inner rings of the nozzle base plate, excluding the jet outlet, must be no less than the throat width T. In other words, the radial dimension of the retaining ring must be no less than the throat width. This ensures processability during machining, assembly, and welding. Preferably, W1 = W2 > 1 mm.

[0049] To reduce fuel flow losses, the minimum width of the channel connecting the oil leak hole 3 and the nozzle 2 is greater than the throat width of the nozzle 2. Specifically, an arc-shaped curve is used to construct the fuel flow path from the oil leak hole to the nozzle inlet throat. The width of the narrowest part of the flow path is H2, and the distance from the nozzle inlet to the flow path boundary is H1. The conditions H2 > T and H1 > 1.5T must be met. That is, the distance from the nozzle 2 inlet to the inner wall of the oil channel is greater than 1.5 times the throat width of the nozzle 2. Otherwise, the 90-degree turn after the two jets of opposite velocities converge here will inevitably cause a significant increase in flow losses. Under the conditions that H2 is greater than T and H1 is greater than 1.5T, the flow loss in this section corresponds to a flow velocity less than 1 / 10 of the nozzle throat velocity. Preferably, when the nozzle 2 is a self-excited sweep nozzle 2 without a feedback channel, the width of the channel connecting the oil leak hole 3 and the nozzle 2 gradually decreases as it approaches the nozzle 2. In this embodiment, taking the structure disclosed in CN113464982 A as an example, the width of the throat of the nozzle 2 is 0.5 mm.

[0050] The number of the nozzles 2 is 6 to 24. In a specific implementation, the number of the nozzles 2 is 7, 8, 9, 10, 11, 12, 13, 14 or 15, 16, 17, 18, 19, 20, 21, 22, 23.

[0051] Example 2

[0052] This embodiment is a further improvement based on embodiment 1. The similarities are not repeated here, and only the differences are described below.

[0053] Referring to Figures 7 to 10 , this embodiment utilizes a self-excited swept nozzle structure without a feedback channel. This self-excited swept nozzle without a feedback channel comprises two inlets, namely, the two inlets shown in Figure 10 , a coupling cavity, and an outlet. The interaction of the two jets within the coupling cavity creates a self-excited swept jet at the outlet. Through a special design, the main flow channel height H of the self-excited swept nozzle without a feedback channel can be reduced by 30% compared to a self-excited swept nozzle with a dual-feedback channel configuration, creating extremely favorable conditions for integrating the self-excited swept nozzle into the head of a centrally staged combustion chamber. Furthermore, under the same throat width, the operating frequency of the self-excited swept nozzle without a feedback channel configuration can be increased by over 50% under the same inlet and outlet pressure drop conditions. At a pressure drop of 1 MPa, it can reach over 2 kHz, far exceeding the combustion pulsation frequency within the combustion chamber and making it less susceptible to combustion oscillation.

[0054] In order to significantly increase the throat size without increasing the overall size of the combustion chamber head structure, changing the position and size of the swirler, or changing the distribution of the injection holes, the nozzle is further designed in this embodiment.

[0055] Please refer to FIG. 10. Specifically, this nozzle is a semi - circle with a radius of R0. Taking its center as the origin, it forms an expansion angle of α with the inner cavity. Two inlet channels are constructed at the intersection with the outer contour of the semi - circle. Using the edge line of the α expansion angle as the center line, translate a distance of J / 2 to both sides respectively, then an inlet channel with a width of J is constructed. The distance that the inlet channel extends outward along the center line is L1. Within the distance of L1, the width of the flow channel is maintained at J1, and outside L1, the flow channel can be freely designed according to the position of the oil leakage hole. The straight edge line of the semi - circle is translated downward by a distance of H1 to form a new boundary of the nozzle inner cavity. The center line of the nozzle inner cavity is translated T / 2 to both sides respectively, then an outlet throat with a width of T can be constructed at the intersection of this lower boundary and the center line. An expansion angle with an angle of β is formed outward from the outlet throat, and its height is H2. A chamfer with a radius of R1 is made at the lower boundary and the translated straight line. The dimensions of the above - mentioned self - excited swept nozzle structure without a feedback channel need to satisfy: 2 < R0 / T < 8, and 0.2 < H1 / T < 4, and 0.5 < H2 / T < 3, and 0.5 < L1 / T < 2, and 60° < α < 150°, and (α - β) > 20°, and (R0 + H1 + H2) / T < 10. Under the above - mentioned dimensional constraints, this self - excited swept nozzle without a feedback channel can smoothly generate self - excited swept oscillating jet flows at the outlet. At the same time, under the same throat size constraints required at the head of the combustion chamber, the size of the nozzle can be significantly reduced, or under the same flow coefficient and space size constraints, the throat size of the nozzle can be significantly increased, and the number of nozzles can be reduced. [[ID=……]](此处原内容中ID=3 - 6无具体内容,保留原文格式)

[0056]

[0057] It should be noted that for the self - excited swept nozzle with a double - feedback channel, its throat is at the inlet of the nozzle, and for the self - excited swept nozzle without a feedback channel, it is the minimum at the outlet of the nozzle.

[0058] It should be noted that the dimension marks shown in the drawings are for the convenience of reading in combination with the text part of this application. The values therein only refer to the structure of a certain model and do not limit the actual dimensions of the solution proposed in this application.

[0059] The structure, features and functions of the present invention have been described in detail based on the embodiments shown in the drawings above. The above is only the preferred embodiment of the present invention, but the present invention is not limited to the scope defined by the drawings. Any changes made according to the concept of the present invention, or equivalent embodiments modified into equivalent changes, still fall within the spirit covered by the description and the drawings, and should be within the protection scope of the present invention.

Claims

1. An oil injection device for a central staged combustion chamber, characterized in that: It includes an injector body (1); The injector body (1) is annular; The injector body (1) is evenly provided with a plurality of nozzles (2) along the circumferential direction, and an oil leakage hole (3) is provided between any two adjacent nozzles (2); the oil leakage hole (3) is communicated with the two adjacent nozzles (2).

2. The fuel injection device of the central stage combustion chamber according to claim 1, characterized in that : The injector body (1) includes a first bottom plate (11), an injection plate (12) and a second bottom plate (13); The first bottom plate (11), the injection plate (12) and the second bottom plate (13) are coaxially arranged and fixedly connected in sequence; The injection plate (12) is provided with an oil passage, and the first bottom plate (11) and the second bottom plate (13) block the injection plate (12) from both sides to form the nozzle (2) and the oil leakage hole (3); The first bottom plate (11) is provided with an annular installation groove (111), and the annular installation groove (111) is communicated with the oil leakage hole (3).

3. The fuel injection device of the central staged combustion chamber according to claim 2, characterized in that: The first bottom plate (11) and the injection plate (12) are integrally formed, and the oil leakage hole (3) is directly opposite to the annular installation groove (111).

4. The fuel injection device of the central staged combustor according to claim 3, characterized in that: The center of the oil leakage hole (3) is located on the angular bisector formed by the center lines of two adjacent nozzles (2), and the diameter of the oil leakage hole (3) is greater than 3 times the throat width of the nozzle (2).

5. The fuel injection device of the central staged combustion chamber according to claim 1, characterized in that: The minimum width of the channel connecting the oil leakage hole (3) and the nozzle (2) is greater than the throat width of the nozzle (2).

6. The fuel injection device of the central staged combustor according to claim 1, characterized in that: The nozzle (2) is a non-feedback channel self-excited swept nozzle (2) or a double-feedback channel self-excited swept nozzle (2).

7. The fuel injection device of the central staged combustion chamber according to claim 6, characterized in that: When the nozzle (2) is a non-feedback channel self-excited swept nozzle (2), the width of the channel connecting the oil leakage hole (3) and the nozzle (2) gradually becomes smaller along the direction close to the nozzle (2).

8. The fuel injection device of the central staged combustion chamber according to claim 7, characterized in that: The width of the throat of the nozzle (2) is 0.4 to 0.8 millimeters.

9. The fuel injection device of the central staged combustor according to claim 6, characterized in that: When the nozzle (2) is a double-feedback channel self-excited swept nozzle, the distance from the inlet of the nozzle (2) to the inner side wall of the oil passage is greater than 1.5 times the throat width of the nozzle (2).

10. The fuel injection device of the central staged combustion chamber according to any one of claims 1-9, characterized in that: The number of the nozzles (2) is 6 to 24.

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