Afterburner two-stage annular mixer and bypass ratio self-adaptive matching method

Abstract

The invention provides an afterburner two-stage annular mixer and a bypass ratio self-adaptive matching method, and relates to the technical field of aero-engines. The first-stage annular mixer is arranged in the casing, and an outer duct is formed between the first-stage annular mixer and the casing; the second-stage annular mixer is arranged in the casing and located on the inner side of the first-stage annular mixer, a flow dividing channel is formed between the first-stage annular mixer and the second-stage annular mixer, the casing and the second-stage annular mixer form a mixing channel, and the outer duct and the flow dividing channel are both communicated with the mixing channel. According to the embodiment of the invention, under the condition of small overflow loss and flow separation risk, the small mixing effect of the mixer is realized, the low cooling gas temperature is ensured, and meanwhile, the requirements of low flow resistance, high efficiency and stable work in a wide outer / inner duct range can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engines, in particular to a two-stage annular mixer of a thrust chamber and a bypass ratio adaptive matching method. BACKGROUND

[0002] With the development of aero-engines, the engine thrust-to-weight ratio is continuously improved. To achieve the improvement of the thrust-to-weight ratio, on the one hand, the turbine and the thrust chamber outlet temperature are continuously improved to increase the thrust, which makes the thrust chamber heat load continuously improve while facing the problems of reduced cooling air quantity and increased cooling air temperature, which brings challenges to the cooling of the thrust chamber. On the other hand, the engine adopts lightweight metal materials such as titanium alloy cases to reduce the structural weight of the engine. Lightweight metal materials often have a lower temperature resistance level, which also makes efficient cooling design particularly important. In addition, it is also necessary to reduce the flow loss of the engine and improve the useful work to improve the efficiency of the engine.

[0003] The aero-engine thrust chamber usually uses a lobed mixer to mix the high-temperature and low-temperature gases in the inner and outer channels to improve the uniformity of the mixed gases. After mixing, the temperature of the downstream cooling air will be further increased, which does not meet the current cooling needs, and the mixing loss is large, which is not conducive to the improvement of the engine thrust performance. The mixing effect of the traditional annular mixer is significantly weaker than that of the lobed mixer, and the cooling air temperature is increased less, which meets the cooling needs. However, the current engine bypass ratio changes in the range of 0.2 to 1.2 or higher, and the conventional mixer cannot meet the needs of the wide inlet working range of the thrust chamber. SUMMARY

[0004] Therefore, the present application provides a two-stage annular mixer of a thrust chamber and a bypass ratio adaptive matching method to achieve the purpose of low flow resistance and efficient and stable operation of the thrust chamber in a wide outer / inner channel range.

[0005] The present application provides the following technical solution: a two-stage annular mixer of a thrust chamber, comprising: a case; a first-stage annular mixer arranged inside the case, the first-stage annular mixer and the case forming an outer channel; and a second-stage annular mixer arranged inside the case and located inside the first-stage annular mixer, the first-stage annular mixer and the second-stage annular mixer forming a flow separation channel, the case and the second-stage annular mixer forming a mixing channel, and the outer channel and the flow separation channel being in communication with the mixing channel.

[0006] The application further provides a bypass ratio self-adaptive matching method, which is implemented by using the two-stage annular mixer of the afterburner, and the bypass ratio self-adaptive matching method comprises the following steps: when the air pressure of the outer bypass airflow entering the split passage is less than the air pressure of the inner bypass airflow, the outer bypass airflow flows out from the outer bypass and the mixing passage; part of the inner bypass airflow flows out from the split passage and the mixing passage, and the other part of the inner bypass airflow flows out from the inner bypass; when the air pressure of the outer bypass airflow entering the split passage is greater than the air pressure of the inner bypass airflow, part of the outer bypass airflow flows out from the outer bypass and the mixing passage, and the other part of the outer bypass airflow flows out from the split passage and the mixing passage; and the inner bypass airflow flows out from the inner bypass.

[0007] Compared with the prior art, the above at least one technical scheme adopted by the application can achieve at least the following beneficial effects: the embodiment of the application realizes smaller mixer mixing action under smaller overflow loss and flow separation risk, guarantees lower cooling gas temperature, and can meet the low-flow-resistance high-efficiency stable working requirements of a wider outer / inner bypass range. BRIEF DESCRIPTION OF DRAWINGS

[0008] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0009] Figure 1 It is a schematic diagram of a two-stage annular mixer of a wide bypass ratio range afterburner. Figure 2 It is a sectional view of a two-stage annular mixer of a wide bypass ratio range afterburner. Figure 3 It is a schematic diagram of a first-stage annular mixer. Figure 4 It is a schematic diagram of an overflow hole of a first-stage annular mixer. Figure 5 It is a schematic diagram of a second-stage annular mixer. Figure 6 It is a schematic diagram of a sawtooth unit of a second-stage annular mixer. Figure 7 It is a schematic diagram of the connection between a first-stage annular mixer and a second-stage annular mixer. Figure 8 It is a schematic diagram of a small-bypass-ratio working principle. Figure 9 It is a schematic diagram of a large-bypass-ratio working principle. Figure 10 It is a schematic diagram of the cross-sectional area of the downstream end of the outer bypass, the cross-sectional area of the downstream end of the split passage and the minimum area of the mixing passage.

[0010] The attached diagram shows the following labels: 1. Casing; 2. First-stage annular mixer; 21. Flat section of the first-stage mixer; 22. Overflow hole; 3. Second-stage annular mixer; 31. Serrated section; 32. Smooth section; 33. Second curved section; 4. Diffuser; 41. Straight section; 42. First curved section; 5. Heat shield; 6. Flame stabilizer; 61. Outer annular flame stabilizer; 62. Shift flame stabilizer; 63. Inner annular flame stabilizer; 7. Bow-shaped frame; 8. Outer duct; 9. Inner duct; 10. Cooling duct; 11. Diverter channel; 12. Mixing channel. Detailed Implementation

[0011] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0012] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0013] like Figures 1 to 9 As shown, this embodiment of the invention provides a two-stage annular mixer for an afterburner, including: a casing 1, a first-stage annular mixer 2, a second-stage annular mixer 3, a diffuser 4, a heat shield 5, a flame stabilizer 6, and an arc-shaped frame 7. The first-stage annular mixer 2 is disposed inside the casing 1, and an outer bypass duct 8 is formed between the first-stage annular mixer 2 and the casing 1; the second-stage annular mixer 3 is disposed inside the casing 1 and located inside the first-stage annular mixer 2, and a flow divider channel 11 is formed between the first-stage annular mixer 2 and the second-stage annular mixer 3. The casing 1 and the second-stage annular mixer 3 form a mixing channel 12, and both the outer bypass duct 8 and the flow divider channel 11 are connected to the mixing channel 12.

[0014] The embodiments of the present invention achieve a smaller mixing effect in the mixer with less overflow loss and flow separation risk, ensuring a lower cooling gas temperature, while meeting the requirements of low flow resistance, high efficiency and stable operation under a fixed area with a mass flow rate ratio of the outer bypass flow a to the inner bypass flow b (hereinafter referred to as bypass ratio, the range of the maximum bypass ratio / minimum bypass ratio is 1 to 4).

[0015] An outer bypass duct 8 is formed between the casing 1 and the first-stage annular mixer 2; an inner bypass duct 9 is formed between the first-stage annular mixer 2, the second-stage annular mixer 3, and the diffuser 4; and a cooling bypass duct 10 is formed between the casing 1 and the heat shield 5. Figure 7 As shown, a flow divider 11 is formed between the first-stage annular mixer 2 and the second-stage annular mixer 3. An arc-shaped frame 7 is installed within the flow divider 11, and the first-stage annular mixer 2 and the second-stage annular mixer 3 are connected by the circumferentially distributed arc-shaped frames 7. The arc-shaped frames 7 are conventional support structures. The casing 1 and the second-stage annular mixer 3 form a mixing channel 12. The diffuser 4 consists of a straight section 41 and a first curved section 42. The flame stabilizer 6 consists of an outer ring flame stabilizer 61, a standby flame stabilizer 62, and an inner ring flame stabilizer 63.

[0016] Both the first-stage annular mixer 2 and the second-stage annular mixer 3 are annular structures, with the second-stage annular mixer 3 located inside the first-stage annular mixer 2. The rightmost end of the first-stage annular mixer 2 is located in the first curved section 42 region, and the entire second-stage annular mixer 3 is located in the first curved section 42 region, meaning they are both located in the diffusion stage, which helps to reduce flow losses.

[0017] like Figure 3 As shown, the first-stage annular mixer 2 consists of a first-stage mixer flat section 21 and overflow holes 22. Multiple overflow holes 22 are evenly distributed circumferentially. Each overflow hole 22 has a triangular structure with a gradually increasing cross-sectional width along the airflow direction, ensuring the overflow capacity of the overflow holes 22 and effectively reducing flow losses. The specific structure of the overflow holes 22 is as follows... Figure 4 As shown, where Figure 4 The airflow direction indicates the direction of gas flow. The axis of the triangular structure used to illustrate the overflow hole 22 is parallel to the airflow direction, and the apex of the triangle is facing the incoming flow direction.

[0018] like Figure 5 As shown, the second-stage annular mixer 3 consists of a serrated section 31, a smooth section 32, and a second curved section 33. The serrated section 31 includes multiple serrated units, each of which has a triangular structure with the top of the triangle facing the intake direction. The multiple serrated units are evenly distributed circumferentially along the smooth section 32. The profile of the second curved section 33 is designed according to the flow field matching method of "gradual flow followed by rapid flow," "gradual flow followed by rapid flow," and "rapid flow followed by gradual flow" (the gradual flow and rapid flow mentioned in the text refer to the angle between the tangent at a certain set point on the second curved section 33 and the axis. The gradual flow and rapid flow are also relative. When in the gradual flow followed by rapid flow stage, the angle between the tangent in the first part and the axis should be greater than the angle between the tangent in the second part and the axis. The gradual flow and rapid flow followed by gradual flow are analogous to the above methods and will not be elaborated here). This design avoids flow separation inside the second curved section 33. Figure 6The second stage annular mixer sawtooth unit is shown in a schematic view, the sawtooth unit is triangular, and the airflow direction refers to the gas flow direction entering the second stage annular mixer 3, and is only used to indicate that the front end of the triangular structure faces the incoming flow direction.

[0019] The rightmost cross section of the first stage annular mixer 2, the cross-sectional area of the downstream end of the outer duct 8 is S1, the cross-sectional area of the downstream end of the shunt passage 11 is S2, and the minimum area of the mixing passage 12 is S3. In order to ensure efficient and reliable operation of the two-stage annular mixer, S1+S2> S3 needs to be ensured, such as Figure 10

[0020] When the aircraft engine is working, the bypass ratio changes with the altitude, speed and throttle size of the engine, and therefore the afterburner needs to realize stable operation under the condition of changing bypass ratio, but when the bypass ratio range is too wide, the afterburner bypass area design is difficult to meet the requirements of large and small bypass ratios. In order to ensure a lower cooling gas temperature, the annular mixer with non-adjustable structure and mixing function is adopted, the applicable range of the bypass ratio is narrow, and generally the maximum value of the bypass ratio / the minimum value of the bypass ratio is 1 to 2.5. Therefore, the present application provides a two-stage annular mixer structure, and further provides a wide-range bypass ratio self-adaptive matching method, which expands the applicable range of the annular mixer bypass ratio, as shown in Figure 8 and Figure 9 The method comprises the following steps: As shown in Figure 8 In the small-bypass-ratio working state, the flow rate of the outer duct gas flow a is small, the flow rate in the mixing passage 12 is low, a part of the inner duct gas flow b enters the mixing passage 12 through the shunt passage 11, occupies part of the flow passage area of the mixing passage 12, and increases the flow rate of the outer duct gas flow a entering the mixing passage 12, thereby improving the downstream gas flow mixing, diffusing and cooling the inlet of the cooling duct 10. Since S1+S2> S3, the mixing passage 12 cannot completely pass the outer duct gas flow a and the inner duct gas flow b, and therefore a part of the inner duct gas flow b overflows and flows to the downstream through the inner duct 9. Under the action of the circumferentially distributed sawtooth segment 31, the overflow loss can be significantly reduced.

[0021] As shown in Figure 9 In the large-bypass-ratio working state, the flow rate of the outer duct gas flow a is large, a part of the outer duct gas flow a directly enters the mixing passage 12, and the other part enters the mixing passage 12 through the overflow hole 22 after entering the shunt passage 11, thereby occupying the flow passage area of the shunt passage 11. The amount of gas entering the mixing passage 12 through the shunt passage 11 from the inner duct gas flow b is reduced, and most of the inner duct gas flow b flows through the inner duct 9. Under the action of the circumferentially distributed sawtooth segment 31, the overflow loss can be significantly reduced.

[0022] ​The size of the outer flow a directly reflects that: when the outer flow enters the pressure of the flow channel 11 is less than the pressure of the inner flow, it is considered that the flow of the outer flow a is smaller; when the outer flow a enters the pressure of the flow channel 11 is greater than the pressure of the inner flow, it is considered that the flow of the outer flow a is larger.

[0023] It should be noted that, Figure 8 and Figure 9 a is the outer flow, the corresponding arrow at a indicates the flow direction of the outer flow, b is the inner flow, and the corresponding arrow at b indicates the flow direction of the inner flow.

[0024] The embodiment of the application can realize small mixing effect of the mixer, and can meet the low flow resistance and high efficiency and stable work of the afterburner.

[0025] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A two-stage annular mixer with an afterburner, characterized in that, include: Casing (1); The first-stage annular mixer (2) is located inside the casing (1), and an outer bypass (8) is formed between the first-stage annular mixer (2) and the casing (1). The second-stage annular mixer (3) is located inside the casing (1) and inside the first-stage annular mixer (2). A flow divider channel (11) is formed between the first-stage annular mixer (2) and the second-stage annular mixer (3). A mixing channel (12) is formed between the casing (1) and the second-stage annular mixer (3). The outer bypass (8) and the flow divider channel (11) are both connected to the mixing channel (12).

2. The two-stage annular mixer with an afterburner according to claim 1, characterized in that, The downstream end of the first-stage annular mixer (2) is provided with an overflow hole (22), and the outer duct (8) can be connected to the diversion channel (11) through the overflow hole (22).

3. The two-stage annular mixer with an afterburner according to claim 2, characterized in that, There are multiple overflow holes (22), which are evenly distributed along the circumferential spacing of the first-stage annular mixer (2).

4. The two-stage annular mixer with an afterburner according to claim 1, characterized in that, The two-stage annular mixer of the afterburner also includes a diffuser (4), which is located inside the second-stage annular mixer (3), and an inner channel (9) is formed between the second-stage annular mixer (3) and the diffuser (4).

5. The two-stage annular mixer with an afterburner according to claim 4, characterized in that, The diffuser (4) includes a straight section (41) and a first curved section (42) arranged sequentially along the gas flow direction. The downstream end of the first-stage annular mixer (2) is located in the axial region where the first curved section (42) is located, and the second-stage annular mixer (3) is located in the axial region where the first curved section (42) is located.

6. The two-stage annular mixer with an afterburner according to claim 1, characterized in that, The second-stage toroidal mixer (3) includes: Smooth segment(32); The second curved surface segment (33) is connected to the downstream end of the smooth segment (32); The serrated segment (31) is connected to the upstream end of the smooth segment (32).

7. The two-stage annular mixer with an afterburner according to claim 6, characterized in that, The serrated section (31) includes multiple serrated units, each of which has a triangular structure with the top of the triangular structure facing the air intake direction. The multiple serrated units are evenly distributed along the circumferential spacing of the smooth section (32).

8. The two-stage annular mixer with an afterburner according to claim 1, characterized in that, The cross-sectional area of ​​the downstream end of the duct (8) is S1, the cross-sectional area of ​​the downstream end of the diversion channel (11) is S2, the minimum area of ​​the mixing channel (12) is S3, and S1+S2>S3.

9. A bypass ratio adaptive matching method, implemented using a two-stage annular mixer in an afterburner as described in any one of claims 1 to 8, characterized in that, The bypass ratio adaptive matching method includes: When the pressure of the outer bypass airflow entering the split channel (11) is less than the pressure of the inner bypass airflow, the outer bypass airflow flows out through the outer bypass channel (8) and the mixing channel (12); part of the inner bypass airflow flows out through the split channel (11) and the mixing channel (12), and the other part of the inner bypass airflow flows out through the inner bypass channel (9); When the pressure of the outer bypass airflow entering the split channel (11) is greater than the pressure of the inner bypass airflow, part of the outer bypass airflow flows out through the outer bypass channel (8) and the mixing channel (12), and the other part of the outer bypass airflow flows out through the split channel (11) and the mixing channel (12); the inner bypass airflow flows out through the inner bypass channel (9).

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