Diffuser gas flow path circulation system

Abstract

The present invention discloses a diffuser gas flow path circulation system, which relates to the field of gas turbines. The system includes a combustion cylinder and a diffuser, wherein the diffuser is connected to the combustion cylinder. The diffuser includes a conveying air flow inlet. The airflow enters the diffuser through the conveying air flow inlet, is decelerated, and is output from the conveying air flow outlet of the diffuser to the combustion cylinder. A first air flow branch is defined in the airflow conveying direction from the diffuser to the combustion cylinder. The combustion cylinder returns a portion of the airflow received from the diffuser to the diffuser as a circulating airflow, thereby weakening the boundary layer separation of the airflow in the diffuser. A second air flow branch is defined in the airflow return direction from the combustion cylinder to the diffuser. This application utilizes the uneven distribution of total gas pressure within the combustion cylinder to draw a portion of high-pressure gas from the combustion cylinder and spray it into the boundary layer of the flow path within the diffuser through a circulation pipeline, thereby activating the low-energy fluid in the boundary layer and enhancing the diffuser's anti-separation capability, thereby reducing the total pressure loss of the gas within the combustion cylinder.

Description

Technical Field

[0001] The present invention relates to the field of gas turbines, and in particular to a diffuser gas flow passage circulation system. Background Art

[0002] In a gas turbine, the diffuser is located at the compressor outlet and connected to the combustion chamber. It diffuses the airflow at the compressor outlet, reducing the velocity of the gas entering the combustion chamber, thereby minimizing the total pressure loss of the gas within the combustion chamber.

[0003] When the compressor uses cantilevered stators, the total pressure loss at the flow channel of the compressor outlet is more serious, the boundary layer of the flow channel in the diffuser gradually thickens along the flow direction, and the diffuser is prone to flow separation, thereby increasing the speed of the gas entering the combustion cylinder and exacerbating the total pressure loss of the gas in the combustion cylinder.

[0004] To ensure that there is no flow separation in the diffuser, the diffuser length needs to be controlled before flow separation occurs. At this time, the diffuser's static pressure lift coefficient is small and the outlet velocity is large. Therefore, the existing technology usually reduces flow separation by increasing the diffuser's axial length, reducing the diffuser's outlet cross-sectional area and other geometric parameters. However, increasing the diffuser length will gradually thicken the diffuser boundary layer, causing the diffuser outlet velocity to increase, and the effect of improving the diffuser's static pressure lift coefficient is not obvious. At the same time, geometric parameters such as the diffuser's axial length and the diffuser's outlet cross-sectional area are limited by the overall structural geometry. The diffuser's internal and external flow channel profiles also need to consider factors such as processing costs, and the degree of freedom in the design of the diffuser profile is very small.

[0005] Patent CN109339875A discloses a mixing diffuser with bypass air. It includes an annular baffle that acts as a pressure diffuser. One end of the baffle connects to the turbine rear casing, and the other extends to the outside of the heat shield inlet. Together, the baffle and the turbine rear cone form a gradually expanding channel through which the high-speed combustion gases flowing from the turbine's last-stage guide vanes diffuse and decelerate. The baffle, the turbine rear casing, and the plenum chamber form an annular bleed air collecting chamber, which connects to the compressor via a compressor bleed duct. Part of the gas introduced from the compressor enters the heat shield, while the remainder flows through bleed slits in the baffle and into the afterburner. A valve is installed on the compressor bleed duct, which is closed in turbojet mode and open in ramjet mode. This technology provides a uniform and moderate velocity and temperature field for the heat shield and afterburner inlet by drawing air from the engine compressor, which ensures that the engine can achieve greater propulsion efficiency in different operating modes. However, it does not take into account the fact that the boundary layer of the flow channel in the diffuser is prone to flow separation, resulting in a large total pressure loss of the gas in the combustion and compression cylinder.

[0006] In view of the above technical problems, the present invention is specially introduced. Summary of the Invention

[0007] The main purpose of the present invention is to provide a diffuser gas flow path circulation system to solve the problem that when the compressor adopts cantilevered stator blades, the boundary layer of the flow path in the diffuser is easily separated, resulting in a large total pressure loss of the gas in the combustion cylinder.

[0008] In order to achieve the above-mentioned purpose, the present invention provides a diffuser gas flow path circulation system, which is characterized in that it includes a combustion cylinder, a diffuser, and the diffuser is connected to the combustion cylinder. The diffuser includes a conveying air flow inlet. The air flow enters the diffuser through the conveying air flow inlet and is decelerated and then output from the conveying air flow outlet of the diffuser to the combustion cylinder. A first air flow branch is defined in the air flow conveying direction from the diffuser to the combustion cylinder. The combustion cylinder returns a part of the air flow received from the diffuser to the diffuser as a circulating air flow to weaken the air flow boundary layer separation in the diffuser. A second air flow branch is defined in the air flow return direction from the combustion cylinder to the diffuser.

[0009] Preferably, it also includes a circulation pipeline, and the combustion cylinder returns part of the airflow received from the diffuser to the diffuser through the circulation pipeline, defining a second airflow branch from the combustion cylinder to the circulation pipeline to the diffuser in the direction from the combustion cylinder to the diffuser.

[0010] Preferably, the combustion cylinder comprises a circulating air flow inlet, which is located on a side of the combustion cylinder close to the diffuser.

[0011] Preferably, the diffuser comprises a circulating airflow outlet, which is opened at a position of the diffuser close to a boundary layer separation starting position of the diffuser.

[0012] Preferably, the circulation pipeline includes a plurality of pipes connected to each other, the plurality of pipes including a first pipe located at the end in the direction of the circulating airflow, and the circulating airflow enters the diffuser boundary layer after being accelerated through the first pipe.

[0013] Preferably, the cross-sectional area of ​​the first duct decreases along the direction of the circulating airflow.

[0014] Preferably, the first pipe includes a first wall surface and a second wall surface, the first wall surface and the second wall surface are elliptical arc surfaces, and the first wall surface and the second wall surface are non-coaxially distributed.

[0015] Preferably, the first wall and the second wall are tangent to the diffuser flow channel.

[0016] Preferably, the circulation pipeline further includes a second pipe, which is located upstream of the first pipe in the direction of the circulation airflow and is adjacent to the first pipe.

[0017] Preferably, both ends of the second pipe are connected to the circulating air flow inlet and the first pipe respectively, and are configured to reduce backflow of the circulating air flow at the circulating air flow inlet.

[0018] Preferably, the second pipe is a straight pipe, and the second pipe is tangent to the first wall surface and the second wall surface of the first pipe.

[0019] Preferably, the circulation pipeline further includes a third pipeline, and the third pipeline connects the circulation air flow inlet and the second pipeline.

[0020] Preferably, the third pipeline is a straight pipeline, and the third pipeline is transitionally connected to the circulating air flow inlet and the second pipeline respectively.

[0021] Preferably, the third pipe is a curved pipe, and the cross-sectional area of ​​the third pipe gradually decreases along the direction of the circulating airflow to avoid backflow of the circulating airflow at the outlet.

[0022] Preferably, the inner diameter of the circulating air flow inlet is 0.2 to 0.3 times the height of the flow channel of the conveying air flow inlet.

[0023] Preferably, the inner diameter of the circulating air flow outlet is 0.02 to 0.04 times the height of the conveying air flow inlet flow channel.

[0024] Preferably, the maximum arc inner diameter of the first wall is 0.4 to 0.5 times the height of the conveying air inlet flow channel, and the minimum arc inner diameter of the first wall is 0.3 to 0.4 times the height of the conveying air inlet flow channel.

[0025] Preferably, the maximum arc inner diameter of the second wall is 0.4 to 0.5 times the height of the conveying air inlet flow channel, and the minimum arc inner diameter of the second wall is 0.4 to 0.5 times the height of the conveying air inlet flow channel.

[0026] Preferably, a plurality of circulation lines are included, and the plurality of circulation lines are distributed around the circumference of the combustion cylinder and the diffuser.

[0027] Preferably, the circulation pipeline is distributed circumferentially around the combustion cylinder and the diffuser.

[0028] Based on the above technical solution, the present invention has at least the following beneficial effects:

[0029] 1. The present invention proposes to guide the high-pressure gas in the combustion cylinder to the boundary layer of the flow channel in the diffuser through a circulation pipeline. By activating the low-energy fluid in the boundary layer, the anti-separation ability of the diffuser boundary layer is enhanced, and the total pressure loss of the gas in the combustion cylinder is effectively reduced.

[0030] 2. The present invention proposes connecting multiple pipes to form a circulation pipeline, and at the same time making the first pipe connected to the diffuser into a tapered form along the airflow direction, so that the airflow in the air inlet channel is in a flow acceleration state, improving the problem that the boundary layer of the flow channel in the diffuser gradually thickens along the flow direction, which is prone to flow separation.

[0031] 3. The present invention proposes that the first pipe connecting the diffuser is composed of two non-concentric elliptical arcs, which are tangent to the flow channel profile inside the diffuser. This structural design reduces the airflow loss entering the diffuser, makes it easier to activate the low-energy fluid in the boundary layer, and achieves the purpose of eliminating flow separation in the diffuser; and avoids problems such as airflow backflow at the circulating airflow inlet.

[0032] 4. By optimizing the inlet and outlet positions of the circulation pipeline, the low-energy fluid in the boundary layer is fully activated, thereby enhancing the anti-separation ability of the diffuser. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 This is a schematic diagram of the structure of the diffuser gas flow path circulation system in Example 1 of the present application. Figure 1 ;

[0035] Figure 2 This is a schematic diagram of the structure of the diffuser gas flow circulation system in Example 1 of the present application. Figure 2 ;

[0036] Figure 3 It is a structural schematic diagram of the diffuser gas flow path circulation system of Example 2 of the present application.

[0037] The above drawings include the following reference numerals:

[0038] 100, combustion cylinder; 110, circulating air inlet; 120, circulating pipeline;

[0039] 121, first pipe; 1212, first wall; 1214, second wall

[0040] 123, second pipeline; 125, third pipeline;

[0041] 200, diffuser; 210, conveying air flow inlet; 220, circulating air flow outlet;

[0042] 300, first airflow branch; 400, second airflow branch DETAILED DESCRIPTION

[0043] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] The present invention is further described in detail below with reference to specific examples. These examples should not be construed as limiting the scope of protection claimed in the present invention.

[0045] In this description, it should be noted that, unless otherwise specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention. Furthermore, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0046] Example 1:

[0047] The present invention provides a diffuser gas flow passage circulation system. The system utilizes the uneven distribution of total gas pressure in the combustion cylinder to draw out a portion of high-pressure gas from the combustion cylinder and spray it into the boundary layer of the diffuser flow passage through a self-circulation pipeline, thereby activating the low-energy fluid in the boundary layer, thereby enhancing the diffuser's anti-separation ability, reducing the diffuser outlet velocity, and thus reducing the total pressure loss of the gas in the combustion cylinder.

[0048] exist Figure 1 An embodiment of the present invention is shown in FIG. As shown in the figure, the circulation system includes a combustion cylinder 100 and a diffuser 200. The diffuser 200 is connected to the combustion cylinder 100. The diffuser 200 includes a conveying air flow inlet 210. The air flow enters the diffuser 200 through the conveying air flow inlet 210 and is decelerated and then output from the conveying air flow outlet of the diffuser 200 to the combustion cylinder 100. A first air flow branch 300 is defined in the air flow conveying direction from the diffuser 200 to the combustion cylinder 100. The combustion cylinder 100 returns a portion of the air flow received from the diffuser 200 to the diffuser 200 as a circulating air flow to the diffuser 200, thereby weakening the air flow boundary layer separation in the diffuser 200. A second air flow branch 400 is defined in the air flow return direction from the combustion cylinder 100 to the diffuser 200.

[0049] Specifically, such as Figure 2 As shown, the circulation system includes a circulation line 120. The combustion cylinder 100 returns a portion of the airflow received from the diffuser 200 to the diffuser 200 through the circulation line 120, defining a second airflow branch 400 from the combustion cylinder 100 to the circulation line 120 and then to the diffuser 200 in the direction from the combustion cylinder 100 to the diffuser 200. The circulation line 120 sprays the airflow toward the boundary layer of the flow channel within the diffuser, activating the low-energy fluid in the boundary layer, thereby enhancing the diffuser's anti-separation capability.

[0050] The combustion cylinder 100 includes a circulating air flow inlet 110 and a circulating air flow outlet 220. In order to further improve the anti-separation capability of the diffuser, the positions of the circulating air flow inlet and the circulating air flow outlet are further optimized in the present application.

[0051] Specifically, the circulating air flow inlet 110 is located on the side of the combustion cylinder 100 close to the diffuser 200. The total pressure inside the combustion cylinder at this position is relatively high. By smoothly introducing the high-pressure gas in the combustion cylinder into the circulation pipeline 120, the low-energy fluid in the boundary layer is fully activated, thereby enhancing the anti-separation ability of the diffuser.

[0052] The circulating airflow outlet 220 is opened at a position of the diffuser 200 close to the starting position of the boundary layer separation of the diffuser 200, so as to facilitate the airflow to be sprayed toward the boundary layer of the flow channel in the diffuser, activate the low-energy fluid in the boundary layer, and better eliminate the flow separation of the diffuser.

[0053] In order to further increase the fluid velocity of the diffuser boundary layer and optimize the effect of the airflow in the circulation pipeline on eliminating the diffuser boundary layer, this application further optimizes the design of the circulation pipeline.

[0054] Specifically, if Figure 2 As shown, in Example 1 of the present application, the circulation line 120 includes a plurality of pipes connected to one another, including a first pipe 121 located at the end in the direction of the circulating airflow. The circulating airflow is accelerated through the first pipe 121 and enters the boundary layer of the diffuser 200. To ensure that the airflow in the first pipe 121 is in an accelerated flow state, the cross-sectional area of ​​the first pipe 121 decreases along the direction of the circulating airflow.

[0055] Specifically, the first duct 121 includes a first wall 1212 and a second wall 1214. Both walls are elliptical arcs and are non-coaxially distributed. This design ensures that the cross-sectional area of ​​the first duct 121 gradually decreases along the direction of the circulating airflow, accelerating the airflow within the first duct 121. Both the first wall 1212 and the second wall 1214 are tangential to the airflow delivery channel of the diffuser 200. This structural design reduces airflow losses entering the diffuser 200 and facilitates the activation of low-energy fluid within the boundary layer, thereby eliminating flow separation within the diffuser.

[0056] In addition, the circulation pipeline 120 also includes a second pipe 123, which is a linear pipe in appearance and structure, and is tangent to the first wall 1212 and the second wall 1214 of the first pipe 121. This pipe is located upstream of the first pipe 121 in the direction of the circulating airflow and is immediately adjacent to the first pipe 121. Its two ends are respectively connected to the circulating airflow inlet 110 and the first pipe 121, and is used to reduce the backflow of the circulating airflow at the circulating airflow inlet 110.

[0057] In order to further avoid the problem of air flow backflow at the circulating air flow outlet, the circulation pipeline and the circulation inlet and outlet sizes are further optimized in this application.

[0058] In a specific embodiment of the application, the inner diameter of the circulating air inlet 110 of the circulation system is 0.2 to 0.3 times the height of the flow channel of the conveying air inlet 210, and the inner diameter of the circulating air outlet 220 is 0.02 to 0.04 times the height of the flow channel of the conveying air inlet 210.

[0059] In addition, the maximum arc inner diameter of the first wall 1212 of the first pipe 121 in the circulation system is 0.4 to 0.5 times the height of the flow channel of the conveying air inlet 210, and the minimum arc inner diameter of the first wall 1212 is 0.3 to 0.4 times the height of the flow channel of the conveying air inlet 210.

[0060] In addition, the maximum arc inner diameter of the second wall surface 1214 of the first pipe 121 in the circulation system is 0.4 to 0.5 times the flow channel height of the conveying air inlet 210, and the minimum arc inner diameter of the second wall surface 1214 is 0.4 to 0.5 times the flow channel height of the conveying air inlet 210.

[0061] In actual use, the specific size and position of parameters such as the circulating air flow inlet and circulating air flow outlet need to be determined according to the internal flow of the diffuser.

[0062] Preferably, the circulation system may include multiple circulation lines 120 distributed circumferentially around the combustion cylinder 100 and the diffuser 200. This distribution allows airflow to be drawn from multiple locations, accelerated through the first conduit 121, and then enter the boundary layer of the diffuser 200, activating the low-energy fluid within the boundary layer and thereby enhancing the diffuser's anti-separation capability. In this application, the cross-section of the circulation lines 120 is circular or rectangular.

[0063] Preferably, the circulation pipeline 120 of the circulation system can also be distributed circumferentially around the combustion cylinder 100 and the diffuser 200. After being accelerated through one circulation pipeline, it enters the next circulation pipeline and finally enters the circulation air flow inlet 110 of the diffuser 200. The air flow in the circulation pipeline has a relatively high speed. When it is sprayed toward the boundary layer of the flow channel inside the diffuser, it can activate the low-energy fluid within the boundary more quickly, thereby enhancing the anti-separation ability of the diffuser.

[0064] Example 2:

[0065] Combine Figure 1-3As shown, in this embodiment, the circulation system includes a combustion cylinder 100 and a diffuser 200. The diffuser 200 is connected to the combustion cylinder 100. The diffuser 200 includes a conveying air flow inlet 210. The air flow enters the diffuser 200 through the conveying air flow inlet 210 and is decelerated and then output from the conveying air flow outlet of the diffuser 200 to the combustion cylinder 100. A first air flow branch 300 is defined in the air flow conveying direction from the diffuser 200 to the combustion cylinder 100. The combustion cylinder 100 returns a portion of the air flow received from the diffuser 200 to the diffuser 200 as a circulating air flow to the diffuser 200, thereby weakening the air flow boundary layer separation in the diffuser 200. A second air flow branch 400 is defined in the air flow return direction from the combustion cylinder 100 to the diffuser 200.

[0066] Specifically, the circulation system includes a circulation line 120. The combustion cylinder 100 returns a portion of the airflow received from the diffuser 200 to the diffuser 200 through the circulation line 120. A second airflow branch 400 is defined in the direction from the combustion cylinder 100 to the diffuser 200, from the combustion cylinder 100 to the circulation line 120, and then to the diffuser 200. The circulation line 120 sprays the airflow toward the boundary layer of the flow channel within the diffuser, activating the low-energy fluid within the boundary layer and thereby enhancing the diffuser's anti-separation capability.

[0067] The combustion cylinder 100 includes a circulating air flow inlet 110 and a circulating air flow outlet 220. In order to further improve the anti-separation capability of the diffuser, the positions of the circulating air flow inlet and the circulating air flow outlet are further optimized in the present application.

[0068] Specifically, the circulating air flow inlet 110 is located on the side of the combustion cylinder 100 close to the diffuser 200. The total pressure inside the combustion cylinder at this position is relatively high. By smoothly introducing the high-pressure gas in the combustion cylinder into the circulation pipeline 120, the low-energy fluid in the boundary layer is fully activated, thereby enhancing the anti-separation ability of the diffuser.

[0069] The circulating airflow outlet 220 is opened at a position of the diffuser 200 close to the starting position of the boundary layer separation of the diffuser 200, so as to facilitate the airflow to be sprayed toward the boundary layer of the flow channel in the diffuser, activate the low-energy fluid in the boundary layer, and better eliminate the flow separation of the diffuser.

[0070] In order to further increase the fluid velocity of the diffuser boundary layer and optimize the effect of the airflow in the circulation pipeline on eliminating the diffuser boundary layer, this application further optimizes the design of the circulation pipeline.

[0071] Specifically, in Example 1 of the present application, the circulation circuit 120 includes a plurality of interconnected pipes, including a first pipe 121 located at the end in the direction of the circulating airflow. The circulating airflow is accelerated through the first pipe 121 and enters the boundary layer of the diffuser 200. To ensure that the airflow in the first pipe 121 is in an accelerated flow state, the cross-sectional area of ​​the first pipe 121 decreases along the direction of the circulating airflow.

[0072] Specifically, the first duct 121 includes a first wall 1212 and a second wall 1214. Both walls are elliptical arcs and are non-coaxially distributed. This design ensures that the cross-sectional area of ​​the first duct 121 gradually decreases along the direction of the circulating airflow, accelerating the airflow within the first duct 121. Both the first wall 1212 and the second wall 1214 are tangential to the airflow delivery channel of the diffuser 200. This structural design reduces airflow losses entering the diffuser 200 and facilitates the activation of low-energy fluid within the boundary layer, thereby eliminating flow separation within the diffuser.

[0073] In addition, the circulation pipeline 120 also includes a second pipe 123, which is a linear pipe in appearance and structure, and is tangent to the first wall 1212 and the second wall 1214 of the first pipe 121. This pipe is located upstream of the first pipe 121 in the direction of the circulating airflow and is immediately adjacent to the first pipe 121. Its two ends are respectively connected to the circulating airflow inlet 110 and the first pipe 121, and is used to reduce the backflow of the circulating airflow at the circulating airflow inlet 110.

[0074] like Figure 3 As shown, the circulation pipeline 120 also includes a third pipeline 125, and the two sides of the third pipeline 125 are respectively connected to the circulation air flow inlet 110 and the second pipeline 123. By introducing the third pipeline 125 between the second pipeline 123 and the circulation air flow inlet 110, the circulation air flow is promoted to enter the circulation pipeline 120 through the circulation air flow inlet 110, the low-energy fluid in the boundary layer is fully activated, and the anti-separation capability of the diffuser boundary layer is enhanced.

[0075] The third duct 125 can be a straight duct or a curved duct, and is transitionally connected to the circulating air inlet 110 and the second duct 123. Preferably, the third duct 125 is tangent to the circulating air inlet 110 to further promote airflow into the third duct 125.

[0076] Preferably, the cross-sectional areas of various parts of the third pipe 125 gradually decrease along the direction of the circulating airflow, so as to avoid backflow of the airflow at the circulating airflow inlet 110 .

[0077] In order to further avoid the problem of air flow backflow at the circulating air flow outlet, the circulation pipeline and the circulation inlet and outlet sizes are further optimized in this application.

[0078] In a specific embodiment of the application, the inner diameter of the circulating air inlet 110 of the circulation system is 0.2 to 0.3 times the height of the flow channel of the conveying air inlet 210, and the inner diameter of the circulating air outlet 220 is 0.02 to 0.04 times the height of the flow channel of the conveying air inlet 210.

[0079] In addition, the maximum arc inner diameter of the first wall 1212 of the first pipe 121 in the circulation system is 0.4 to 0.5 times the height of the flow channel of the conveying air inlet 210, and the minimum arc inner diameter of the first wall 1212 is 0.3 to 0.4 times the height of the flow channel of the conveying air inlet 210.

[0080] In addition, the maximum arc inner diameter of the second wall surface 1214 of the first pipe 121 in the circulation system is 0.4 to 0.5 times the flow channel height of the conveying air inlet 210, and the minimum arc inner diameter of the second wall surface 1214 is 0.4 to 0.5 times the flow channel height of the conveying air inlet 210.

[0081] In actual use, the specific size and position of parameters such as the circulating air flow inlet and circulating air flow outlet need to be determined according to the internal flow of the diffuser.

[0082] Preferably, the circulation system may include multiple circulation lines 120 distributed circumferentially around the combustion cylinder 100 and the diffuser 200. This distribution allows airflow to be drawn from multiple locations, accelerated through the first conduit 121, and then enter the boundary layer of the diffuser 200, activating the low-energy fluid within the boundary layer and thereby enhancing the diffuser's anti-separation capability. In this application, the cross-section of the circulation lines 120 is circular or rectangular.

[0083] Preferably, the circulation pipeline 120 of the circulation system can also be distributed circumferentially around the combustion cylinder 100 and the diffuser 200. After being accelerated through one circulation pipeline, it enters the next circulation pipeline and finally enters the circulation air flow inlet 110 of the diffuser 200. The air flow in the circulation pipeline has a relatively high speed. When it is sprayed toward the boundary layer of the flow channel inside the diffuser, it can activate the low-energy fluid within the boundary more quickly, thereby enhancing the anti-separation ability of the diffuser.

[0084] In summary, from the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0085] 1. The present invention proposes to guide the high-pressure gas in the combustion cylinder to the boundary layer of the flow channel in the diffuser through a circulation pipeline. By activating the low-energy fluid in the boundary layer, the anti-separation ability of the diffuser boundary layer is enhanced, and the total pressure loss of the gas in the combustion cylinder is effectively reduced.

[0086] 2. The present invention proposes connecting multiple pipes to form a circulation pipeline, and at the same time making the first pipe connected to the diffuser into a tapered form along the airflow direction, so that the airflow in the air inlet channel is in a flow acceleration state, improving the problem that the boundary layer of the flow channel in the diffuser gradually thickens along the flow direction, which is prone to flow separation.

[0087] 3. The present invention proposes that the first pipe connecting the diffuser is composed of two non-concentric elliptical arcs, which are tangent to the flow path profile of the diffuser. This structural design reduces the airflow loss entering the diffuser and makes it easier to activate the low-energy fluid in the boundary layer, thereby achieving the purpose of eliminating flow separation in the diffuser; and avoids the problem of airflow backflow at the circulating airflow inlet.

[0088] 4. By optimizing the inlet and outlet positions of the circulation pipeline, the low-energy fluid in the boundary layer is fully activated, thereby enhancing the anti-separation ability of the diffuser.

[0089] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A diffuser gas flow path circulation system, characterized in that: The invention comprises a combustion cylinder (100) and a diffuser (200), wherein the diffuser (200) is connected to the combustion cylinder (100), and the diffuser (200) comprises a conveying airflow inlet (210). The airflow enters the diffuser (200) through the conveying airflow inlet (210), is decelerated, and is output from the conveying airflow outlet of the diffuser (200) to the combustion cylinder (100). A first airflow branch (300) is defined in the airflow conveying direction from the diffuser (200) to the combustion cylinder (100). The combustion cylinder (100) returns a portion of the airflow received from the diffuser (200) to the diffuser (200) as a circulating airflow to the diffuser (200), thereby weakening the airflow boundary layer separation in the diffuser (200). A second airflow branch (400) is defined in the airflow return direction from the combustion cylinder (100) to the diffuser (200); The invention also includes a circulation pipeline (120), wherein the combustion cylinder (100) returns a portion of the airflow received from the diffuser (200) to the diffuser (200) through the circulation pipeline (120), and defines a second airflow branch (400) from the combustion cylinder (100) to the circulation pipeline (120) to the diffuser (200) in the direction from the combustion cylinder (100) to the diffuser (200).

2. The diffuser gas flow path circulation system according to claim 1, characterized in that: The combustion cylinder (100) comprises a circulating air flow inlet (110), and the circulating air flow inlet (110) is located on a side of the combustion cylinder (100) close to the diffuser (200).

3. The diffuser gas flow path circulation system according to claim 2, characterized in that: The diffuser (200) comprises a circulating airflow outlet (220), and the circulating airflow outlet (220) is opened at a position of the diffuser (200) close to a boundary layer separation starting position of the diffuser (200).

4. The diffuser gas flow path circulation system according to claim 3, characterized in that: The circulation pipeline (120) comprises a plurality of pipes connected to each other, wherein the plurality of pipes comprises a first pipe (121) located at the end in the direction of the circulating airflow, and the circulating airflow is accelerated through the first pipe (121) and then enters the boundary layer of the diffuser (200).

5. The diffuser gas flow path circulation system according to claim 4, characterized in that: The cross-sectional area of ​​the first pipe (121) decreases along the direction of the circulating airflow.

6. The diffuser gas flow path circulation system according to claim 4 or 5, characterized in that: The first pipe (121) comprises a first wall surface (1212) and a second wall surface (1214), the first wall surface (1212) and the second wall surface (1214) are elliptical arc surfaces, and the first wall surface (1212) and the second wall surface (1214) are non-coaxially distributed.

7. The diffuser gas flow path circulation system according to claim 6, characterized in that: The first wall surface (1212) and the second wall surface (1214) are both tangent to the flow passage of the diffuser (200).

8. The diffuser gas flow path circulation system according to claim 6, characterized in that: The circulation pipeline (120) further includes a second pipe (123), wherein the second pipe (123) is located upstream of the first pipe (121) in the direction of the circulation airflow and is closely adjacent to the first pipe (121).

9. The diffuser gas flow path circulation system according to claim 8, characterized in that: The second pipe (123) has two ends connected to the circulating air inlet (110) and the first pipe (121), respectively, and is configured to reduce backflow of the circulating air at the circulating air inlet (110).

10. The diffuser gas flow path circulation system according to claim 9, characterized in that: The second pipe (123) is a straight pipe, and the second pipe (123) is tangent to the first wall surface (1212) and the second wall surface (1214) of the first pipe (121).

11. The diffuser gas flow path circulation system according to claim 8, characterized in that: The circulation pipeline (120) further comprises a third pipeline (125), wherein the third pipeline (125) connects the circulation air flow inlet (110) and the second pipeline (123).

12. The diffuser gas flow path circulation system according to claim 11, characterized in that: The third pipe (125) is a straight pipe, and the third pipe (125) is transitionally connected to the circulating air flow inlet (110) and the second pipe (123) respectively.

13. The diffuser gas flow path circulation system according to claim 11, characterized in that: The third pipe (125) is a curved pipe, and the cross-sectional area of ​​the third pipe (125) gradually decreases along the direction of the circulating airflow, thereby preventing airflow backflow at the circulating airflow inlet (110).

14. The diffuser gas flow path circulation system according to any one of claims 2 to 4, characterized in that: The inner diameter of the circulating air flow inlet (110) is 0.2 to 0.3 times the height of the flow channel of the conveying air flow inlet (210).

15. The diffuser gas flow path circulation system according to claim 3 or 4, characterized in that: The inner diameter of the circulating air flow outlet (220) is 0.02 to 0.04 times the height of the flow channel of the conveying air flow inlet (210).

16. The diffuser gas flow path circulation system according to claim 6, characterized in that: The maximum arc inner diameter of the first wall surface (1212) is 0.4 to 0.5 times the height of the flow channel of the conveying air flow inlet (210), and the minimum arc inner diameter of the first wall surface (1212) is 0.3 to 0.4 times the height of the flow channel of the conveying air flow inlet (210).

17. The diffuser gas flow path circulation system according to claim 6, characterized in that: The maximum arc inner diameter of the second wall surface (1214) is 0.4 to 0.5 times the height of the flow channel of the conveying air flow inlet (210), and the minimum arc inner diameter of the second wall surface (1214) is 0.4 to 0.5 times the height of the flow channel of the conveying air flow inlet (210).

18. The diffuser gas flow path circulation system according to any one of claims 1 to 5, characterized in that: The invention comprises a plurality of circulation pipes (120), wherein the plurality of circulation pipes (120) are distributed circumferentially around the combustion cylinder (100) and the diffuser (200).

19. The diffuser gas flow path circulation system according to any one of claims 1 to 5, characterized in that: The circulation pipeline (120) is circumferentially distributed around the combustion cylinder (100) and the diffuser (200).

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