Exhaust diffuser and gas turbine

Abstract

The invention relates to the technical field of gas turbines, in particular to an exhaust diffuser and a gas turbine. The exhaust diffuser comprises a barrel-shaped inner boundary, a barrel-shaped outer boundary, a flow guide type end cover and a controller, the barrel-shaped inner boundary and the barrel-shaped outer boundary are coaxially arranged and form an annular flow channel allowing fluid to diffuse from an inlet to an outlet, and the flow guide type end cover is axially connected with the tail end of the barrel-shaped inner boundary and forms a step structure sunken in the axis direction. The diameter of the flow guide type end cover is gradually narrowed towards the outlet direction of the annular flow channel, a suction hole is formed in the connecting position of the flow guide type end cover and the cylindrical inner boundary, an injection hole is formed in the tail end of the flow guide type end cover, the suction hole and the injection hole are both communicated with a flow driving device in the flow guide type end cover, and the controller is in signal connection with the flow driving device. The gas turbine comprises the exhaust diffuser. The exhaust diffuser and the gas turbine can optimize a downstream flow field and can be flexibly adjusted according to working conditions.

Description

Technical Field

[0001] This invention relates to the field of gas turbine technology, and more particularly to an exhaust diffuser and a gas turbine including the exhaust diffuser. Background Technology

[0002] The exhaust diffuser serves as a transition section between the turbine and the waste heat boiler, reducing exhaust gas velocity, converting dynamic pressure to static pressure, improving the pressure stability of the exhaust system, reducing energy loss, and enhancing unit efficiency. However, existing exhaust diffusers generate a large-scale separation and recirculation zone behind the bearing housing end cover. This separation and recirculation zone leads to significant flow losses, reduces the efficiency of turbine components, and further increases when operating conditions deviate from design conditions. Therefore, optimized design of the flow field behind the bearing housing end cover is necessary.

[0003] Currently, numerous attempts have been made to optimize the flow field behind the bearing housing end cap in order to minimize the flow loss of the exhaust diffuser and improve its static pressure recovery capability. For example, patent CN116122924A discloses an end cap assembly for a gas turbine, which provides circulation space for the wake by setting an extension section with cavities and openings, reducing the wake influence area, improving flow field uniformity, thereby reducing total pressure loss and improving the static pressure recovery coefficient; patent CN114687817A discloses a central body of an exhaust diffuser, which optimizes the tail shape to form a flow channel that first contracts and then expands, reducing the backflow area and weakening the backflow effect, thereby reducing exhaust loss, improving static pressure recovery capability and turbine efficiency; patent CN103032171A discloses an exhaust diffuser that guides the airflow to form favorable vortices by setting a recess at the hub end, reducing wake interference, increasing the effective flow channel area, thereby improving diffuser performance, outlet velocity and pressure distribution. While these attempts can effectively reduce the gas backflow effect of the exhaust diffuser and optimize the downstream flow field, they can only be designed for a specific operating condition and cannot be flexibly adjusted according to changes in operating conditions. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the present invention provides an exhaust diffuser and gas turbine that can optimize the downstream flow field and can be flexibly adjusted according to the operating conditions.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] This invention provides an exhaust diffuser, comprising an inner cylindrical boundary, an outer cylindrical boundary, a flow-guiding end cap, and a controller. The inner and outer cylindrical boundaries are coaxially arranged to form an annular flow channel for fluid to diffuse from the inlet to the outlet. The flow-guiding end cap is axially connected to the end of the inner cylindrical boundary and forms a stepped structure recessed towards the axis. The diameter of the flow-guiding end cap gradually narrows towards the outlet direction of the annular flow channel. A suction hole is provided at the connection between the flow-guiding end cap and the inner cylindrical boundary. An injection hole is arranged at the end of the flow-guiding end cap. Both the suction hole and the injection hole are connected to a flow driving device inside the flow-guiding end cap. The controller is signal-connected to the flow driving device.

[0007] Preferably, the outer wall of the inner boundary of the cylindrical shape is connected and fixed to the inner wall of the outer boundary of the cylindrical shape through a support plate structure.

[0008] Preferably, the flow-guiding end cap is in the shape of a semi-ellipsoid, and an injection hole is arranged at the end of the flow-guiding end cap.

[0009] Preferably, the flow-guiding end cap is in the shape of a frustum, and the end of the flow-guiding end cap has multiple injection holes arranged circumferentially.

[0010] Preferably, it also includes a suction opening adjustment device, on which a rotating ring is rotatably fitted at the connection between the guide-type end cap and the inner boundary of the cylindrical shape, and the thickness of the rotating ring is less than 1 / 3 of the thickness of the stepped structure. The controller controls the suction opening adjustment device to drive the rotating ring to rotate clockwise / counterclockwise. When the suction adjustment hole on the rotating ring coincides with the suction hole, the suction hole is fully opened.

[0011] Preferably, a plurality of suction holes are provided circumferentially at the connection between the flow-guiding end cap and the inner boundary of the cylindrical shape, and a plurality of suction adjustment holes are provided on the rotating ring accordingly. When one suction adjustment hole coincides with one suction hole, the remaining suction adjustment holes also coincide with one suction hole respectively.

[0012] Preferably, both the suction hole and the suction adjustment hole are strip-shaped holes.

[0013] Preferably, it also includes an injection opening adjustment device. The rotating cover on the injection opening adjustment device is rotatably disposed at the end of the flow guide end cap. The controller controls the injection opening adjustment device to drive the rotating cover to rotate clockwise / counterclockwise. The end of the flow guide end cap has multiple injection holes arranged circumferentially. The rotating cover has multiple injection adjustment holes correspondingly opened. When one injection adjustment hole coincides with one injection hole, the other injection adjustment holes also coincide with one injection hole respectively.

[0014] Preferably, the flow drive device is a negative pressure fan, with the suction hole connected to the air inlet of the negative pressure fan and the injection hole connected to the air outlet of the negative pressure fan.

[0015] The present invention also provides a gas turbine including the exhaust diffuser of any of the above.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] The exhaust diffuser of this invention combines a flow-guiding end cap with a flow-driven device. While the flow-guiding end cap guides the flow and reduces flow separation at the inner boundary of the cylindrical section, the controller can also control the flow-driven device to draw in low-momentum fluid at the junction of the flow-guiding end cap and the inner boundary of the cylindrical section, reducing the separation zone at this junction. Furthermore, it injects high-momentum fluid into the separation zone at the end of the flow-guiding end cap, reducing large-scale separation and backflow at the end of the end cap, thereby reducing flow field losses and optimizing the downstream flow field. Moreover, the flow-driven device can be flexibly and actively adjusted according to the operating conditions of the gas turbine via the controller.

[0018] The gas turbine of the present invention naturally possesses the aforementioned beneficial effects due to the use of the exhaust diffuser described above, which will not be elaborated further here. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the first type of exhaust diffuser in an embodiment of the present invention.

[0020] Figure 2 This is a front view of the assembly of the flow guide end cap and the rotating ring on the first type of exhaust diffuser in an embodiment of the present invention.

[0021] Figure 3 This is a side view of the assembly of the flow guide end cap and the rotating ring on the first type of exhaust diffuser in an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of the structure of the second type of exhaust diffuser in an embodiment of the present invention.

[0023] Figure 5 This is a front view of the assembly of the flow guide end cap, rotating ring, and rotating cover on the second type of exhaust diffuser in this embodiment of the invention.

[0024] Figure 6 This is a side view of the assembly of the upper guide-type end cap, rotating ring, and rotating cover of the second type of exhaust diffuser in an embodiment of the present invention.

[0025] The reference numerals in the attached figures are explained as follows:

[0026] 1. Inner cylindrical boundary; 2. Outer cylindrical boundary; 3. Flow guide end cap; 301. Suction hole; 302. Injection hole; 303. Fluid suction channel; 304. Fluid discharge channel; 4. Annular flow channel; 5. Flow drive device; 6. Support plate structure; 7. Rotating ring; 701. Suction adjustment hole; 8. Rotating cap; 801. Injection adjustment hole. Detailed Implementation

[0027] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0028] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0031] See Figures 1 to 6 This embodiment provides an exhaust diffuser, including a cylindrical inner boundary 1, a cylindrical outer boundary 2, a flow guide end cap 3, and a controller. The cylindrical inner boundary 1 and the cylindrical outer boundary 2 are coaxially arranged and form an annular flow channel 4 for fluid to diffuse from the inlet to the outlet. The flow guide end cap 3 is axially connected to the end of the cylindrical inner boundary 1 and forms a stepped structure recessed in the axial direction. The diameter of the flow guide end cap 3 gradually narrows towards the outlet direction of the annular flow channel 4. A suction hole 301 is provided at the connection between the flow guide end cap 3 and the cylindrical inner boundary 1. An injection hole 302 is arranged at the end of the flow guide end cap 3. Both the suction hole 301 and the injection hole 302 are connected to a flow driving device 5 inside the flow guide end cap 3. The controller is signal connected to the flow driving device 5.

[0032] Stepped structures are common in exhaust diffusers, and low-momentum fluid separation zones often appear in the areas where these structures are located. In this embodiment, the exhaust diffuser combines a flow-guiding end cap 3 with a flow-driving device 5. While the flow-guiding end cap 3 guides the flow and reduces flow separation at the end of the cylindrical inner boundary 1, the controller can also control the flow-driving device 5 to draw in low-momentum fluid at the connection between the flow-guiding end cap 3 and the cylindrical inner boundary 1, reducing the separation zone at this point. Furthermore, it injects higher-momentum fluid into the separation zone at the end of the flow-guiding end cap 3, reducing large-scale separation and backflow at the end of the flow-guiding end cap 3, thereby reducing flow field losses and optimizing the downstream flow field. Moreover, the flow-driving device 5 can be flexibly and actively adjusted according to the operating conditions of the gas turbine via the controller.

[0033] Furthermore, the exhaust diffuser in this embodiment combines the flow-guiding end cap 3 with the flow-driving device 5, further optimizing the downstream flow field based on the flow-guiding end cap 3. Compared to a solution using only the flow-guiding end cap, the size and length of the flow-guiding end cap 3 in this embodiment can be made smaller while achieving the same optimization effect. Simultaneously, the presence of the flow-driving device 5 in this embodiment reduces the requirements for the profile complexity of the flow-guiding end cap 3, which helps to reduce aerodynamic design difficulty and improve adaptability.

[0034] Furthermore, relying solely on the guide-type end cap 3 to adjust the flow field often requires customized aerodynamic design based on the unit model and operating conditions to achieve optimal results. When deviating from specific operating conditions, low-momentum fluid regions in the form of separated backflow still exist at the connection between the guide-type end cap 3 and the inner boundary 1 of the cylindrical shape, as well as at the end of the guide-type end cap 3, making it difficult to adapt to operation adjustments under varying conditions. However, the exhaust diffuser in this embodiment combines the guide-type end cap 3 with the flow drive device 5, thus obviously avoiding this problem.

[0035] It should be noted that the controller can control the flow rate and rate of fluid suction and injection through the flow drive device 5.

[0036] Better, see Figure 1 and Figure 4 In this embodiment, the suction port 301 is connected to the flow drive device 5 inside the flow guide end cap 3 through the fluid suction channel 303; the injection port 302 is connected to the flow drive device 5 inside the flow guide end cap 3 through the fluid discharge channel 304.

[0037] Preferably, in this embodiment, the controller is a PLC.

[0038] Preferably, see Figure 1 and Figure 4 The outer wall of the cylindrical inner boundary 1 is connected and fixed to the inner wall of the cylindrical outer boundary 2 through the support plate structure 6.

[0039] Preferably, see Figures 1 to 3 The flow-guiding end cap 3 can be a semi-ellipsoidal shape. In this case, an injection hole 302 can be arranged at the end of the flow-guiding end cap 3; also, see Figures 4 to 6 The flow-guiding end cap 3 can also be a frustum shape. In this case, multiple injection holes 302 can be arranged circumferentially at the end of the flow-guiding end cap 3.

[0040] Preferably, see Figure 1 , Figure 2 , Figure 4 and Figure 5 The exhaust diffuser in this embodiment also includes a suction opening adjustment device. A rotating ring 7 on the suction opening adjustment device is rotatably fitted at the connection between the flow-guiding end cap 3 and the cylindrical inner boundary 1. The thickness of the rotating ring 7 is less than 1 / 3 of the thickness of the stepped structure. The controller controls the suction opening adjustment device to drive the rotating ring 7 to rotate clockwise / counterclockwise. When the suction adjustment hole 701 on the rotating ring 7 coincides with the suction hole 301, the suction hole 301 is fully open. By controlling the clockwise / counterclockwise rotation of the rotating ring 7, the controller can adjust the degree of coincidence between the suction adjustment hole 701 and the suction hole 301, thereby controlling the intake amount of low-momentum fluid.

[0041] It should be noted that the rotating ring 7 is made very thin, with a thickness not exceeding 1 / 3 of the thickness of the stepped structure. This can prevent the separation zone from shifting and achieve the purpose of eliminating low-momentum fluid at the connection between the flow-guiding end cap 3 and the cylindrical inner boundary 1.

[0042] Preferably, in this embodiment, the suction opening adjustment device includes a drive motor and a rotating ring 7. The drive shaft of the drive motor and the rotating ring 7 are driven by gear meshing. The controller is signal-connected to the drive motor.

[0043] Preferably, see Figure 2 and Figure 5 Multiple suction holes 301 are circumferentially provided at the connection between the flow-guiding end cap 3 and the cylindrical inner boundary 1. Correspondingly, multiple suction adjustment holes 701 are provided on the rotating ring 7. When one suction adjustment hole 701 coincides with one suction hole 301, the remaining suction adjustment holes 701 also coincide with one suction hole 301 respectively. The arrangement of multiple suction holes 301 can increase the suction volume of low-momentum fluid by the flow drive device 5 and effectively reduce the separation zone at the connection between the flow-guiding end cap 3 and the cylindrical inner boundary 1.

[0044] Preferably, in this embodiment, one or more suction holes 301 can be arranged at the connection between the flow-guiding end cap 3 and the cylindrical inner boundary 1 as needed.

[0045] Preferably, see Figure 2 and Figure 5 Both the suction hole 301 and the suction adjustment hole 701 are strip-shaped holes.

[0046] Preferably, see Figure 4 and Figure 6 The exhaust diffuser in this embodiment also includes an injection opening adjustment device. A rotating cover 8 on the injection opening adjustment device is rotatably mounted at the end of the flow-guiding end cap 3. The controller controls the injection opening adjustment device to drive the rotating cover 8 to rotate clockwise / counterclockwise. Multiple injection holes 302 are arranged circumferentially at the end of the flow-guiding end cap 3. Multiple injection adjustment holes 801 are correspondingly provided on the rotating cover 8. When one injection adjustment hole 801 coincides with one injection hole 302, the remaining injection adjustment holes 801 also coincide with one injection hole 302 respectively. Similar to the suction opening adjustment device described above, when the injection adjustment hole 801 coincides with the injection hole 302, it can be considered that the injection hole 302 is fully open. The controller can adjust the degree of coincidence between the injection adjustment hole 801 and the injection hole 302 by controlling the rotating cover 8 to rotate clockwise / counterclockwise, thereby controlling the discharge volume of the high-momentum fluid and effectively reducing the large-scale separation backflow at the end of the flow-guiding end cap 3.

[0047] Preferably, in this embodiment, the injection opening adjustment device includes a drive motor and a rotating cover 8. The drive shaft of the drive motor and the rotating cover 8 are driven by gear meshing. The controller is signal-connected to the drive motor.

[0048] Preferably, in this embodiment, the end of the flow-guiding end cap 3 may be provided with one or more rings of injection holes 302 as needed.

[0049] Better, see Figure 6 In this embodiment, both the injection hole 302 and the injection adjustment hole 801 are circular holes.

[0050] Specifically, see Figure 4 and Figure 6 In this embodiment, the flow guide end cap 3 is in the shape of a frustum, and multiple injection holes 302 are arranged circumferentially at the end of the flow guide end cap 3. The rotating cap 8 on the injection opening adjustment device is in the shape of a disc.

[0051] In practical use, based on flow field monitoring and operational experience, the downstream flow field can be optimized by opening the flow drive device 5, suction port 301, and injection port 302 via the controller. When the flow deviates from the design conditions, there will often be a larger separation zone at the end of the guide-type end cap 3. In this case, the flow drive device 5, suction port 301, and injection port 302 can be further enlarged to ensure the optimization effect of the downstream flow field.

[0052] It should be noted that the controller controls the suction opening adjustment device and the injection opening adjustment device independently.

[0053] Preferably, the flow drive device 5 is a negative pressure fan, with the suction port 301 connected to the air inlet of the negative pressure fan and the injection port 302 connected to the air outlet of the negative pressure fan. The controller can control the flow rate and speed of fluid suction and injection by controlling the rotational speed of the negative pressure fan.

[0054] This embodiment also provides a gas turbine, including the exhaust diffuser described above.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. An exhaust diffuser, characterized in that, The device includes a cylindrical inner boundary (1), a cylindrical outer boundary (2), a flow guide end cap (3), and a controller. The cylindrical inner boundary (1) and the cylindrical outer boundary (2) are coaxially arranged and form an annular flow channel (4) for the fluid to diffuse from the inlet to the outlet. The flow guide end cap (3) is axially connected to the end of the cylindrical inner boundary (1) and forms a stepped structure recessed in the axial direction. The diameter of the flow guide end cap (3) gradually narrows towards the outlet direction of the annular flow channel (4). A suction hole (301) is provided at the connection between the flow guide end cap (3) and the cylindrical inner boundary (1). An injection hole (302) is arranged at the end of the flow guide end cap (3). The suction hole (301) and the injection hole (302) are both connected to the flow drive device (5) inside the flow guide end cap (3). The controller is signal connected to the flow drive device (5).

2. The exhaust diffuser according to claim 1, characterized in that, The outer wall of the cylindrical inner boundary (1) is connected and fixed to the inner wall of the cylindrical outer boundary (2) through a support plate structure (6).

3. The exhaust diffuser according to claim 1, characterized in that, The flow-guiding end cap (3) is a semi-ellipsoidal shape, and an injection hole (302) is arranged at the end of the flow-guiding end cap (3).

4. The exhaust diffuser according to claim 1, characterized in that, The flow-guiding end cap (3) is in the shape of a frustum, and the end of the flow-guiding end cap (3) is circumferentially arranged with a plurality of injection holes (302).

5. The exhaust diffuser according to claim 1, characterized in that, It also includes a suction opening adjustment device. The rotating ring (7) on the suction opening adjustment device is rotatably fitted at the connection between the flow guide end cap (3) and the cylindrical inner boundary (1). The thickness of the rotating ring (7) is less than 1 / 3 of the thickness of the stepped structure. The controller controls the suction opening adjustment device to drive the rotating ring (7) to rotate clockwise / counterclockwise. When the suction adjustment hole (701) on the rotating ring (7) coincides with the suction hole (301), the suction hole (301) is fully opened.

6. The exhaust diffuser according to claim 5, characterized in that, The flow-guiding end cap (3) and the cylindrical inner boundary (1) are provided with a plurality of suction holes (301) in the circumferential direction. The rotating ring (7) is provided with a plurality of suction adjustment holes (701). When a suction adjustment hole (701) coincides with a suction hole (301), the other suction adjustment holes (701) also coincide with a suction hole (301) respectively.

7. The exhaust diffuser according to claim 5, characterized in that, Both the suction hole (301) and the suction adjustment hole (701) are strip-shaped holes.

8. The exhaust diffuser according to claim 1, characterized in that, It also includes an injection opening adjustment device. The rotating cover (8) on the injection opening adjustment device is rotatably disposed at the end of the flow-guiding end cap (3). The controller controls the injection opening adjustment device to drive the rotating cover (8) to rotate clockwise / counterclockwise. The end of the flow-guiding end cap (3) is circumferentially arranged with multiple injection holes (302). The rotating cover (8) is correspondingly provided with multiple injection adjustment holes (801). When one injection adjustment hole (801) coincides with one injection hole (302), the other injection adjustment holes (801) also coincide with one injection hole (302) respectively.

9. The exhaust diffuser according to claim 1, characterized in that, The flow drive device (5) is a negative pressure fan. The suction hole (301) is connected to the air inlet of the negative pressure fan, and the injection hole (302) is connected to the air outlet of the negative pressure fan.

10. A gas turbine, characterized in that, Includes the exhaust diffuser as described in any one of claims 1-9.

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