Porous media combustor and gas turbine for suppressing lean premixed combustion oscillations

Abstract

The application provides a porous medium combustor and a gas turbine for inhibiting lean premixed combustion oscillation, which relates to the field of lean premixed combustor structure on a gas turbine combustor, and is characterized in that the combustor comprises an axial rotational flow nozzle, a fixed base and a porous medium flame stabilizing section, the axial rotational flow nozzle and the porous medium flame stabilizing section are connected to the fixed base respectively, and the axial rotational flow nozzle is connected to the porous medium flame stabilizing section; the porous medium flame stabilizing section is internally provided with a serpentine channel to reflect and dissipate the pressure in the combustor for multiple times, so that the pressure entering the axial rotational flow nozzle is reduced. By adopting the porous medium flame stabilizing section and appropriately adjusting the hole density of the porous medium flame stabilizing section, the application can effectively inhibit the disturbance of the jet outer shear layer and the angle backflow area instability to the flame, fully dissipate the pressure fluctuation in the combustor, and achieve the purpose of stable flame combustion.

Description

Technical Field

[0001] This invention relates to the field of lean premixed burner structures in gas turbine combustion chambers, and more specifically, to a porous medium burner and a gas turbine for suppressing lean premixed combustion oscillations. Background Technology

[0002] With increasingly stringent emission requirements, gas turbines and aero-engines commonly employ lean premixed combustion in their combustors to reduce nitrogen oxide (NOx) emissions. The flame is positioned near the lean-burn quenching boundary, making it highly susceptible to external disturbances and resulting in flame pulsation. When this flame thermal release pulsation couples with the system's acoustics (i.e., thermoacoustic coupling), it generates intense combustion oscillations, which can severely damage system components and threaten the safe operation of the entire system.

[0003] The above problems can be solved by passive control methods, such as installing certain devices in the combustion system to suppress or eliminate combustion oscillations. A common device is the Helmholtz resonator, which suppresses combustion oscillations by altering the system's acoustic characteristics to prevent thermo-acoustic coupling. However, this device is bulky and only effective for specific oscillation frequencies. Another device, the nozzle anti-vibration ring, suppresses combustion oscillations by altering the flame's pulsation characteristics to prevent thermo-acoustic coupling. This method is low-cost and simple in structure, but when pressure pulsations occur in the combustion chamber due to localized thermo-acoustic coupling, the acoustic energy cannot be dissipated in time, gradually inducing high-amplitude combustion oscillations. Therefore, it is necessary to develop a combustion oscillation control device that can alter both the system's acoustics and the flame's pulsation characteristics, and has strong adaptability. Based on this, this application proposes a combustion oscillation control device capable of achieving strong adaptability.

[0004] Currently, among the existing technologies, Chinese patent application number CN 109737450 A discloses a combustion chamber combustion oscillation control device and a combustion chamber combustion oscillation control method. This method changes the shape of the flame tube confinement domain according to the flame angle in its natural state, eliminates the flame tube angular vortex region, thereby reducing the influence of large-scale vortex structures on the flame and restricting the movement of the flame. Although it ultimately plays a role in suppressing combustion oscillation, in actual applications, when pressure pulsation occurs in the combustion chamber due to local thermo-acoustic coupling, the acoustic energy cannot be dissipated in time, which will gradually induce high-amplitude combustion oscillation. The versatility and adaptability of the existing technology still cannot meet the actual needs of oscillation combustion suppression.

[0005] Patent document CN211424474 U discloses a combustion chamber structure and a micro gas turbine. The combustion chamber structure includes a gas premixing device, a flame tube, and a premixing cylinder. The premixing cylinder is connected between the gas premixing device and the flame tube to form a premixing channel for introducing gas into the flame tube. The periphery of the premixing cylinder is provided with vibration-damping holes communicating with the premixing channel. This utility model's combustion chamber structure, through ingenious design, reduces the acoustic energy that may be generated by gas combustion without increasing costs, preventing combustion oscillations caused by acoustic energy and ensuring combustion stability. However, it fails to address the influence of large-scale vortices in the flow field on the pulsation of flame heat release. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a porous medium burner and gas turbine that suppresses lean premixed combustion oscillations.

[0007] According to the present invention, a porous medium burner for suppressing lean premixed combustion oscillations includes an axial swirl nozzle, a fixed base, and a porous medium flame stabilizing section. The axial swirl nozzle and the porous medium flame stabilizing section are respectively connected to the fixed base, and the axial swirl nozzle is connected to the porous medium flame stabilizing section.

[0008] The porous medium flame stabilization section has internal channels that reflect and dissipate the pressure in the combustion chamber multiple times, thereby reducing the pressure entering the axial swirling nozzle.

[0009] Preferably, the axial swirl nozzle includes an outer wall, an inner wall, blades, and an annular swirl channel. The inner wall is provided on the inner side of the outer wall. Multiple blades are installed between the inner and outer walls. The annular space between the inner and outer walls is divided into multiple annular swirl channels by the blades.

[0010] Preferably, one end of the axial annular swirl channel is the inlet end face of the swirl nozzle, and the other end of the axial annular swirl channel is the outlet end face of the swirl nozzle;

[0011] The inlet face of the swirl nozzle is the inlet for the premixed air and fuel gas. The premixed gas enters the porous medium flame stabilization section for combustion through the outlet face of the swirl nozzle.

[0012] Preferably, the fixed base includes an inner wall, a limiting surface, and an outlet surface. The outlet surface is provided on the outer side of the inner wall, the outlet surface is connected to the limiting surface, and the limiting surface is located at one end of the inner wall.

[0013] The inner wall of the fixed base is fixed to the outer wall of the axial swirling nozzle by threads, and the outlet end face of the swirling nozzle contacts the limiting surface of the fixed base and ensures concentricity.

[0014] Preferably, the porous medium flame stabilizing section includes an inlet surface, an inner wall surface, and an outer wall surface. The inner wall surface is surrounded by the outer wall surface, and the inlet surface is located at the end of the inner wall surface with the smaller diameter.

[0015] Furthermore, small holes are provided between the inner wall surface of the porous medium flame stabilizing section and the outer wall surface of the porous medium flame stabilizing section.

[0016] Preferably, the internal channel of the small hole is a serpentine channel along the wall thickness direction;

[0017] The number of pores per centimeter of the wall surface of the porous media flame stabilization section is the pore density φ, where φ ranges from 0 to 20 cm. -1 Furthermore, when the pore density φ = 0, the wall of the porous medium flame-stabilizing section is a solid structure.

[0018] Preferably, the outer diameter of the axial annular swirling flow channel, the flow diameter of the outlet face, and the flow diameter of the inlet face of the porous medium flame stabilization section are all set to D1.

[0019] Preferably, the porous medium flame stabilizing section and the fixed base are integrated and processed using additive manufacturing technology;

[0020] Alternatively, the porous medium flame stabilizing section can be processed by additive manufacturing and then welded to the fixed base to maintain coaxiality.

[0021] Preferably, the expansion angle of the porous medium flame stabilizing section is adjusted to θ according to the flame expansion angle, the wall thickness of the porous medium flame stabilizing section is d, and the length of the porous medium flame stabilizing section is adjusted to L according to the flame length.

[0022] The present invention also provides a gas turbine employing a porous medium burner that suppresses lean premixed combustion oscillations.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) By adopting a porous medium flame stabilizing section, the present invention solves the combustion oscillation problem at the outlet of a traditional lean premixed burner and enhances the combustion stability of the burner. The porous medium flame stabilizing section can change the acoustic field characteristics at the nozzle outlet. When the pressure wave in the combustion chamber is transmitted to the upstream nozzle, the pressure wave will not be reflected on the inner wall of the porous medium flame stabilizing section, but will enter the internal serpentine channel of the porous medium flame stabilizing section. After multiple reflections, it will be fully dissipated, greatly reducing the disturbance to the unburned premixed gas and flame at the nozzle outlet.

[0025] (2) Due to the wall boundary effect of the porous medium flame stabilization section, the instability of the outer shear layer of the unburned premixed gas jet is suppressed, and the influence of the angular backflow vortex instability on the stability of the combustion flame is weakened. At the same time, the small holes on the inner wall of the porous medium flame stabilization section will affect the flow characteristics of the inner shear layer of the unburned premixed gas jet, resulting in changes in the flame shape and heat release distribution, thus improving the combustion stability of the nozzle. Attached Figure Description

[0026] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0027] Figure 1 This is a cross-sectional view of a porous media burner;

[0028] Figure 2 This is a three-dimensional structural diagram of an axial swirl nozzle;

[0029] Figure 3 This is a cross-sectional view of an axial swirling nozzle.

[0030] Figure 4 This is a cross-sectional view of the fixed base;

[0031] Figure 5 This is a cross-sectional view of the flame-stabilized section in a porous medium.

[0032] Figure 6 A cross-sectional view of the welding between the fixed base and the porous medium flame stabilizing section;

[0033] Figure 7 A comparison chart of combustion chamber pressure pulsation amplitudes;

[0034] Figure 8 Diagram of the test system;

[0035] Figure 9 A schematic diagram of the physical field of a non-porous media burner;

[0036] Figure 10 This is a schematic diagram of the physical field of a porous media burner.

[0037] As shown in the figure:

[0038] Detailed Implementation

[0039] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0040] Example

[0041] A porous medium burner for suppressing lean premixed combustion oscillations according to the present invention, such as Figure 1-10 As shown, the device includes an axial swirling nozzle 11, a fixed base 12, and a porous media flame stabilizing section 13. The axial swirling nozzle 11 is connected to the fixed base 12, and the porous media flame stabilizing section 13 and the fixed base 12 are integrally processed using additive manufacturing technology; alternatively, the porous media flame stabilizing section 13 is processed by additive manufacturing and then welded to the fixed base 12, maintaining coaxiality. Furthermore, the axial swirling nozzle 11 is connected to the porous media flame stabilizing section 13.

[0042] The axial swirl nozzle 11 includes an outer wall 101, an inner wall 102, blades 103, and an annular swirl channel 104. The inner wall 102 is provided inside the outer wall 101. Multiple blades 103 are installed between the inner wall 102 and the outer wall 101. The annular space between the inner wall 102 and the outer wall 101 is divided into multiple annular swirl channels 104 by the blades 103. The outer diameter of the annular swirl channel 104 is D1. One end of the axial annular swirl channel 104 is the inlet face 105 of the swirl nozzle, which is the inlet of the air and fuel premixed gas. The other end of the axial annular swirl channel 104 is the outlet face 106 of the swirl nozzle. The premixed gas enters the porous medium flame stabilization section 13 for combustion through the outlet face 106 of the swirl nozzle.

[0043] The fixed base 12 includes an inner wall 201, a limiting surface 202, and an outlet surface 203. The outlet surface 203 is provided on the outer side of the inner wall 201. The flow diameter of the outlet surface 203 is D1. The outlet surface 203 is connected to the limiting surface 202, and the limiting surface 202 is located at one end of the inner wall 201. The inner wall 201 of the fixed base is fixed to the outer wall 101 of the axial swirling nozzle by threads, and the outlet end face 106 of the swirling nozzle contacts the limiting surface 202 of the fixed base and ensures concentricity.

[0044] The porous medium flame stabilizing section 13 is trumpet-shaped, with an expansion angle of θ, which can be adjusted according to the actual flame expansion angle. The wall thickness of the porous medium flame stabilizing section 13 is d, and its length is L, which can be adjusted according to the flame length. The porous medium flame stabilizing section 13 includes an inlet surface 301, an inner wall surface 302, and an outer wall surface 303. The flow diameter of the inlet surface 301 is D1. An outer wall surface 303 is provided outside the inner wall surface 302. The inlet surface 301 is the end with the smaller diameter of the inner wall surface 302. A small hole is provided between the inner wall surface 302 and the outer wall surface 303. The hole channel is not straight; the internal channel of the small hole is a serpentine channel. The number of pores per centimeter of the wall surface of the porous medium flame stabilizing section 13 represents the pore density φ, where φ ranges from 0 to 20 cm. -1 A pore density of φ = 0 indicates a solid structure.

[0045] More specifically, Figure 9 This diagram illustrates the physical field of a non-porous media burner. Figure 10 This is a schematic diagram of the physical field of a porous media burner, including an angular backflow vortex 501, an outer shear layer 502 of the jet, a flame 503, an inner shear layer 504 of the jet, and a sound wave 505. As the sound wave 505 propagates upstream, it acts on the flame 503. Simultaneously, the instabilities of the jet shear layer and the angular backflow vortex 501 cause periodic fluctuations in the flame surface. Due to the wall boundary effect of the porous media flame stabilization section 13, the sound pressure is absorbed by the porous media, suppressing the instability of the outer shear layer 501 of the unburned premixed gas jet. The influence of the instability of the angular backflow vortex 501 on the stability of the combustion flame 503 is weakened. Furthermore, the small pores on the inner wall of the porous media flame stabilization section 13 affect the flow characteristics of the inner shear layer of the unburned premixed gas jet, leading to changes in the flame morphology and heat release distribution, thus improving the combustion stability of the nozzle.

[0046] like Figure 8 The diagram shows a test system for suppressing combustion oscillations in lean premixed combustion using a porous media burner. Inlet air disturbance is applied via an upstream loudspeaker to induce combustion oscillations; the amplitude of this disturbance is measured using two microphones on the intake section to ensure consistency across burners with different pore densities. Burners with different pore densities are then used, and under the same test conditions, the pressure pulsation amplitude within the combustion chamber is measured using a dynamic pressure sensor to analyze the effectiveness of different pore densities in suppressing combustion oscillations.

[0047] Example 2

[0048] The present invention also provides a gas turbine that employs the porous medium burner for suppressing lean premixed combustion oscillations as described in Example 1.

[0049] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and 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 this application.

[0050] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A porous medium burner for suppressing lean premixed combustion oscillations, characterized in that, It includes an axial swirling nozzle (11), a fixed base (12), and a porous medium flame stabilizing section (13). The axial swirling nozzle (11) and the porous medium flame stabilizing section (13) are respectively connected to the fixed base (12), and the axial swirling nozzle (11) is connected to the porous medium flame stabilizing section (13). The porous medium flame stabilizing section (13) has a channel inside to reflect and dissipate the pressure in the combustion chamber multiple times, thereby reducing the pressure entering the axial swirling nozzle (11). The porous medium flame stabilizing section (13) includes a porous medium flame stabilizing section inlet surface (301), a porous medium flame stabilizing section inner wall surface (302), and a porous medium flame stabilizing section outer wall surface (303). The porous medium flame stabilizing section outer wall surface (303) is provided outside the porous medium flame stabilizing section inner wall surface (302). The porous medium flame stabilizing section inlet surface (301) is the end of the porous medium flame stabilizing section inner wall surface (302) with a smaller diameter. Furthermore, small holes are provided between the inner wall surface (302) of the porous medium flame stabilizing section and the outer wall surface (303) of the porous medium flame stabilizing section; The internal channel of the small hole is a serpentine channel along the wall thickness direction; The number of pores per centimeter of the wall surface of the porous medium flame stabilizing section (13) is the pore density φ, where φ is 0-20 cm. -1 ; and when the pore density φ=0, the wall of the porous medium flame stabilizing section (13) is a solid structure.

2. The porous medium burner for suppressing lean premixed combustion oscillations according to claim 1, characterized in that, The axial swirling nozzle (11) includes an axial swirling nozzle outer wall (101), an axial swirling nozzle inner wall (102), axial swirling blades (103), and an axial annular swirling channel (104). The axial swirling nozzle inner wall (102) is disposed inside the axial swirling nozzle outer wall (101). A plurality of axial swirling blades (103) are installed between the axial swirling nozzle inner wall (102) and the axial swirling nozzle outer wall (101). The annular space between the axial swirling nozzle inner wall (102) and the axial swirling nozzle outer wall (101) is divided into a plurality of axial annular swirling channels (104) by the axial swirling blades (103).

3. The porous medium burner for suppressing lean premixed combustion oscillations according to claim 2, characterized in that, One end of the axial annular swirling channel (104) is the inlet end face (105) of the swirling nozzle, and the other end of the axial annular swirling channel (104) is the outlet end face (106) of the swirling nozzle. The inlet end face (105) of the swirl nozzle is the inlet of the air and fuel premixed gas, and the premixed gas enters the porous medium flame stabilization section (13) for combustion through the outlet end face (106) of the swirl nozzle.

4. The porous medium burner for suppressing lean premixed combustion oscillations according to claim 3, characterized in that, The fixed base (12) includes an inner wall (201), a limiting surface (202) and an outlet surface (203). The outlet surface (203) is provided on the outer side of the inner wall (201). The outlet surface (203) is connected to the limiting surface (202), and the limiting surface (202) is located at one end of the inner wall (201). The inner wall (201) of the fixed base is fixed to the outer wall (101) of the axial swirling nozzle by threads, and the outlet end face (106) of the swirling nozzle is in contact with the limiting surface (202) of the fixed base and ensures concentricity.

5. The porous medium burner for suppressing lean premixed combustion oscillations according to claim 4, characterized in that, The outer diameter of the axial annular swirling channel (104), the flow diameter of the outlet surface (203), and the flow diameter of the inlet surface (301) of the porous medium flame stabilizing section are all set to D1.

6. The porous medium burner for suppressing lean premixed combustion oscillations according to claim 1, characterized in that, The porous medium flame stabilizing section (13) and the fixed base (12) are integrated by additive manufacturing technology; Alternatively, the porous medium flame stabilizing section (13) can be processed by additive manufacturing and then welded to the fixed base (12) and kept coaxial.

7. The porous medium burner for suppressing lean premixed combustion oscillations according to claim 1, characterized in that, The expansion angle of the porous medium flame stabilizing section (13) is adjusted to θ according to the flame expansion angle, the wall thickness of the porous medium flame stabilizing section (13) is d, and the length of the porous medium flame stabilizing section (13) is adjusted to L according to the flame length.

8. A gas turbine, characterized in that: The porous medium burner for suppressing lean premixed combustion oscillations as described in any one of claims 1-7 is adopted.

Images