Acoustic suppression axial grading soft combustion nozzle based on vortex shedding dissipation

Abstract

The invention provides an acoustic suppression axial grading soft combustion nozzle based on vortex shedding dissipation. The acoustic suppression axial grading soft combustion nozzle comprises an air cavity outer wall, a fuel cavity outer wall and air film holes. By arranging the axial grading nozzles, high-temperature flue gas generated by the head combustor forms pulsating falling vortexes after flowing around the nozzles, the pulsating falling vortexes can interact with the sound field of the combustion chamber, and therefore sound wave energy is converted into vortex motion and finally dissipated into fluid internal energy, and the effect of restraining thermo-acoustic oscillation is achieved. And meanwhile, the fuel and the air are mixed with incoming flow smoke on the outer wall of the air cavity, the tempering phenomenon can be effectively avoided through the combustion organization form, and meanwhile gentle combustion can be easily established. A plurality of rows of fuel holes are formed in the gas cavity, and meanwhile, two adjacent rows of staggered fuel channels can disperse a reaction area, so that NOX emission is reduced. Meanwhile, the durability of the nozzle under the high-temperature flue gas condition is enhanced through the arrangement of the ribs in the cavity and the air film holes in the outer wall of the air cavity. According to the invention, generation of thermoacoustic oscillation can be suppressed.

Description

Technical Field

[0001] The present invention relates to the technical field of gas turbine combustors, and particularly to an axially staged mild combustion nozzle with acoustic suppression based on vortex shedding dissipation. Background Art

[0002] Heavy-duty gas turbines are the core power equipment for efficient energy conversion. With the improvement of environmental protection standards, gas turbine combustion technology has gradually changed from diffusion combustion to lean-premixed combustion. The lean-premixed combustion technology reduces the peak flame temperature and significantly reduces thermal NO X , but it brings the problem that thermoacoustic coupling is likely to occur, resulting in thermoacoustic oscillations and damage to key components of the combustor and its downstream turbine. Using hydrogen produced from renewable energy for clean and low-carbon combustion in heavy-duty gas turbines is also an important part of future energy solutions. However, compared with traditional natural gas fuels, hydrogen has significantly different combustion characteristics due to its high flame propagation speed and low ignition delay time, and has a unique and compact reaction zone morphology, resulting in significant changes in flame thermoacoustic response. Therefore, in order to meet the future development requirements of high parameters and multi-fuel adaptability of gas turbines, it is necessary to achieve low NOx emissions and high combustion stability in gas turbine combustors through effective combustion organization forms. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides an axially staged mild combustion nozzle with acoustic suppression based on vortex shedding dissipation. Based on the traditional axially staged combustion organization form, the pulsating shedding vortices formed by the high-temperature flue gas flowing around the nozzle are coupled with the combustor sound field to suppress thermoacoustic oscillations. At the same time, the low emission of nitrogen oxides can be achieved by reducing the residence time of the high-temperature flue gas and dispersing the reaction zone.

[0004] The present invention sets an axially staged nozzle. The high-temperature flue gas generated by the head burner forms pulsating shedding vortices after flowing around the nozzle, which can interact with the combustor sound field, thereby converting the acoustic wave energy into vortex motion and finally dissipating it into the internal energy of the fluid, achieving the effect of suppressing thermoacoustic oscillations. At the same time, the organization form of mixing and burning fuel and air on the outer wall of the gas cavity and the incoming flue gas can effectively avoid the occurrence of flashback and is conducive to the establishment of mild combustion. Setting multiple rows of fuel holes in the gas cavity and the fuel channels with adjacent rows staggered can disperse the reaction zone, thereby reducing NO X emissions. At the same time, the setting of internal ribs in the cavity and air film holes on the outer wall of the gas cavity enhances the durability of the nozzle under high-temperature flue gas conditions. The present invention can suppress the generation of thermoacoustic oscillations by coupling the shedding vortices generated by the flowing-around nozzle and the acoustic wave motion while reducing the nitrogen oxide emissions in the combustor and avoiding the occurrence of flashback.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An acoustic suppression axial staged soft combustion nozzle based on vortex shedding dissipation, comprising an outer wall of the gas chamber, an outer wall of the fuel chamber and air film holes; an air chamber is formed between the outer wall of the gas chamber and the outer wall of the fuel chamber, including an air chamber windward section, a middle and lower part of the air chamber, a middle and upper part of the air chamber and an air chamber leeward section formed by being separated by a plurality of partition ribs; the outer wall of the fuel chamber wraps the fuel chamber; the partition ribs connect the outer wall of the gas chamber and the outer wall of the fuel chamber; the ribs in the chamber are located on the outer wall of the gas chamber and the outer wall of the fuel chamber; the jet holes and the air film holes are located on the outer wall of the gas chamber; the fuel channels are located on the outer wall of the fuel chamber;

[0007] Wherein, after the fuel enters the fuel chamber, it flows through the fuel channels, and is externally mixed and burned with the cooling air that enters the air chamber and is ejected through the jet holes on the outer wall of the air chamber; the air ejected from the air film holes located on the outer wall of the air chamber forms a layer of low-temperature film on the nozzle surface, separating the nozzle surface from the high-temperature mainstream, and cooling the nozzle wall surface, playing a dual protection role of heat insulation and cooling, and avoiding the ablation of the axial staged nozzle under high-temperature flue gas.

[0008] Preferably, the outer shape of the nozzle has a shape combining an airfoil and a lobe trailing edge. The desired main vortex shedding frequency f is related to the structural parameters of the nozzle and the arrangement angle of attack of the nozzle, and satisfies , where St is the Strouhal number, U is the oncoming flow velocity of the high-temperature flue gas, L is the characteristic length of the airfoil, k is an empirical coefficient depending on the airfoil, and α is the angle of attack defined as the angle between the oncoming flow direction and the chord line of the airfoil. In addition, the existence of the lobe trailing edge can induce a multi-source secondary vortex structure, and the secondary vortex can interact with the main vortex to broaden the vortex shedding frequency range. For a given nozzle structure, during actual use, the desired vortex shedding frequency can be adjusted by adjusting the angle of attack of the nozzle.

[0009] Preferably, the ribs in the chamber are located in the air chamber windward section, the middle and lower part of the air chamber, the middle and upper part of the air chamber and the air chamber leeward section.

[0010] Preferably, the air film holes are located on the outer wall of the air chamber corresponding to the air chamber windward section, the middle and lower part of the air chamber and the top of the nozzle. The cooling air is ejected from the air chamber at a certain angle and momentum and develops downstream along with the oncoming flow.

[0011] Preferably, the fuel channels and the jet holes are located on the outer wall of the fuel chamber and the outer wall of the air chamber corresponding to the middle and upper part of the air chamber, the air chamber leeward section and the top of the nozzle. The high-temperature oncoming flow flue gas after being mixed with the cold air is externally mixed and burned with the air ejected from the jet holes and the fuel flowing through the fuel channels on the outer wall of the air chamber.

[0012] Preferably, the adjacent two rows of the fuel channels located in the middle and upper part of the air chamber and the air chamber leeward section are arranged in a staggered manner.

[0013] Preferably, the thickness w of the gas injection hole satisfies 0 < w ≤ 3d, where d is the inner diameter of the fuel channel.

[0014] In the present invention, through the arrangement of the axial staged nozzle combining the airfoil and the lobe trailing edge, the high-temperature flue gas of the oncoming flow forms pulsating shedding vortices by flowing around, inducing the transfer of the acoustic wave energy in the combustion chamber to the vortex motion and finally dissipating it into the internal energy of the fluid, which can effectively suppress the generation of the thermoacoustic phenomenon in the combustion chamber. At the same time, the organization form of the fuel and air mixing and burning on the outer wall of the gas cavity and the oncoming flue gas can prevent flashback while being beneficial to the establishment of mild combustion. By arranging multiple rows of fuel holes in the gas cavity and staggering the arrangement of two adjacent rows, the reaction zone can be dispersed and the NO X emission can be reduced. At the same time, the setting of the ribs in the cavity and the gas film holes on the outer wall of the gas cavity can effectively prevent the axial staged nozzle from being ablated under the oncoming flow condition of high-temperature flue gas.

[0015] As can be seen from the above technical solutions, the acoustic suppression axial staged mild combustion nozzle based on vortex shedding dissipation of the present invention has the following beneficial effects:

[0016] (1) Compared with the traditional axial staged nozzle, the secondary nozzle of the present invention utilizes the pulsating shedding vortices formed by the flowing around of the high-temperature flue gas, interacts with the sound field, makes the energy transfer from the acoustic wave to the vortex wave and finally dissipates it into the internal energy of the fluid, can suppress the generation of the thermoacoustic oscillation phenomenon in the combustion chamber, and at the same time, the vortex shedding frequency can be adjusted by the nozzle structure and the arrangement attack angle;

[0017] (2) Compared with the traditional axial staged nozzle, the secondary nozzle of the present invention can avoid the generation of flashback through multiple rows of efficiently arranged fuel holes and adopts the organization form of the fuel and air mixing and burning outside the nozzle and the oncoming flue gas, and is beneficial to the establishment of mild combustion and further reduces the nitrogen oxide emission;

[0018] (3) Compared with the traditional axial staged nozzle, the secondary nozzle of the present invention can cool the wall surface and reduce the risk of ablation of the axial staged nozzle under high-temperature conditions through the flow of air in the gas cavity and the setting of the gas film holes on the outer wall of the gas cavity. Description of the Drawings

[0019] Figure 1 is a schematic diagram of the acoustic suppression axial staged mild combustion nozzle based on vortex shedding dissipation according to an embodiment of the present invention;

[0020] Figure 2 is a side sectional view of the acoustic suppression axial staged mild combustion nozzle based on vortex shedding dissipation according to an embodiment of the present invention;

[0021] Figure 3A - A sectional view of the schematic diagram of an acoustic - suppressing axial - staged mild - combustion nozzle based on vortex shedding dissipation according to an embodiment of the present invention.

[0022] Among them, the reference numerals are: 1 - windward section of the gas cavity; 2 - middle - lower part of the gas cavity; 3 - middle - upper part of the gas cavity; 4 - leeward section of the gas cavity; 5 - fuel cavity; 6 - partition rib; 7 - film hole; 8 - outer wall of the gas cavity; 9 - outer wall of the fuel cavity; 10 - rib inside the cavity; 11 - jet hole; 12 - fuel channel; 13 - fuel; 14 - air; 15 - nozzle top. Detailed implementation manners

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] As Figures 1 - 3 shown, an embodiment of the present invention provides an acoustic - suppressing axial - staged mild - combustion nozzle based on vortex shedding dissipation, including an outer wall 8 of the gas cavity, an outer wall 9 of the fuel cavity and a film hole 7; a gas cavity is formed between the outer wall 8 of the gas cavity and the outer wall 9 of the fuel cavity, including a windward section 1 of the gas cavity, a middle - lower part 2 of the gas cavity, a middle - upper part 3 of the gas cavity and a leeward section 4 of the gas cavity separated by a plurality of partition ribs 6; the outer wall 9 of the fuel cavity wraps the fuel cavity 5; the partition ribs 6 connect the outer wall 8 of the gas cavity and the outer wall 9 of the fuel cavity; ribs 10 inside the cavity are located on the outer wall 8 of the gas cavity and the outer wall 9 of the fuel cavity; jet holes 11 and film holes 7 are located on the outer wall 8 of the gas cavity; a fuel channel 12 is located on the outer wall 9 of the fuel cavity, the fuel channel 12 is inserted into the jet hole 11, so that an annular gap is formed between the outer wall of the fuel channel 12 and the inner wall of the jet hole 11, and the fuel channel 12 is arranged on the outer wall 9 of the fuel cavity and is not connected to the outer wall 8 of the gas cavity.

[0025] As Figure 2 shown, in order to avoid the occurrence of flash - back phenomenon, after the fuel 13 enters the fuel cavity 5, it flows through the fuel channel 12 and mixes and burns with the cooling air 14 that enters the gas cavity and is ejected through the jet hole 11 outside the outer wall 8 of the gas cavity. The air ejected from the film hole 7 on the outer wall 8 of the gas cavity forms a low - temperature thin film on the nozzle surface, separating the nozzle surface from the high - temperature main flow and cooling the nozzle wall surface, playing a dual - protection role of heat insulation and cooling, and avoiding the ablation of the axial - staged nozzle under high - temperature flue gas. The partition ribs 6 have openings, as Figure 2 shown, which are used to prevent heat stress concentration, enabling the air in the gas cavity to flow, strengthening convection and preventing local thermal deformation of the nozzle.

[0026] In order to enable the pulsating shedding vortices generated after the high-temperature flue gas of the oncoming flow flows around the axial staging nozzle to interact with the sound field of the combustion chamber, thereby enhancing the damping dissipation loss of the axial staging nozzle for the acoustic pulsation energy of the combustion chamber and playing a role in suppressing thermoacoustic oscillations. The shape of the nozzle is in the form of a combination of an airfoil and a lobe trailing edge. The desired main vortex shedding frequency f is related to the structural parameters of the nozzle and the attack angle of the nozzle arrangement, and satisfies , where St is the Strouhal number, U is the oncoming flow velocity of the high-temperature flue gas, L is the characteristic length of the airfoil, k is an empirical coefficient depending on the airfoil, and α is the attack angle defined as the angle between the oncoming flow direction and the chord line of the airfoil. Figure 2 In, d is the inner diameter of the fuel channel; w is the thickness of the jet hole.

[0027] In addition, the existence of the lobe trailing edge can induce a multi-source secondary vortex structure, and the secondary vortices can interact with the main vortices to broaden the range of vortex shedding frequencies. For a given nozzle structure, during actual use, the desired vortex shedding frequency can be adjusted by adjusting the attack angle of the nozzle.

[0028] Preferably, in order to enable the axial staging nozzle to operate normally under the condition of the oncoming flow of high-temperature flue gas, a combined scheme of internal cooling and external cooling is adopted. In order to strengthen the heat transfer between the cooling air 14 and the inner surface of the nozzle, the cavity ribs 10 are located in the windward section 1, the middle and lower part 2, the middle and upper part 3, and the leeward section 4 of the air cavity. Since the cavity ribs 10 are arranged according to the internal heat flux density distribution of the air cavity and do not necessarily have to be in the same plane, therefore Figure 3 the cavity ribs 10 in the middle and upper part 3 and the leeward section 4 of the air cavity are not shown in.

[0029] Preferably, in order to separate the nozzle surface from the oncoming flow of high-temperature flue gas and cool the nozzle surface, the film holes 7 are located on the outer wall 8 of the air cavity corresponding to the windward section 1, the middle and lower part 2, and the top 15 of the nozzle. The cooling air 14 is ejected from the air cavity at a certain angle and momentum, and develops downstream along with the oncoming flow, forming a low-temperature film on the nozzle surface, which plays a dual role of heat insulation and cooling protection.

[0030] Preferably, in order to disperse the reaction zone and reduce nitrogen oxide emissions, the fuel channels 12 and the jet holes 11 are located on the outer wall 9 of the fuel cavity and the outer wall 8 of the air cavity corresponding to the middle and upper part 3, the leeward section 4, and the top 15 of the nozzle. The high-temperature oncoming flow flue gas after being mixed with cold air is mixed and burned with the cooling air 14 ejected from the jet holes 11 and the fuel 13 flowing through the fuel channels 12 outside the outer wall 8 of the air cavity, which is beneficial to the establishment of mild combustion and realizes low emissions of nitrogen oxides.

[0031] Preferably, in order to suppress thermoacoustic oscillations, the adjacent two rows of the fuel channels 12 located in the middle and upper part 3 and the leeward section 4 of the air cavity are arranged in a staggered manner.

[0032] Preferably, in order to ensure the mixing efficiency, the thickness w of the gas injection hole 11 satisfies 0 < w ≤ 3d, where d is the inner diameter of the fuel passage 12.

[0033] It should be noted that in the drawings or the main text of the specification, the experimental methods not shown or described are all forms known to those of ordinary skill in the art and are not described in detail. In addition, the above definitions of each component are not limited to the specific structures and shapes mentioned in the embodiments. Those of ordinary skill in the art can make simple changes or substitutions thereto. For example:

[0034] (1) The part where the root of the gas cavity is connected to the fuel cavity may not be integrally manufactured. The front section of the gas cavity can be connected to the fuel cavity through a connecting piece. The gas cavity can also have a lateral inlet, as long as the same function can be achieved.

[0035] (2) In the embodiment of the present invention, the rib 10 in the cavity is a straight rib. In addition, the shape of the rib in the cavity can also be V-shaped or other forms. The parameters such as the shape, angle, and spacing of the rib need to be designed in combination with the comprehensive cooling effect evaluation of the actual heat transfer characteristics and flow resistance characteristics.

[0036] (3) In the embodiment of the present invention, the film cooling hole 7 for cooling the wall surface uses a traditional cylindrical hole. In addition, other film cooling hole shapes such as a dustpan-shaped hole, a groove-shaped hole, a dumbbell-shaped hole, a convergent-divergent-shaped hole, a funnel-shaped hole, and a bi-directional divergent-shaped hole can be used as alternatives. The shape of the film cooling hole 7 needs to be designed according to the heat flux density on the nozzle surface so that it can better cover the wall surface.

[0037] (4) In the embodiment of the present invention, the main cooling structure adopted is the rib 10 in the cavity and the film cooling hole 7. In addition, a composite cooling structure of impingement plus film cooling can also be adopted, as long as the function of effectively cooling the nozzle can be achieved.

[0038] (5) In the embodiment of the present invention, the end surface of the fuel passage 12 is flush with the outer wall 8 of the gas cavity. In addition, the end surface of the fuel passage 12 can also be slightly lower than the outer wall 8 of the gas cavity, so that the fuel 13 and the air 14 can be premixed in advance.

[0039] (6) In an actual gas turbine combustion chamber, acoustic modes of multiple frequencies may occur. In the embodiment of the present invention, the main method is the combination of the airfoil and the trailing edge of the lobe. It can also be optimized and coupled designed according to the acoustic modes of the gas turbine combustion chamber. For example, the axial staged nozzle can be designed in the form of a variable cross-section cylinder, as long as the same function can be achieved.

[0040] (7) The present invention can provide demonstrations of parameters containing specific values. However, these parameters do not need to be exactly equal to the corresponding values, but can be approximated within an acceptable error tolerance or design constraint.

[0041] (8) The orientation terms mentioned in the implementation, such as "front", "rear", etc., are only for the direction of reference to the attached drawings and do not limit the protection scope of the present invention.

[0042] In summary, the present invention utilizes the high-temperature flue gas to flow around to form pulsating shedding vortices, inducing the transfer of energy from sound waves to vortex waves. Then, the vortex motion converted from the sound wave energy will ultimately become the internal energy of the fluid through viscous dissipation, thereby achieving the effect of absorbing sound wave energy and suppressing thermoacoustic oscillations. At the same time, the arrangement of mixing and burning the fuel flowing through the fuel channel and the air ejected from the air injection holes on the outer wall of the gas cavity with the oncoming flue gas can effectively avoid flashback under the condition of the oncoming high-temperature flue gas and is conducive to the establishment of gentle combustion. By arranging multiple rows of fuel holes in the gas cavity and staggering the adjacent two rows, it can play a role in dispersing the reaction zone and reducing NO X emissions. At the same time, the setting of the ribs in the cavity and the air film holes on the outer wall of the gas cavity can effectively prevent the axial staging nozzle from being ablated under the condition of the oncoming high-temperature flue gas.

[0043] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. The above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An acoustic suppression axial staged mild combustion nozzle based on vortex shedding dissipation, characterized in that, It includes an outer wall of the gas cavity, an outer wall of the fuel cavity, and film holes; a gas cavity is formed between the outer wall of the gas cavity and the outer wall of the fuel cavity, including a windward section of the gas cavity, a middle-lower part of the gas cavity, a middle-upper part of the gas cavity, and a leeward section of the gas cavity formed by being separated by a plurality of partition ribs; the outer wall of the fuel cavity wraps the fuel cavity; the partition ribs connect the outer wall of the gas cavity and the outer wall of the fuel cavity; ribs inside the cavity are located on the outer wall of the gas cavity and the outer wall of the fuel cavity; injection holes and film holes are located on the outer wall of the gas cavity; fuel channels are located on the outer wall of the fuel cavity; Among them, after the fuel enters the fuel cavity, it flows through the fuel channels and mixes and burns with the cooling air that enters the gas cavity and is ejected through the injection holes outside the outer wall of the gas cavity; the air ejected from the film holes located on the outer wall of the gas cavity forms a low-temperature thin film on the nozzle surface, separating the nozzle surface from the high-temperature mainstream, and cooling the nozzle wall surface, playing a dual protection role of heat insulation and cooling, and avoiding the ablation of the axial staging nozzle under high-temperature flue gas.

2. The acoustic suppression axial staging mild combustion nozzle based on vortex shedding dissipation according to claim 1, wherein, The outer shape of the nozzle is a combination of an airfoil shape and a lobe trailing edge. The desired shedding frequency f of the main vortex is related to the structural parameters of the nozzle and the angle of attack of the nozzle arrangement, and satisfies , where St is the Strouhal number, U is the incoming flow velocity of the high-temperature flue gas, L is the characteristic length of the airfoil, k is an empirical coefficient depending on the airfoil, and α is the angle of attack defined as the angle between the incoming flow direction and the chord line of the airfoil.

3. The acoustic suppression axial staging mild combustion nozzle based on vortex shedding dissipation according to claim 2, wherein, The existence of the lobe trailing edge is used to induce a multi-source secondary vortex structure, and the interaction between the secondary vortex and the primary vortex broadens the range of vortex shedding frequencies.

4. An acoustic suppression axial staged mild combustion nozzle based on vortex shedding dissipation according to claim 3, characterized in that For a given nozzle structure, the desired vortex shedding frequency is adjusted by adjusting the angle of attack of the nozzle.

5. An acoustic suppression axial staged mild combustion nozzle based on vortex shedding dissipation according to claim 1, characterized in that, The ribs inside the cavity are located in the windward section of the gas cavity, the middle-lower part of the gas cavity, the middle-upper part of the gas cavity, and the leeward section of the gas cavity.

6. The acoustic suppression axial staged mild combustion nozzle based on vortex shedding dissipation according to claim 1, characterized in that, The film holes are located on the outer wall of the gas cavity corresponding to the windward section of the gas cavity, the middle-lower part of the gas cavity, and the top of the nozzle; the cooling air is ejected from the gas cavity at a certain angle and momentum and develops downstream along with the oncoming flow.

7. An acoustic suppression axial staged mild combustion nozzle based on vortex shedding dissipation according to claim 1, characterized in that, The fuel channels and the injection holes are located on the outer wall of the fuel cavity and the outer wall of the gas cavity corresponding to the middle-upper part of the gas cavity, the leeward section of the gas cavity, and the top of the nozzle.

8. An acoustic suppression axial staging soft combustion nozzle based on vortex shedding dissipation according to claim 7, characterized in that, The high-temperature oncoming flow flue gas after mixing with the cold air mixes and burns with the air ejected from the injection holes and the fuel flowing through the fuel channels outside the outer wall of the gas cavity.

9. An acoustic suppression axial staging gentle combustion nozzle based on vortex shedding dissipation according to claim 7, characterized in that, The adjacent two rows of the fuel channels located in the middle-upper part of the gas cavity and the leeward section of the gas cavity are arranged in a staggered manner.

10. An acoustic suppression axial staged mild combustion nozzle based on vortex shedding dissipation according to claim 1, characterized in that, The thickness w of the injection holes satisfies 0 < w ≤ 3d, where d is the inner diameter of the fuel channels.

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