Low cost reflow combustion chamber

Abstract

The application discloses a low-cost backflow combustion chamber, which comprises a hot end casing, a flame tube, an inner ring of an exhaust turning section, an outer ring of the exhaust turning section, a fuel nozzle and a vortex generator, and is characterized in that the hot end casing is formed by adopting electron beam welding to connect in a ring shape in a low stress area of the hot end casing; the flame tube comprises a flame tube inner ring and a flame tube outer ring which are arranged in a sleeve structure, and the flame tube inner ring and the flame tube outer ring are connected by electron beam welding in a ring shape in a low temperature working area; the inner ring of the exhaust turning section is connected to an exhaust end of the flame tube inner ring, the outer ring of the exhaust turning section is arranged at an exhaust end of the flame tube outer ring in a spaced mode, and the inner ring of the exhaust turning section and the outer ring of the exhaust turning section are respectively formed by plate processing and plate stamping; and unified fastening screws are used in assembling of all parts. The combustion chamber can effectively reduce maintenance cost, machining cost, purchasing cost and management cost, and realizes a low cost target.

Description

Technical Field

[0001] This invention relates to the field of aero-engine combustion chamber technology, and in particular, to a low-cost recirculation combustion chamber. Background Technology

[0002] Modern small and medium-sized aero engines generally adopt a recirculation combustion chamber structure layout, as shown in the attached figure. Figure 1 As shown, its main advantage is that it can effectively shorten the engine shaft length and alleviate rotor dynamics problems. A typical recirculation combustion chamber mainly consists of an outer casing, flame tube, exhaust bend section, vortex generator, fuel injector, fuel main pipe, and electric nozzle. The exhaust bend section reverses the flow direction of the high-temperature combustion gas by 180°, realizing the structural intent of the recirculation combustion chamber; it consists of inner and outer rings. Civilian engines not only need technological success and airworthiness success, but also commercial success and industrialization. This makes cost control one of the keys to a model's commercial success.

[0003] Current technological status: The outer combustion chamber casing and the outer turbine casing are usually connected by bolts, which is heavy and has high processing costs, and integrated design of the two is rare; the flame tube and exhaust bend section are in contact with high-temperature combustion gases for a long time, requiring cooling design. As the engine temperature rises continuously, the amount of cold air available to cool the high-temperature walls decreases. To meet the requirements of long service life, the cooling structure is often designed to be more complex, and even expensive high-temperature resistant materials are used, which greatly increases the processing and maintenance costs of the combustion chamber; to obtain sufficient strength, the outer combustion chamber casing, flame tube, and exhaust bend section are usually processed by forging and machining; due to the structural characteristics of the combustion chamber and the machining capabilities, the casing, flame tube, and exhaust bend section usually need to be designed as multiple sections and then assembled by welding.

[0004] Problems with existing recirculating combustors: To meet the long service life requirements of combustors, existing combustors are usually made of expensive high-temperature resistant materials, forged and machined, and then assembled by multiple welds to form the combustor. The forging blanks have large machining allowances and high blank costs, resulting in extremely high combustor processing costs. At the same time, there are unreasonable selections of welding methods and welding positions, resulting in poor combustor maintainability and high maintenance costs. The selection of fasteners does not take into account procurement and management costs, resulting in inconsistent fastener specifications and increasing fastener costs. Summary of the Invention

[0005] This invention provides a low-cost recirculation combustion chamber to solve the technical problems of high processing, maintenance and repair costs of existing recirculation combustion chambers.

[0006] The technical solution adopted in this invention is as follows:

[0007] A low-cost recirculation combustion chamber includes: a hot-end casing integrated with a combustion chamber casing and a turbine casing; a flame tube formed from sheet metal; an inner and outer ring of an exhaust bend section corresponding to the flame tube; a fuel nozzle; and a vortex generator. The flame tube is connected to the hot-end casing, the vortex generator is connected to the head of the flame tube, and the fuel nozzle is connected to the hot-end casing with its injection end connected to the vortex generator. The hot-end casing is formed by circumferential welding in its low-stress region using electron beam welding. The flame tube includes an inner and outer ring of the flame tube, which are connected by circumferential welding in their low-temperature operating regions using electron beam welding. The inner ring of the exhaust bend section is connected to the exhaust end of the inner ring of the flame tube, and the outer ring of the exhaust bend section is spaced apart at the exhaust end of the outer ring of the flame tube. The inner and outer rings of the exhaust bend section are formed by sheet metal processing and sheet metal stamping, respectively.

[0008] Furthermore, the hot-end casing includes a casing front flange formed by machining sheet metal, and a casing middle section and a casing turbine section formed by machining forgings; the casing front flange, casing middle section and casing turbine section are arranged sequentially along the axial direction, and are connected in pairs by electron beam welding to form two first circumferential welds, one of which is close to the fuel nozzle and the other is located outside the fuel nozzle; a dedicated combustion chamber inspection port seat and multiple component mounting seats are also connected to the casing front flange by electron beam welding, and a dedicated turbine inspection port seat is also connected to the casing middle section by electron beam welding.

[0009] Furthermore, the air inlet end of the outer ring of the flame tube and the air inlet end of the inner ring of the flame tube are circumferentially welded by electron beam welding to form the head of the flame tube, and the circumferential weld between the two forms a first second circumferential weld; the flame tube also includes a rear section of the outer ring of the flame tube located at the exhaust end of the outer ring of the flame tube and extending axially, the inner end of the rear section of the outer ring of the flame tube and the annular step provided at the exhaust end of the outer ring of the flame tube are circumferentially welded by electron beam welding, and the circumferential weld between the two forms a second second circumferential weld.

[0010] Furthermore, the outer ring of the exhaust bend section is a double-wall structure formed by connecting the inner wall and the outer wall of the outer ring, and the inner wall and the outer wall of the outer ring are respectively stamped from sheet metal; the air intake ends of the inner wall and the outer wall of the outer ring are sealed and combined and extend axially to form an outward convex ring, which is located in the rear section of the outer ring of the flame tube and is spaced apart from the rear section of the outer ring of the flame tube; the exhaust ends of the inner wall and the outer wall of the outer ring are combined and fixed to the diffuser.

[0011] Furthermore, a first impact hole is provided on the outer wall of the outer ring, and a divergence hole is provided on the inner wall of the outer ring, so that the external cooling airflow passes through the first impact hole and the divergence hole in sequence and rushes into the inner cavity of the flame tube to impact and diverge the inner wall of the outer ring for cooling.

[0012] Furthermore, the inner ring of the exhaust bend section is a double-wall structure formed by connecting the outer wall of the inner ring and the inner wall of the inner ring, and the outer wall of the inner ring and the inner wall of the inner ring are respectively machined from sheet metal; the air inlet end of the outer wall of the inner ring is connected to the exhaust end of the inner ring of the flame tube by electron beam welding; the air inlet end of the inner wall of the inner ring is connected to the outer wall of the inner ring by electron beam welding.

[0013] Furthermore, a film cooling hole and a second impact hole are also provided on the outer wall of the inner ring; the film cooling hole is used to allow external cooling airflow to enter the inner cavity of the flame tube to perform film cooling on the upstream wall of the inner ring; the second impact hole is used to allow external cooling airflow to enter the impact cavity between the outer wall of the inner ring and the inner wall of the inner ring to perform impact cooling on the wall of the inner ring.

[0014] Furthermore, the air inlet end of the outer wall of the inner ring is a Z-shaped ring with a "Z"-shaped cross section. The air film holes are evenly spaced along the circumference of the Z-shaped ring, and each air film hole penetrates the Z-shaped ring axially. The tail end of the Z-shaped ring has a welding step, and the air inlet end of the inner wall of the inner ring is connected to the welding step by electron beam welding.

[0015] Furthermore, the vortex generator includes a two-stage vortex generator and a first-stage vortex generator arranged coaxially, and a cover ring fitted on the exhaust end of the first-stage vortex generator and connecting the two-stage vortex generators; the two-stage vortex generators, the first-stage vortex generator and the cover ring are respectively formed by bar stock machining, and the two-stage vortex generators and the first-stage vortex generator, and the two-stage vortex generators and the cover ring are respectively fixedly connected by spot welding.

[0016] Furthermore, the fuel injector is fixed to the hot end casing with fastening screws; all parts in the low-cost recirculation combustion chamber are assembled using fastening screws of the same specification.

[0017] The present invention has the following beneficial effects:

[0018] The recirculation combustion chamber of this invention, to reduce the weight and processing cost of the combustion chamber casing and turbine casing, integrates the combustion chamber casing and turbine casing into a single hot-end casing. Furthermore, the hot-end casing is formed by circumferential welding in its low-stress area using electron beam welding. Electron beam welding results in minimal deformation, and positional accuracy requirements can be guaranteed without post-weld alignment, eliminating the risk of weld cracks caused by alignment. This significantly improves the processing yield of the hot-end casing and reduces its processing cost. Limited by the structure and machining capabilities of the flame tube, the flame tube needs to be composed of an inner and outer ring. To reduce the weight of the flame tube, [the following is a more detailed description of the design, which is not directly related to the invention.] By welding the two components together and placing the weld seam in its low-temperature operating zone, lifespan is extended, thereby reducing maintenance costs. Simultaneously, considering the structural characteristics of the inner and outer rings of the flame tube, the outer and inner rings are machined from sheet metal blanks, significantly shortening the processing cycle and reducing the amount of material processed, effectively controlling the blank and machining costs of the flame tube. Similarly, the inner and outer rings of the exhaust bend section are formed from sheet metal by machining and stamping, respectively, resulting in a simple structure and low manufacturing cost, thus significantly shortening the processing cycle and reducing the amount of material processed, effectively controlling the blank and machining costs of the exhaust bend section. All parts are assembled using fastening screws of a uniform specification. The low-cost recirculation combustion chamber of this invention comprehensively considers processing costs, procurement costs, management costs, maintenance and repair costs, and achieves the goal of low cost. Moreover, the combustion chamber of this invention has been used in a certain civilian engine, and the cost control meets the requirements of the civilian engine. It has been tested under ultra-high temperature and endurance tests, and has completed 3000 hours of accelerated spectrum equivalent tests on two complete engines without the occurrence of cracks or ablation problems that affect engine safety. This shows that the invention takes into account both the requirements of long service life and low cost.

[0019] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 This is a cross-sectional view of the existing gas turbine recirculation combustion chamber;

[0022] Figure 2 This is a schematic cross-sectional view of the low-cost recirculation combustion chamber according to a preferred embodiment of the present invention;

[0023] Figure 3 yes Figure 2 Schematic diagram of the integrated hot-end casing structure;

[0024] Figure 4 This is a schematic diagram of the flame tube structure formed from sheet metal processing;

[0025] Figure 5 yes Figure 2 A schematic diagram of the cross-sectional structure of the outer ring of the central exhaust bend section;

[0026] Figure 6 yes Figure 2 Schematic diagram of the arrangement of diverging holes on the inner wall of the outer ring;

[0027] Figure 7 This is a cross-sectional diagram of the inner ring of the exhaust bend section;

[0028] Figure 8 This is a schematic diagram of the arrangement of the second impact holes on the outer wall of the inner ring;

[0029] Figure 9 yes Figure 2 A schematic diagram of the main structure of a medium-sized vortex generator;

[0030] Figure 10 yes Figure 9 Schematic diagram of the cross-sectional structure along the middle AA direction;

[0031] Figure 11 yes Figure 9 A cross-sectional structural schematic diagram of a mid-stage eddy current generator;

[0032] Figure 12 This is a schematic diagram of the fuel injector fastening structure.

[0033] Legend:

[0034] 1. Hot-end casing; 101. First circumferential weld; 11. Casing front flange; 12. Casing middle section; 13. Casing turbine section; 14. Combustion chamber inspection port seat; 15. Turbine inspection port seat; 16. Component mounting seat; 2. Flame tube; 201. Second circumferential weld; 21. Flame tube outer ring; 22. Rear section of flame tube outer ring; 23. Flame tube inner ring; 3. Exhaust bend section inner ring; 301. Z-ring; 3 02. Film gas hole; 303. Second impact hole; 31. Inner ring inner wall; 32. Inner ring outer wall; 4. Outer ring of exhaust bend section; 401. Diverging hole; 41. Outer ring inner wall; 42. Outer ring outer wall; 5. Swirl generator; 51. Two-stage swirl generator; 511. First oblique cut hole; 52. First-stage swirl generator; 521. Second oblique cut hole; 53. Cover ring; 6. Fuel nozzle; 7. Impact chamber; 8. Fastening screw. Detailed Implementation

[0035] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0036] Reference Figure 2A preferred embodiment of the present invention provides a low-cost recirculation combustion chamber, comprising: a hot-end casing 1 integrated with a combustion chamber casing and a turbine casing; a flame tube 2 formed by machining sheet metal; an inner ring 3 and an outer ring 4 of an exhaust bend section corresponding to the flame tube 2; a fuel nozzle 6; and a vortex generator 5. The flame tube 2 is connected to the hot-end casing 1, the vortex generator 5 is connected to the head of the flame tube 2, and the fuel nozzle 6 is connected to the hot-end casing 1 with its injection end connected to the vortex generator 5. The hot-end casing 1 is formed by circumferential welding using electron beam welding in its low-stress region. The flame tube 2 includes an inner ring 23 and an outer ring 21 of the flame tube, which are joined together by circumferential welding using electron beam welding in their low-temperature operating regions. The inner ring 3 of the exhaust bend section is connected to the exhaust end of the inner ring 23 of the flame tube, and the outer ring 4 of the exhaust bend section is spaced apart at the exhaust end of the outer ring 21 of the flame tube. The inner ring 3 and the outer ring 4 of the exhaust bend section are respectively formed by processing sheet metal.

[0037] In this invention, the recirculating combustion chamber integrates the combustion chamber casing and turbine casing into a single hot-end casing 1 to reduce the weight and processing cost of the combustion chamber casing and turbine casing. The hot-end casing 1 is further formed by circumferential welding in its low-stress area using electron beam welding. Electron beam welding results in minimal deformation, and positional accuracy requirements can be guaranteed without post-weld alignment, eliminating the risk of weld cracks caused by alignment. This significantly improves the processing yield of the hot-end casing 1 and reduces its processing cost. Due to limitations in the structure and machining capabilities of the flame tube 2, the flame tube 2 needs to be composed of an inner flame tube ring 23 and an outer flame tube ring 21. To reduce the weight of the flame tube 2, [further details are needed]. By welding the two together and placing the weld in its low-temperature operating zone, the service life is improved, thereby reducing maintenance costs. At the same time, taking into account the structural features of the inner and outer rings of the flame tube 2, the outer ring 21 and the inner ring 23 of the flame tube are respectively machined from sheet metal blanks and stamped from sheet metal blanks, which greatly shortens the processing cycle and reduces the amount of processing, thus effectively controlling the blank cost and machining cost of the flame tube 2. Similarly, the inner ring 3 and the outer ring 4 of the exhaust bend section are respectively formed by sheet metal processing, which has a simple structure and low manufacturing cost, thus greatly shortening the processing cycle and reducing the amount of processing, thus effectively controlling the blank cost and machining cost of the exhaust bend section. The low-cost recirculation combustion chamber of this invention comprehensively considers processing costs, procurement costs, management costs, maintenance and repair costs, and achieves the goal of low cost. Moreover, the combustion chamber of this invention has been used in a certain civilian engine, and the cost control meets the requirements of the civilian engine. It has been tested under ultra-high temperature and endurance tests, and has completed 3000 hours of accelerated spectrum equivalent tests on two complete engines without the occurrence of cracks or ablation problems that affect engine safety. This shows that the invention takes into account both the requirements of long service life and low cost.

[0038] Optionally, such as Figure 2 and Figure 3As shown, the hot-end casing 1 includes a casing front flange 11 formed by machining sheet metal, and a casing middle section 12 and a casing turbine section 13 formed by machining forgings. In this optional scheme, the hot-end casing 1 includes a casing front flange 11 as the front mounting edge, a casing middle section 12 as the middle section, and a casing turbine section 13 as the rear mounting edge. Based on the structural characteristics of the front mounting edge, the casing front flange 11 is machined using a low-cost sheet metal blank machining method, which effectively controls the blank and machining costs of the hot-end casing 1. Due to the large wall thickness span of the casing middle section 12 and the casing turbine section 13, a forging machining method is adopted. The casing front flange 11, casing middle section 12, and casing turbine section 13 are arranged sequentially along the axial direction, and are connected in pairs by electron beam welding to form two first circumferential welds 101. One first circumferential weld 101 is close to the fuel nozzle 6, and the other first circumferential weld 101 is located outside the fuel nozzle 6. The hot-end casing 1 of the present invention has only two main circumferential welds, which reduces the number of circumferential welds and effectively reduces welding and weld inspection costs. Moreover, both circumferential welds are located in the low-stress zone of the hot-end casing 1, which can effectively reduce the risk of weld cracking. Furthermore, all welds can be completed in one welding operation, ensuring positional accuracy without the need for calibration, thereby eliminating stress concentration in the welds caused by calibration, improving weld life, solving the problem of weld cracking in existing outer casings, and reducing processing and maintenance costs.

[0039] Furthermore, such as Figure 3 As shown, a dedicated combustion chamber inspection port seat 14 and multiple component mounting seats 16 are connected to the front flange 11 of the casing via electron beam welding, and a dedicated turbine inspection port seat 15 is connected to the middle section 12 of the casing via electron beam welding. In this optional scheme, the main body, the inspection port seat, and various mounting seats are combined by electron beam welding. All electron beam welding is completed in one operation, resulting in low welding costs. At the same time, electron beam welding causes minimal deformation, and positional accuracy requirements can be guaranteed without calibration after welding, eliminating the risk of weld cracks caused by calibration, greatly improving the processing qualification rate of the hot-end casing 1, and reducing manufacturing costs. In addition, the hot-end casing 1 is designed with dedicated combustion chamber inspection ports corresponding to the combustion chamber inspection port seat 14 and turbine inspection ports corresponding to the turbine inspection port seat 15, for use by inserting a borescope into the hot-end casing 1 to inspect the combustion chamber and gas turbine, reducing borescope inspection time, lowering the maintenance costs of the combustion chamber and turbine, and allowing inspection of all gas turbine blades, which also greatly improves the maintainability of the turbine.

[0040] Optionally, such as Figure 2 and Figure 4As shown, the air inlet end of the outer ring 21 and the air inlet end of the inner ring 23 of the flame tube are formed into the head of the flame tube 2 by electron beam welding, and the circumferential weld between the two forms the first and second circumferential weld seam 201. In this optional solution, in order to reduce the weight of the flame tube 2, it is usually assembled by welding. In this invention, all weld seams are set in the low-temperature zone during its operation, such as the air inlet ends of both, to avoid weld seam failure due to high temperature, solve the problem of weld seam cracking in existing flame tubes, and reduce its maintenance and repair costs; and the inner ring 23 and the outer ring 21 of the flame tube are both machined from low-cost sheet metal blanks and are formed by electron beam welding, resulting in low processing and maintenance costs.

[0041] Furthermore, such as Figure 3 As shown, the flame tube 2 also includes a rear section 22 of the outer ring 21, located at the exhaust end and extending axially. The inner end of the rear section 22 is connected to the annular step at the exhaust end of the outer ring 21 by electron beam welding, forming a second annular weld 201 at the weld joint. In this optional embodiment, the rear section 22 of the outer ring 22 also adopts a low-cost sheet metal processing method, reducing its processing cost, and the use of electron beam welding results in low maintenance costs.

[0042] Optionally, such as Figure 2 and Figure 5 As shown, the outer ring 4 of the exhaust bend section is a double-wall structure formed by connecting the inner wall 41 and the outer wall 42 of the outer ring. The inner wall 41 and the outer wall 42 are both formed by stamping sheet metal, reducing processing costs. The air intake ends of the inner wall 41 and the outer wall 42 are sealed together and extend axially to form a convex ring. The convex ring is located inside the rear section 22 of the outer ring of the flame tube and is spaced apart from the rear section 22 of the outer ring of the flame tube. The exhaust ends of the inner wall 41 and the outer wall 42 are then combined and fixed to the diffuser. In this alternative solution, the outer ring 4 of the exhaust bend section is assembled from the inner wall 41 and the outer wall 42 of the outer ring, eliminating the use of welding and forming it by stamping from sheet metal, which can effectively reduce processing costs. Compared with the existing structure, where the outer ring 4 of the exhaust bend section is radially overlapped with the rear section 22 of the outer ring of the flame tube, the wall temperature of the outer ring 4 of the exhaust bend section is higher than that of the rear section 22 of the outer ring of the flame tube at the overlap point. During the operation of the combustion chamber, the outer ring 4 of the exhaust bend section compresses the rear section 22 of the outer ring of the flame tube radially, which can easily cause cracks in the rear section 22 of the outer ring of the flame tube. In this invention, the outer ring 4 of the exhaust bend section and the rear section 22 of the outer ring of the flame tube are designed to be spaced apart radially to avoid the outer ring 4 of the exhaust bend section compressing the rear section 22 of the outer ring of the flame tube, thereby improving the life of the flame tube 2 and reducing its processing and maintenance costs.

[0043] Furthermore, such as Figure 5As shown, the outer ring 4 of the exhaust bend section has a double-wall structure. The inner wall 41 of the outer ring is subjected to the scouring of the high-temperature combustion chamber for a long time, and the wall temperature is usually high. Therefore, in the structure of the present invention, a first impact hole is also provided on the outer wall 42 of the outer ring, and a divergence hole 401 is also provided on the inner wall 41 of the outer ring, so that the external cooling airflow passes through the first impact hole and the divergence hole 401 in sequence and rushes into the inner cavity of the flame tube to impact and diverge the inner wall 41 of the outer ring, effectively reducing the combustion surface wall temperature of the outer ring 4 of the exhaust bend section, increasing the service life of the outer ring 4 of the exhaust bend section, solving the technical problem that the existing outer ring 4 of the exhaust bend section is prone to ablation and cracking, and reducing the processing and maintenance costs of the outer ring 4 of the exhaust bend section.

[0044] Furthermore, such as Figure 5 and Figure 6 As shown, the diverging holes 401 are arranged in multiple concentric circles on the inner wall 41 of the outer ring, and adjacent circles of diverging holes 401 are staggered circumferentially. The diameter of each diverging hole 401 is the same, and the cooling area of ​​each circle of diverging holes 401 is consistent. Preferably, multiple diverging holes 401 in each circle are evenly spaced circumferentially. The number of circles of diverging holes 401 is determined according to the size of the outer ring 4 of the exhaust bend section, generally 18 to 22 circles. The diameter of all diverging holes 401 and the cooling area (A1) of each row of diverging holes are consistent. The upstream is a tangential hole, and the downstream is an axial hole. The cooling area of ​​each circle of diverging holes 401 refers to the remaining annular area after deducting the area occupied by the diverging holes at the position of each circle of diverging holes. The diameter of each diverging hole 401 is the same, and the cooling area of ​​each circle of diverging holes 401 is consistent, thereby making the cooling airflow uniform on the wall surface of the inner wall 41 of the outer ring and improving the cooling effect.

[0045] Preferably, such as Figure 5 As shown, the diverging hole 401 located upstream in the gas flow direction is a tangential hole that cuts through the inner wall 41 of the outer ring along the circumferential direction; the diverging hole 401 located downstream in the gas flow direction is an axial hole that cuts through the inner wall 41 of the outer ring along the radial direction. This structural arrangement of the diverging hole 401 allows the cooling airflow to be ejected close to the inner wall surface of the outer ring 41, thereby further improving the cooling effect and cooling uniformity of the inner wall 41 of the outer ring and reducing the maintenance cost of the outer ring 4 in the exhaust bend section.

[0046] Optionally, such as Figure 2 and Figure 7As shown, the inner ring 3 of the exhaust bend section is a double-wall structure formed by connecting the outer wall 32 and the inner wall 31 of the inner ring, and the outer wall 32 and the inner wall 31 of the inner ring are respectively machined from sheet metal. In this optional solution, the inner ring 3 of the exhaust bend section adopts a simple double-wall structure, which is formed by electron beam welding of the inner wall 31 and the outer wall 32 of the inner ring. The weld is made by electron beam welding. When the inner wall 31 of the inner ring fails, it can be replaced, resulting in low maintenance costs. Moreover, the processing method is low-cost sheet metal machining. The air inlet end of the outer wall 32 of the inner ring is connected to the exhaust end of the inner ring 23 of the flame tube by electron beam welding; the air inlet end of the inner wall 31 of the inner ring is connected to the outer wall 32 of the inner ring by electron beam welding. The processing cost is low, and the combination of the inner wall 31 and the outer wall 32 of the inner ring by electron beam welding separates the load-bearing and temperature-bearing functions, thereby effectively improving the service life of the inner ring 3 of the exhaust bend section and reducing the processing cost.

[0047] In this optional embodiment, a film cooling hole 302 and a second impact hole 303 are also provided on the outer wall of the inner ring 32. The film cooling hole 302 is used to allow external cooling airflow to enter the inner cavity of the flame tube for film cooling of the upstream wall surface of the inner ring 31. The second impact hole 303 is used to allow external cooling airflow to enter the impact cavity 7 between the outer wall of the inner ring 32 and the inner wall of the inner ring 31 for impact cooling of the wall surface of the inner ring 31. In this optional solution, the inner ring 3 of the exhaust bend section also adopts a double-wall structure. The upstream wall surface of the inner ring inner wall 31 is cooled by air film through the air film holes 302 provided on the outer wall 32 of the inner ring. At the same time, the wall surface of the inner ring inner wall 31 is cooled by impact through the second impact holes 303 provided on the outer wall 32 of the inner ring. The combination of air film cooling and impact cooling on the inner ring inner wall 31 can effectively ensure the wall temperature of the inner ring inner wall 31 and a small temperature gradient, thereby greatly increasing the service life of the inner ring 3 of the exhaust bend section. This solves the technical problems of easy ablation and weld cracking in the existing double-wall exhaust bend section inner ring 3, and reduces the processing and maintenance costs of the inner ring 3 of the exhaust bend section.

[0048] In this optional solution, such as Figure 7 As shown, the air inlet end of the inner ring outer wall 32 is a Z-shaped ring 301 with a "Z"-shaped cross-section. Gas film holes 302 are evenly spaced along the circumference of the Z-shaped ring 301, and each gas film hole 302 penetrates the Z-shaped ring 301 axially. During operation, external cooling airflow is injected axially into the inner cavity of the flame tube through the gas film holes 302. Then, under the action of the combustion gas flow within the flame tube, it is driven towards the outlet of the flame tube. During this flow, a cooling gas film is formed on the inner wall surface of the inner ring inner wall 31, thereby cooling the upstream wall surface of the inner ring inner wall 31. The tail end of the Z-shaped ring 301 has a welding step, and the air inlet end of the inner ring inner wall 31 is circumferentially welded to the welding step using electron beam welding.

[0049] Furthermore, such as Figure 8As shown, the second impact holes 303 are arranged in multiple concentric circles on the outer wall 32 of the inner ring, and adjacent circles of second impact holes 303 are staggered circumferentially, with the number of second impact holes 303 increasing along the direction of gas flow. In this optional scheme, the number of rows of second impact holes 303 is determined according to the size of the inner ring 3 of the exhaust bend section, generally 5 to 8 rows, all second impact holes 303 have the same diameter, and the annular area (A) cooled by each row of impact holes is the same. During operation, as the radial height of the inner ring 3 of the exhaust bend section decreases, the wall temperature increases. The upper end of the inner ring 3 of the exhaust bend section is designed with a film cooling system attached to the wall to achieve a lower wall temperature. This allows more cooling air to be used for cooling the downstream section of the inner ring 3 of the exhaust bend section. To adapt to the structural characteristics of the inner ring 3 of the exhaust bend section, the number of second impact holes 303 in each row generally increases as the radial height of the inner ring 3 of the exhaust bend section decreases, and all second impact holes 303 are designed with the same diameter to better cool the downstream section of the inner wall 31 of the inner ring and reduce the maintenance cost of the inner ring 3 of the exhaust bend section.

[0050] Furthermore, such as Figure 7 As shown, the diameter of each second impact hole 303 is equal, and the last ring of second impact holes 303 along the gas flow direction vertically penetrates the outer wall 32 of the inner ring along the height direction, while the remaining second impact holes 303 penetrate the outer wall 32 of the inner ring perpendicularly to the wall surface; in actual design, such as Figure 7 As shown, the number of second impact holes 303 in the first and second rows is the same. The number of second impact holes 303 in the third and fourth rows is twice that of the first and second rows. The number of second impact holes 303 after the fourth row increases exponentially with the decrease in radial height of the inner ring 3 of the exhaust bend section. For example, the number of second impact holes 303 in the fifth row is 2.5 times that of the first and second rows, and the number of second impact holes 303 in the sixth row is 3 times that of the first and second rows. During operation, due to the inconsistent thermal deformation of the inner wall 31 and the outer wall 32 of the inner ring, the impact cavity 7 formed by the two will decrease. To ensure excellent cooling effect at the outlet of the inner ring 3 of the exhaust bend section, the last row of second impact holes 303 is designed as vertical holes to directly cool the outlet of the inner ring 3 of the exhaust bend section, thereby reducing the maintenance cost of the inner ring 3 of the exhaust bend section.

[0051] Optionally, such as Figure 9 As shown, the vortex generator 5 includes two coaxially arranged vortex generators 51 and a first-stage vortex generator 52, and a cover ring 53 fitted onto the exhaust end of the first-stage vortex generator 52 and connecting the two-stage vortex generators 51. The two-stage vortex generators 51, the first-stage vortex generator 52, and the cover ring 53 are all formed by a bar press, and the two-stage vortex generators 51 and the first-stage vortex generator 52, and the two-stage vortex generators 51 and the cover ring 53 are respectively fixedly connected by spot welding. In this optional embodiment, the vortex generator 5 is formed by a bar press, which has a simpler structure and lower processing cost compared with the blade-type vortex generator.

[0052] In this optional solution, such as Figure 10-11 As shown, the outer ring surface of the two-stage vortex generator 51 has two rings of first oblique-cut holes 511 arranged sequentially along the axial direction, and the outer ring surface of the first-stage vortex generator 52 has one ring of second oblique-cut holes 521. The helical directions of the two rings of first oblique-cut holes 511 are the same and opposite to the helical direction of the second oblique-cut hole 521, or the helical directions of the two rings of first oblique-cut holes 511 are opposite, and the helical direction of the second oblique-cut hole 521 is opposite to the helical direction of the first oblique-cut hole 511 closest to it. In this optional scheme, the air intake method of the vortex generator 5 is designed as oblique hole air intake, avoiding the use of vortex generator blades with high processing costs and greatly reducing the processing cost of the vortex generator.

[0053] Optionally, such as Figure 12 As shown, the fuel injector 6 is fixed to the hot-end casing 1 by fastening screws 8. All parts in the low-cost recirculation combustion chamber are assembled using fastening screws 8 of a uniform specification. Considering the possibility of low cost from a procurement perspective, all screws are designed to a uniform specification, reducing the procurement and management costs of the screws.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-cost recirculation combustion chamber, characterized in that, include: The integrated combustion chamber casing and turbine casing are designed as a single unit. The hot-end casing (1) comprises a flame tube (2) machined from sheet metal, an inner ring (3) and an outer ring (4) of the exhaust bend section corresponding to the flame tube (2), a fuel nozzle (6), and a vortex generator (5). The hot-end casing (1) includes a front flange (11) machined from sheet metal, and... The casing middle section (12) and casing turbine section (13) are formed by forging and machining. The casing front flange (11), casing middle section (12) and casing turbine section (13) are arranged in sequence along the axial direction, and are connected in pairs by electron beam welding to form two first ring welds (101). One of the first ring welds (101) is close to the fuel nozzle (6), and the other first ring weld (101) is located outside the fuel nozzle (6). The flame tube (2) is connected inside the hot end casing (1), the vortex generator (5) is connected to the head of the flame tube (2), and the fuel nozzle (6) is connected to the hot end casing (1) and the injection end is connected to the vortex generator (5). The hot end casing (1) is formed by circumferential welding in its low-stress region using electron beam welding. The flame tube (2) includes an inner ring (23) and an outer ring (21) of the flame tube, which are arranged in an inner and outer sleeve. The inner ring (23) and the outer ring (21) of the flame tube are connected by electron beam welding ring in their low-temperature working zone. The inner ring (3) of the exhaust bend section is connected to the exhaust end of the inner ring (23) of the flame tube, and the outer ring (4) of the exhaust bend section is spaced apart at the exhaust end of the outer ring (21) of the flame tube. The inner ring (3) and the outer ring (4) of the exhaust bend section are respectively formed by processing sheet metal. The inner ring (3) of the exhaust bend section is a double-wall structure formed by connecting the outer wall (32) of the inner ring and the inner wall (31) of the inner ring. The outer wall (32) of the inner ring and the inner wall (31) of the inner ring are respectively formed by sheet metal processing. The outer wall (32) of the inner ring is also provided with a film cooling hole (302) and a second impact hole (303). The film cooling hole (302) is used to allow external cooling airflow to enter the inner cavity of the flame tube to perform film cooling on the upstream wall surface of the inner wall (31). The second impact hole (303) is used to allow external cooling airflow to enter the impact cavity (7) between the outer wall (32) of the inner ring and the inner wall (31) of the inner ring to perform impact cooling on the wall surface of the inner wall (31). The air inlet end of the inner ring outer wall (32) is a Z-shaped ring (301) with a "Z" shaped cross section. The air film holes (302) are evenly spaced along the circumference of the Z-shaped ring (301), and each air film hole (302) passes through the Z-shaped ring (301) axially. The tail end of the Z-shaped ring (301) has a welding step. The air inlet end of the inner ring inner wall (31) and the welding step are connected by circumferential welding through electron beam welding. The second impact holes (303) are arranged in multiple concentric circles on the outer wall (32) of the inner ring, and the second impact holes (303) of adjacent two circles are staggered in the circumferential direction, and the number of second impact holes (303) increases along the gas flow direction. The diameter of each second impact hole (303) is equal, and the last ring of second impact holes (303) along the gas flow direction penetrates vertically through the outer wall (32) of the inner ring along the height direction, while the remaining second impact holes (303) penetrate the outer wall (32) of the inner ring perpendicular to the wall surface of the outer wall (32).

2. The low-cost recirculation combustion chamber according to claim 1, characterized in that, A dedicated combustion chamber inspection port seat (14) and multiple component mounting seats (16) are also connected to the front flange (11) of the casing by electron beam welding, and a dedicated turbine inspection port seat (15) is also connected to the middle section (12) of the casing by electron beam welding.

3. The low-cost recirculation combustion chamber according to claim 1, characterized in that, The air inlet end of the outer ring (21) of the flame tube and the air inlet end of the inner ring (23) of the flame tube are formed into the head of the flame tube (2) by electron beam welding, and the two ring welds form the first second ring weld (201). The flame tube (2) also includes a rear section (22) of the outer ring of the flame tube located at the exhaust end of the outer ring (21) and extending axially. The inner end of the rear section (22) of the outer ring of the flame tube is connected to the annular step provided at the exhaust end of the outer ring (21) of the flame tube by electron beam welding, and the two form a second annular weld (201) at the annular weld.

4. The low-cost recirculation combustion chamber according to claim 3, characterized in that, The outer ring (4) of the exhaust turning section is a double-wall structure formed by connecting the inner wall (41) and the outer wall (42) of the outer ring, and the inner wall (41) and the outer wall (42) of the outer ring are respectively formed by stamping of sheet metal; The inner wall (41) and outer wall (42) of the outer ring are sealed at the air inlet and extend axially to form an outer convex ring. The outer convex ring is located inside the rear section (22) of the outer ring of the flame tube and is spaced apart from the rear section (22) of the outer ring of the flame tube. The exhaust ends of the inner wall of the outer ring (41) and the outer wall of the outer ring (42) are combined and fixed to the diffuser.

5. The low-cost recirculation combustion chamber according to claim 4, characterized in that, The outer ring outer wall (42) is also provided with a first impact hole, and the outer ring inner wall (41) is also provided with a divergence hole (401) so that the external cooling airflow passes through the first impact hole and the divergence hole (401) in sequence and then rushes into the inner cavity of the flame tube to impact and diverge the outer ring inner wall (41) for cooling.

6. The low-cost recirculation combustion chamber according to claim 1, characterized in that, The air inlet end of the outer wall of the inner ring (32) is connected to the exhaust end of the inner ring (23) of the flame tube by electron beam welding; The air inlet end of the inner ring inner wall (31) is connected to the outer ring inner wall (32) by electron beam welding.

7. The low-cost recirculation combustion chamber according to claim 1, characterized in that, The vortex generator (5) includes a two-stage vortex generator (51) and a first-stage vortex generator (52) arranged coaxially, and a cover ring (53) sleeved on the exhaust end of the first-stage vortex generator (52) and connected to the two-stage vortex generator (51). The two-stage eddy current generator (51), the first-stage eddy current generator (52) and the cover ring (53) are respectively formed by bar stock forming, and the two-stage eddy current generator (51) and the first-stage eddy current generator (52) and the two-stage eddy current generator (51) and the cover ring (53) are respectively fixedly connected by spot welding.

8. The low-cost recirculation combustion chamber according to claim 1, characterized in that, The fuel nozzle (6) is fixed to the hot end casing (1) by fastening screws (8); The components in the low-cost recirculation combustion chamber are assembled using fastening screws of the same specification (8).

Images