A concentric staged high-temperature-rise combustion chamber and method employing a swirl-non-swirl combined intake head structure

Abstract

The application discloses a concentric staged high-temperature-rise combustion chamber and method adopting a combined inlet head structure of swirl and non-swirl, and belongs to the field of aero-engine combustion chambers.The combustion chamber comprises a combustion chamber casing, a sudden expansion diffuser at the inlet of the combustion chamber casing and a flame tube in the combustion chamber casing; the flame tube is in a ring cavity structure and comprises a head, an outer wall of the flame tube and an inner wall of the flame tube; the head comprises a head baffle connected with the inner wall and the outer wall of the flame tube, a main combustion stage and a pre-combustion stage installed on the head baffle; the main combustion stage adopts a direct mixing combustion form and adopts a combined ventilation mode of swirl and non-swirl; the pre-combustion stage is coaxially installed in a central hole of the main combustion stage, and an annular cavity is formed between the outer wall of the pre-combustion stage and the inner wall of the main combustion stage; and the combustion zones of the main combustion stage and the pre-combustion stage are relatively independent by controlling the radial dimension of the annular cavity.The application solves the problems of adjusting and controlling the temperature field of the combustion chamber.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine combustion chambers, specifically relating to a concentric staged high-temperature combustion chamber and method employing a swirl-non-swirl combined inlet head structure. Background Technology

[0002] Advanced aero-engine main combustors are developing towards higher temperature rise and higher heat capacity. The reason why higher temperature rise has become a key development direction for future aero-engine combustors is determined by the pursuit of a high thrust-to-weight ratio. Increasing the thrust-to-weight ratio requires not only increasing the overall compressor pressure ratio but also increasing the combustor exit temperature. Under the condition that other engine parameters remain unchanged, for every 50°C increase in combustor exit temperature, engine thrust can increase by 7% to 8%. This is achieved by increasing the overall fuel-air ratio in the combustor, thereby increasing the combustor exit temperature. The thrust-to-weight ratios of a certain third-generation and fourth-generation turbofan engine are 7-8 and 9-11, respectively, while the thrust-to-weight ratio of its next-generation aero-engine is at the 15-20 level. For combustors with a thrust-to-weight ratio of around 10, such as the European EJ200 (FAR=0.038) and Pratt & Whitney F119 (FAR=0.037), the technology has been fully explored within the conventional technical range to increase the fuel-air ratio, but the fuel-air ratio has consistently failed to exceed 0.04.

[0003] In conventional combustion chambers, the combustion air volume is around 20%-40%. As combustion chamber temperature rises, the amount of air participating in combustion increases significantly, with the head intake reaching 50%-70% of the total air volume. This poses challenges to ignition and flame stability in the combustion chamber, and also limits the available air volume for cooling and mixing, leading to significant wall cooling issues. Furthermore, the substantial increase in combustion chamber outlet temperature and hot spot temperature further complicates the control of the outlet temperature field. In addition, under conditions of high head intake volume, the head cyclone separator structure must consider the dimensional limitations imposed by the flame tube height, head spacing, and number of heads. Therefore, solutions need to be sought in aerodynamic and thermodynamic structures and fuel atomization design to overcome these technical challenges.

[0004] As the upstream of the combustion zone, the combustion head organization is crucial. High-temperature combustion technologies developed domestically and internationally mainly include multi-stage swirl combustion, vortex combustion, variable geometry combustion, and central staged combustion. Among these, multi-stage swirl combustion has relatively low complexity and remains a conventional technology; vortex combustion faces challenges such as high difficulty in heat protection of the combustion chamber walls, long flame length, and poor uniformity of outlet temperature distribution under high fuel-air ratio conditions; variable geometry combustion has a complex control system, significantly increasing cost and weight, and its actuators are prone to deformation and ablation under high-temperature environments. To improve combustion chamber temperature rise while simultaneously considering low-temperature stability, combustion chamber wall cooling, and outlet temperature field requirements, fuel staging and combustion air zoning can be adopted. Central staged combustion achieves rapid mixing and efficient combustion of fuel and air through spatial overlap of combustion zones, shortening the flame tube length and reducing the need for mixing and cooling air to ensure suitable outlet temperature distribution quality. However, this technology has a high head design complexity, requiring additional nozzles for fuel staging, resulting in a large head mass and radial dimensions.

[0005] Furthermore, due to confidentiality reasons, few technical details regarding high-temperature combustion chambers have been publicly disclosed. Current research on staged combustion largely focuses on commercial engine combustion chambers, using lean premixing and pre-evaporation to reduce emissions, broaden stable operating ranges, and lower thermoacoustic vibrations. These combustion chambers typically have relatively low temperature rise and less stringent requirements for outlet temperature distribution. Moreover, the high equivalence ratio in the combustion zone under high air-fuel ratio conditions and the limited use of premixing methods mean that many research findings are not applicable to high-temperature combustion chambers in engines with higher thrust-to-weight ratios. Summary of the Invention

[0006] The technical problem to be solved:

[0007] To overcome the shortcomings of existing technologies, this invention provides a concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure. It employs a concentric staged combustion organization method, with the main combustion stage featuring a swirl-non-swirl combined intake configuration. Non-swirl intake holes are provided on the inner sidewall downstream of the swirl blades in the main combustion stage's swirl channel. The non-swirl intake air mixes with the swirl intake air within the channel, resulting in weakly swirling air at the main combustion stage outlet. This, combined with fuel supply from the main combustion stage nozzle, forms direct mixing combustion. The pre-combustion stage consists of two stages of swirl, combined with centrifugal nozzles to form diffusion combustion. The main combustion stage combustion zone encloses the pre-combustion stage combustion zone. The radial distance between the main and pre-combustion stages is relatively large, and the swirl number at the outermost stage outlet is relatively low, making each combustion zone in the concentric staged combustion relatively independent. Furthermore, the main combustion stage nozzle is integrated with the swirl generator, eliminating the need for additional nozzles. The flame tube is equipped with jet holes, whose intake air is used for recirculation combustion and downstream outlet temperature distribution adjustment. By adopting this swirl-non-swirl combined intake head structure, the radial dimension of the swirler can be controlled under high head intake conditions in the high-temperature combustion chamber, so as to meet the spatial layout requirements of the combustion chamber head. At the same time, it is beneficial for the combustion chamber to have a good outlet temperature field under a wide operating condition, so as to meet the requirements of high-temperature combustion.

[0008] The technical solution of the present invention is: a concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure, including a combustion chamber casing and a diffuser located at its inlet, and a flame tube therein;

[0009] The flame tube is an annular cavity structure, including a head, an outer wall, and an inner wall. The head is connected to the fuel supply rod, and the outer wall is connected to the igniter. The flame tube head includes a head baffle connected to the inner and outer walls, and a main combustion stage and a pre-combustion stage installed on the head baffle. The main combustion stage adopts a direct mixing combustion method, and reduces the swirl number of the air introduced into the swirling structure by using a combination of swirling and non-swirling airflow. The pre-combustion stage is coaxially installed in the central hole of the main combustion stage, and an annular cavity is formed between the outer wall of the pre-combustion stage and the inner wall of the main combustion stage. By controlling the radial dimension of the annular cavity, the combustion zones of the main combustion stage and the pre-combustion stage are relatively independent.

[0010] A further technical solution of the present invention is: a main combustion stage swirl channel is formed between the inner and outer ring walls of the main combustion stage by setting main combustion stage swirl blades, and a non-swirl air inlet is set on the inner ring wall of the main combustion stage to introduce air into the swirl channel in a non-swirl manner to mix with swirl air;

[0011] The inner ring wall of the main combustion stage has a built-in main combustion stage fuel passage. Fuel flows axially through the main combustion stage fuel inlet, oil collection tank and branch passage in sequence in the passage, and is sprayed out from the main combustion stage nozzle set at the branch passage outlet, and directly mixes and burns with the swirling and non-swirling mixed air.

[0012] A further technical solution of the present invention is: the non-swirl air inlet is a straight through hole arranged in a circumferential array on the inner ring wall downstream of the swirl blade of the main combustion stage, and the non-swirl air introduced accounts for 30% to 40% of the total intake volume of the main combustion stage; and the non-swirl air inlet and the fuel passage of the main combustion stage are staggered to avoid mutual interference.

[0013] A further technical solution of the present invention is: the oil collection groove is an annular cavity located upstream of the non-swirling air inlet. Its input end is connected to the fuel supply rod through the main combustion stage fuel inlet, and multiple branch channels are led out downstream along the circumference. Downstream of the outlet of each branch channel corresponds to a main combustion stage nozzle. The fuel in the branch channel is led out through the main combustion stage nozzle to the same direction as the normal direction of the main combustion stage step end face.

[0014] The main combustion stage nozzle is a direct-injection nozzle with an inner diameter of 0.4-1.0 mm, which is used to inject fuel into the combustion zone from the branch channel outlet to the end face of the main combustion stage step.

[0015] A further technical solution of the present invention is that the angle between the fuel injection direction of the main combustion stage nozzle and the central axis of the main combustion stage is -20 to 30 degrees.

[0016] A further technical solution of the present invention is as follows: the pre-combustion stage includes a pre-combustion stage nozzle, an inner swirler, and an outer swirler arranged coaxially from the inside to the outside. The inlet of the pre-combustion stage nozzle is connected to the fuel supply rod, and its outlet faces the end of the inner swirler. The end of the inner swirler is connected to a venturi tube, and the end of the outer swirler is an annular stepped end face extending radially outward, with several cooling holes opened on the stepped end face. Air passes through the swirling channels of the inner and outer swirlers to form two-stage swirling air and generates a recirculation zone. The two-stage swirling air shears and atomizes the fuel supplied by the pre-combustion stage nozzle at the venturi tube outlet to form a stable combustion diffusion flame.

[0017] A further technical solution of the present invention is: the pre-combustion stage is installed on the inner ring wall of the main combustion stage through a plurality of circumferentially arranged connecting parts, so that the distance between the inner wall surface of the swirl channel of the main combustion stage and the venturi throat of the pre-combustion stage is 22-35mm, so as to realize that the two combustion zones are independent of each other.

[0018] A further technical solution of the present invention is: several through holes are opened on the head baffle and the inner and outer walls of the flame tube; the through holes on the head baffle serve as head cooling holes; the through holes on the inner and outer walls of the flame tube introduce air from the combustion chamber and outer annular cavity channels into the flame tube for recirculation combustion and adjustment of downstream outlet temperature distribution.

[0019] A further technical solution of the present invention is: the sudden expansion diffuser includes a pre-diffuser and a sudden expansion section; the pre-diffuser is used to decelerate and pressurize the incoming flow at the combustion chamber inlet, and the sudden expansion section divides the decelerated and pressurized incoming flow into a head intake flow, an outer annular cavity channel flow, and an inner annular cavity channel flow, so as to meet the intake requirements of the head and the outer wall and inner wall of the flame tube.

[0020] A method for achieving high-temperature combustion in a combustion chamber, comprising the following specific steps:

[0021] A sudden expansion section is installed at the combustion chamber inlet to decelerate, pressurize, and divert the incoming flow from the combustion chamber inlet;

[0022] The flame tube head is designed as a swirling-non-swirling combined air intake head structure, including a head baffle connected to the inner and outer walls of the flame tube, and a main combustion stage and a pre-combustion stage installed on the head baffle. The main combustion stage adopts a direct mixing combustion form, and through a combination of swirling and non-swirling airflow, the air introduced into the non-swirling structure reduces the swirl number of the air introduced into the swirling structure. The pre-combustion stage is coaxially installed in the central hole of the main combustion stage, and an annular cavity is formed between the outer wall of the pre-combustion stage and the inner wall of the main combustion stage. By controlling the radial dimension of the annular cavity, the combustion zones of the main combustion stage and the pre-combustion stage are relatively independent.

[0023] Cooling holes are made in the head baffle;

[0024] Jet holes are opened on the inner and outer walls of the flame tube to introduce air from the combustion chamber and outer annular cavity into the flame tube for recirculation combustion and adjustment of downstream outlet temperature distribution.

[0025] Beneficial effects

[0026] The beneficial effects of this invention are as follows:

[0027] (1) This invention adopts a concentric staged combustion organization design, with a large radial distance between the main and pre-combustion stages and a relatively low swirl number at the outermost stage outlet, making each combustion zone relatively independent and without spatial overlap. Simultaneously, jet orifices are provided on the flame tube, with the intake air used for recirculation combustion and downstream outlet temperature distribution adjustment. The flame tube is cooled using a highly efficient cooling method. This configuration is beneficial for improving the airflow structure and fuel distribution at the head of the combustion chamber, and ensures a good outlet temperature field in the combustion chamber under wide operating conditions, meeting the high-temperature combustion requirements of high thrust-to-weight ratio engines.

[0028] (2) The combustion chamber head of the present invention adopts a swirl-non-swirl combined intake head structure. The inner wall downstream of the swirl blades in the main combustion stage swirl channel is provided with a non-swirl intake hole. The non-swirl intake air and the swirl intake air are mixed in the channel, so that the main combustion stage outlet is a weak swirl air, which, together with the fuel supply from the main combustion stage nozzle, forms a direct mixed combustion. By adopting this swirl-non-swirl combined intake head structure, the radial dimension of the swirl generator can be controlled under the condition of high head intake volume in the high-temperature combustion chamber, so as to meet the spatial layout requirements of the combustion chamber head.

[0029] (3) In this invention, all main combustion stage nozzles are direct-injection nozzles, with their circumferential centers located on the central axis of the pre-combustion stage nozzles, forming a concentric arrangement. The main combustion stage nozzles are integrated with the swirler, eliminating the need for additional nozzles and reducing head mass. The pre-combustion stage employs swirling, stable diffusion combustion, while the main combustion stage does not use premixed combustion but rather direct mixing combustion to avoid problems such as backfire, spontaneous combustion, and oscillating combustion caused by distortion of the combustion chamber inlet flow field during military aircraft maneuvers.

[0030] (4) The high-temperature combustion chamber configuration of the present invention is simple, and all the components of the head can be disassembled, which is convenient for processing, assembly and replacement. At the same time, the main combustion stage, pre-combustion stage and head baffle can be adjusted according to actual needs to achieve different swirl number combinations and head flow distribution intake ratios. It has strong applicability in engineering tests. Attached Figure Description

[0031] Figure 1 Cross-sectional view and working schematic diagram of the concentric staged high-temperature combustion chamber;

[0032] Figure 2 Schematic diagram of a concentric staged high-temperature combustion chamber;

[0033] Figure 3 Schematic diagram of the combined swirl-non-swirl intake head structure;

[0034] Figure 4 Cross-sectional view of the main combustion stage structure of a concentric staged high-temperature combustion chamber;

[0035] Figure 5 Schematic diagram of the main combustion stage structure of a concentric staged high-temperature combustion chamber;

[0036] Figure 6 Cross-sectional view of the pre-combustion stage structure of a concentric staged high-temperature combustion chamber;

[0037] Figure 7 Schematic diagram of the pre-combustion stage structure of a concentric staged high-temperature combustion chamber;

[0038] Explanation of reference numerals in the attached diagram: 1-Combustion chamber inlet flow, 2-Head inlet flow, 3-Outer annular cavity channel flow, 4-Inner annular cavity channel flow, 5-Pre-diffuser, 6-Sudden diffuser section, 7-Head, 8-Sudden diffuser, 9-Combustion chamber casing, 10-Flame tube outer wall, 11-Flame tube inner wall, 12-Jet orifice, 13-Fuel supply rod, 14-Nozzle mounting seat, 15-Igniter, 16-Cap, 17-Main combustion stage, 18-Pre-combustion stage, 19-Head baffle, 20-Swirl generator mounting seat, 21-Head cooling hole, 22-Swirl generator mounting threaded hole 23-Main combustion stage swirl blade, 24-Non-swirl inlet, 25-Inlet section, 26-Converging section, 27-Outlet section, 28-Fuel collection groove, 29-Branch passage, 30-Main combustion stage nozzle, 31-Main combustion stage stepped end face, 32-Main combustion stage swirl passage, 33-Main combustion stage fuel passage, 34-Connecting groove, 35-Swirl generator assembly hole, 36-Pre-combustion stage nozzle, 37-Venturi tube, 38-First stage swirl blade, 39-Second stage swirl blade, 40-Pre-combustion stage swirl passage, 41-Stepped end face cooling hole, 42-Connecting boss. Detailed Implementation

[0039] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0040] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," 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 invention 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 invention.

[0041] Based on the fact that the existing combustion chamber technology cannot be used for high-temperature rise of engines with higher thrust-to-weight ratio, the intake volume of the high-temperature rise combustion chamber head is large. If the main combustion stage only uses swirl blades for intake, the radial dimension of the main combustion stage will be large under the condition that the effective intake area (area A*flow coefficient Cd) is fixed, resulting in a large overall size of the swirl, which in turn affects the spatial layout between adjacent heads of the combustion chamber and other problems. This invention provides a concentric staged high-temperature combustion chamber with a combined swirl-non-swirl intake head structure, including a combustion chamber casing and a diffuser located at its inlet, and a flame tube inside. The flame tube is an annular cavity structure, including a head, an outer wall, and an inner wall, wherein the head is connected to the fuel supply rod, and the outer wall is connected to the igniter. The flame tube head includes a head baffle connected to the inner and outer walls of the flame tube, and a main combustion stage and a pre-combustion stage installed on the head baffle. The main combustion stage adopts a direct mixing combustion form, and through a combination of swirl and non-swirl ventilation, the air introduced into the non-swirl structure reduces the swirl number of the air introduced into the swirl structure. The pre-combustion stage is coaxially installed in the central hole of the main combustion stage, and an annular cavity is formed between the outer annular wall of the pre-combustion stage and the inner annular wall of the main combustion stage. By controlling the radial dimension of the annular cavity, the combustion zones of the main combustion stage and the pre-combustion stage are relatively independent.

[0042] The swirl-non-swirl combined intake head structure of this invention enables controllable radial dimensions of the swirl in a high-temperature combustion chamber under high head intake conditions. A portion of the main combustion stage intake is diverted and introduced through non-swirl intake holes (the flow coefficient Cd of this method is relatively larger than that of the swirl blades, and the non-swirl intake holes are arranged radially), thereby reducing the radial dimensions of the main combustion stage. This satisfies the spatial layout requirements of the combustion chamber head and also helps the combustion chamber to have a good outlet temperature field under wide operating conditions, meeting the requirements of high-temperature combustion.

[0043] The above technical solution will be further explained below with reference to the accompanying drawings:

[0044] Reference Figure 1 and Figure 2 As shown, this embodiment describes a concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure. The combustion air is supplied by the main combustion stage intake, pre-combustion stage intake, head baffle cooling intake, and return air from the flame tube jet orifice.

[0045] Figure 1This is a cross-sectional view and working schematic diagram of the concentric staged high-temperature combustion chamber structure of the present invention. After the combustion chamber inlet flow 1 enters the combustion chamber, it is decelerated and diffused by the pre-diffuser 5 in the sudden diffuser 8. In the sudden diffusion section 6, the combustion chamber inlet flow is divided into the head inlet flow 2, the outer annular cavity channel flow 3, and the inner annular cavity channel flow 4 to meet the air intake requirements of the head 7 and the outer wall 10 and inner wall 11 of the flame tube. By rationally organizing the flow field in the combustion chamber, it is easy to organize combustion efficiently and stably.

[0046] Figure 2 This is a schematic diagram of a concentric staged high-temperature combustion chamber. The combustion chamber mainly consists of a diffuser 8, a combustion chamber casing 9, a fuel supply rod 13, an igniter 15, a head 7, an outer wall 10 of the flame tube, and an inner wall 11 of the flame tube. Both the outer wall 10 and the inner wall 11 of the flame tube are equipped with jet holes 12. Jet air enters the flame tube through the jet holes 12 for backflow combustion and downstream outlet temperature distribution adjustment. The jet holes 12 can be circular flat holes, horseshoe-shaped flat holes, inwardly flanged holes, or composite holes. Both the outer wall 10 and the inner wall 11 of the flame tube have cooling air inlets. The cooling method can be divergent cooling, film cooling, impact / divergent cooling, or impact / film cooling. The flame tube cooling air inlets are used to cool the wall surface. The amount of cooling air in the flame tube accounts for 20%-30% of the total inlet air in the combustion chamber. By rationally arranging the flame tube cooling holes, the flame tube wall temperature can be controlled, thereby extending the service life of the flame tube. The diffuser 8 and the combustion chamber casing 9 are integrated and made of stainless steel. The outer wall 10 and inner wall 11 of the flame tube are both made of nickel-based high-temperature alloy. The head 7 is connected to the outer wall 10 and inner wall 11 of the flame tube by bolts via a head baffle 19 and a cap 16. The fuel supply rod 13 is connected to the combustion chamber casing 9 by threads via a nozzle mounting seat 14. The igniter 15 is mounted on the combustion chamber casing 9 by threads or bolts. In a specific embodiment, the jet holes 12 on the outer wall 10 and inner wall 11 of the flame tube are circular straight holes, and the cooling method for the outer wall 10 and inner wall 11 of the flame tube is divergent cooling, with divergent cooling holes provided on the wall surface.

[0047] Figure 3 This is a schematic diagram of the combined swirl and non-swirl intake head structure. The head 7 consists of a main combustion stage 17, a pre-combustion stage 18, and a head baffle 19. The head baffle 19 includes a swirl generator mounting base 20 and head cooling holes 21. The head cooling holes 21 can be straight holes or oblique holes with a circumferential angle. The head baffle can be made of nickel-based high-temperature alloy or stainless steel.

[0048] Figure 4 This is a cross-sectional view of the main combustion stage structure of the concentric staged high-temperature combustion chamber. Figure 5 This is a schematic diagram of the main combustion stage structure of a concentric staged high-temperature combustion chamber. (For example...) Figure 4 and Figure 5 As shown, the main combustion stage 17 includes main combustion stage swirl vanes 23, non-swirl intake ports 24, main combustion stage swirl channels 32, main combustion stage fuel channels 33, main combustion stage nozzles 30, main combustion stage stepped end faces 31, connecting grooves 34, and swirl assembly holes 35. The non-swirl intake ports 24 are located on the inner sidewall downstream of the main combustion stage swirl vanes 23 in the main combustion stage swirl channel 32. Depending on the engine pressure ratio, non-swirl air accounts for 30% to 40% of the total intake air volume of the main combustion stage. The main combustion stage air flows in through the main combustion stage swirl vanes 23 and the non-swirl intake ports 24 respectively. The two intake air streams mix in the main combustion stage swirl channel 32, resulting in weakly swirling air at the outlet of the main combustion stage 17. The main combustion stage nozzles 30 are located on the main combustion stage step end face 31 and are evenly arranged circumferentially on the same circumference. The injection direction of each main combustion stage nozzle 30 is the same as the normal direction of the main combustion stage step end face 31, and the angle with the central axis of the three-stage cyclone separator is -20 to 30 degrees. The non-cyclone air inlet holes 24 are evenly arrayed circumferentially. The main combustion stage fuel passages 33 are located at the intervals of each array and are connected downstream to the main combustion stage nozzles 30. Fuel is injected into the combustion zone through the main combustion stage nozzles 30. After being sheared, broken, atomized, and mixed by the swirling air of the pre-combustion stage 18 and the main combustion stage 17, the fuel is burned in the main combustion stage 17 by direct mixing. The main combustion stage is made of nickel-based high-temperature alloy material and is manufactured by 3D printing technology and machining. The intake air volume of the high-temperature combustion chamber head is generally high. Considering the limited space layout of the head, the main combustion stage swirl blades 23 are single-stage swirls and can adopt axial swirl, radial swirl, or oblique swirl configurations. The main combustion stage swirl channel 32 includes an inlet section 25, a converging section 26, and an outlet section 27. Non-swirl inlet holes 24 are located within the inner wall of the converging section 26; their diameter and number are calculated based on the non-swirl intake volume. The outlet section 27 can have an outward expanding type, a single-sided converging type, or an inner and outer wall converging type. The inner wall of the main combustion stage swirl channel 32 contains a main combustion stage fuel passage 33, consisting of a fuel collection groove 28 and branch passages 29. All main combustion stage nozzles 30 are direct-injection nozzles; the number of main combustion stage nozzles 30 ranges from 4 to 20, selected based on the fuel flow rate of the combustion chamber under design conditions, the fuel stage ratio between the main combustion stage 17 and the pre-combustion stage 18, and the pressure drop of the main combustion stage nozzles 30. In this specific embodiment, the main combustion stage swirl blades 23 adopt an axial swirl configuration, the non-swirl inlet holes 24 are arranged in three rows of 24, the number of main combustion stage nozzles 30 is 8, and the angle between the injection direction and the central axis of the three-stage swirler is 15 degrees. The wall configuration of the outlet section 27 adopts an outward expansion type. In this embodiment, the inner diameter of the main combustion stage nozzles 30 is selected to be 0.4-1.0 mm.

[0049] Figure 6 This is a cross-sectional view of the pre-combustion stage structure of the concentric staged high-temperature combustion chamber. Figure 7 This is a schematic diagram of the pre-combustion stage structure of a concentric staged high-temperature combustion chamber. (See diagram below.) Figure 6 and Figure 7 As shown, the pre-combustion stage 18 includes a pre-combustion stage nozzle 36, a venturi tube 37, a first-stage swirl vane 38 and a second-stage swirl vane 39, a pre-combustion stage swirl channel 40, a stepped end face cooling hole 41, and a connecting boss 42. The pre-combustion stage nozzle 36 is located at the center of the pre-combustion stage 18 and is coaxial with the pre-combustion stage 18. The pre-combustion stage 18 utilizes the two-stage swirl air flowing into the pre-combustion stage swirl channel 40 to generate a recirculation zone, and shears and atomizes the fuel supplied by the pre-combustion stage nozzle 36 at the outlet of the venturi tube 37 to form a stable combustion diffusion flame. The pre-combustion stage is made of nickel-based high-temperature alloy material and is manufactured using 3D printing technology and machining. The first-stage swirl vane 38 and the second-stage swirl vane 39 adopt an axial swirl, or radial swirl, or oblique swirl configuration. The first-stage swirl blades 38 and the second-stage swirl blades 39 are arranged in the same swirl when the absolute value of the difference in swirl number Sn is 0 ≤ Sn < 0.25, and in opposite swirl when the absolute value of the difference in swirl number Sn is Sn ≥ 0.25. The stepped end-face cooling holes 41 are used to cool the stepped end-face between the main combustion stage 17 and the pre-combustion stage 18. The diameter and circumferential number of the stepped end-face cooling holes 41 are calculated based on the cooling gas volume at the stepped end-face. The pre-combustion stage nozzle 36 is a pressure atomizing centrifugal nozzle, and the center of the main combustion stage nozzle 30 in the circumferential direction is located on the central axis of the pre-combustion stage nozzle 36, forming a concentric arrangement. In a specific embodiment, the first-stage swirl blades 38 and the second-stage swirl blades 39 of the pre-combustion stage 18 both adopt an axial swirl configuration and are arranged in the same swirl, with the swirl direction opposite to that of the main combustion stage swirl blades 23.

[0050] like Figure 5 and Figure 7 As shown, the pre-combustion stage 18 is assembled with the main combustion stage 17 by inserting the connecting boss 42 into the corresponding connecting groove 34, and its axial position is fixed by bolts. The main combustion stage 17 is connected to the cyclone mounting base 20 and fixed by the four peripheral cyclone mounting threaded holes 22. The main combustion stage 17, the pre-combustion stage 18, and the head baffle 19 together form the head 7. The upstream of the main combustion stage nozzle 30 and the pre-combustion stage nozzle 36 are connected to the fuel supply rod 13 by welding, threads, or bolts.

[0051] The main combustion stage 17 employs a swirl-non-swirl combined intake configuration, combined with fuel supply from the main combustion stage nozzle 30, to form a direct mixing combustion mode. The pre-combustion stage 18 adopts a diffusion combustion mode. Air enters the combustion zone after being cooled by the head baffle 19. The jet air from the flame tube is supplied from the jet holes 12 on the outer wall 10 and inner wall 11 of the flame tube and partially flows back to the central recirculation zone to provide supplementary combustion for the high-temperature combustion zone. The amount of air participating in combustion in the combustion chamber is supplied by the intake air from the head 7 and the recirculation air from the jet holes 12, with the flow rate accounting for 50%-70% of the total air volume entering the combustion chamber. The intake air volume of the pre-combustion stage 18 and the main combustion stage 17 accounts for 10%-30% and 20%-50% of the total air volume entering the combustion chamber, respectively. The intake air volume from the head cooling hole 21 accounts for 2%-10% of the total air volume entering the combustion chamber, and the jet holes 12 account for 20%-40% of the total air volume entering the combustion chamber.

[0052] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A concentric staged high-temperature combustion chamber employing a swirl-non-swirl combined intake head structure, characterized in that: This includes the combustion chamber casing and the diffuser located at its inlet, and the flame tube inside it; The flame tube is an annular cavity structure, including a flame tube head, an outer wall, and an inner wall. The flame tube head is connected to the fuel supply rod, and the outer wall is connected to the igniter. The flame tube head includes a head baffle connected to the inner and outer walls, and a main combustion stage and a pre-combustion stage installed on the head baffle. The main combustion stage adopts a direct mixing combustion method, and reduces the swirl number of the air introduced into the swirl structure by using a combination of swirling and non-swirling airflow. The pre-combustion stage is coaxially installed in the central hole of the main combustion stage, and an annular cavity is formed between the outer wall of the pre-combustion stage and the inner wall of the main combustion stage. By controlling the radial dimension of the annular cavity, the combustion zones of the main combustion stage and the pre-combustion stage are relatively independent.

2. The concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure according to claim 1, characterized in that: The main combustion stage forms a swirl channel between its inner and outer ring walls by setting swirl blades. The inner ring wall of the main combustion stage is provided with a non-swirl air inlet, which introduces air into the swirl channel in a non-swirl manner to mix with the swirl air. The inner ring wall of the main combustion stage has a built-in main combustion stage fuel passage. Fuel flows axially through the main combustion stage fuel inlet, oil collection tank and branch passage in sequence in the main combustion stage fuel passage, and is sprayed out from the main combustion stage nozzle set at the branch passage outlet, and directly mixes and burns with the swirling and non-swirling mixed air.

3. The concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure according to claim 2, characterized in that: The non-swirl intake holes are straight holes arranged in a circumferential array on the inner ring wall downstream of the swirl blades of the main combustion stage. The non-swirl air introduced accounts for 30% to 40% of the total intake volume of the main combustion stage. The non-swirl intake holes and the fuel passage of the main combustion stage are staggered to avoid mutual interference.

4. The concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure according to claim 3, characterized in that: The oil collection trough is an annular cavity located upstream of the non-swirling air inlet. Its input end is connected to the fuel supply rod through the main combustion stage fuel inlet, and multiple branch channels are led downstream along the circumference. Downstream of the outlet of each branch channel corresponds to a main combustion stage nozzle. The fuel in the branch channel is led out through the main combustion stage nozzle to the same direction as the normal direction of the main combustion stage step end face. The main combustion stage nozzle is a direct-injection nozzle from the branch channel outlet to the end face of the main combustion stage step, with an inner diameter of 0.4-1.0 mm, used to inject fuel into the combustion zone.

5. The concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure according to claim 4, characterized in that: The angle between the fuel injection direction of the main combustion stage nozzle and the central axis of the main combustion stage is -20 to 30 degrees.

6. The concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure according to claim 5, characterized in that: The pre-combustion stage includes a pre-combustion stage nozzle, an inner swirler, and an outer swirler arranged coaxially from the inside to the outside. The inlet of the pre-combustion stage nozzle is connected to the fuel supply rod, and its outlet faces the end of the inner swirler. The end of the inner swirler is connected to a venturi tube, and the end of the outer swirler is an annular stepped end face extending radially outward, with several cooling holes opened on the stepped end face. Air passes through the swirling channels of the inner and outer swirlers to form two stages of swirling air and generate a recirculation zone. The two stages of swirling air shear and atomize the fuel supplied by the pre-combustion stage nozzle at the venturi tube outlet to form a stable combustion diffusion flame.

7. The concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure according to claim 6, characterized in that: The pre-combustion stage is installed on the inner ring wall of the main combustion stage through multiple circumferentially arranged connectors, so that the distance between the inner wall surface of the swirl channel of the main combustion stage and the venturi throat of the pre-combustion stage is 22-35mm, so as to realize that the two combustion zones are independent of each other.

8. The concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure according to claim 7, characterized in that: The head baffle and the inner and outer walls of the flame tube are provided with several through holes; the through holes on the head baffle serve as head cooling holes; the through holes on the inner and outer walls of the flame tube introduce air from the combustion chamber and outer annular cavity into the flame tube for recirculation combustion and adjustment of downstream outlet temperature distribution.

9. A concentric staged high-temperature combustion chamber with a swirl-non-swirl combined intake head structure according to claim 8, characterized in that: The aforementioned sudden diffusion diffuser includes a pre-diffuser and a sudden diffusion section; the pre-diffuser is used to decelerate and pressurize the incoming flow from the combustion chamber inlet, and the sudden diffusion section divides the decelerated and pressurized incoming flow into a head intake flow, an outer annular cavity channel flow, and an inner annular cavity channel flow to meet the intake requirements of the head and the outer and inner walls of the flame tube.

10. A method for achieving high-temperature combustion in the combustion chamber according to any one of claims 1-9, characterized in that: A sudden expansion section is installed at the combustion chamber inlet to decelerate, pressurize, and divert the incoming flow from the combustion chamber inlet; The flame tube head is designed as a swirling-non-swirling combined air intake head structure, including a head baffle connected to the inner and outer walls of the flame tube, and a main combustion stage and a pre-combustion stage installed on the head baffle. The main combustion stage adopts a direct mixing combustion form, and through a combination of swirling and non-swirling airflow, the air introduced into the non-swirling structure reduces the swirl number of the air introduced into the swirling structure. The pre-combustion stage is coaxially installed in the central hole of the main combustion stage, and an annular cavity is formed between the outer wall of the pre-combustion stage and the inner wall of the main combustion stage. By controlling the radial dimension of the annular cavity, the combustion zones of the main combustion stage and the pre-combustion stage are relatively independent. Cooling holes are made in the head baffle; Jet holes are opened on the inner and outer walls of the flame tube to introduce air from the combustion chamber and outer annular cavity into the flame tube for recirculation combustion and adjustment of downstream outlet temperature distribution.

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