S-shaped spray pipe with multi-area wall thickness distribution and application

Abstract

The invention discloses a multi-area wall thickness distributed S-shaped spray pipe and application, and belongs to the field of aero-engines. Regional division is conducted on different areas of the S-shaped spray pipe, local swelling of the lower wall face of the first bent section of the spray pipe can be effectively restrained by controlling the wall thickness of the first bent section area, and local expansion deformation of the upper wall face and the lower wall face of the middle of the second bent section of the spray pipe can be effectively restrained by controlling the wall thickness of the second bent section area. Deformation of the nozzle lip and upwarp deformation of the outlet straight section can be effectively inhibited by controlling the wall thickness of the outlet straight section area. According to the technical scheme, deformation of the spray pipe is restrained through the multi-area wall thickness size design of the S-shaped spray pipe, and compared with a traditional uniform-wall-thickness S-shaped spray pipe structure in engineering, the utilization efficiency is higher, and collaborative optimization is conducted aiming at structural area layout size parameters and wall thickness size parameters; the structural strength and the same structural rigidity level can be guaranteed, and meanwhile the obvious structural weight advantage is achieved.

Description

Technical Field

[0001] This invention belongs to the field of aero-engines, specifically relating to an S-shaped nozzle with multi-regional wall thickness distribution and its application. Background Technology

[0002] The S-curve nozzle, a core component for achieving stealth in low-observable aircraft, functions primarily to physically shield the high-temperature turbine components of the engine through a complex S-shaped flow channel, significantly reducing infrared signatures from the exhaust system while maintaining aerodynamic performance. However, in actual operation, under the coupling of multiple physics fields, severe structural deformation problems arise due to the coupling of high-temperature gradients, unsteady pressure pulsations, and the thermal expansion effects of non-uniform materials. Such deformation can lead to aerodynamic shape deviations and even nozzle structural failure. Therefore, reasonable methods are needed to suppress the structural deformation of the S-curve nozzle. Specifically: Local bulges and warping: such as local bulges on the lower wall of the first bend, local bulges in the middle of the second bend, and twisting of the exit lip.

[0003] Overall upward deformation: The entire rear half of the nozzle (especially the rear part of the second bend and the straight section such as the exit) is lifted.

[0004] These deformations not only directly cause the aerodynamic profile to shift, resulting in thrust loss, flow field distortion and other aerodynamic performance deterioration, but in severe cases, stress concentration can lead to structural fatigue or failure, directly threatening flight safety.

[0005] Currently, structural reinforcement in engineering often involves uniformly increasing the nozzle wall thickness. While this significantly improves the load-bearing capacity and deformation resistance of the target structure, it also leads to problems such as excessive structural weight and material redundancy. In the design of S-bend nozzles, there is still a lack of optimization design work targeting the structural thickness dimensions of different regions, and research and application of multi-region wall thickness nozzle models in the structural design of S-bend nozzles are limited.

[0006] In the design of S-bend nozzles, it is necessary to fully utilize the nozzle wall structure in different regions and to coordinately optimize the structural area layout dimensions and wall thickness parameters. Compared with traditional S-bend nozzles with uniform wall thickness, the S-bend nozzle of this invention, designed with optimized wall thickness in multiple regions, has higher structural utilization efficiency. Summary of the Invention

[0007] The technical problem to be solved: To overcome the shortcomings of existing technologies, this invention provides an S-bend nozzle with multi-regional wall thickness distribution and its application. This method, based on deformation mechanisms, achieves an optimal balance between stiffness / strength and weight of the S-bend nozzle through coordinated global optimization of regional layout and wall thickness dimensions. This invention ensures that the S-bend nozzle meets structural stiffness and strength requirements under complex multiphysics loads while achieving optimal material distribution, thus achieving the ultimate goal of lightweight design.

[0008] The technical solution of this invention is: a design method for an S-bend nozzle with multi-region wall thickness distribution, comprising the following steps: Step 1, Deformation Mode Analysis and Region Division: Analyze the deformation mode of the S-bend nozzle under multi-physics coupled load. Based on the severity of deformation and the difference in modes, divide the nozzle along the flow direction into multiple design regions, including at least the first bend section, the second bend section, and the straight section at the nozzle exit. The interface between each region is perpendicular to the symmetrical cross section of the nozzle. Step 2, Design Parameter Definition: Define the axial layout dimensions of the upper wall surface at the axial position of each region's interface on the upper and lower walls of the nozzle. L ui Axial layout dimensions of the lower wall L di At the same time, define the wall thickness parameters corresponding to each region. D i The L ui The axial distance from the intersection of the plane extending from the interface and the upper wall of the straight section at the nozzle exit to the nozzle inlet end is [missing information]. L di It is the axial distance from the point where the interface and the plane extending from the lower wall of the nozzle inlet end intersect to the nozzle inlet end. Step 3: Establish a collaborative optimization model: using the layout size parameters defined in Step 2. L ui , L di and wall thickness dimensional parameters D i As a design variable, minimizing the total mass of the S-bend nozzle structure is the optimization objective, and the maximum deformation of the nozzle is not allowed to exceed a set threshold. d 0 and the maximum equivalent stress does not exceed the allowable stress of the material. σ A multi-parameter collaborative optimization mathematical model is established with 0 as the constraint condition. Step 4, Model Solving and Parameter Optimization: Solve the optimization model established in Step 3 to obtain the optimal combination of design parameters that minimizes the total structural mass while satisfying the constraints, including the optimal layout dimensions for each region. , and wall thickness dimensions ; Step 5, Structure Generation: Based on the optimal design parameters obtained in Step 4, generate a three-dimensional structural model of an S-bend nozzle with multi-region variable thickness distribution; the wall of each region starts from the nozzle flow channel surface and is generated along its outer normal direction, with corresponding thicknesses. .

[0009] A further technical solution of the present invention is: in step 1, the first bend of the nozzle is divided into two sub-regions, the second bend of the nozzle is divided into three sub-regions, and the straight section of the nozzle outlet is an independent region. A further technical solution of the present invention is: in step 2, the defined layout dimension parameters include at least the axial layout dimension parameters of the upper wall surface of a bend in the nozzle. Axial layout dimensions of the lower wall ; Axial layout dimensions of the upper wall surface of the interface at the front end of the second bend of the nozzle Axial layout dimensions of the lower wall And the axial layout dimensions of the upper wall of the backend interface. Axial layout dimensions of the lower wall .

[0010] A further technical solution of the present invention is: in step 3, the objective function and constraints are:

[0011] In the formula, The total weight of the S-curve nozzle structure is used as the objective function for parameter optimization. These are the axial layout dimensions of the lower wall of the S-curve nozzle. These are the axial layout dimensions of the upper wall of the S-curve nozzle. d max This represents the maximum deformation of the nozzle. σ max This represents the maximum equivalent stress of the nozzle.

[0012] A further technical solution of the present invention is: in step 4, a surrogate model optimization method is used for solving, specifically including: Step 4.1: Generate sample points within the design variable space using experimental design methods; Step 4.2: Obtain the objective function value and constraint condition value corresponding to each sample point through finite element calculation; Step 4.3: Based on the sample data, construct a proxy model of the objective function and constraints with respect to the design variables; Step 4.4: Based on the aforementioned proxy model, an optimization algorithm is used to find the optimal solution. A further technical solution of the present invention is: after optimization in step 4, the preferred parameter range obtained satisfies: The axial layout dimensions of the upper wall surface of the bend section of the nozzle Total length of nozzle L 30% to 32%, axial layout dimensions of the lower wall surface for L 12% to 14%; The axial layout dimensions of the upper wall surface at the front end interface of the second bend section of the nozzle. for L 20% to 22%, lower wall axial layout dimensions for L 66%–68%; Axial layout dimensions of the wall surface at the rear interface for L 52% to 54%, axial layout dimensions of the lower wall surface for L 96% to 98%.

[0013] A further technical solution of the present invention is: after optimization in step 4, the preferred range of the obtained wall thickness dimension parameters satisfies: The wall thickness of the two sub-regions in the bend of the nozzle D 1. D Both are 0.95–1.05 mm; The wall thickness of the three sub-regions in the second bend of the nozzle D 3. D 4. D The thicknesses of 5 are 1.15–1.25 mm, 1.55–1.65 mm, and 1.45–1.55 mm, respectively. wall thickness in the straight section area such as the nozzle exit D 6 is 1.65~1.75mm.

[0014] A further technical solution of the present invention is: in the structural model generated in step 5, a rounded corner transition structure is provided at the junction of adjacent areas with different wall thicknesses to suppress stress concentration.

[0015] An S-bend nozzle with multi-region wall thickness distribution is designed and manufactured by the S-bend nozzle design method with multi-region wall thickness distribution, and its wall thickness distribution corresponds to the optimal design parameter combination obtained by the optimization method.

[0016] The application of an S-shaped nozzle with multi-regional wall thickness distribution in an aero-engine exhaust system involves connecting the inlet end of the S-shaped nozzle to the turbine outlet of the aero-engine. This serves to shield high-temperature engine components for infrared stealth while simultaneously utilizing its wall thickness distribution to suppress structural deformation. The wall structure of the S-bend nozzle is divided along the axial direction into at least a first-bend section region, a second-bend section region, and a straight section region such as the nozzle outlet, all with different wall thicknesses. The nozzle first bend region and / or nozzle second bend region are further divided along the axial direction into at least two sub-regions with different wall thicknesses. The interfaces of each region are perpendicular to the symmetrical cross-section of the nozzle. The wall thickness distribution of each region is synergistically optimized so that, under the aerodynamic and thermal loads generated by the engine operation, the wall thickness distribution of the first bend section of the nozzle effectively suppresses the local bulging deformation of the lower wall surface of the first bend section, the wall thickness distribution of the second bend section of the nozzle effectively suppresses the local expansion deformation of the upper and lower walls in the middle of the second bend section, and the wall thickness of the straight section of the nozzle exit effectively suppresses the lip deformation and overall upward warping deformation. Thus, while meeting the requirements of structural stiffness and strength, the nozzle structure is made lightweight.

[0017] Beneficial effects The beneficial effects of this invention are as follows: By applying the technical solution of this invention to the S-curve nozzle, and through appropriate regional division of the nozzle structure and reasonable design of regional thickness, the structural utilization efficiency of the nozzle can be effectively improved. The technical challenge of this invention lies in the need for targeted regional layout and thickness dimension optimization design based on the specific deformation characteristics of the S-curve nozzle to achieve a reasonable allocation of wall thickness resources. Considering the complex deformation mode of the S-curve nozzle itself, a uniform wall thickness nozzle model would lead to a large amount of redundant nozzle wall material and low structural utilization efficiency. Therefore, it is necessary to adjust the regional positions according to its specific deformation characteristics and optimize the wall thickness dimensions of multiple regions to meet the overall and local stiffness and strength requirements, resulting in a significant structural weight advantage. The application of the technical solution of this invention can fully utilize the structural potential, reduce the overall structural mass to meet the requirements of lightweight structure, and improve the maneuverability of aircraft.

[0018] When the uniform wall thickness nozzle model is 1.5 mm, the deformation distribution of the uniform wall thickness S-bend nozzle and the S-bend nozzle with multi-region wall thickness distribution were calculated using the finite element method. The deformation distribution cloud diagrams of the two nozzle structures are shown below. Figure 7 As shown in the figure. The analysis and calculation results show that, through the optimized design of the wall thickness dimensions of the multi-region nozzle, the maximum deformation of the S-bend nozzle with multi-region wall thickness distribution is basically maintained at the original level compared with the uniform wall thickness S-bend nozzle, and the weight of the nozzle is effectively reduced. This proves the effectiveness of the multi-region wall thickness distribution structure designed in this invention.

[0019] When using a traditional uniform wall thickness S-bend nozzle structure, with a wall thickness of 1.5mm in each region and a fixed support constraint at the nozzle inlet, the maximum deformation of the nozzle structure is 0.23mm, and the weight of the uniform wall thickness S-bend nozzle structure is 1.53kg. It can be seen that in the technical solution of this invention, the S-bend nozzle structure with optimized wall thickness in multiple regions maintains the maximum deformation at approximately the same level, while its structural weight is 89.54% of that of the traditional uniform wall thickness structure. This means that the technical solution of this invention can maintain the original level of structural deformation of the S-bend nozzle while having a significant advantage in terms of structural weight. Comparison of the technical solution of this invention with traditional web-type structures Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an S-bend nozzle with multi-regional wall thickness distribution, which is an optional embodiment of the present invention. Figures 2-4 This is a front view of an S-bend nozzle with multi-region wall thickness distribution, which is an optional embodiment of the present invention. Figure 5 This is a top view of an S-bend nozzle with multi-region wall thickness distribution, which is an optional embodiment of the present invention. Figure 6 These are deformation distribution cloud maps of the multi-region wall thickness distribution S-bend nozzle in this embodiment of the invention and the traditional uniform wall thickness S-bend nozzle. Figure 7 This is a deformation distribution cloud map of the S-bend nozzle in an embodiment of the present invention; Figure 8 This is a stress distribution cloud diagram of the S-bend nozzle in an embodiment of the present invention; Explanation of the attached diagram labels: 1-2, nozzle first bend section area; 3-5, nozzle second bend section area; 6, nozzle exit and other straight section areas. Detailed Implementation 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.

[0021] 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.

[0022] Regarding the deformation problem of S-bend nozzles, existing engineering techniques have the following limitations: Uniform thicknessing is inefficient: the most traditional and direct method is to increase the overall nozzle wall thickness to improve stiffness. While this method is simple and reliable and can suppress deformation to some extent, it comes at the cost of introducing a large amount of ineffective structural mass. Because the deformation modes and stress states differ significantly across regions of an S-shaped nozzle, uniform wall thickness implies severe material redundancy in low-stress / small-deformation regions, resulting in extremely low structural utilization efficiency, which contradicts the aerospace industry's extreme demand for lightweight construction.

[0023] External reinforcement structures introduce new problems: To avoid uniform thickening, some solutions employ welding or assembly of external stiffeners, webs, etc. (e.g., CN116591860A). While these methods can specifically enhance local stiffness, they introduce new drawbacks: significantly increasing overall weight and structural complexity; introducing additional connection interfaces (such as welds and fasteners), which become potential sources of fatigue and thermal resistance; and worsening the internal flow field and heat dissipation, potentially interfering with cooling airflow and forming new heat points.

[0024] A lack of systematic variable thickness design methods based on deformation mechanisms exists: Currently, optimization designs for S-bend nozzles primarily focus on aerodynamic shape (e.g., CN114776461B) or stealth characteristics, while insufficient attention is paid to the coordinated design of lightweighting and stiffness of the structure itself. Although the concept of "using different thicknesses in different parts" is well-known, an efficient, reliable, and engineeringable design system has not yet been established for scientifically dividing the optimization area based on the unique and complex multiphysics coupling deformation mode of S-bend nozzles, and for collaboratively determining the optimal matching relationship between the area layout and wall thickness dimensions. Existing technologies often rely on trial and error or local adjustments, making it difficult to find the globally optimal solution in the core contradiction between "stiffness / strength" and "weight."

[0025] Based on the above problems, this invention proposes a design method for an S-bend nozzle with multi-regional wall thickness distribution, comprising the following steps: Step 1, Deformation Mode Analysis and Region Division: Analyze the deformation mode of the S-bend nozzle under multi-physics coupled load. Based on the severity of deformation and the difference in modes, divide the nozzle along the flow direction into multiple design regions, including at least the first bend section, the second bend section, and the straight section at the nozzle exit. The interface between each region is perpendicular to the symmetrical cross section of the nozzle. Step 2, Design Parameter Definition: Define the axial layout dimensions of the upper wall surface at the axial position of each region's interface on the upper and lower walls of the nozzle. L ui Axial layout dimensions of the lower wall L di At the same time, define the wall thickness parameters corresponding to each region. Di The L ui The axial distance from the intersection of the plane extending from the interface and the upper wall of the straight section at the nozzle exit to the nozzle inlet end is [missing information]. L di It is the axial distance from the point where the interface and the plane extending from the lower wall of the nozzle inlet end intersect to the nozzle inlet end. Step 3: Establish a collaborative optimization model: using the layout size parameters defined in Step 2. L ui , L di and wall thickness dimensional parameters D i As a design variable, minimizing the total mass of the S-bend nozzle structure is the optimization objective, and the maximum deformation of the nozzle is not allowed to exceed a set threshold. d 0 and the maximum equivalent stress does not exceed the allowable stress of the material. σ A multi-parameter collaborative optimization mathematical model is established with 0 as the constraint condition. Step 4, Model Solving and Parameter Optimization: Solve the optimization model established in Step 3 to obtain the optimal combination of design parameters that minimizes the total structural mass while satisfying the constraints, including the optimal layout dimensions for each region. , and wall thickness dimensions ; Step 5, Structure Generation: Based on the optimal design parameters obtained in Step 4, generate a three-dimensional structural model of an S-bend nozzle with multi-region variable thickness distribution; the wall of each region starts from the nozzle flow channel surface and is generated along its outer normal direction, with corresponding thicknesses. .

[0026] Specifically, in step 4, a surrogate model optimization method is used to solve the problem, which includes: Step 4.1: Generate sample points within the design variable space using experimental design methods; Step 4.2: Obtain the objective function value and constraint condition value corresponding to each sample point through finite element calculation; Step 4.3: Based on the sample data, construct a proxy model of the objective function and constraints with respect to the design variables; Step 4.4: Based on the aforementioned proxy model, an optimization algorithm is used to find the optimal solution. The present invention also proposes an S-bend nozzle with multi-region wall thickness distribution, which is designed and manufactured by the S-bend nozzle design method with multi-region wall thickness distribution, and its wall thickness distribution corresponds to the optimal design parameter combination obtained by the optimization method.

[0027] This invention also proposes the application of an S-shaped nozzle with multi-regional wall thickness distribution in the exhaust system of an aero-engine. The inlet end of this S-shaped nozzle is connected to the turbine outlet of the aero-engine to shield high-temperature components for infrared stealth, while simultaneously utilizing its wall thickness distribution to suppress structural deformation. The wall structure of the S-bend nozzle is divided along the axial direction into at least a first-bend section region, a second-bend section region, and a straight section region such as the nozzle outlet, all with different wall thicknesses. The nozzle first bend region and / or nozzle second bend region are further divided along the axial direction into at least two sub-regions with different wall thicknesses. The interfaces of each region are perpendicular to the symmetrical cross-section of the nozzle. The wall thickness distribution of each region is synergistically optimized so that, under the aerodynamic and thermal loads generated by the engine operation, the wall thickness distribution of the first bend section of the nozzle effectively suppresses the local bulging deformation of the lower wall surface of the first bend section, the wall thickness distribution of the second bend section of the nozzle effectively suppresses the local expansion deformation of the upper and lower walls in the middle of the second bend section, and the wall thickness of the straight section of the nozzle exit effectively suppresses the lip deformation and overall upward warping deformation. Thus, while meeting the requirements of structural stiffness and strength, the nozzle structure is made lightweight.

[0028] The above technical solution will be further analyzed below with reference to the accompanying drawings and examples: In one embodiment, refer to Figure 1 As shown, an S-bend nozzle structure with multi-region wall thickness distribution includes a two-region first bend section, a three-region second bend section, and a straight exit section. Analysis of the S-bend nozzle's deformation modes reveals that the main deformations are: overall upward warping deformation of the rear of the second bend section and the straight exit section; local bulging of the lower wall of the first bend section, the upper / lower walls of the middle of the second bend section, and local warping deformation of the upper wall of the straight exit section. Therefore, controlling the wall thickness of the first bend section effectively suppresses local bulging of the lower wall of the first bend section; controlling the wall thickness of the second bend section effectively suppresses local expansion deformation of the upper and lower walls of the middle of the second bend section; and controlling the wall thickness of the straight exit section effectively suppresses nozzle lip deformation and upward warping deformation in the straight exit section. Further optimization of the multi-region layout dimensions and wall thickness parameters further unlocks the nozzle structure's potential, achieving weight reduction while meeting the nozzle structure's stiffness and strength requirements.

[0029] The region located in the first bend of the nozzle consists of two parts, the second bend consists of three parts, and the straight section at the outlet consists of one part. Each region starts from the nozzle flow channel surface and generates a nozzle wall along the outer normal direction. The interface of each region is perpendicular to the symmetrical section of the nozzle. The axial length of the intersection line between the interface and the plane of the upper wall of the straight section at the nozzle outlet from the nozzle inlet end is taken as the axial layout dimension parameter of the upper wall. The axial length of the intersection line between the interface and the plane of the lower wall at the nozzle inlet end from the nozzle inlet end is taken as the axial layout dimension parameter of the lower wall.

[0030] In one embodiment, refer to Figure 5 As shown, 12 parameters, including the layout dimensions and wall thickness of each region of the S-bend nozzle structure, are selected as optimization design parameters. The stiffness and strength requirements of the nozzle structure are used as optimization boundary constraints, and the minimization of the total structural mass is used as the optimization objective for multi-parameter optimization. The multi-region wall thickness distribution S-bend nozzle structure dimension optimization model is as follows:

[0031] In the formula, The total weight of the S-curve nozzle structure is used as the objective function for parameter optimization. These are the axial layout dimensions of the lower wall of the S-curve nozzle. These are the axial layout dimensions of the upper wall of the S-curve nozzle. , The optimization range is defined as a 30mm section centered at the midpoint of the nozzle's first bend centerline, specifically 8.55–68.55mm and 65.43–125.43mm. , The optimized range is defined as a 30mm section centered on the cross-section at one-third of the distance from the nozzle exit end to the nozzle inlet end along the friction path of the second bend of the nozzle. The optimized ranges are 199.34–259.34mm and 68.56–128.56mm respectively. , The optimization range is defined as a 30mm section centered on the cross-section along the nozzle's second bend, at approximately 2 / 3 of the distance from the nozzle's centerline. The optimized ranges are 243.51–303.51mm and 178.12–238.12mm, respectively. The wall thickness parameters for the design area corresponding to the S-curve nozzle are optimized within a range of 1–2 mm. , These represent the maximum deformation and maximum stress of the S-curve nozzle, respectively. The maximum deformation limit for the S-curve nozzle is designed as follows: here, the maximum deformation of the S-curve nozzle with a uniform wall thickness of 1.5mm is taken as 0.23mm. The maximum design stress for the S-curve nozzle is set to 100 MPa.

[0032] In one embodiment, the Latin hypercube sampling method (LHS) is used to generate sample points within the optimization range of each design parameter for calculation, establishing a sample space containing 600 sample points. A low-precision surrogate model is obtained by fitting a first- or second-order polynomial to the optimization objective, constraints, and the intrinsic relationships between design variables. To further improve the fitting accuracy of the surrogate model, the range of design parameter values ​​is adjusted along the convergence direction of each optimization variable based on the preliminary optimization results of the low-precision surrogate model, thus controlling the design variables. , The value is 1mm, and design variables are discarded. , Using the same method, a sample space containing 300 sample points was established to obtain a higher-precision surrogate model and the optimization objective. The correlation coefficient of the regression equations relating to the design parameters Constraints The correlation coefficient of the regression equations relating to the design parameters Constraints The correlation coefficient of the regression equations relating to the design parameters As can be seen, the correlation coefficients of the three regression equations are all above 0.85, indicating that the established surrogate model has high fitting accuracy and can be used for multi-region structural dimensional parameter optimization of S-curve nozzles. The optimization objective... and constraints , The fitting formula is as follows:

[0033]

[0034] In one embodiment, the axial layout dimensions of the upper wall of the bend of the nozzle are... Approximately 30% to 32% of the total nozzle length; the axial layout dimensions of the lower wall of the bend section of the nozzle. It is approximately 12% to 14% of the total length of the nozzle, to avoid excessive material redundancy due to improper area allocation, which would lead to a decrease in structural utilization efficiency.

[0035] In one embodiment, the axial layout dimensions of the upper wall surface of the front end (viewed from the nozzle exit end to the nozzle inlet end) and rear end region of the nozzle's two-bend section are as follows: , These represent 20%–22% and 52%–54% of the total nozzle length, respectively; the axial layout dimensions of the lower wall surface of the front and rear sections of the nozzle's two-bend segment are, respectively. , The proportions are 66%–68% and 96%–98% of the total nozzle length, respectively, to avoid poor local deformation suppression due to improper area allocation.

[0036] In one embodiment, the wall thickness of the two regions of the bend in the nozzle is, i.e. , ,suggestion The value range is 0.95 to 1.05 mm. The value range is 0.95 to 1.05 mm.

[0037] In one embodiment, the wall thickness of the three regions of the second bend of the nozzle, i.e. , , ,suggestion The value range is 1.15~1.25mm. The value range is 1.55~1.65mm. The value range is 1.45–1.55 mm. The wall thickness of the straight section region, such as the nozzle exit, is... The recommended value is 1.65–1.75 mm. This difference in wall thickness is the result of optimized design, avoiding excessive thickness leading to structural weight exceeding limits or insufficient thickness causing processing difficulties and localized stiffness.

[0038] Because the second bend section of the nozzle and the straight section at the exit overlap significantly with the easily deformable areas of the structure, changes in wall thickness in these areas have a significant impact on local structural deformation. This is mainly manifested in the local expansion deformation areas on the upper and lower walls in the middle of the second bend section and the lip deformation area in the straight section at the exit. Therefore, a coordinated optimization design of the structural area layout and wall thickness parameters is implemented to suppress local deformation. Optimization results show that a reasonable allocation of local wall thickness is beneficial for controlling the stiffness of the easily deformable areas of the S-bend nozzle, reducing material input in areas with small deformations, and ensuring structural strength and stiffness while reducing nozzle weight.

[0039] In one embodiment, local stress concentration caused by structural wall thickness differences in the S-bend nozzle can be further suppressed by machining fillets at the junctions of wall thicknesses in each region. It is recommended that structural fillets be applied at the junctions of the upper and lower walls in the second bend of the nozzle to control local structural stress.

[0040] In one embodiment, refer to Figure 1-3 As shown, this is an S-bend nozzle structure with multi-region wall thickness distribution, including nozzle bend sections 1-2, nozzle second bend sections 3-5, and straight sections such as the nozzle exit 6. The above nozzle regions together constitute the wall structure of the S-bend nozzle. By optimizing the design of the wall thickness distribution of each region, the overall stiffness and local stiffness of the S-bend nozzle structure are improved while the structure is reduced in weight.

[0041] Furthermore, in this embodiment, the nozzle inlet diameter is 120mm, the total nozzle length is 312mm, the total length of the first bend section is 109.6mm, the total length of the second bend section is 165.2mm, and the length of the straight section at the outlet is 37.2mm.

[0042] Specifically, in this embodiment, each region of the S-bend nozzle starts at the nozzle flow channel surface and generates a nozzle wall along the outer normal direction, with the interface of each region perpendicular to the symmetrical cross-section of the nozzle. The axial layout dimension parameters of the upper wall of the first bend of the S-bend nozzle are 30%–32% of the total nozzle length; in this embodiment, 30.6% is used, i.e., 95.4 mm. The axial layout dimension parameters of the lower wall are 12%–14% of the total nozzle length; in this embodiment, 12.4% is used, i.e., 38.6 mm.

[0043] Specifically, in this embodiment, the wall thickness of the front end region of the first bend of the S-bend nozzle (viewed from the nozzle outlet end to the nozzle inlet end) is 0.95 to 1.05 mm, and is taken as 1 mm in this embodiment; the wall thickness of the rear end region of the first bend is 0.95 to 1.05 mm, and is taken as 1 mm in this embodiment.

[0044] Specifically, in this embodiment, the axial layout dimension parameters of the upper wall surface at the interface of the front end of the second bend section of the S-bend nozzle (viewed from the nozzle outlet end to the nozzle inlet end) are 20% to 22% of the total nozzle length, and in this embodiment, 22.0% is taken, i.e., 68.6 mm; the axial layout dimension parameters of the lower wall surface are 66% to 68% of the total nozzle length, and in this embodiment, 66.4% is taken, i.e., 207.2 mm. The axial layout dimension parameters of the upper wall surface at the rear end of the second bend section are 52% to 54% of the total nozzle length, and in this embodiment, 52.1% is taken, i.e., 162.7 mm; the axial layout dimension parameters of the lower wall surface are 96% to 98% of the total nozzle length, and in this embodiment, 96.5% is taken, i.e., 301.0 mm. Specifically, in this embodiment, the wall thickness of the front end region of the second bend section of the S-bend nozzle (viewed from the nozzle outlet end to the nozzle inlet end) is 1.15 to 1.25 mm, and is 1.24 mm in this embodiment; the wall thickness of the middle region of the second bend section is 1.55 to 1.65 mm, and is 1.65 mm in this embodiment; the wall thickness of the rear end region of the second bend section is 1.45 to 1.55 mm, and is 1.47 mm in this embodiment.

[0045] Specifically, in this embodiment, the wall thickness of the straight section area such as the S-bend nozzle outlet is 1.65 to 1.75 mm, and in this embodiment, it is 1.73 mm.

[0046] In this embodiment, the total weight of the nozzle structure is 1.37 kg. The deformation and stress distribution cloud diagram obtained through finite element simulation is shown below. Figure 8As shown in the figure. The analysis and calculation results show that by optimizing the wall thickness dimensions of the multi-region layout, the maximum deformation of the nozzle can be maintained at the original level. While meeting the structural strength requirements, the total weight of the structure is significantly reduced, proving the effectiveness of the multi-region wall thickness distribution structure designed in this invention.

[0047] 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 design method for an S-bend nozzle with multi-regional wall thickness distribution, characterized in that, Includes the following steps: Step 1, Deformation Mode Analysis and Region Division: Analyze the deformation mode of the S-bend nozzle under multi-physics coupled load. Based on the severity of deformation and the difference in modes, divide the nozzle along the flow direction into multiple design regions, including at least the first bend section, the second bend section, and the straight section at the nozzle exit. The interface between each region is perpendicular to the symmetrical cross section of the nozzle. Step 2, Design Parameter Definition: Define the axial layout dimensions of the upper wall surface at the axial position of each region's interface on the upper and lower walls of the nozzle. L ui Axial layout dimensions of the lower wall L di At the same time, define the wall thickness parameters corresponding to each region. D i The L ui The axial distance from the intersection of the plane extending from the interface and the upper wall of the straight section at the nozzle exit to the nozzle inlet end is [missing information]. L di It is the axial distance from the point where the interface and the plane extending from the lower wall of the nozzle inlet end intersect to the nozzle inlet end. Step 3: Establish a collaborative optimization model: using the layout size parameters defined in Step 2. L ui , L di and wall thickness dimensional parameters D i As a design variable, minimizing the total mass of the S-bend nozzle structure is the optimization objective, and the maximum deformation of the nozzle is not allowed to exceed a set threshold. d 0 and the maximum equivalent stress does not exceed the allowable stress of the material. σ A multi-parameter collaborative optimization mathematical model is established with 0 as the constraint condition. Step 4, Model Solving and Parameter Optimization: Solve the optimization model established in Step 3 to obtain the optimal combination of design parameters that minimizes the total structural mass while satisfying the constraints, including the optimal layout dimensions for each region. , and wall thickness dimensions ; Step 5, Structure Generation: Based on the optimal design parameters obtained in Step 4, generate a three-dimensional structural model of an S-bend nozzle with multi-region variable thickness distribution; the wall of each region starts from the nozzle flow channel surface and is generated along its outer normal direction, with corresponding thicknesses. .

2. The design method for an S-bend nozzle with multi-region wall thickness distribution according to claim 1, characterized in that: In step 1, the first bend of the nozzle is divided into two sub-regions, the second bend of the nozzle is divided into three sub-regions, and the straight section of the nozzle exit is an independent region.

3. The design method for an S-bend nozzle with multi-region wall thickness distribution according to claim 2, characterized in that: In step 2, the defined layout dimension parameters include at least the axial layout dimension parameters of the upper wall of the nozzle bend. Axial layout dimensions of the lower wall ; Axial layout dimensions of the upper wall surface of the interface at the front end of the second bend of the nozzle Axial layout dimensions of the lower wall And the axial layout dimensions of the upper wall of the backend interface. Axial layout dimensions of the lower wall .

4. The S-bend nozzle design method with multi-region wall thickness distribution according to claim 3, characterized in that: In step 3, the objective function and constraints are as follows: In the formula, The total weight of the S-curve nozzle structure is used as the objective function for parameter optimization. These are the axial layout dimensions of the lower wall of the S-curve nozzle. These are the axial layout dimensions of the upper wall of the S-curve nozzle. d max This represents the maximum deformation of the nozzle. σ max This represents the maximum equivalent stress of the nozzle.

5. The S-bend nozzle design method with multi-region wall thickness distribution according to claim 4, characterized in that: In step 4, a surrogate model optimization method is used to solve the problem, specifically including: Step 4.1: Generate sample points within the design variable space using experimental design methods; Step 4.2: Obtain the objective function value and constraint condition value corresponding to each sample point through finite element calculation; Step 4.3: Based on the sample data, construct a proxy model of the objective function and constraints with respect to the design variables; Step 4.4: Based on the aforementioned proxy model, an optimization algorithm is used to find the optimal solution.

6. The S-bend nozzle design method with multi-region wall thickness distribution according to claim 5, characterized in that: After optimization in step 4, the obtained preferred parameter range satisfies: The axial layout dimensions of the upper wall surface of the bend section of the nozzle Total length of nozzle L 30% to 32%, axial layout dimensions of the lower wall surface for L 12% to 14%; The axial layout dimensions of the upper wall surface at the front end interface of the second bend section of the nozzle. for L 20% to 22%, lower wall axial layout dimensions for L 66%–68%; Axial layout dimensions of the wall surface at the rear interface for L 52% to 54%, axial layout dimensions of the lower wall surface for L 96% to 98%.

7. The design method for an S-bend nozzle with multi-region wall thickness distribution according to claim 6, characterized in that: After optimization in step 4, the preferred range of the obtained wall thickness dimension parameters satisfies: The wall thickness of the two sub-regions in the bend of the nozzle D 1. D Both are 0.95–1.05 mm; The wall thickness of the three sub-regions in the second bend of the nozzle D 3. D 4. D The thicknesses of 5 are 1.15–1.25 mm, 1.55–1.65 mm, and 1.45–1.55 mm, respectively. wall thickness in the straight section area such as the nozzle exit D 6 is 1.65~1.75mm.

8. The S-bend nozzle design method with multi-region wall thickness distribution according to claim 1, characterized in that: In the structural model generated in step 5, a rounded transition structure is provided at the junction of adjacent areas with different wall thicknesses to suppress stress concentration.

9. An S-bend nozzle with multi-regional wall thickness distribution, characterized in that: The S-bend nozzle is designed and manufactured using the S-bend nozzle design method with multi-region wall thickness distribution as described in any one of claims 1-8, and its wall thickness distribution corresponds to the optimal design parameter combination obtained through the optimization method.

10. The application of an S-bend nozzle with multi-region wall thickness distribution according to any one of claims 1-8 in an aero-engine exhaust system, characterized in that, The inlet end of this S-shaped nozzle is connected to the turbine outlet of an aero-engine to shield high-temperature components of the engine for infrared stealth, while its wall thickness distribution suppresses structural deformation; among other things, The wall structure of the S-bend nozzle is divided along the axial direction into at least a first-bend section region, a second-bend section region, and a straight section region such as the nozzle outlet, all with different wall thicknesses. The nozzle first bend region and / or nozzle second bend region are further divided along the axial direction into at least two sub-regions with different wall thicknesses. The interfaces of each region are perpendicular to the symmetrical cross-section of the nozzle. The wall thickness distribution of each region is synergistically optimized so that, under the aerodynamic and thermal loads generated by the engine operation, the wall thickness distribution of the first bend section of the nozzle effectively suppresses the local bulging deformation of the lower wall surface of the first bend section, the wall thickness distribution of the second bend section of the nozzle effectively suppresses the local expansion deformation of the upper and lower walls in the middle of the second bend section, and the wall thickness of the straight section of the nozzle exit effectively suppresses the lip deformation and overall upward warping deformation. Thus, while meeting the requirements of structural stiffness and strength, the nozzle structure is made lightweight.

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