An Optimization Design Method for S-Bend Nozzles for Aero-engines Considering Structural Deformation

Abstract

This invention discloses an optimization design method for S-curve nozzles used in aero-engines that considers structural deformation, belonging to the field of aero-engines. The method selects key geometric parameters of the S-curve nozzle as characteristic parameters, chooses the structural deformation value at a characteristic location and two aerodynamic performance parameters as objective functions, then conducts orthogonal experimental design and constructs a response surface model based on the characteristic parameters and objective functions. After each optimization step, a cyclical evaluation is performed to obtain the final optimization result. This invention solves the problem of high aerodynamic performance loss caused by large structural deformation in S-curve nozzles used in aero-engines in existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of aero-engines, specifically relating to an optimization design method for S-curve nozzles of aero-engines that takes into account structural deformation. Background Technology

[0002] For aero-engines, prolonged high-speed flight generates aerodynamic loads from the high-speed, high-pressure flow inside and outside the nozzle, causing deformation of the S-shaped nozzle. This complex deformation significantly alters the nozzle's aerodynamic characteristics, severely impacting its stability and tactical effectiveness, and potentially causing incalculable damage to combat aircraft. Taking a traditional S-shaped nozzle as an example, the wall deformation cloud diagram after experiencing aerodynamic loads and the interaction of its complex structure is shown below. Figure 1 As shown, severe deformation occurs on both the upper and lower walls at a distance of 2 / 3 of the axial distance from the S-bend inlet, with a maximum deformation of 44 mm. At the nozzle exhaust port, localized deformation occurs on the upper wall of the nozzle outlet, reaching 29 mm. The wall deformation profile of a traditional S-bend nozzle after experiencing aerodynamic loads and the interaction of its complex structure is shown in the diagram. Figure 2 As shown. Existing common methods to suppress S-curve nozzle deformation are to increase the nozzle wall thickness or implement auxiliary support points for hoisting. However, this method not only increases the nozzle weight but also affects the assembly of the nozzle with the aero-engine and aircraft to a certain extent. Structural deformation suppression and aerodynamic performance optimization design should be carried out from the S-curve nozzle profile design.

[0003] Due to the complexity of S-curve nozzle design parameters, optimal aerodynamic design no longer involves simply changing a single design variable, but rather constraining and optimizing multiple design parameters together. Traditional S-curve nozzle optimization design methods often involve parametric studies of different design parameters to obtain the variation of aerodynamic performance of a single parameter with the design parameter. This method cannot precisely consider the quantitative correlation between each parameter and aerodynamic performance, and it cannot reasonably predict parameters outside the expected range. Furthermore, current nozzle design methods do not consider the impact of structural deformation caused by actual wall pressure loads. This deformation will significantly affect the aerodynamic performance of the S-curve nozzle, resulting in a significant discrepancy between the design target and reality. As S-curve nozzles experience more complex operating conditions and the number of controllable design parameters increases, it is necessary to develop optimization design methods for aero-engine S-curve nozzles that consider structural deformation, in order to obtain the optimal S-curve nozzle design while taking into account the changes in aerodynamic performance caused by structural deformation. Summary of the Invention

[0004] The technical problem to be solved:

[0005] To overcome the shortcomings of existing technologies, this invention provides an optimization design method for S-curve nozzles used in aero-engines that considers structural deformation. Key geometric parameters of the S-curve nozzle are selected as characteristic parameters, and the structural deformation values ​​at characteristic locations and two aerodynamic performance parameters are selected as objective functions. Then, orthogonal experimental design is performed, and a response surface model is constructed based on the characteristic parameters and objective functions. After each optimization step, a cyclical evaluation is conducted to obtain the final optimization result. This method aims to at least solve the problem of high aerodynamic performance loss caused by large structural deformation in S-curve nozzles used in aero-engines in existing technologies.

[0006] The technical solution of this invention is: an optimization design method for an S-curve nozzle for an aero-engine considering structural deformation, characterized by the following specific steps:

[0007] Step 1: Determine the design parameters of the S-curve nozzle;

[0008] Step 2: Establish different S-bend nozzle geometric models based on the different geometric parameters in Step 1;

[0009] Step 3: Select key geometric parameters as characteristic parameters, and select the structural deformation values ​​at key locations and the aerodynamic performance parameters of the S-bend nozzle as objective functions;

[0010] Step 4: Based on the characteristic parameters in Step 3, design orthogonal experiments by giving the range of characteristic parameters to obtain the experimental scheme;

[0011] Step 5: Based on the orthogonal test scheme in Step 4, use finite element software to calculate the structural deformation values ​​and aerodynamic performance parameters at key locations in all orthogonal test schemes, and obtain the response surface model between characteristic parameters and objective function;

[0012] Step Six: Based on the response surface model in Step Five, calculate the accuracy of the response surface function fitting (R²). 2 ) Evaluation, if R 2 If the value is ≥0.8, the requirement is met; otherwise, modify the design objective and proceed to step five.

[0013] Step 7: Based on the response surface model in Step 5, input the design objective, setting the design objective to minimize the structural deformation value and maximize the aerodynamic performance parameters of the S-bend nozzle, at which point the performance is optimal;

[0014] Step 8: Based on the response surface model from Step 5 and the design objectives from Step 6, output the optimization results;

[0015] Step 9: Determine whether the optimization results meet the aerodynamic design requirements, which are required to achieve the aerodynamic performance needed for the component design; if the aerodynamic design requirements are met, proceed to Step 10; otherwise, modify the design objectives and proceed to Step 5.

[0016] Step 10: Determine whether the calculation error between the actual model and the optimization result meets the accuracy requirement, which is ±5%. If the accuracy requirement is met, proceed to Step 11; otherwise, modify the variable range and proceed to Step 4.

[0017] Step 11: Output the optimal solution that meets the design requirements. The result under the current optimization conditions is the optimal design result of the S-curve nozzle that balances optimal aerodynamic performance and minimum structural deformation.

[0018] A further technical solution of the present invention is as follows: In step one, the design parameters of the S-curve nozzle are extracted according to the overall and assembly requirements of the aero-engine, including: nozzle design pressure ratio, nozzle inlet Mach number, nozzle inlet airflow temperature, nozzle inlet diameter, nozzle outlet width-to-height ratio, nozzle length-to-diameter ratio, and nozzle obstruction rate.

[0019] A further technical solution of the present invention is: in step three, the key geometric parameters are key characteristic parameters related to the aerodynamic performance of the nozzle, including the outlet width-to-height ratio, length-to-diameter ratio, and obstruction rate; the key positions are the positions where deformation is most sensitive and concentrated.

[0020] A further technical solution of the present invention is that the key positions are the upper wall surface of the nozzle outlet, the lower wall surface of the nozzle outlet, and the upper and lower wall surfaces at a distance of 2 / 3 of the axial distance from the S-bend inlet.

[0021] A further technical solution of the present invention is: the aerodynamic performance parameters are the thrust coefficient and the thrust vector angle, wherein the thrust coefficient is the ratio of the axial thrust calculated by the nozzle to the theoretically calculated ideal thrust; the thrust vector angle is caused by the deflection of the jet flow and is the angle between the engine axis and the axis of the actual thrust of the nozzle, that is, the angle between the velocity of the nozzle along the flow direction and the vertical direction.

[0022] A further technical solution of the present invention is: the characteristic parameters in step four are: the width-to-height ratio of the outlet is 2-10, the length-to-diameter ratio is 2.2-3, and the occlusion rate is 0-1.

[0023] A further technical solution of the present invention is: in step five, the fitting formula for the structural deformation value at the key location is:

[0024] The structural deformation value at the midpoint of the upper wall of the nozzle exit = -116.9790625 + 3.81846875 × exit aspect ratio + 88.7175 × length-to-diameter ratio + 17.669 × obstruction rate + 0.575 × exit aspect ratio × length-to-diameter ratio + 0.363 × exit aspect ratio × obstruction rate - 7.03375 × length-to-diameter ratio × obstruction rate - 0.3824140625 × exit aspect ratio^2 - 15.57109375 × length-to-diameter ratio^2 + 0.0625 × obstruction rate^2

[0025] Structural deformation value at the midpoint of the lower wall of the nozzle exit = -27.810423749996 + 6.61942125 × exit aspect ratio + 9.3444937499972 × length-to-diameter ratio + 17.669 × obstruction rate - 2.95475625 × exit aspect ratio × length-to-diameter ratio + 0.719 × exit aspect ratio × obstruction rate - 25.345975 × length-to-diameter ratio × obstruction rate + 0.078563906249999 × exit aspect ratio^2 + 5.5626093750005 × length-to-diameter ratio^2 + 46.65591 × obstruction rate^2

[0026] Structural deformation value at the midpoint of the wall at 2 / 3 of the axial distance from the S-bend inlet.

[0027] = 522.88299375 - 28.997834375 × Outlet Aspect Ratio - 325.3946875 × Length-to-Diameter Ratio - 12.6568 × Obstruction Rate + 9.7635 × Outlet Aspect Ratio × Length-to-Diameter Ratio + 4.1698 × Outlet Aspect Ratio × Obstruction Rate - 42.958875 × Length-to-Diameter Ratio × Obstruction Rate + 0.16258046874999 × Outlet Aspect Ratio^2 + 59.155078125001 × Length-to-Diameter Ratio^2 + 60.57565 × Obstruction Rate^2

[0028] Structural deformation value at the midpoint of the lower wall at 2 / 3 of the axial distance from the S-bend inlet

[0029] = 346.2821125 - 17.886134375 × Outlet width-to-height ratio - 216.32178125 × Aspect ratio - 5.4644500000006 × Obstruction rate + 6.13440625 × Outlet width-to-height ratio × Aspect ratio + 4.8766125 × Outlet width-to-height ratio × Obstruction rate - 53.944625 × Aspect ratio × Obstruction rate - 0.061696875000005 × Outlet width-to-height ratio^2 + 43.932500000001 × Aspect ratio^2 + 75.1095 × Obstruction rate^2.

[0030] A further technical solution of the present invention is: in step five, the fitting formula for the aerodynamic performance parameters is:

[0031] Thrust coefficient = 0.9807210996945 - 0.0011848391901339 × Exit aspect ratio + 0.0015775459339617 × Length-to-diameter ratio - 0.010156632676063 × Obstruction rate

[0032] Thrust vector angle = -0.020598961176471 + 0.0565757121875 × exit width-to-height ratio - 0.161803378125 × length-to-diameter ratio + 1.03690268 × obstruction rate.

[0033] A further technical solution of the present invention is that the orthogonal experimental design is completed based on Design Expert 8.0 software.

[0034] Beneficial effects

[0035] The beneficial effects of this invention are as follows: The S-curve nozzle optimization design method for aero-engines, which considers structural deformation and applies the technology of this invention, can obtain the correlation between the objective function and characteristic parameters, and optimize to obtain an S-curve nozzle for aero-engines with small structural deformation and high aerodynamic performance, while ensuring that the error between the optimized predicted value and the actual value is small and the optimization accuracy is high. The S-curve nozzle optimization design method for aero-engines, which considers structural deformation and applies the technology of this invention, can solve the problem that current nozzle design methods do not consider the influence of structural deformation caused by actual wall pressure loads, resulting in a large discrepancy between the design target and the actual output.

[0036] Since S-curve nozzles need to maintain high aerodynamic performance and flight axis stability under design conditions, the optimization design of S-curve nozzles to suppress structural deformation must ensure that the thrust coefficient of the S-curve nozzle is as high as possible and the thrust vector angle is maintained around 0°, while minimizing the deformation of key parts of the nozzle. Therefore, the S-curve nozzle optimization design method for aero-engines that considers structural deformation, based on the technology of this invention, can solve the problem that current nozzle design methods do not consider the influence of structural deformation caused by actual wall pressure loads, resulting in a large discrepancy between design objectives and actual output. Attached Figure Description

[0037] Figure 1 This is a cloud map of the wall deformation of a traditional S-curve nozzle after experiencing the interaction between aerodynamic loads and its complex structure.

[0038] Figure 2 This is a diagram of the wall deformation profile of a traditional S-curve nozzle after experiencing the interaction between aerodynamic loads and its complex structure.

[0039] Figure 3 This is a schematic flowchart of an optional S-curve nozzle optimization design method for aero-engines that takes into account structural deformation, according to an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the positions of four key parameter points in an optional S-curve nozzle optimization design method for aero-engines that takes into account structural deformation, according to an embodiment of the present invention. Detailed Implementation

[0041] 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.

[0042] This invention addresses the significant aerodynamic performance loss caused by the large structural deformation of S-curve nozzles used in existing aero-engine technologies. It provides an optimized design method for S-curve nozzles used in aero-engines that considers structural deformation, comprising the following steps:

[0043] Step 1: Determine the design parameters of the S-curve nozzle. The overall design parameters of the aero-engine's S-curve nozzle need to be determined, including but not limited to: nozzle design pressure ratio, nozzle inlet Mach number, nozzle inlet airflow temperature, nozzle inlet diameter, nozzle outlet aspect ratio, nozzle length-to-diameter ratio, and nozzle obstruction rate.

[0044] Step 2: Establish geometric models of different S-curve nozzles. Based on the different geometric parameters in Step 1, establish different geometric models of S-curve nozzles.

[0045] Step 3: Select key geometric parameters as feature parameters, and select the structural deformation values ​​at key locations and the aerodynamic performance parameters of the S-bend nozzle as objective functions.

[0046] Step four: Based on the characteristic parameters in step three, orthogonal experimental design is carried out with the range of characteristic parameters to obtain the experimental scheme.

[0047] Step 5: Based on the orthogonal test schemes in Step 4, use finite element software to calculate the structural deformation values, thrust coefficients, and thrust vector angle parameters at key locations in all orthogonal test schemes, and obtain the response surface model between the characteristic parameters and the objective function.

[0048] Step six: Based on the response surface model in step five, calculate the accuracy of the response surface function fitting (R²). 2 ) Evaluation, if R 2 If the value is ≥0.8, the requirement is met; otherwise, modify the design target and proceed to step five.

[0049] Step 7: Based on the response surface model in Step 5, input the design objective. Set the design objective to minimize the structural deformation value and maximize the aerodynamic performance parameters of the S-bend nozzle. At this point, the performance is optimal.

[0050] Step 8: Based on the response surface model from Step 5 and the design objectives from Step 6, output the optimization results.

[0051] Step nine: Determine whether the optimization results meet the aerodynamic design requirements, which are to achieve the aerodynamic performance required by the component design. If the aerodynamic design requirements are met, proceed to step ten; otherwise, modify the design objectives and proceed to step five.

[0052] Step 10: Determine whether the calculation error between the actual model and the optimization result meets the accuracy requirement of ±5%. If the accuracy requirement is met, proceed to Step 11; otherwise, modify the variable range and proceed to Step 4.

[0053] Step 11: Output the optimal solution that meets the design requirements. The result under the current optimization conditions is the optimized design result of the S-curve nozzle that balances optimal aerodynamic performance and minimum structural deformation.

[0054] The S-curve nozzle optimization design method for aero-engines, which considers structural deformation and applies the technology of this invention, can obtain the correlation between the objective function and characteristic parameters, and optimize to obtain an S-curve nozzle for aero-engines with small structural deformation and high aerodynamic performance. Simultaneously, it ensures that the error between the optimized predicted value and the actual value is small, resulting in high optimization accuracy. This method addresses the problem that current nozzle design methods do not consider the influence of structural deformation caused by actual wall pressure loads, leading to significant discrepancies between design objectives and actual outputs.

[0055] The above technical solution will be further explained below with reference to the accompanying drawings and specific experimental data.

[0056] See Figures 3-4 A flowchart and architecture of an optimization design method for an S-curve nozzle for aero-engines considering structural deformation are presented. To address the problem that current nozzle design methods do not consider the structural deformation caused by actual wall pressure loads, resulting in a significant discrepancy between design objectives and actual outputs, this invention proposes an optimization design method for an S-curve nozzle for aero-engines considering structural deformation, comprising the following steps:

[0057] Step 1: Determine the design parameters of the S-curve nozzle. The overall design parameters of the aero-engine's S-curve nozzle need to be determined, including but not limited to: nozzle design pressure ratio, nozzle inlet Mach number, nozzle inlet airflow temperature, nozzle inlet diameter, nozzle outlet aspect ratio, nozzle length-to-diameter ratio, and nozzle obstruction rate.

[0058] Step 2: Establish geometric models of different S-curve nozzles. Based on the different geometric parameters in Step 1, establish different geometric models of S-curve nozzles.

[0059] Step 3: Select three key geometric parameters (nozzle exit width-to-height ratio, length-to-diameter ratio, and obstruction rate) as characteristic parameters, and select six variables—structural deformation values ​​at four key locations (A, B, C, and D), the thrust coefficient of the S-bend nozzle, and the thrust vector angle—as the objective function. The nozzle exit width-to-height ratio is defined as the ratio of the nozzle exit width W to the exit height H; the nozzle length-to-diameter ratio is defined as the ratio of the total nozzle length L to the nozzle inlet diameter D; and the nozzle obstruction rate is defined as the degree of obstruction, with a rate of 1 indicating complete obstruction and a rate of 0 indicating complete unobstructed obstruction. Locations A and B are the center points of the upper and lower walls at the nozzle exit, respectively; locations C and D are the midpoints of the upper and lower walls of the S-bend nozzle at 2 / 3L from the inlet. The thrust coefficient of the nozzle (C...) fg The axial thrust F obtained from the nozzle calculations is... xCompared with the theoretically calculated ideal thrust F i The ratio, calculated using the formula: C fg =F x / F i The thrust vector angle β of the nozzle is caused by the deflection of the jet stream and is the angle between the engine axis and the axis of actual nozzle thrust, i.e., the velocity U of the nozzle along the flow direction. x and the vertical direction U y The included angle is calculated using the formula: β = arctan(U y / U x ).

[0060] Step 4: Based on the three characteristic parameters in Step 3, the range of characteristic parameters is given, where the width-to-height ratio of the outlet ranges from 2 to 10, the length-to-diameter ratio ranges from 2.2 to 3, and the occlusion rate ranges from 0 to 1. Orthogonal experimental design is carried out, and the experimental scheme is shown in Table 1.

[0061] Table 1 Orthogonal Experiment Scheme

[0062] Serial Number Export aspect ratio Aspect Ratio Occlusion rate 1 10 2.6 0 2 2 2.6 1 3 6 2.6 0.5 4 2 2.6 0 5 6 2.6 0.5 6 10 2.2 0.5 7 10 3 0.5 8 2 2.2 0.5 9 6 3 1 10 10 2.6 1 11 2 3 0.5 12 6 2.6 0.5 13 6 3 0 14 6 2.6 0.5 15 6 2.6 0.5 16 6 2.2 1 17 6 2.2 0

[0063] Step 5: Based on the orthogonal experimental schemes in Step 4, use finite element software to calculate the structural deformation values, thrust coefficients, and thrust vector angle parameters at key locations A, B, C, and D in all orthogonal experimental schemes, as shown in Table 2. Obtain the response surface model between the characteristic parameters and the objective function; the fitting formula is as follows:

[0064] Structural deformation value at point A = -116.9790625 + 3.81846875 × (exit width-to-height ratio) + 88.7175 × (length-to-diameter ratio) + 17.669 × (shading rate) + 0.575 × (exit width-to-height ratio) × (length-to-diameter ratio) + 0.363 × (exit width-to-height ratio) × (shading rate) - 7.03375 × (length-to-diameter ratio) × (shading rate) - 0.3824140625 × (exit width-to-height ratio)^2 - 15.57109375 × (length-to-diameter ratio)^2 + 0.0625 × (shading rate)^2

[0065] Structural deformation value at point B = -27.810423749996 + 6.61942125 × (exit width-to-height ratio) + 9.3444937499972 × (length-to-diameter ratio) + 17.669 × (shading rate) - 2.95475625 × (exit width-to-height ratio) × (length-to-diameter ratio) + 0.719 × (exit width-to-height ratio) × (shading rate) - 25.345975 × (length-to-diameter ratio) × (shading rate) + 0.078563906249999 × (exit width-to-height ratio^2) + 5.5626093750005 × (length-to-diameter ratio^2) + 46.65591 × (shading rate^2)

[0066] Structural deformation value at point C = 522.88299375 - 28.997834375 × (exit width-to-height ratio) - 325.3946875 × (length-to-diameter ratio) - 12.6568 × (shading rate) + 9.7635 × (exit width-to-height ratio) × (length-to-diameter ratio) + 4.1698 × (exit width-to-height ratio) × (shading rate) - 42.958875 × (length-to-diameter ratio) × (shading rate) + 0.16258046874999 × (exit width-to-height ratio^2) + 59.155078125001 × (length-to-diameter ratio^2) + 60.57565 × (shading rate^2)

[0067] Structural deformation value at point D = 346.2821125 - 17.886134375 × (exit width-to-height ratio) - 216.32178125 × (length-to-diameter ratio) - 5.4644500000006 × (shading rate) + 6.13440625 × (exit width-to-height ratio) × (length-to-diameter ratio) + 4.8766125 × (exit width-to-height ratio) × (shading rate) - 53.944625 × (length-to-diameter ratio) × (shading rate) - 0.061696875000005 × (exit width-to-height ratio^2) + 43.932500000001 × (length-to-diameter ratio^2) + 75.1095 × (shading rate^2)

[0068] Thrust coefficient = 0.9807210996945 - 0.0011848391901339 × Exit aspect ratio + 0.0015775459339617 × Length-to-diameter ratio - 0.010156632676063 × Obstruction rate

[0069] Thrust vector angle = -0.020598961176471 + 0.0565757121875 × exit aspect ratio - 0.161803378125 × length-to-diameter ratio + 1.03690268 × obstruction rate

[0070] Table 2 Calculated values ​​of the objective function

[0071] Serial Number Aspect Ratio Aspect Ratio Occlusion rate Point A Point B Point C Point D Thrust coefficient Thrust vector angle 1 10 2.6 0 24.042 31.3719 52.9342 51.518 0.9724895 -0.18483033 2 2 2.6 1 16.97 4.1401 18.677 19.626 0.9732844 0.82366434 3 6 2.6 0.5 27.335 6.273 26.4 27.535 0.9706686 0.52466095 4 2 2.6 0 19.044 28.0041 65.4226 73.7839 0.9836414 -0.1623691 5 6 2.6 0.5 27.335 6.273 26.4 27.535 0.9706686 0.52466095 6 10 2.2 0.5 20.529 10.733 25.4238 22.7017 0.9690857 0.88981539 7 10 3 0.5 24.967 3.69243 54.0877 43.3921 0.9678987 0.85947598 8 2 2.2 0.5 14.323 3.69243 54.0877 43.3921 0.9787825 0.16474497 9 6 3 1 30.231 4.135 35.435 35.566 0.9679944 0.63896286 10 10 2.6 1 24.872 13.2599 39.547 36.373 0.9683432 1.05039114 11 2 3 0.5 15.081 15.5623 20.2652 24.8223 0.9800236 -0.02161082 12 6 2.6 0.5 27.335 6.273 26.4 27.535 0.9706686 0.52466095 13 6 3 0 29.179 43.694 100.063 105.195 0.9784572 -0.26954194 14 6 2.6 0.5 27.335 6.273 26.4 27.535 0.9706686 0.52466095 15 6 2.6 0.5 27.335 6.273 26.4 27.535 0.9706686 0.52466095 16 6 2.2 1 23.353 4.09838 19.138 23.066 0.9628986 0.84417377 17 6 2.2 0 16.674 23.3806 49.3989 49.5393 0.978559 -0.17367724

[0072] Step six: Based on the response surface model in step five, calculate the accuracy of the response surface function fitting (R²). 2 ) Evaluation, if R 2 If the value is ≥0.8, the requirement is met; otherwise, modify the design objective and proceed to step five. 2 The values ​​are shown in Table 3:

[0073] Table 3 R 2 result

[0074]

[0075]

[0076] Step 7: Based on the response surface model in Step 5, input the design objectives. The design objectives are set as minimizing the structural deformation values ​​at the four key locations A, B, C, and D, and maximizing the thrust coefficient and thrust vector angle of the S-bend nozzle.

[0077] Step 8: Based on the response surface model from Step 5 and the design objectives from Step 6, output the optimization results, as shown in Table 4.

[0078] Table 4 Optimization Results

[0079] Export aspect ratio Aspect Ratio Occlusion rate 2.00 2.35 0.37

[0080] Step nine: Determine whether the optimization results meet the aerodynamic design requirements, which are to achieve the aerodynamic performance required by the component design. If the aerodynamic design requirements are met, proceed to step ten; otherwise, modify the design objectives and proceed to step five.

[0081] Step 10: Determine whether the calculation error between the actual model and the optimization result meets the accuracy requirement of ±5%. If the accuracy requirement is met, proceed to Step 11; otherwise, modify the variable range and proceed to Step 4. In this embodiment, the comparison between the optimization result and the actual result is shown in Table 5, which meets the accuracy requirement of less than ±5%.

[0082] Table 5 Comparison of Optimization Results and Actual Results

[0083]

[0084]

[0085] Step 11: Output the optimal solution that meets the design requirements. The result under the current optimization conditions is the optimized design result of the S-bend nozzle that balances optimal aerodynamic performance and minimum structural deformation. In this embodiment, the optimization result in step 7 is the optimal design result.

[0086] 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 method for optimizing the design of an S-curve nozzle for an aero-engine, considering structural deformation, characterized in that... The specific steps are as follows: Step 1: Determine the design parameters of the S-curve nozzle; Step 2: Establish different S-bend nozzle geometric models based on the different geometric parameters in Step 1; Step 3: Select key geometric parameters as characteristic parameters, and select the structural deformation values ​​at key locations and the aerodynamic performance parameters of the S-bend nozzle as objective functions; Step 4: Based on the characteristic parameters in Step 3, design orthogonal experiments by giving the range of characteristic parameters to obtain the experimental scheme; Step 5: Based on the orthogonal test scheme in Step 4, use finite element software to calculate the structural deformation values ​​and aerodynamic performance parameters at key locations in all orthogonal test schemes, and obtain the response surface model between characteristic parameters and objective function; Step Six: Based on the response surface model in Step Five, calculate the accuracy of the response surface function fitting (R²). 2 ) Evaluation, if R 2 If the value is ≥0.8, the requirement is met; otherwise, modify the design objective and proceed to step five. Step 7: Based on the response surface model in Step 5, input the design objective, setting the design objective to minimize the structural deformation value and maximize the aerodynamic performance parameters of the S-bend nozzle, at which point the performance is optimal; Step 8: Based on the response surface model from Step 5 and the design objectives from Step 6, output the optimization results; Step 9: Determine whether the optimization results meet the aerodynamic design requirements, which are required to achieve the aerodynamic performance needed for the component design; if the aerodynamic design requirements are met, proceed to Step 10; otherwise, modify the design objectives and proceed to Step 5. Step 10: Determine whether the calculation error between the actual model and the optimization result meets the accuracy requirement, which is ±5%. If the accuracy requirement is met, proceed to step eleven; otherwise, modify the variable range and proceed to step four. Step 11: Output the optimal solution that meets the design requirements. The result under the current optimization conditions is the optimal design result of the S-curve nozzle that balances optimal aerodynamic performance and minimum structural deformation.

2. The method for optimizing the design of an S-curve nozzle for an aero-engine considering structural deformation as described in claim 1, characterized in that: In step one, the design parameters of the S-curve nozzle are extracted based on the overall and assembly requirements of the aero-engine, including: nozzle design pressure ratio, nozzle inlet Mach number, nozzle inlet airflow temperature, nozzle inlet diameter, nozzle outlet width-to-height ratio, nozzle length-to-diameter ratio, and nozzle obstruction rate.

3. The method for optimizing the design of an S-curve nozzle for an aero-engine considering structural deformation as described in claim 2, characterized in that: In step three, the key geometric parameters are key characteristic parameters related to the aerodynamic performance of the nozzle, including the outlet width-to-height ratio, length-to-diameter ratio, and obstruction rate; the key locations are the locations where deformation is most sensitive and concentrated.

4. The method for optimizing the design of an S-curve nozzle for an aero-engine considering structural deformation as described in claim 3, characterized in that: The key locations are the upper wall surface of the nozzle exit, the lower wall surface of the nozzle exit, and the upper and lower wall surfaces at a distance of 2 / 3 of the axial distance from the S-bend inlet.

5. The method for optimizing the design of an S-curve nozzle for an aero-engine considering structural deformation according to claim 4, characterized in that: The aerodynamic performance parameters are the thrust coefficient and the thrust vector angle. The thrust coefficient is the ratio of the axial thrust calculated from the nozzle to the theoretically calculated ideal thrust. The thrust vector angle is caused by the deflection of the jet stream and is the angle between the engine axis and the axis of the actual thrust of the nozzle, that is, the angle between the velocity of the nozzle along the flow direction and the vertical direction.

6. The method for optimizing the design of an S-curve nozzle for an aero-engine considering structural deformation as described in claim 5, characterized in that: The characteristic parameters in step four are as follows: the width-to-height ratio of the outlet is 2-10, the length-to-diameter ratio is 2.2-3, and the occlusion rate is 0-1.

7. The method for optimizing the design of an S-curve nozzle for an aero-engine considering structural deformation as described in claim 6, characterized in that: In step five, the fitting formula for the structural deformation value at the key location is: The structural deformation value at the midpoint of the upper wall of the nozzle exit = -116.9790625 + 3.81846875 × exit aspect ratio + 88.7175 × length-to-diameter ratio + 17.669 × obstruction rate + 0.575 × exit aspect ratio × length-to-diameter ratio + 0.363 × exit aspect ratio × obstruction rate - 7.03375 × length-to-diameter ratio × obstruction rate - 0.3824140625 × exit aspect ratio^2 - 15.57109375 × length-to-diameter ratio^2 + 0.0625 × obstruction rate^2 Structural deformation value at the midpoint of the lower wall of the nozzle exit = -27.810423749996 + 6.61942125 × exit aspect ratio + 9.3444937499972 × length-to-diameter ratio + 17.669 × obstruction rate - 2.95475625 × exit aspect ratio × length-to-diameter ratio + 0.719 × exit aspect ratio × obstruction rate - 25.345975 × length-to-diameter ratio × obstruction rate + 0.078563906249999 × exit aspect ratio^2 + 5.5626093750005 × length-to-diameter ratio^2 + 46.65591 × obstruction rate^2 The structural deformation value at the midpoint of the wall at 2 / 3 of the axial distance from the S-bend inlet is calculated as follows: 522.88299375 - 28.997834375 × outlet width-to-height ratio - 325.3946875 × length-to-diameter ratio - 12.6568 × obstruction rate + 9.7635 × outlet width-to-height ratio × length-to-diameter ratio + 4.1698 × outlet width-to-height ratio × obstruction rate - 42.958875 × length-to-diameter ratio × obstruction rate + 0.16258046874999 × outlet width-to-height ratio^2 + 59.155078125001 × length-to-diameter ratio^2 + 60.57565 × obstruction rate^2 The structural deformation value at the midpoint of the lower wall at 2 / 3 of the axial distance from the S-bend inlet is calculated as follows: 346.2821125 - 17.886134375 × outlet width-to-height ratio - 216.32178125 × length-to-diameter ratio - 5.4644500000006 × obstruction rate + 6.13440625 × outlet width-to-height ratio × length-to-diameter ratio + 4.8766125 × outlet width-to-height ratio × obstruction rate - 53.944625 × length-to-diameter ratio × obstruction rate - 0.061696875000005 × outlet width-to-height ratio^2 + 43.932500000001 × length-to-diameter ratio^2 + 75.1095 × obstruction rate^2.

8. The method for optimizing the design of an S-curve nozzle for an aero-engine considering structural deformation according to claim 7, characterized in that: In step five, the fitting formula for the aerodynamic performance parameters is: Thrust coefficient = 0.9807210996945 - 0.0011848391901339 × Exit aspect ratio + 0.0015775459339617 × Length-to-diameter ratio - 0.010156632676063 × Obstruction rate Thrust vector angle = -0.020598961176471 + 0.0565757121875 × exit width-to-height ratio -0.161803378125×Aspect Ratio +1.03690268×Obscuration Rate.

9. The method for optimizing the design of an S-curve nozzle for an aero-engine considering structural deformation as described in claim 8, characterized in that: The orthogonal experimental design was completed using Design Expert 8.0 software.

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