A comprehensive multi-condition multi-constraint hybrid laminar control tail optimization design method

Abstract

The application provides a kind of mixed laminar flow control tail optimization design method of comprehensive multi-condition and multi-constraint, comprising the following steps: according to the optimization target and constraint condition of multiple actual conditions of vertical tail, the optimization mathematical model of vertical tail is established;Design variables are constructed;The design variables include vertical tail geometric parameter design variables and vertical tail suction coefficient design variables;Based on the vertical tail reference configuration, the optimization design space of each design variable is determined;Optimization design is carried out.The application has good multi-condition and multi-constraint processing capability, can consider the balance of friction resistance and pressure difference resistance in optimization design, while ensuring that the stall characteristics of vertical tail do not deteriorate during take-off and landing stage, and the laminar flow range of airfoil does not change abruptly under small side slip state, and can consider various complex engineering constraints, thereby effectively improving the drag reduction effect of mixed laminar flow control tail, and making the design result more in line with actual engineering needs.

Description

Technical Field

[0001] This invention belongs to the field of aircraft optimization design technology, specifically relating to a hybrid laminar flow control vertical tail optimization design method that integrates multiple operating conditions and constraints. Background Technology

[0002] Frictional drag accounts for approximately 55% of the total drag of high-subsonic civil aircraft. At the same Reynolds number, the frictional drag of the laminar boundary layer is significantly less than that of the turbulent boundary layer. Therefore, laminar flow design for the vertical tail components of an aircraft can effectively reduce frictional drag, thereby improving flight efficiency. Currently, the main technologies for achieving laminar flow on aircraft vertical tail components include: Natural Laminar Flow (NLF), Laminar Flow Control (LFC), and Hybrid Laminar Flow Control (HLFC). Among these technologies, Hybrid Laminar Flow Control can create a large-scale laminar flow on the vertical tail surface with relatively low energy consumption, achieving a significant drag reduction effect.

[0003] Hybrid laminar flow control technology suppresses the growth of crossflow (CF) waves by introducing air at the leading edge and suppresses crossflow (TS) waves by designing a reasonable pressure gradient downstream. This allows for the maintenance of a large-scale laminar flow at a significant leading-edge sweep angle, resulting in significant drag reduction. The CF wave is an inviscid, unstable wave generated by velocity-type inflection points within the boundary layer; it is excited in the pressure-adaptive region and suppressed in the pressure-adaptive region. The TS wave is a viscous, unstable wave, suppressed in the pressure-adaptive region and excited in the pressure-adaptive region. For the vertical tail of high-subsonic civil aircraft, such as the A320, the large sweep angle means that natural laminar flow design cannot effectively suppress the crossflow instability caused by the sweep. Laminar flow control technology using large-scale air intake results in high energy consumption and heavy structural weight. Hybrid laminar flow control, however, achieves significant drag reduction with less energy consumption and without a significant increase in structural weight, thus gaining widespread research and application.

[0004] In the aerospace field, research on optimization design methods for hybrid laminar flow control vertical tails is limited. While the few publicly available optimization design techniques for hybrid laminar flow control vertical tails can reduce intake energy consumption and improve drag reduction, they do not specifically consider the multi-condition characteristics of the vertical tail in practical engineering problems. For example, they fail to consider the low-speed stall characteristics and drag reduction effect under sideslip conditions during the design process, leading to performance degradation of the designed vertical tail during takeoff, landing, and small sideslip conditions. Therefore, it is difficult to obtain design results that are practical for engineering applications. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a hybrid laminar flow control tail optimization design method that integrates multiple operating conditions and constraints, which can effectively solve the above-mentioned problems.

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

[0007] This invention provides a hybrid laminar flow control tail optimization design method integrating multiple operating conditions and constraints, comprising the following steps:

[0008] Step S1: Select the baseline configuration of the vertical tail; set optimization objectives and constraints based on multiple actual working conditions of the vertical tail, and establish a mathematical model for vertical tail optimization.

[0009] Step S2: Construct design variables; the design variables include vertical tail geometric parameter design variables and vertical tail intake coefficient design variables; based on the vertical tail baseline configuration, determine the optimization design space for each of the design variables;

[0010] Step S3: Using the vertical tail reference configuration as the initial reference configuration for optimization design, sampling is performed in the optimization design space of the vertical tail geometric parameter design variables and the optimization design space of the vertical tail intake coefficient design variables to obtain a sample point set;

[0011] Step S4: Based on the sample point set, generate the vertical tail optimized configuration;

[0012] Step S5: Evaluate the aerodynamic performance of the optimized vertical tail configuration obtained in step S4 using computational fluid dynamics numerical simulation.

[0013] Step S6: Determine whether the aerodynamic performance of the vertical tail optimization configuration evaluated in step S5 satisfies the vertical tail optimization mathematical model in step S1. If it satisfies, the iteration terminates and step S8 is executed; otherwise, step S7 is executed.

[0014] Step S7: Using the point addition criterion algorithm, determine new sample points in the optimization design space of the vertical tail geometric parameter design variables and the optimization design space of the vertical tail intake coefficient design variables, and integrate the new sample points and the original sample point set into a new sample point set; update the sample point set in step S4, and return to step S4.

[0015] Step S8: Output the final generated vertical tail optimized configuration, which is the final optimized vertical tail configuration.

[0016] Preferably, the objective function and constraints of the vertical tail optimization mathematical model are as follows:

[0017] min.β1×Q V / Q V0 +β2×C D / CD0 +β3×(S0 / S Laminar )

[0018] st

[0019] S Z / B＝0.25_0 ≤0.6

[0020] S Z / B＝0.50_0 ≤0.6

[0021] S Laminar_2_U ≥0.45

[0022] S Laminar_2_L ≥0.45

[0023] Le i ≥Le i0

[0024] Te i ≥Te i0

[0025] Thk i ≥Thk i0

[0026] Where: β1, β2, and β3 are the coefficients of the first, second, and third terms, respectively; β1 + β2 + β3 = 1;

[0027] Q V C represents the optimized inspiratory volumetric flow rate of the vertical tail; D Q represents the optimized drag coefficient of the vertical tail at a sideslip angle of 0°; V0 C represents the inspiratory volumetric flow rate of the vertical tail baseline configuration; D0 S represents the drag coefficient of the vertical tail reference configuration at a sideslip angle of 0°; Laminar S0 represents the laminar flow range of the optimized vertical tail at a sideslip angle of 0°; S0 represents the laminar flow range of the baseline configuration of the vertical tail at a sideslip angle of 0°.

[0028] S Z / B＝0.25_0 S Z / B＝0.50_0 These represent the optimized transition positions of the vertical tail at 25% and 50% span positions with a sideslip angle of 0°, respectively.

[0029] S Laminar_2_U S Laminar_2_L These represent the laminar flow range on the leeward and windward sides of the vertical tail at a sideslip angle of 2°, respectively.

[0030] i = 1, 2, 3, representing the spanwise positions of the vertical tail at 25%, 50%, and 75%, respectively; Le i Te represents the thickness of the optimized vertical tail at position 25%c of the i-th spanwise station; iThis represents the thickness of the optimized vertical tail at 75%c of the spanwise position of the i-th station; Thk i This represents the maximum thickness of the vertical tail obtained through optimization.

[0031] Le i0 Te represents the thickness of the vertical tail reference configuration at position 25%c of the spanwise position of the i-th station; i0 This represents the thickness of the vertical tail reference configuration at 75%c position at the i-th spanwise station; Thk i0 This indicates the maximum thickness of the vertical tail reference configuration.

[0032] Preferably, β1, β2 and β3 are 0.2, 0.4 and 0.4, respectively.

[0033] Preferably, the vertical tail inhalation coefficient is defined as C q =-(ρ S V S ) / (ρ ∞ V ∞ ), where ρ s V s ρ represents the airflow density at the wall and the intake velocity perpendicular to the wall, respectively; ∞ V ∞ These represent the airflow density and free flow velocity in the far field, respectively.

[0034] Inspiratory volumetric flow rate is S Suction ×ρ S ×V S Among them, S Suction This represents the area of ​​the intake region.

[0035] The hybrid laminar flow control tail optimization design method provided by this invention, which integrates multiple operating conditions and multiple constraints, has the following advantages:

[0036] To address the multi-condition challenges faced by vertical tails in practical engineering problems, this invention, based on the design concept of simultaneously considering intake parameters and aerodynamic shape, comprehensively balances frictional drag and differential pressure drag in the optimized design. This ensures that the stall characteristics of the vertical tail do not deteriorate during takeoff and landing, and that the laminar flow range on the vertical tail surface does not change abruptly under small sideslip conditions. Simultaneously, it can consider various complex engineering constraints, such as maintaining the vertical tail thickness, the slope of the low-speed lift line, and the stall angle of attack, thereby further improving the drag reduction effect of the mixed laminar flow control vertical tail. Ultimately, a mixed laminar flow control vertical tail that better meets the needs of practical engineering is obtained. Attached Figure Description

[0037] Figure 1 This is a flowchart of a hybrid laminar flow control vertical tail optimization design method that integrates multiple operating conditions and multiple constraints, provided by the present invention.

[0038] Figure 2This is a schematic diagram of the planar geometry, airfoil configuration, and air intake region of the baseline configuration of an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the vertical tail root airfoil optimization design space according to an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the airfoil optimization design space for the vertical tail Z / B = 50% spanwise position according to an embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram of the vertical tail fin tip airfoil optimization design space according to an embodiment of the present invention;

[0042] Figure 6 This is a schematic diagram of the design space for optimizing the intake coefficient of different intake regions of the vertical tail according to an embodiment of the present invention;

[0043] Figure 7 This is a convergence process diagram of the optimized design of the hybrid laminar flow control vertical tail according to an embodiment of the present invention;

[0044] Figure 8 This is a comparison diagram of the wing root airfoil of the BASE configuration and the OPT configuration according to an embodiment of the present invention;

[0045] Figure 9 This is a comparison diagram of the BASE configuration and the OPT configuration of the airfoil with Z / B = 50% spanwise position according to an embodiment of the present invention;

[0046] Figure 10 This is a comparison diagram of the wingtip airfoils of the BASE and OPT configurations according to embodiments of the present invention;

[0047] Figure 11 This is a comparison diagram of the intake coefficient distribution in different intake regions of the BASE and OPT configurations according to embodiments of the present invention;

[0048] Figure 12 This is a pressure distribution diagram of the BASE configuration Z / B = 25% station in an embodiment of the present invention at sideslip angles of 0° to 2°.

[0049] Figure 13 This is a pressure distribution diagram of the BASE configuration Z / B = 50% station in an embodiment of the present invention at a sideslip angle of 0° to 2°.

[0050] Figure 14 This is a pressure distribution diagram of the BASE configuration Z / B = 75% station in an embodiment of the present invention at sideslip angles of 0° to 2°.

[0051] Figure 15 This is a pressure distribution diagram of the OPT configuration Z / B=25% station in an embodiment of the present invention at a sideslip angle of 0° to 2°.

[0052] Figure 16 This is a pressure distribution diagram of the OPT configuration Z / B=50% station in an embodiment of the present invention at a sideslip angle of 0° to 2°.

[0053] Figure 17 This is a pressure distribution diagram of the OPT configuration Z / B=75% station in an embodiment of the present invention at a sideslip angle of 0° to 2°.

[0054] Figure 18 This is a comparison diagram of the lift lines of the BASE and OPT configurations in embodiments of the present invention.

[0055] in:

[0056] 1 indicates the base configuration airfoil root profile;

[0057] 2 represents the lower bound of the vertical tail root airfoil optimization design space;

[0058] 3 represents the upper bound of the vertical tail root airfoil optimization design space;

[0059] 4 indicates an airfoil with a base configuration Z / B = 50% spanwise position;

[0060] 5 represents the lower bound of the airfoil optimization design space at the vertical tail position with Z / B = 50% spanwise.

[0061] 6 represents the upper limit of the airfoil optimization design space at the vertical tail position with Z / B = 50% spanwise.

[0062] 7 indicates the BASE configuration wingtip airfoil;

[0063] 8 represents the lower bound of the vertical tail fin tip airfoil optimization design space;

[0064] 9 represents the upper limit of the space for optimizing the airfoil shape at the tip of the vertical tail fin;

[0065] 10 indicates the distribution of the intake coefficient in different intake regions of the BASE configuration;

[0066] 11 represents the lower bound of the design space for optimizing the intake coefficient in different intake regions;

[0067] 12 represents the upper bound of the design space for optimizing the intake coefficient in different intake regions;

[0068] 13 indicates the wing root airfoil of the OPT configuration;

[0069] 14 indicates an airfoil with an OPT configuration Z / B = 50% spanwise position;

[0070] 15 indicates the wingtip airfoil of the OPT configuration;

[0071] 16 indicates the distribution of the intake coefficient in different intake regions of the OPT configuration;

[0072] 17 represents the pressure distribution at a BASE configuration station with Z / B = 25% at a sideslip angle of 0°;

[0073] 18 represents the pressure distribution at a BASE configuration station with Z / B = 25% at a sideslip angle of 1°;

[0074] 19 represents the pressure distribution at a BASE configuration station with Z / B = 25% at a sideslip angle of 2°;

[0075] 20 represents the pressure distribution at a sideslip angle of 0° at a BASE configuration station with Z / B = 50%.

[0076] 21 represents the pressure distribution at a sideslip angle of 1° at a BASE configuration station with Z / B = 50%.

[0077] 22 represents the pressure distribution at a sideslip angle of 2° at a BASE configuration station with Z / B = 50%.

[0078] 23 represents the pressure distribution at a sideslip angle of 0° at a station with a Z / B ratio of 75% in the BASE configuration.

[0079] 24 represents the pressure distribution at a sideslip angle of 1° at a BASE configuration station with Z / B = 75%.

[0080] 25 represents the pressure distribution at a sideslip angle of 2° at a BASE configuration station with Z / B = 75%.

[0081] 26 represents the pressure distribution at the OPT configuration Z / B = 25% station with a sideslip angle of 0°;

[0082] 27 represents the pressure distribution at the OPT configuration Z / B = 25% station with a sideslip angle of 1°;

[0083] 28 represents the pressure distribution at the OPT configuration Z / B = 25% station with a sideslip angle of 2°;

[0084] 29 represents the pressure distribution at the OPT configuration with Z / B = 50% of the stations at a sideslip angle of 0°;

[0085] 30 indicates the pressure distribution at the OPT configuration with Z / B = 50% of the positions at a sideslip angle of 1°;

[0086] 31 indicates the pressure distribution at the OPT configuration with Z / B = 50% of the positions at a sideslip angle of 2°;

[0087] 32 indicates the pressure distribution at the OPT configuration with Z / B = 75% of the stations at a sideslip angle of 0°;

[0088] 33 indicates the pressure distribution at the OPT configuration with Z / B = 75% of the positions at a sideslip angle of 1°;

[0089] 34 represents the pressure distribution at the OPT configuration with Z / B = 75% of the stations at a sideslip angle of 2°;

[0090] 35 represents the lift line of the BASE configuration;

[0091] 36 represents the lift line of the OPT configuration. Detailed Implementation

[0092] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the invention.

[0093] This invention primarily focuses on the optimized design of vertical tail components for civil aircraft employing hybrid laminar flow control technology. Based on design principles considering intake parameters and aerodynamic shape, it develops an optimized design method for hybrid laminar flow control vertical tails that is more suitable for the actual engineering needs of civil aircraft vertical tails. This method is based on an efficient global proxy optimization algorithm and possesses good multi-condition and multi-constraint handling capabilities. The key features of this invention are: the ability to comprehensively consider the balance between frictional drag and differential pressure drag in the optimized design, while ensuring that the stall characteristics of the vertical tail do not deteriorate during takeoff and landing, and that the laminar flow range on the vertical tail surface does not change abruptly under small sideslip conditions. Furthermore, it can consider various complex engineering constraints, thereby effectively improving the drag reduction effect of the hybrid laminar flow control vertical tail and making the design results more consistent with actual engineering needs.

[0094] Compared to existing hybrid laminar flow control optimization design methods, the optimization design method of this invention comprehensively considers various actual operating conditions of civil aircraft vertical tails under complex engineering constraints, such as the balance between frictional drag and differential pressure drag, the stall characteristics of the vertical tail during takeoff and landing, and the laminar flow range on the surface of the vertical tail under small sideslip conditions. This can effectively improve the drag reduction effect of hybrid laminar flow control vertical tails, while ensuring that the design results are more in line with actual engineering needs.

[0095] See Figure 1 This invention provides a hybrid laminar flow control tail optimization design method integrating multiple operating conditions and constraints, comprising the following steps:

[0096] Step S1: Select the baseline configuration of the vertical tail; set optimization objectives and constraints based on multiple actual working conditions of the vertical tail, and establish a mathematical model for vertical tail optimization.

[0097] As a specific form, the objective function and constraints of the vertical tail optimization mathematical model are as follows:

[0098] min.β1×Q V / Q V0 +β2×C D / C D0 +β3×(S0 / SLaminar )

[0099] st

[0100] S Z / B＝0.25_0 ≤0.6

[0101] S Z / B＝0.50_0 ≤0.6

[0102] S Laminar_2_U ≥0.45

[0103] S Laminar_2_L ≥0.45

[0104] Le i ≥Le i0

[0105] Te i ≥Te i0

[0106] Thk i ≥Thk i0

[0107] Where: β1, β2 and β3 are the first coefficient, the second coefficient and the third coefficient, respectively; β1+β2+β3=1; the preferred method is: β1, β2 and β3 are 0.2, 0.4 and 0.4 respectively.

[0108] Q V C represents the optimized inspiratory volumetric flow rate of the vertical tail; D Q represents the optimized drag coefficient of the vertical tail at a sideslip angle of 0°; V0 C represents the inspiratory volumetric flow rate of the vertical tail baseline configuration; D0 S represents the drag coefficient of the vertical tail reference configuration at a sideslip angle of 0°; Laminar S0 represents the laminar flow range of the optimized vertical tail at a sideslip angle of 0°; S0 represents the laminar flow range of the baseline configuration of the vertical tail at a sideslip angle of 0°.

[0109] S Z / B＝0.25_0 S Z / B＝0.50_0 These represent the optimized transition positions of the vertical tail at 25% and 50% span positions with a sideslip angle of 0°, respectively.

[0110] S Laminar_2_U S Laminar_2_L These represent the laminar flow range on the leeward and windward sides of the vertical tail at a sideslip angle of 2°, respectively.

[0111] i = 1, 2, 3, representing the spanwise positions of the vertical tail at 25%, 50%, and 75%, respectively; Le i Te represents the thickness of the optimized vertical tail at position 25%c of the i-th spanwise station;i This represents the thickness of the optimized vertical tail at 75%c of the spanwise position of the i-th station; Thk i This represents the maximum thickness of the vertical tail obtained through optimization.

[0112] Le i0 Te represents the thickness of the vertical tail reference configuration at position 25%c of the spanwise position of the i-th station; i0 This represents the thickness of the vertical tail reference configuration at 75%c position at the i-th spanwise station; Thk i0 This indicates the maximum thickness of the vertical tail reference configuration.

[0113] Step S2: Construct design variables; the design variables include vertical tail geometric parameter design variables and vertical tail intake coefficient design variables; based on the vertical tail baseline configuration, determine the optimization design space for each of the design variables;

[0114] Step S3: Using the vertical tail reference configuration as the initial reference configuration for optimization design, sampling is performed in the optimization design space of the vertical tail geometric parameter design variables and the optimization design space of the vertical tail intake coefficient design variables to obtain a sample point set;

[0115] Step S4: Based on the sample point set, generate the vertical tail optimized configuration;

[0116] Step S5: Evaluate the aerodynamic performance of the optimized vertical tail configuration obtained in step S4 using computational fluid dynamics numerical simulation.

[0117] Step S6: Determine whether the aerodynamic performance of the vertical tail optimization configuration evaluated in step S5 satisfies the vertical tail optimization mathematical model in step S1. If it satisfies, the iteration terminates and step S8 is executed; otherwise, step S7 is executed.

[0118] Step S7: Using the point addition criterion algorithm, determine new sample points in the optimization design space of the vertical tail geometric parameter design variables and the optimization design space of the vertical tail intake coefficient design variables, and integrate the new sample points and the original sample point set into a new sample point set; update the sample point set in step S4, and return to step S4.

[0119] Step S8: Output the final generated vertical tail optimized configuration, which is the final optimized vertical tail configuration.

[0120] The hybrid laminar flow control vertical tail optimization design method of this invention employs a highly efficient global proxy optimization algorithm, capable of considering the multi-condition and multi-constraint characteristics of civil aircraft vertical tail design. Its optimization design process comprehensively considers the balance between frictional drag and pressure drag, while ensuring that the stall characteristics of the vertical tail during takeoff and landing do not deteriorate and that the laminar flow range on the vertical tail surface does not change abruptly under small sideslip conditions. Furthermore, it can consider various complex engineering constraints. Therefore, it improves the drag reduction effect and engineering practicality of the hybrid laminar flow control vertical tail.

[0121] The following is an example:

[0122] The inventors used their developed optimization design method to conduct multiple rounds of optimization design on a vertical tail baseline configuration (BASE), resulting in an optimized configuration, OPT. The planar geometry and intake region configuration of the vertical tail baseline configuration are as follows: Figure 2 As shown, a three-stage inhalation method was employed, dividing the region from the leading edge of the tail to 20% of the chord length into three segments: 0%–6%, 6%–12%, and 12%–20%. Figure 2 The design uses C1, C2, and C3 to represent the first, second, and third inhalation zones, respectively; each zone uses a different inhalation coefficient, defined as C1. q =-(ρ S V S ) / (ρ ∞ V ∞ ), where ρ s V s ρ represents the airflow density at the wall and the intake velocity perpendicular to the wall, respectively. ∞ V ∞ These represent the airflow density and free flow velocity at the far field, respectively. To more intuitively illustrate the difference in inhalation volume, inhalation volume is defined as: Q = S Suction ×ρ S ×V S , of which S Suction This represents the area of ​​the air intake region. The main design conditions and constraints considered during the design process include 0° and 2° sideslip angles during cruise, tail thickness, low-speed stall characteristics, and drag reduction effects, specifically:

[0123] The mathematical model for the optimization problem is as follows:

[0124] min.0.2×Q V / Q V0 +0.4×C D / C D0 +0.4×(S0 / S Laminar )

[0125] st

[0126] S Z / B＝0.25_0≤0.6

[0127] S Z / B＝0.50_0 ≤0.6

[0128] S Laminar_2_U ≥0.45

[0129] S Laminar_2_L ≥0.45

[0130] Le i ≥Le i0

[0131] Te i ≥Te i0

[0132] Thk i ≥Thk i0

[0133] In the formula:

[0134] Q V C represents the optimized inspiratory volumetric flow rate of the vertical tail; D Q represents the optimized drag coefficient of the vertical tail at a sideslip angle of 0°; V0 C represents the inspiratory volumetric flow rate of the vertical tail baseline configuration; D0 S represents the drag coefficient of the vertical tail reference configuration at a sideslip angle of 0°; Laminar S0 represents the laminar flow range of the optimized vertical tail at a sideslip angle of 0°; S0 represents the laminar flow range of the baseline configuration of the vertical tail at a sideslip angle of 0°.

[0135] S Z / B＝0.25_0 S Z / B＝0.50_0 These represent the optimized transition positions of the vertical tail at 25% and 50% span positions with a sideslip angle of 0°, respectively. This constraint on the transition position is an innovative constraint of this invention. Specifically, the inventors discovered through research that by constraining the transition position to prevent it from being too far back, not only can the pressure drag and friction drag be balanced, but the position of the maximum thickness is also indirectly constrained to prevent it from being too far back, thus ensuring the stall characteristics of the vertical tail at low speeds and preventing the stall characteristics of the vertical tail from deteriorating during takeoff and landing.

[0136] S Laminar_2_U S Laminar_2_L These represent the laminar flow range on the leeward and windward sides of the vertical tail at a sideslip angle of 2°, respectively.

[0137] i = 1, 2, 3, representing the spanwise positions of the vertical tail at 25%, 50%, and 75%, respectively; Le i Te represents the thickness of the optimized vertical tail at position 25%c of the i-th spanwise station; iThis represents the thickness of the optimized vertical tail at 75%c of the spanwise position of the i-th station; Thk i This represents the maximum thickness of the vertical tail obtained through optimization.

[0138] Le i0 Te represents the thickness of the vertical tail reference configuration at position 25%c of the spanwise position of the i-th station; i0 This represents the thickness of the vertical tail reference configuration at 75%c position at the i-th spanwise station; Thk i0 This indicates the maximum thickness of the vertical tail reference configuration.

[0139] Therefore, the mathematical model for the optimization problem provided by this invention has the following characteristics:

[0140] (1) The maximum thickness of the vertical tail in each section of the airfoil along the span, the thickness at the 25%c position, and the thickness at the 75%c position are not less than the reference configuration, and the planar shape of the vertical tail does not change compared with the reference configuration; where c represents the chord length.

[0141] (2) Taking into account the transition position and laminar flow range under sideslip angles of 0° and 2° in the sideslip state, the aerodynamic characteristics under each sideslip state are guaranteed, and the robustness of the scheme is guaranteed;

[0142] Specifically, by constraining the transition position at a sideslip angle of 0°, the lateral aerodynamic performance of the vertical tail at low speeds is ensured, and the stall angle of attack and lift slope are not significantly reduced compared to the baseline configuration.

[0143] By constraining the laminar flow range on the leeward and windward sides at a 2° sideslip angle, the laminar flow range is made to be over 45%, thereby minimizing component resistance.

[0144] Using the wing root of the vertical tail, the Z / B=50% spanwise position, the three airfoil profiles at the wingtip, and the intake coefficients of different intake regions as design variables, while keeping the tip-root ratio, aspect ratio, leading-edge sweep angle, and wing area of ​​the vertical tail constant, the BASE configuration is used as the baseline configuration for the initial optimization design. Figures 3-6 This demonstrates the design space (range of variation of design variables) for this optimization. Figure 7 The convergence process of the optimized design is given. Figures 8-11 The airfoil and intake coefficient distributions for the BASE and OPT configurations at typical sites are shown.

[0145] The aerodynamic performance of the baseline vertical tail configuration (BASE) and the OPT configuration (optimized vertical tail configuration obtained by the present invention) were evaluated and compared using computational fluid dynamics (CFD) numerical simulation. The evaluation calculation conditions were: (1) Mach number of 0.78 and Reynolds number of 2.5 × 10⁻⁶. 7(1) The sideslip angle is 0° to 2°; (2) The Mach number is 0.3 and the Reynolds number is 2.0 × 10⁻⁶. 7 The sideslip angle is 0° to 19°. Turbulence simulation is performed using the SA model, with e... N The method performs transition prediction, using two critical perturbation amplification factors [N] for transition prediction. tr_TS N tr_CF The values ​​were taken as [6.5, 7.5] respectively. The comparison results are as follows: Figures 12-17 As shown. From Figures 12-17 As can be seen, the OPT configuration of the vertical tail enhances the pressure gradient and range on the surface of the vertical tail during cruise, weakens the adverse pressure gradient near the leading edge of the vertical tail during sideslip, and shortens the length of the leading edge acceleration zone. It successfully suppresses the growth of CF / TS waves on the windward / leeward side of the vertical tail during sideslip, significantly increases the laminar flow range of the vertical tail during cruise and sideslip, and thus reduces the surface friction drag of the vertical tail.

[0146] Table 1 shows the laminar flow range and drag coefficient of the upper and lower surfaces of the vertical tail during cruise and sideslip conditions:

[0147] Table 1. Comparison of aerodynamic characteristics of BASE and OPT configurations at the design point (Ma = 0.78, Re = 2.5 × 10⁻⁶) 7 (β = 0°~2°)

[0148]

[0149] As shown in Table 1, compared to the non-breathing BASE configuration, the vertical tail OPT configuration achieved a laminar flow range of 57.70% during cruise, and the total drag coefficient decreased from 50.15 cts to 31.74 cts, resulting in a drag reduction of 36.71% for the vertical tail components. Furthermore, near the design state at sideslip angles of 0° to 2°, the windward and leeward sides of the vertical tail OPT configuration maintained a laminar flow range of over 45%, and the thickness at the 25%c and 75%c positions and the maximum thickness of the OPT configuration did not decrease.

[0150] Finally, the lateral force coefficients of the vertical tail BASE and OPT configurations at different sideslip angles at low speeds were evaluated, and the results are as follows: Figure 18 As shown: The slope dC of the linear segment of the lateral force coefficient of the vertical tail BASE at low speed. N_BASE / dβ=0.05565 / deg; Slope dC of the linear segment of the lateral force coefficient in the OPT configuration at low speeds. N_OPT / dβ=0.05505 / deg; Stall angle β of the vertical tail base at low speed. Stall_BASE =14°; Stall angle β of OPT configuration at low speeds Stall_OPT =15°.

[0151] As can be seen, the lift line slope of the OPT configuration is basically the same as that of the reference configuration, and the stall angle is no lower than that of the reference configuration. While achieving the drag reduction design goal, it does not reduce other aerodynamic performance of the vertical tail.

[0152] The comprehensive design and calculation results show that the hybrid laminar flow control tail optimization design method of the present invention can comprehensively consider various actual working conditions and various engineering constraints, and can design a design scheme with good drag reduction effect and better meet engineering needs.

[0153] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hybrid laminar flow control tail optimization design method integrating multiple operating conditions and constraints, characterized in that, Includes the following steps: Step S1: Select the vertical tail reference configuration; Based on the various actual working conditions of the vertical tail, optimization objectives and constraints are set, and a mathematical model for vertical tail optimization is established. Step S2, construct design variables; The design variables include vertical tail geometric parameters and vertical tail intake coefficient. Based on the aforementioned vertical tail reference configuration, the optimal design space for each of the aforementioned design variables is determined; Step S3: Using the vertical tail reference configuration as the initial reference configuration for optimization design, sampling is performed in the optimization design space of the vertical tail geometric parameter design variables and the optimization design space of the vertical tail intake coefficient design variables to obtain a sample point set; Step S4: Based on the sample point set, generate the vertical tail optimized configuration; Step S5: Evaluate the aerodynamic performance of the optimized vertical tail configuration obtained in step S4 using computational fluid dynamics numerical simulation. Step S6: Determine whether the aerodynamic performance of the vertical tail optimization configuration evaluated in step S5 satisfies the vertical tail optimization mathematical model in step S1. If it does, the iteration terminates and step S8 is executed. If not satisfied, proceed to step S7; Step S7: Using the point addition criterion algorithm, determine new sample points in the optimization design space of the vertical tail geometric parameter design variables and the optimization design space of the vertical tail intake coefficient design variables, and integrate the new sample points and the original sample point set into a new sample point set. Update the sample point set in step S4 and return to step S4; Step S8: Output the final generated vertical tail optimized configuration, which is the final optimized vertical tail configuration. The objective function and constraints of the vertical tail optimization mathematical model are as follows: min. ; st; ； ； ； ； ； ； ； in: , and These are the first coefficient, the second coefficient, and the third coefficient, respectively. ; This represents the inspiratory volumetric flow rate of the optimized vertical tail. This represents the drag coefficient of the vertical tail at a sideslip angle of 0° obtained through optimization. This indicates the intake volumetric flow rate of the vertical tail reference configuration; This represents the drag coefficient of the vertical tail reference configuration at a sideslip angle of 0°; This indicates the laminar flow range of the optimized vertical tail at a sideslip angle of 0°; This indicates the laminar flow range of the vertical tail reference configuration at a sideslip angle of 0°; S Z / B=0.25_0 S Z / B=0.50_0 These represent the optimized transition positions of the vertical tail at 25% and 50% span positions with a sideslip angle of 0°, respectively. S Laminar_2_U S Laminar_2_L These represent the laminar flow range on the leeward and windward sides of the vertical tail at a sideslip angle of 2°, respectively. i=1, 2, 3, representing the spanwise positions of the vertical tail at 25%, 50%, and 75%, respectively; This represents the thickness of the optimized vertical tail at position 25%c of the i-th spanwise station; This represents the thickness of the optimized vertical tail at the 75%c position of the i-th spanwise station; This represents the maximum thickness of the vertical tail obtained through optimization. This represents the thickness of the vertical tail reference configuration at position 25%c of the i-th spanwise station; This represents the thickness of the vertical tail reference configuration at 75%c position at the i-th spanwise station; This indicates the maximum thickness of the vertical tail reference configuration.

2. The hybrid laminar flow control vertical tail optimization design method based on multiple operating conditions and constraints as described in claim 1, characterized in that, , and The values ​​are 0.2, 0.4, and 0.4, respectively.

3. The hybrid laminar flow control vertical tail optimization design method based on multiple operating conditions and constraints as described in claim 1, characterized in that, The vertical tail inhalation coefficient is defined as ,in, , These represent the airflow density at the wall surface and the intake velocity perpendicular to the wall surface, respectively. , These represent the airflow density and free-flow velocity in the far field, respectively. Inspiratory volumetric flow rate is ;in, This represents the area of ​​the intake region.

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