Pneumatic and mechanism integrated optimization design method for aircraft three-dimensional high lift device

Abstract

The invention discloses a pneumatic and mechanism integrated optimization design method for a three-dimensional high-lift device of an aircraft, which belongs to the technical field of aircrafts and comprises the following steps of: performing parametric modeling on the three-dimensional high-lift device of the aircraft; randomly generating a plurality of sample points according to a value range of a design variable defined by parametric modeling to form an initial optimization population; marking the sample points as feasible design or infeasible design according to the mechanism size and the flap collision interference state; calculating the take-off and landing performance of the sample points marked as feasible design; and performing optimization processing on the initial optimization population by adopting a multi-objective evolutionary algorithm, and iteratively searching an optimal design variable by taking the maximum lift coefficient of the take-off configuration at a given angle of attack and the maximum lift coefficient of the landing configuration at the given angle of attack as optimization objectives and taking the mechanism size and the flap collision interference state as constraint conditions. According to the method, the feasibility of the mechanism of the three-dimensional high lift device is ensured, and meanwhile, the take-off and landing performance of the aircraft is improved.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft, and in particular to a method for optimizing the integrated aerodynamic and mechanical design of a three-dimensional lift-enhancing device for an aircraft. Background Art

[0002] Since the 1980s, the aerodynamic shape and mechanism type of high-lift devices have gradually developed from complex to simple and reliable, and the influence of multidisciplinary performance indicators such as structure, mechanism, and noise has been increasingly considered in the process of aerodynamic optimization. The mechanism of the high-lift device has the function of supporting and guiding the flaps to the target take-off and landing position. As the type of high-lift device tends to be simpler, the focus of the mechanism design has shifted from achieving complex positioning to reducing weight and maintenance costs, which has brought more constraints to the aerodynamic optimization design. The types of high-lift device mechanisms currently widely used are simple hinge mechanisms, four-bar linkages, and connecting rod slide mechanisms.

[0003] The traditional design of aircraft lift-enhancing devices generally follows the process of two-dimensional design followed by three-dimensional simulation, and aerodynamic optimization followed by mechanism design. The integrated aerodynamic and mechanism optimization design method of two-dimensional lift-enhancing devices can ensure the feasibility of mechanism design in two-dimensional multi-segment airfoils. However, for more complex mechanisms such as connecting rods and slide rails, the two-dimensional optimization design results cannot be directly applied to the three-dimensional configuration of the aircraft, so that the actual three-dimensional mechanism parameters need to be recalculated, and it may be impossible to solve a feasible mechanism, resulting in repeated iterations or even redesign. On the other hand, considering the interference between aircraft components, the spanwise torsion angle and the changes in airfoil thickness and curvature, etc., it cannot be guaranteed that the three-dimensional high-lift configuration generated based on the optimal two-dimensional multi-segment airfoil will achieve the optimal three-dimensional aerodynamic performance.

[0004] Judging from the patents that have been published in China, the existing aerodynamic and structural integrated optimization design methods for lift-enhancing devices are mainly aimed at two-dimensional multi-section airfoils, and there is a lack of methods for three-dimensional wings or wing-body combinations. Summary of the invention

[0005] The purpose of the present invention is to provide a method for optimizing the design of aerodynamic and mechanical integration of a three-dimensional aircraft lift-enhancing device, so as to solve the problems mentioned in the above background.

[0006] To achieve the above-mentioned purpose, the present invention provides a method for optimizing the design of aerodynamic and mechanical integration of a three-dimensional aircraft lift-enhancing device, the steps comprising: S1. Parametric modeling of the multi-segment wing of the aircraft's three-dimensional high-lift device is performed, design variables are defined, and the initial configuration of the high-lift device is obtained. The design variables include shape parameters and slot parameters; S2. According to the value range of the design variables defined by the parametric modeling, a number of sample points are randomly generated to form an initial optimization population; S3. Calculate the three-dimensional space mechanism size and collision interference state of each sample point in the obtained optimization population. If the three-dimensional space mechanism size satisfies the constraint and no collision interference occurs during the flap deployment process, the sample point is marked as a feasible design; otherwise, the sample point is marked as an infeasible design. S4. Calculate the take-off and landing performance of the sample points marked as feasible designs, including the lift coefficient of the take-off configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack; S5. A multi-objective evolutionary algorithm is used to optimize the initial optimization population. The optimization objectives are to maximize the lift coefficient of the takeoff configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack. The mechanism size and flap collision interference state are used as constraints to iteratively search for the optimal design variables.

[0007] Preferably, the parametric modeling method in step S1 is to use the quadratic curve method to generate a two-dimensional profile shape of the flap, obtain a three-dimensional flap shape based on the inner and outer flap profiles, and then move the three-dimensional flap to the take-off and landing positions required by the slot parameters through the translation and rotation of the rigid body to obtain the take-off and landing configurations of the three-dimensional high-lift device, respectively.

[0008] Preferably, the three-dimensional space mechanism in step S3 is a connecting rod slide rail mechanism, and the design parameters of the connecting rod slide rail mechanism are the coordinates of the hinge connecting the crank and the connecting rod and the starting and ending position coordinates of the slider on the slide rail.

[0009] Preferably, the three-dimensional space mechanism size and collision interference state of each sample point in the optimized population calculated in step S3 include: using the Newton-Raphson method to solve the mechanism design parameters of the sample point according to the geometric relationship of each rod of the three-dimensional space mechanism, judging whether the size of the mechanism satisfies the constraints based on the mechanism design parameters, and then calculating the flap trajectory based on the geometric relationship of each rod of the mechanism to determine the collision interference state.

[0010] Preferably, in step S3, the dimensions of the three-dimensional space mechanism satisfy the constraint conditions and no collision interference occurs during the flap deployment process is defined as: ; In the formula, It indicates the distance from the slider to the leading edge of the wing during the movement of the three-dimensional space mechanism. It represents the distance from the slider component to the wing plane during the movement of the three-dimensional space mechanism. is the crank angle, c is the local chord length of the wing, Indicates the collision interference status of the flaps.

[0011] Preferably, calculating the lift coefficient of the take-off configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack in step S4 includes: modifying the aircraft external flow field background grid and the flap boundary layer grid of the initial configuration according to the geometric model, using the overlapping grid method to generate calculation grids for the take-off configuration and the landing configuration, respectively, and solving the lift coefficient of the take-off configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack based on the RANS equation and the kw-SST turbulence model.

[0012] Preferably, in the optimization process of step S5, the new sample point generated by the multi-objective optimization algorithm is judged: if the structure of the new sample point does not meet the constraint conditions, the new sample point is eliminated, its aerodynamic performance is not calculated, and the next new sample point is directly generated.

[0013] Therefore, the present invention adopts the above-mentioned aerodynamic and mechanical integrated optimization design method for a three-dimensional aircraft lift-enhancing device, which has the following beneficial effects: (1) The aerodynamic performance of the aircraft three-dimensional lift-enhancing device of the present invention is synchronously designed and optimized with the three-dimensional spatial structure, thus avoiding repeated iterations of the design.

[0014] (2) Compared with the two-dimensional aerodynamic and structural integration optimization design method of the lift-enhancing device, this method is more direct and practical in constraining the feasibility of the three-dimensional spatial mechanism and has a better effect on optimizing the aerodynamic performance.

[0015] (3) The solution of the feasibility constraints of three-dimensional spatial mechanisms is relatively simple and only relies on the numerical solution of the equation set without the need to call simulation software.

[0016] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of a method for optimizing the design of aerodynamic and mechanical integration of a three-dimensional aircraft lift-enhancing device according to the present invention; Figure 2 A schematic diagram of a connecting rod slide rail mechanism of a pneumatic and mechanical integrated optimization design method for a three-dimensional aircraft lift-enhancing device according to the present invention; Figure 3 This is a schematic diagram of the external parameters of the lift-enhancing device of the present invention; Figure 4 This is a schematic diagram of the seam channel parameters of the lift-enhancing device of the present invention; Figure 5 A schematic diagram of an overlapping grid used in the CFD calculation of the aerodynamic performance of the lift-enhancing device of the present invention; Reference numerals

[0018] 1. Crank; 2. Connecting rod; 3. Slider; 4. Slide rail; 5. Rear beam. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] Example The Fuller flap is a common aircraft trailing edge lift-enhancing device, and its mechanism types are mainly simple hinge mechanism, four-bar mechanism, and connecting rod slide mechanism. The optimization of flap shape and slot parameters and the design of the mechanism are the key to the design of the lift-enhancing device.

[0021] Reference Figure 1 The present invention provides an integrated optimization design method for aerodynamics and mechanisms of a three-dimensional aircraft lift-enhancing device. In this embodiment, a single three-dimensional Fuller flap and its connecting rod slide rail mechanism are selected for synchronous optimization design. Take-off performance and landing performance are optimization targets, and the feasibility of the mechanism (including mechanism size and collision interference state) is a constraint condition.

[0022] The steps include: S1. Parametric modeling is performed on the multi-segment wings of the aircraft's three-dimensional lift-enhancing device, and design variables are defined to obtain the initial configuration of the lift-enhancing device. The design variables include shape parameters and slot parameters.

[0023] In this embodiment, the quadratic curve method is used to generate the two-dimensional cross-sectional shape of the flap, and the three-dimensional flap shape is obtained based on the inner and outer flap sections. Then, the three-dimensional flap is moved to the takeoff and landing positions required by the slot parameters through the translation and rotation of the rigid body, and the takeoff and landing configurations of the three-dimensional high-lift device are obtained respectively.

[0024] like Figure 3 As shown in the figure, for the flap profile, the leading edge and upper surface of the flap are composed of three smooth and continuous quadratic curves AB, BC, and CD, and the rest of the flap is consistent with the corresponding main wing shape. Parameter K controls the curvature of the quadratic curve AB near the leading edge of the flap, and parameter q controls the shape of the quadratic curves AB and BC, that is, the upper surface shape of the flap. Among them, A, B, C, and D represent the control points of the flap profile; K represents the flap leading edge curvature control parameter; and q represents the flap upper surface shape control parameter.

[0025] The start and end profiles of the flap along the span direction are controlled by two pairs of parameters K and q to generate their shapes. These two pairs of parameters can take different values, thereby expanding the geometric shape design space of the three-dimensional flap. Figure 3 After the two flap sections along the span direction are drawn, the three-dimensional flap shape is generated using the guide line of the flap trailing edge, and then the flaps are moved to the take-off and landing positions required by the slot parameters through the translation and rotation of the rigid body to obtain the aerodynamic shape of the three-dimensional proliferation device.

[0026] S2. According to the value range of the design variables defined by parametric modeling, a number of sample points are randomly generated to form an initial optimization population.

[0027] In this embodiment, there are 6 design variables, namely K and q of the inner flap section, K and q of the outer flap section, and the slot parameter O of the takeoff configuration. f and G f , slot parameter O of landing configuration f and G f， Definition reference of design variables Figure 3 and Figure 4 , where O f Indicates flap overlap; G f Indicates the flap slot width; q f represents the flap deflection angle, and the number of initial optimization population is 30.

[0028] S3. Calculate the three-dimensional space mechanism size and collision interference state of each sample point in the optimized population. If the three-dimensional space mechanism size meets the constraints and no collision interference occurs during the flap deployment process, the sample point is marked as a feasible design, otherwise the sample point is marked as an infeasible design.

[0029] In this embodiment, the three-dimensional space mechanism is a connecting rod slide rail mechanism, that is, a spatial RSSP mechanism. The design parameters of the connecting rod slide rail mechanism are the coordinates of the hinge connecting the crank and the connecting rod and the coordinates of the start and end positions of the slider on the slide rail, such as Figure 2 As shown in the figure, A1, B1, C1, and D1 represent the four points on the flap surface that are not coplanar when the Fuller flap is retracted; A2, B2, C2, and D2 represent the four points on the flap surface that are not coplanar when the Fuller flap is deployed to the take-off position. The spatial RSSP mechanism can be divided into a crank (RS) component and a slider (SP) component. According to the geometric relationship between the rods of the mechanism, the hinge coordinates of these two components are solved respectively. The cross-sectional position of the mechanism is located at 25% of the flap span. The process of unfolding the flap from the retracted position to the take-off and landing position can be regarded as a three-position guidance problem for a rigid body, and there is the following rigid body displacement matrix: ; ; in, D1to2 Represents the flaps extending from the stowed position to the take-off position matrix, D 1to3 Represents the flaps extended from the stowed position to the landing position matrix, and the subscripts 1, 2, and 3 represent the stowed, take-off, and landing positions of the flaps, respectively.

[0030] According to the fixed length and orthogonal conditions of the crank, the RS component is solved, assuming that point O is the intersection of the rotation plane of the crank spherical surface pair point P and the rotation axis u. The RS component geometric equation is established: ; ; ; In the formula, O represents the hinge between the crank and the wing structure; P represents the hinge between the crank and the connecting rod; Q represents the hinge between the connecting rod and the slider; Will ( i =2,3) into the above formula, we can get a set of 3 unknown vectors , , and 6 equations, a total of 9 unknowns. Given the coordinates of point O, that is, the vector , the coordinates of point P and the direction of the rotation axis can be solved by the Newton-Raphson method.

[0031] The SP component is solved according to the linear motion condition of the spherical pair Q point on the slider. , , The three points are collinear, and the subscripts 1, 2, and 3 represent the flap retraction, takeoff, and landing positions, respectively. Let k be an unknown constant, and establish the linear guidance equation of the slider: ; Will Substituting the above formula, we can get a set of equations containing 4 unknowns and 3 equations. Given the z coordinate of point Q (it can be assumed that point Q is located near the section where the mechanism is located), we can solve it by the Newton-Raphson method. Through the above method, we can solve the mechanism parameters and mechanism trajectory under any design variables, and then solve whether the mechanism meets the constraints.

[0032] In this embodiment, the definition that the dimensions of the three-dimensional space mechanism satisfy the constraint conditions and no collision interference occurs during the flap deployment process includes: definition and are the distances from the slider to the leading edge of the wing and the wing plane during the movement of the mechanism, respectively. is the crank angle, and the upper and lower limits of these two values ​​define the size constraints of the mechanism. c is the local chord length of the wing. Logical variable Represents the collision interference state of the flap. The collision interference state refers to whether the flap collides with the fixed wing during the deployment of the mechanism. Compared with the backward movement in the xy plane, the spanwise displacement of the flap during the deployment process is very small. Ignoring the small spanwise displacement of the flap, the mechanism can be projected onto the xy plane, and the three-dimensional mechanism can be approximated as a two-dimensional mechanism, which is convenient for calculating the initial motion component of the overlap point between the upper surface of the flap and the trailing edge of the main wing when the crank rotates 1° If this component is positive, it means that the flap is tilted up at a large angle while retreating, and the upper surface of the flap will collide with the trailing edge of the main wing. ;on the contrary, The constraints of an institution can be defined as: .

[0033] S4. Calculate the take-off and landing performance of the sample points marked as feasible designs, including the lift coefficient of the take-off configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack.

[0034] In this embodiment, the aircraft external flow field background grid and flap boundary layer grid of the initial configuration are modified according to the geometric model, and the calculation grids of the takeoff configuration and the landing configuration are generated respectively by the overlapping grid method. Based on the CFD algorithm, that is, the RANS equation and the kw-SST turbulence model, the lift coefficient of the takeoff configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack are solved. For an aircraft with a single Fuller flap, the overlapping grids are as shown in the attached figure. Figure 5 As shown, the aircraft external flow field mesh is the background mesh, and the boundary layer mesh of the flap is the component mesh.

[0035] S5. The initial optimization population is optimized using a multi-objective evolutionary algorithm (NSGA-II). The optimization objectives are to maximize the lift coefficient of the takeoff configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack. The optimal design variables are iteratively searched for with the mechanism size and flap collision interference state as constraints. During the optimization process, the new sample points generated by the multi-objective optimization algorithm are judged: if the mechanism of the new sample point does not meet the constraints, the new sample point is eliminated, its aerodynamic performance is not calculated, and the next new sample point is directly generated.

[0036] In this embodiment, the optimal design variables are obtained by weighing on the Pareto frontier surface of the optimization target obtained by the multi-objective optimization algorithm according to different aircraft design requirements.

[0037] Therefore, the present invention adopts the above-mentioned aerodynamic and structural integrated optimization design method for the three-dimensional lift-enhancing device of an aircraft. By synchronously designing and optimizing the aerodynamic performance and the three-dimensional spatial structure of the three-dimensional lift-enhancing device of the aircraft, repeated iterations of the design are avoided. In addition, the three-dimensional design of the lift-enhancing device is performed, and the constraints on the feasibility of the structure are more direct and practical, and the optimization effect on the aerodynamic performance is better.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for optimizing the design of aerodynamic and mechanical integration of a three-dimensional aircraft lift-enhancing device, characterized in that the steps include: S1. Perform parametric modeling on the multi-segment wing of the aircraft's three-dimensional high-lift device, define design variables, and obtain the initial configuration of the high-lift device, where the design variables include shape parameters and slot parameters; S2. According to the value range of the design variables defined by the parametric modeling, a number of sample points are randomly generated to form an initial optimization population; S3. Calculate the three-dimensional space mechanism size and collision interference state of each sample point in the obtained optimization population. If the three-dimensional space mechanism size satisfies the constraint and no collision interference occurs during the flap deployment process, the sample point is marked as a feasible design; otherwise, the sample point is marked as an infeasible design. S4. Calculate the take-off and landing performance of the sample points marked as feasible designs, including the lift coefficient of the take-off configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack; S5. A multi-objective evolutionary algorithm is used to optimize the initial optimization population. The optimization objectives are to maximize the lift coefficient of the takeoff configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack. The mechanism size and flap collision interference state are used as constraints to iteratively search for the optimal design variables.

2. The method for optimizing the design of aerodynamic and mechanical integration of a three-dimensional aircraft lift-enhancing device according to claim 1, characterized in that: The parametric modeling method in step S1 is to use the quadratic curve method to generate the two-dimensional profile shape of the flap, obtain the three-dimensional flap shape based on the inner and outer flap profiles, and then move the three-dimensional flap to the take-off and landing positions required by the slot parameters through the translation and rotation of the rigid body, and obtain the take-off and landing configurations of the three-dimensional high-lift device respectively.

3. The method for optimizing the aerodynamic and mechanical integration of a three-dimensional aircraft lift-enhancing device according to claim 2, characterized in that: In step S3, the three-dimensional space mechanism is a connecting rod slide rail mechanism, and the design parameters of the connecting rod slide rail mechanism are the coordinates of the hinge connecting the crank and the connecting rod and the coordinates of the start and end positions of the slider on the slide rail.

4. The method for optimizing the design of aerodynamic and mechanical integration of a three-dimensional aircraft lift-enhancing device according to claim 3, characterized in that: The three-dimensional space mechanism size and collision interference state of each sample point in the optimization population calculated in step S3 include: using the Newton-Raphson method to solve the mechanism design parameters of the sample point according to the geometric relationship of each rod of the three-dimensional space mechanism, judging whether the size of the mechanism meets the constraints based on the mechanism design parameters, and then calculating the flap trajectory based on the geometric relationship of each rod of the mechanism to determine the collision interference state.

5. The method for optimizing the design of aerodynamic and mechanical integration of a three-dimensional aircraft lift-enhancing device according to claim 4, characterized in that: In step S3, the three-dimensional space mechanism size satisfies the constraint conditions and no collision interference occurs during the flap deployment process, which is defined as: ； In the formula, It indicates the distance from the slider to the leading edge of the wing during the movement of the three-dimensional space mechanism. It represents the distance from the slider component to the wing plane during the movement of the three-dimensional space mechanism. is the crank angle, c is the local chord length of the wing, Indicates the collision interference status of the flaps.

6. The method for optimizing the design of aerodynamic and mechanical integration of a three-dimensional aircraft lift-enhancing device according to claim 5, characterized in that: Calculating the lift coefficient of the takeoff configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack in step S4 includes: modifying the aircraft external flow field background grid and the flap boundary layer grid of the initial configuration according to the geometric model, using the overlapping grid method to generate the calculation grids of the takeoff configuration and the landing configuration respectively, and solving the lift coefficient of the takeoff configuration at a given angle of attack and the lift coefficient of the landing configuration at a given angle of attack based on the RANS equation and the kw-SST turbulence model.

7. The method for optimizing the design of aerodynamic and mechanical integration of a three-dimensional aircraft lift-enhancing device according to claim 6, characterized in that: In the optimization process of step S5, the new sample points generated by the multi-objective optimization algorithm are judged: if the structure of the new sample point does not meet the constraint conditions, the new sample point is eliminated, its aerodynamic performance is not calculated, and the next new sample point is directly generated.

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