Aerodynamic layout optimization design method and system for matching ducted fan blades with ducts

Abstract

The present application discloses an aerodynamic layout optimization design method and system for matching ducted fan blades with ducts, the method comprising: based on the initial design parameters of the ducted fan, simultaneously establishing a blade tip area grid and setting an initial load distribution; optimizing by an alternating iterative method, updating the gap distribution and the duct profile in sequence; processing the coupling effect between optimization methods by a comprehensive evaluation function, and adjusting the optimization parameters according to the evaluation results; determining the final optimization scheme when the relative change value of the comprehensive evaluation function is less than a preset value and meets the target process requirements. Through the scheme of the present application, the formation of a separation vortex system can be suppressed and the shock wave boundary layer interference effect can be improved.

Description

Technical Field

[0001] The present application relates to the field of blade type structures, and in particular to an aerodynamic layout optimization design method and system for matching ducted fan blades with ducts. Background Art

[0002] As a highly efficient propulsion device, ducted fans are widely used in military drones, civil aircraft and other fields. Its working principle is to generate airflow acceleration through rotating blades, and to improve propulsion efficiency with the help of the flow-guiding effect of the duct wall. The performance of ducted fans directly affects the propulsion efficiency, endurance and maneuverability of the aircraft, among which the matching design of blades and ducts is one of the key factors determining the overall performance. In the prior art, the design of ducted fans mainly relies on a simplified aerodynamic parameter matching method. This method achieves a preliminary match with the duct by adjusting the blade geometric parameters, such as blade angle, chord length, torsion angle, etc. The traditional design method uses a quasi-two-dimensional flow model and empirical formula, which can meet the basic performance requirements to a certain extent. However, with the development of aviation power technology and the increase in application needs, the limitations of this simplified design method have become increasingly prominent.

[0003] Specifically, the existing ducted fan design technology has the following technical problems and deficiencies: Traditional design methods have obvious deficiencies in dealing with complex flow characteristics in the blade tip area. Due to the failure to fully consider the complex interference effect between the tip leakage flow and the boundary layer of the duct wall, significant performance loss will occur under high load conditions. When the ducted fan is operating under high load, a complex three-dimensional separated vortex system structure will form in the blade tip area. These vortices not only increase local flow losses, but also strongly interfere with the main flow channel, resulting in increased distortion of the downstream flow field. Experimental verification shows that this flow loss will cause the thrust coefficient to decrease by about 8%-12%, seriously affecting the working efficiency and stability of the ducted fan. Existing designs generally adopt a fixed hub ratio and blade load distribution scheme, lacking consideration of adaptability to multiple working conditions. In practical applications, ducted fans need to maintain good performance under different flight conditions, especially under high angle of attack and transonic conditions. However, the current design method cannot effectively cope with the changes in flow characteristics under these complex conditions. Under high angle of attack conditions, the distortion of the inlet flow field will lead to uneven blade load distribution and aggravate the instability of the tip leakage flow. In transonic conditions, the interference between the tip shock wave and the boundary layer is more prominent, which can easily cause local flow separation. Measured data show that the combined effect of these factors causes the efficiency of the ducted fan under non-design point conditions to be 15%-20% lower than that of the design point. Traditional design methods are relatively simple in the selection of optimization targets, focusing mainly on the efficiency of the design point and ignoring the balance of performance under all conditions. Existing technologies usually adopt the steady flow assumption and fail to fully consider the impact of unsteady effects on system performance. Especially under large flow conditions, the unsteady interference between the blades and the duct will cause pressure pulsation, which not only affects the aerodynamic efficiency, but may also induce structural vibration problems. In addition, the existing design methods have limited control means for the tip clearance flow, and it is difficult to effectively suppress the negative impact of the leakage flow on the main flow channel.

[0004] Therefore, there is an urgent need for a technical solution that can suppress the formation of separation vortex systems and improve the shock wave boundary layer interference effect. Summary of the invention

[0005] In order to solve the deficiencies of the prior art, the embodiment of the present application provides an aerodynamic layout optimization design method and system for matching ducted fan blades with ducts. The present application solves the technical problem that under high load conditions in the prior art, the blade tip area is prone to local separation of vortices.

[0006] In a first aspect, an embodiment of the present application provides an aerodynamic layout optimization design method for matching a ducted fan blade with a duct, comprising: based on the initial design parameters of the ducted fan, simultaneously establishing a blade tip area grid and setting an initial load distribution; optimizing by an alternating iterative method, updating the gap distribution and the duct profile in sequence; processing the coupling effect between the optimization methods by a comprehensive evaluation function, and adjusting the optimization parameters according to the evaluation results; wherein the comprehensive evaluation function comprises: ,in, Indicates the evaluation results. represents the change in total pressure loss in the blade tip area, represents the load distribution deviation, Represents the change in average Mach number; when the relative change value of the comprehensive evaluation function is less than the preset value and meets the target process requirements, the final optimization plan is determined.

[0007] In a possible implementation, establishing a blade tip region grid includes: constructing a mixed grid in the blade tip region so that the number of radial grid layers is not less than a set value; and arranging multiple layers of grids radially in the blade tip clearance region.

[0008] In a possible implementation, setting the initial load distribution includes: establishing an initial blade load distribution function according to design parameters of the ducted fan; and fitting the circulation distribution function using a polynomial.

[0009] In one possible implementation, the gap distribution is updated, including: dividing a plurality of calculation stations along the blade tip edge, and calculating the leakage flow intensity function at each station; arranging measurement points on the inner wall of the duct at preset angles, and calculating the wall interference term at each measurement point; using a genetic algorithm to solve the optimization coefficient to obtain a target gap distribution function to update the gap distribution.

[0010] In a possible implementation, the duct profile is updated, including: obtaining an initial duct profile and calculating a pressure coefficient distribution; modifying the duct profile according to a pressure gradient; solving a coupled optimization control equation using a time-marching method; and determining a source term function by a local curvature change rate of the duct profile.

[0011] In one possible implementation, an alternating iterative method is used for optimization, including: performing a tip clearance optimization iteration under the current duct profile; calculating a new load distribution based on the updated clearance distribution; updating the duct profile using the new load distribution; checking convergence, and re-performing tip clearance optimization iteration if convergence has not occurred.

[0012] In a possible implementation, the target gap distribution function includes: ,in, represents the gap distribution, represents the initial gap distribution, Indicates the leakage flow intensity, represents the wall interference term, and Represents the optimization coefficient.

[0013] In one possible implementation, the coupled optimization control equation includes: ,in, Indicated in radius The blade load distribution function at Indicates time, represents the velocity vector, represents the gradient of the load distribution, represents the diffusion coefficient, The Laplace operator representing the load distribution, represents the source function, The equation of the curve representing the duct profile.

[0014] In the second aspect, an embodiment of the present application further provides an aerodynamic layout optimization design system for matching ducted fan blades with ducts, which is used to implement the aerodynamic layout optimization design method as described in any of the above embodiments, and the system includes: a fan calculation unit, a duct calculation unit and a collaborative control unit; wherein the fan calculation unit is used to update the gap distribution; the duct calculation unit is used to update the duct profile; the collaborative control unit is used to establish a blade tip area grid and set the initial load distribution based on the initial design parameters of the ducted fan; an alternating iterative method is used for optimization; a comprehensive evaluation function is used to process the coupling effect between the optimization methods, and the optimization parameters are adjusted according to the evaluation results; when the relative change value of the comprehensive evaluation function is less than the preset value and meets the target process requirements, the final optimization scheme is determined.

[0015] In the third aspect, an embodiment of the present application also provides an aerodynamic layout optimization device for matching ducted fan blades with ducts, comprising: a processor, a memory, and a system bus; wherein the processor and the memory are connected via the system bus; the memory is used to store one or more programs, and the one or more programs include instructions, which, when executed by the processor, enable the processor to execute the method described in any one of the above embodiments.

[0016] In the aerodynamic layout optimization design method, system and equipment for matching ducted fan blades with ducts provided above, the embodiment of the present application establishes an adaptive clearance control model by describing the interaction mechanism between the tip leakage flow and the wall boundary layer, which can dynamically adjust the tip clearance according to the local flow characteristics and effectively suppress the formation of the separation vortex system. Furthermore, in some embodiments, by establishing a dynamic matching relationship between the blade load and the duct profile, the duct profile can be adaptively adjusted according to the flow characteristics under different working conditions to improve the shock wave-boundary layer interference effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic flow chart of an aerodynamic layout optimization design method for matching ducted fan blades with ducts provided in an embodiment of the present application;

[0019] Figure 2 A schematic flow chart of a blade clearance distribution updating method provided in an embodiment of the present application;

[0020] Figure 3 A schematic diagram of a flow chart of a duct profile updating method provided in an embodiment of the present application;

[0021] Figure 4 A schematic block diagram of an aerodynamic layout optimization design system for matching ducted fan blades with ducts provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure unless otherwise specifically stated.

[0023] Those skilled in the art can understand that the terms "first", "second" and the like in the embodiments of the present disclosure are only used to distinguish different steps, devices or modules, etc., and neither represent any specific technical meaning nor represent the necessary logical order between them. It should also be understood that in the embodiments of the present disclosure, "multiple" can refer to two or more, and "at least one" can refer to one, two or more. It should also be understood that for any component, data or structure mentioned in the embodiments of the present disclosure, in the absence of explicit limitation or contrary revelation given in the context, it can generally be understood as one or more. In addition, the term "and / or" in the present disclosure is only a description of the association relationship of the associated objects, indicating that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present disclosure generally indicates that the associated objects before and after are an "or" relationship. It should also be understood that the description of each embodiment in the present disclosure emphasizes the differences between the embodiments, and the same or similar parts can refer to each other. For the sake of brevity, they will not be repeated one by one.

[0024] At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present disclosure and its application or use. The techniques, methods and devices known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and devices should be considered part of the specification. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] Figure 1 A schematic flow chart of an aerodynamic layout optimization design method for matching ducted fan blades with ducts provided in an embodiment of the present application.

[0027] like Figure 1As shown, at step S101, based on the initial design parameters of the ducted fan, the tip area grid is established and the initial load distribution is set. Since the change of the tip clearance will directly affect the blade load distribution, and the modification of the duct profile will also change the flow characteristics of the tip area, it is necessary to solve the two optimization methods in a coordinated manner. The initialization stage first starts two optimization processes based on the initial design parameters of the ducted fan: establish the tip area grid and initialize the clearance value, and set the initial blade load distribution. and ducted lines .

[0028] The step of establishing the blade tip region grid includes: constructing a mixed grid in the blade tip region so that the number of radial grid layers is not less than a set value; and arranging multiple layers of grids radially in the blade tip clearance region.

[0029] The initial load distribution is set, including: establishing an initial blade load distribution function according to the design parameters of the ducted fan; and fitting the circulation distribution function using a polynomial.

[0030] Taking the ducted fan VF120 model as an example, this model has the following basic parameters: design speed 33000rad / min, inlet total temperature 288.15K, inlet total pressure 101.325kPa, design point flow 0.65kg / s, fan total pressure ratio 1.12. Establish the flow field calculation grid in the tip area, use OH type mixed grid in the tip area, and the radial grid number is not less than 25 layers to ensure that the y+ value is less than 2.5. The initial value of the tip clearance δ0 is set to 0.8% of the blade height, which is about 0.32mm. Arrange 8-12 layers of grids radially in the gap area to ensure that the leakage flow characteristics can be accurately captured. Determine the initial load distribution, and establish the initial blade load distribution function based on the design parameters of the VF120 ducted fan: ,in, is the radial position, is the air density, is the angular velocity of the blade, taking the hub radius , blade tip radius , initial load adjustment factor k = 1.35. Circulation distribution function A fifth-order polynomial fit is used to ensure a smooth transition of the blade tip load. The general form of the polynomial is: The main purpose of this polynomial fitting is to ensure and The circulation distribution between them is reasonable, and the transition is smooth under boundary conditions.

[0031] At step S102, an alternating iterative method is used for optimization, and the gap distribution and the duct profile are updated in sequence. Among them, the alternating iterative method is used for optimization, including: performing a tip clearance optimization iteration under the current duct profile; calculating a new load distribution based on the updated gap distribution; updating the duct profile using the new load distribution; checking convergence, and re-performing tip clearance optimization iteration if it has not converged. It should be noted that the key control parameters in the iterative process, the relaxation factors for gap optimization and load distribution are 0.65-0.79, the maximum limit of the duct profile correction amount is 1.5% of the initial radius, and the convergence criterion can be that the objective function change between two consecutive iterations is less than 0.1%.

[0032] Further, wherein the gap distribution is updated (such as Figure 2 As shown in the figure, it includes: dividing a plurality of calculation stations along the blade tip edge, calculating the leakage flow intensity function at each station; arranging measurement points on the inner wall of the duct according to preset angles, and calculating the wall interference term at each measurement point; solving the optimization coefficient by using a genetic algorithm to obtain a target gap distribution function to update the gap distribution.

[0033] Among them, the duct profile is updated (such as Figure 3 As shown in FIG. 1 ), including: obtaining the initial duct profile and calculating the pressure coefficient distribution; modifying the duct profile according to the pressure gradient; solving the coupled optimization control equations using the time marching method; and determining the source term function through the local curvature change rate of the duct profile.

[0034] In step S103, the coupling effect between the optimization methods is processed by a comprehensive evaluation function, and the optimization parameters are adjusted according to the evaluation results; in order to process the coupling effect between the two optimization methods, the comprehensive evaluation function includes: ,in, Indicates the evaluation results. represents the change in total pressure loss in the blade tip area, represents the load distribution deviation, Represents the average Mach number change. After each complete optimization cycle, evaluate The optimization parameters of the next cycle are adjusted accordingly.

[0035] At step S104, when the relative change value of the comprehensive evaluation function is less than the preset value and meets the target process requirements, the final optimization solution is determined. In one embodiment, the final optimization solution is determined when the following conditions are met: The relative change of the value is less than 0.1%, there is no obvious separation in the blade tip area, and the duct profile meets the processing requirements.

[0036] Figure 2A schematic flow chart of a blade clearance distribution updating method provided in an embodiment of the present application.

[0037] like Figure 2 As shown, in step S201, multiple calculation stations are divided along the blade tip edge, and the leakage flow intensity function is calculated at each station. Taking the ducted fan VF120 model mentioned above as an example, the leakage flow intensity function is calculated based on the design conditions. In the specific calculation, the blade tip edge is divided into 50 calculation stations, and the integral calculation is performed at each station: , where the dynamic viscosity of air is taken as ,density Calculated based on local temperature and pressure. At the tip of the blade where the maximum load is (about 70% of the axial chord length), the typical tangential velocity About 180m / s.

[0038] Preferably, in the calculation of the leakage flow intensity of the blade tip edge of the ducted fan, 50 calculation stations are arranged along the blade tip edge, and integral calculation is performed at each station: , where the parameters are defined as follows: Represents a specific position in the cylindrical coordinate system The leakage flow intensity at , in kg / (m·s); is the axial coordinate, is the radial coordinate, is the circumferential coordinate. In actual calculation, The value range of is [0, c], where c is the axial chord length of the blade; r is the tip radius; and θ takes 50 uniformly distributed calculation positions in the range of [0, 2π]. is the local air flow density, which can be obtained by the ideal gas state equation: ,in is the local static pressure, is the gas constant (for air =287.058 J / (kg·K)), is the local static temperature. Under the design conditions of the ducted fan VF120 model, due to the high-speed rotation and compression effect, the typical density value in the blade tip area is about 1.08 kg / m³. is the tangential velocity component. In the blade tip area, the tangential velocity distribution can be fitted by the following polynomial: ,in, is the arc length coordinate along the blade surface, is the reference speed at the blade tip (about 232 m / s), and the coefficient is obtained based on the fan characteristic curve fitting. = -0.187, =0.246, = -0.298. n is the outward normal unit vector at the calculation station. μ is the air dynamic viscosity, which is 1.789×10^-5 kg / (m·s) at 288.15K. represents the gradient of the tangential velocity in the normal direction and can be calculated using the second-order central difference format: ,in is the normal grid spacing, which is about 0.015 mm in the blade tip area to ensure the calculation accuracy. ds is the curve integral differential element, which is integrated along the blade tip edge.

[0039] In step S202, measuring points are arranged on the inner wall of the duct according to a preset angle, and the wall interference term at each measuring point is calculated. In one embodiment, a measuring point is arranged on the inner wall of the duct every 7.5° along the circumferential direction, and the axial spacing is not greater than 5 mm. The wall interference term is calculated at each measuring point: , wall shear stress Through calculation, under design conditions, the typical value range is 180-250Pa. Obtained by velocity difference at the first layer of grid on the wall.

[0040] Specifically, in the calculation of the wall interference term at the measuring point on the inner wall of the duct: , where the parameters are defined as follows: I(x) represents the wall interference term at the axial position x, in N / m. The integration area is the local wall area centered on the measuring point, with an axial range of [x-Δx, x+Δx] and a circumferential range of [θ-Δθ, θ+Δθ], where Δx = 1.8 mm and Δθ = 4.25°. is the wall shear stress, and its typical value range under design conditions is 215-280Pa, which can be calculated by the wall friction coefficient: ,in is the wall friction coefficient, and the following empirical relationship can be used: , Re is based on the local reference speed The Reynolds number. represents the velocity gradient at the wall, which is obtained by the velocity difference of the first layer of grid on the wall: ,in is the height of the first layer of grid on the wall, which is approximately 0.012 mm on the duct wall to ensure that the y+ value is less than 2. is the velocity value at the center of the first layer of grid, is the velocity value at the wall (no-slip boundary condition). is the area integral differential.

[0041] In step S203, a genetic algorithm is used to solve the optimization coefficients to obtain a target gap distribution function to update the gap distribution. The target gap distribution function includes: ,in, represents the gap distribution, represents the initial gap distribution, Indicates the leakage flow intensity, represents the wall interference term, and Represents the optimization coefficient.

[0042] Specifically, a genetic algorithm is used to optimize the coefficients and Solve the problem, set the population size to 50, and the iteration number to 100. The optimization goal is to minimize the total pressure loss in the blade tip area. The constraints include: 0.2 ≤ α ≤ 0.8, 0.1 ≤ β ≤0.5, and the minimum gap is not less than 0.25 mm (considering processing and thermal expansion margins). Finally, the optimal gap distribution is obtained through iterative calculation.

[0043] Figure 3 A schematic flow chart of a duct profile updating method provided in an embodiment of the present application.

[0044] like Figure 3 As shown, in step S301, the initial duct profile is obtained and the pressure coefficient distribution is calculated. First, the initial duct profile is obtained. , an elliptical profile is used at the inlet lip, with a curvature radius ratio of 2.8. Then the pressure coefficient distribution is calculated: ,in, and are the static pressure and velocity of the incoming flow respectively. Under the design point condition, the Mach number at the lip is about 0.584.

[0045] Specifically, in the calculation of the pressure coefficient distribution of the duct profile: , where the parameters are defined as follows: Represents the pressure coefficient at the axial position x, a dimensionless number. is the local static pressure, which can be obtained by solving the three-dimensional RANS equation. In the duct inlet lip area, the static pressure distribution can be expressed as follows: ,in is the characteristic pressure difference (about 18.5 kPa), k is the pressure attenuation coefficient (≈2.82), and L is the characteristic length of the duct. is the static pressure of incoming flow, which is 101.325 kPa under design conditions. is the incoming flow density, which is 1.225 kg / m³ under standard atmospheric conditions. is the incoming flow velocity. Under the design point conditions, it can be calculated through the mass flow rate and the inlet area: ,in For the design mass flow rate of 0.65 kg / s, under standard inlet conditions, the average inlet axial velocity is calculated by the flow continuity equation to be approximately 168 m / s, and A is the inlet area (≈0.0143 m²).

[0046] At step S302, the duct profile is modified according to the pressure gradient. According to the pressure gradient and the Mach number distribution, the duct profile is modified: .

[0047] In one implementation scenario, in the duct profile correction calculation: , where the parameters are defined as follows: is the modified duct profile radius distribution. is the initial duct profile, and an elliptical profile is used at the inlet lip. The duct profile can be expressed as a piecewise function:

[0048] when When , the elliptic equation is used: ,in is the throat radius (≈86.4 mm), a is the minor semi-axis of the ellipse (≈5.2 mm), and b is the major semi-axis of the ellipse (≈14.56 mm).

[0049] when When , the polynomial is used: , where the coefficient is obtained based on fan performance optimization = 0.0312, = -0.0168, = 0.0094, L is the total length of the duct.

[0050] is the axial gradient of the pressure coefficient, calculated by second-order central difference: , where Δx is the axial grid spacing, which is about 0.42 mm. M(x) is the local Mach number distribution, which can be calculated using the one-dimensional isentropic flow relationship: ,in is the total inlet pressure (101.325 kPa), is the specific heat ratio (1.4). Under the design condition, the typical Mach number at the lip is about 0.612. The integral is numerically calculated using the trapezoidal rule, and the axial step size is 0.42 mm. dx is the axial integral differential. The integral range is [0, L], where L is the total duct length. The integral is numerically calculated using the trapezoidal rule, and the axial step size is 0.5 mm.

[0051] In step S303, the time-marching method is used to solve the coupled optimization control equation. The coupled optimization control equation includes: ,in, Indicated in radius The blade load distribution function at Indicates time, represents the velocity vector, represents the gradient of the load distribution, represents the diffusion coefficient, The Laplace operator representing the load distribution, represents the source function, The equation of the curve representing the duct profile.

[0052] The implicit time marching method can be used to solve the coupled optimization control equations, with a time step of 2×10^-5s and a diffusion coefficient of D = 0.15m² / s.

[0053] At step S304, the source term function is determined by the local curvature change rate of the duct profile. Specifically, the source term function S[R(x)] is determined by the local curvature change rate of the duct profile. Key control parameters in the optimization process: number of blades 12, duct length / diameter ratio 1.15, design point Mach number 0.584, hub ratio 0.494.

[0054] In addition, commercial CFD software such as ANSYS CFX or FLUENT can be used for flow field calculation, and the turbulence model uses the SSTk-ω model. When optimizing the clearance, special attention should be paid to the mesh quality in the tip area. A structured grid can be used to ensure that the orthogonality is not less than 0.85. During the load distribution optimization process, it is necessary to ensure that the blade strength meets the requirements. Finite element analysis can be used to verify the structural reliability of the final solution. In actual processing, the machining accuracy of the tip clearance is required to be high, and five-axis CNC machining equipment can be used for precision assembly. The optimized duct profile needs to consider the processing technology to avoid complex surfaces that are difficult to process.

[0055] Figure 4 A schematic block diagram of an aerodynamic layout optimization design system for matching ducted fan blades with ducts provided in an embodiment of the present application. It should be understood that the system shown in the figure is exemplary and not restrictive. This means that the system architecture involved is not limited to a specific form or design, but is presented as an example. In other words, the architecture shown in the figure can be regarded as a way of expression to clearly describe related concepts and relationships, and does not exclude other forms of architecture. Therefore, when interpreting the architecture in the picture, it should be understood that the model is flexible and diverse, and its purpose is to provide an exemplary description rather than a restrictive provision on a specific form.

[0056] The present application discloses an aerodynamic layout optimization design system for matching ducted fan blades with ducts, which is used to implement the aerodynamic layout optimization design method as described in any of the above embodiments, and the system includes: a fan calculation unit 401, a duct calculation unit 402 and a collaborative control unit 403; wherein the fan calculation unit 401 is used to update the gap distribution; the duct calculation unit 402 is used to update the duct profile; the collaborative control unit 403 is used to establish a blade tip area grid and set an initial load distribution based on the initial design parameters of the ducted fan; an alternating iterative method is used for optimization; a comprehensive evaluation function is used to process the coupling effect between optimization methods, and the optimization parameters are adjusted according to the evaluation results; when the relative change value of the comprehensive evaluation function is less than the preset value and meets the target process requirements, the final optimization scheme is determined.

[0057] Taking the VF120 ducted fan as an example, the optimization implementation process under cruise conditions (speed 28000rad / min) is as follows: First, the initial tip leakage flow intensity is calculated. The typical value at the 70% axial chord length position is: , the calculated value of the wall boundary layer interference term is: , the optimal coefficient obtained by optimization iteration: = 0.435, = 0.283. The final gap value at this position is: . After the load distribution is optimized, the tip tangential velocity under this condition is reduced to 152m / s, and the shock wave intensity is significantly weakened. The maximum correction amount of the duct profile is about 1.2mm, located 85mm downstream of the lip. Through the above optimization design, under cruise conditions, the total pressure loss coefficient in the tip area is reduced from the original 0.082 to 0.064, and the flow separation area is reduced by about 32%.

[0058] In summary, the existing ducted fan blade and duct matching design mainly adopts a simple aerodynamic parameter matching method, that is, the blade angle, chord length and other geometric parameters are adjusted to achieve matching with the duct. This method has the following specific technical problems: Because the traditional design method does not take into account the complex interference effect between the tip leakage flow and the boundary layer of the duct wall, under high load conditions, local separation vortex systems appear in the tip area, resulting in increased flow losses and a thrust coefficient reduction of about 8%-12%. The existing design uses a fixed hub ratio and blade load distribution, which cannot adapt to the changes in flow characteristics under different working conditions. Especially under high angle of attack and transonic conditions, the tip shock wave and boundary layer interference intensifies, causing local flow separation, making the efficiency of the ducted fan drop by 15%-20% compared with the design point under these conditions.

[0059] In order to solve the above technical problems, the embodiment of the present application is based on the complex flow control theory, and establishes an adaptive clearance control model by accurately describing the interaction mechanism between the tip leakage flow and the wall boundary layer. This model can dynamically adjust the tip clearance according to the local flow characteristics, and effectively suppress the formation of the separation vortex system. Based on the fluid-solid coupling theory, by establishing a dynamic matching relationship between the blade load and the duct profile, real-time optimization of the load distribution is achieved. This method can adaptively adjust the duct profile according to the flow characteristics under different working conditions, and improve the shock wave-boundary layer interference effect.

[0060] Through the synergistic effect of the above embodiments, the embodiment scheme of the present application has the following technical effects: Under high-load conditions, through optimized tip clearance control, leakage loss is reduced and the thrust coefficient is increased by about 6%-8%. Through the coordinated optimization of load dynamic distribution and duct profile, the fan efficiency under high angle of attack and transonic conditions is improved by 10%-12%. The combined use of the two methods significantly improves the performance stability of the ducted fan over a wide range of operating conditions, and the operating range is expanded by about 15%.

[0061] Furthermore, an embodiment of the present application also provides an aerodynamic layout optimization device for matching ducted fan blades with ducts, comprising: a processor, a memory, and a system bus; the processor and the memory are connected via the system bus; the memory is used to store one or more programs, and the one or more programs include instructions, which, when executed by the processor, enable the processor to execute any of the above methods.

[0062] Furthermore, an embodiment of the present application also provides a computer program product, which, when executed on a terminal device, enables the terminal device to execute any of the above methods.

[0063] It can be known from the description of the above implementation mode that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment method can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product can be stored in a storage medium such as ROM / RAM, a disk, an optical disk, etc., including several instructions for enabling a computer device (which can be a personal computer, a server, or a network communication device such as a media gateway, etc.) to execute the methods described in the various embodiments of the present application or certain parts of the embodiments.

[0064] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0065] It should also be noted that, in the embodiments of the present application, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements that are not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the statement "comprise one..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0066] The above description of the disclosed embodiments enables professionals and technicians in the field to implement or use the present application. Various modifications to these embodiments will be apparent to professionals and technicians in the field, and the general principles defined in the embodiments of the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the embodiments of the present application, but will conform to the widest range consistent with the principles and novel features disclosed in the embodiments of the present application.

Claims

1. A method for optimizing the aerodynamic layout of a ducted fan blade and duct matching, characterized in that: include: Based on the initial design parameters of the ducted fan, the tip area grid is established and the initial load distribution is set at the same time; in the initialization stage, based on the initial design parameters of the ducted fan, two optimization processes are started at the same time: the tip area grid is established and the clearance value is initialized. , set the initial blade load distribution and initial duct profile : ， in, is the radial position, is the air density, is the angular velocity of the blade, taking the hub radius = 42mm, blade tip radius = 85mm, initial load adjustment factor k = 1.35; circulation distribution function is the fifth-order polynomial fitting function; The optimization is performed in an alternating iterative manner, with the gap distribution and duct profile updated in sequence, including: Among them, the gap distribution update includes: dividing multiple calculation stations along the blade tip edge, calculating the leakage flow intensity function at each station; arranging measurement points on the inner wall of the duct according to preset angles, and calculating the wall interference term at each measurement point; using a genetic algorithm to solve the optimization coefficient to obtain the target gap distribution function to update the gap distribution; The duct profile update includes: obtaining the initial duct profile, calculating the pressure coefficient distribution; and correcting the duct profile according to the pressure gradient: ;in, is the modified duct profile radius distribution; represents the pressure coefficient at the axial position x, is the axial gradient of the pressure coefficient; M(x) is the local Mach number distribution; is the initial duct profile, M(x) is the local Mach number distribution; is the initial duct profile, = ,in is the throat radius, a is the minor semi-axis of the ellipse, and b is the major semi-axis of the ellipse; when When , the polynomial is used: = , The coefficient is obtained based on the fan performance optimization = 0.0312, = -0.0168, = 0.0094, L is the total length of the duct; The time-marching method is used to solve the coupled optimization control equations; the source function is determined by the local curvature change rate of the duct profile; Among them, an alternating iteration method is used for optimization, including: performing a tip clearance optimization iteration under the current duct profile; calculating a new load distribution based on the updated clearance distribution; updating the duct profile using the new load distribution; checking convergence, and re-performing tip clearance optimization iteration if it does not converge; The coupling effect between the optimization methods is processed by a comprehensive evaluation function, and the optimization parameters are adjusted according to the evaluation results; wherein the comprehensive evaluation function includes: ， in, Indicates the evaluation results. represents the change in total pressure loss in the blade tip area, represents the load distribution deviation, represents the average Mach number change; When the relative change value of the comprehensive evaluation function is less than the preset value and meets the target process requirements, the final optimization plan is determined.

2. The aerodynamic layout optimization design method according to claim 1, characterized in that: in, Create a blade tip area mesh, including: Construct a hybrid grid in the blade tip area so that the number of radial grid layers is not less than the set value; Multiple layers of grids are arranged radially in the tip clearance area.

3. The aerodynamic layout optimization design method according to claim 1, characterized in that: in, Set the initial load distribution, including: An initial blade load distribution function is established based on the design parameters of the ducted fan; The circulation distribution function was fitted using a polynomial.

4. The aerodynamic layout optimization design method according to claim 1, characterized in that: in, Target gap distribution function, including: ， in, represents the gap distribution, Indicates the initialization gap value, Indicates the leakage flow intensity, represents the wall interference term, and Represents the optimization coefficient.

5. The aerodynamic layout optimization design method according to claim 1, characterized in that: in, Coupled optimization governing equations, including: ， in, Indicated in radius The blade load distribution function at Indicates time, represents the velocity vector, represents the gradient of the load distribution, represents the diffusion coefficient, The Laplace operator representing the load distribution, represents the source function, The equation of the curve representing the duct profile.

6. An aerodynamic layout optimization design system for matching ducted fan blades with ducts, used to implement the aerodynamic layout optimization design method according to any one of claims 1 to 5, characterized in that: The system comprises: a fan calculation unit, a duct calculation unit and a collaborative control unit; wherein, The fan calculation unit is used to update the gap distribution; The duct calculation unit is used to update the duct profile; The collaborative control unit is used to establish a blade tip area grid and set an initial load distribution based on the initial design parameters of the ducted fan; to optimize by an alternating iterative method; to process the coupling effect between the optimization methods by a comprehensive evaluation function, and to adjust the optimization parameters according to the evaluation results; and to determine a final optimization solution when the relative change value of the comprehensive evaluation function is less than a preset value and meets the target process requirements.

7. An aerodynamic layout optimization device for matching ducted fan blades with ducts, characterized in that: include: A processor, a memory, and a system bus; wherein the processor and the memory are connected via the system bus; The memory is used to store one or more programs, wherein the one or more programs include instructions, and when the instructions are executed by the processor, the processor executes the method according to any one of claims 1 to 5.

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