Method for determining rotor design parameters of coaxial double-rotor plateau loading unmanned aerial vehicle

Abstract

The invention discloses a method for determining rotor design parameters of a coaxial dual-rotor plateau loading unmanned aerial vehicle. The method comprises the following steps: constructing a basic rotor model; establishing a plateau flow field coupling model; dynamic environment parameter mapping: constructing a dynamic model to quantify non-linear correlation between air density and aerodynamic load under different altitude conditions, and calculating an influence rule of altitude on aerodynamic load distribution and rotor consumption power under target tension; carrying out plateau adaptive rotor shape constraint design: mapping plateau environment parameters to rotor torsion angle, chord length distribution and airfoil profile parameters, and analyzing transient aerodynamic response in combination with a time spectrum method and a multi-grid method; and multi-objective collaborative optimization: based on the comprehensive optimization objective function, considering the aerodynamic coupling effect and environmental adaptability between the upper and lower rotors of the coaxial double rotors, taking a phase difference angle of blades of the upper and lower rotors as a variable, taking minimization of lift loss caused by aerodynamic interference as an objective, and generating rotor design parameters through a multi-objective optimization algorithm.

Description

Technical Field

[0001] The present invention relates to the technical fields of electric power inspection UAVs, rotor design, and the like, and in particular to a method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-bearing UAV. Background Art

[0002] At present, the optimization design of conventional helicopter rotor shape is mainly based on the momentum blade element theory and lift line method to carry out theoretical design of rotor negative twist distribution, chord length distribution and airfoil distribution. The expected rotor aerodynamic performance is obtained through theoretical formulas, and then the performance parameters of the rotor are verified through wind tunnel tests. The above theoretical method can quickly estimate the rotor design performance, but the estimation accuracy of the increasingly complex three-dimensional rotor aerodynamic performance is insufficient, and it is unable to consider the complex aerodynamic interference phenomenon of the tilt-rotor multi-rotor aircraft, resulting in a large gap between the theoretically designed tilt-rotor performance and the actual aerodynamic performance.

[0003] In the prior art, accurate rotor comprehensive performance design evaluation indicators are obtained to obtain a target rotor that is closer to the actual aerodynamic performance. However, since the comprehensive performance indicators are usually set based on steady-state conditions, and the air density of the rotor is reduced in a plateau environment, it is easy to affect the thrust and energy consumption of the rotor. Therefore, optimizing the rotor parameters under steady-state conditions cannot solve the problem of reduced thrust and increased energy consumption of the rotor in a plateau environment.

[0004] There is an aerodynamic interference problem with coaxial twin rotors. Due to the counter-rotation of the upper and lower rotors, the mutual coupling of their wake vortex systems will lead to a complex superposition of the induced velocity field, which in turn causes asymmetry in lift distribution and energy loss. Specifically, the downwash airflow generated by the upper rotor will directly affect the inflow conditions of the lower rotor, causing dynamic changes in the local angle of attack of the lower rotor blades, thereby reducing aerodynamic efficiency and increasing power consumption. In addition, the low-density air on the plateau will weaken the lift generation ability of the rotor, while aggravating the diffusion and dissipation of the vortex core, further amplifying the aerodynamic interference effect between the upper and lower rotors, manifested as stronger vibration noise and dynamic stall risk. This interference not only affects the hovering stability and endurance of the drone, but also increases the difficulty of flight attitude control under high-altitude strong turbulence conditions. Therefore, optimizing the phase difference angle and shape parameters of the coaxial twin rotors and suppressing the negative impact of aerodynamic interference on lift and energy consumption are the key to improving the flight performance of drones in plateau environments.

[0005] Therefore, a method for determining rotor design parameters based on a plateau environment is provided to realize that the reduced air density in a plateau environment affects the thrust and energy consumption of the rotor, so as to solve the problem that conventional rotor design methods perform parameter optimization design of the rotor under steady-state conditions. In a plateau environment, the reduced air density can easily affect the thrust and energy consumption of the rotor, which is a problem that technical personnel in this field urgently need to solve.

[0006] In addition, at present, the demand for power inspection drones to operate in high-altitude, mountainous and complex meteorological environments is increasing, especially in high-voltage transmission line inspection tasks in plateau areas. UAVs need to maintain stable flight performance and control accuracy under low pressure, low temperature and strong turbulence conditions. However, traditional rotor design methods are mostly based on standard atmospheric environmental parameters, and do not fully consider the significant impact of low-density air on the aerodynamic efficiency of the rotor, resulting in insufficient lift, sudden increase in energy consumption, and a significant decrease in endurance of drones in low Reynolds number flow fields. In addition, existing rotor optimization technologies are mostly aimed at steady-state aerodynamic performance in plain environments, and lack the ability to actively adapt to transient airflow disturbances in the plateau (such as sudden crosswind changes and near-ground vortex ring effects), making it easy for drones to lose their attitude when flying close to power facilities, and even causing inspection missions to be interrupted. Therefore, there is an urgent need for a rotor design method that integrates dynamic parameters of the plateau environment and multidisciplinary optimization objectives to improve the operational reliability and mission adaptability of drones in extreme climates and complex airspaces. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a method for determining the rotor design parameters of a coaxial twin-rotor plateau load-bearing UAV. First, by obtaining the temperature, humidity, vibration environmental stress and altitude of the plateau environment, the environmental parameters under different altitude conditions are quantified, and the plateau environmental parameters are introduced to optimize the design of the rotor, which can improve the performance of the rotor in high-altitude areas, so that the rotor can better adapt to the high-altitude, low-pressure and low-temperature environment (especially suitable for the stable flight requirements of power inspection UAVs in complex airspaces such as plateau mountainous areas and high-voltage transmission line corridors), ensure the stable operation of the rotor in high-altitude areas (to ensure the attitude control accuracy and safety of the UAV when operating close to power facilities in strong side winds and low-density flow fields), optimize the rotor design through different optimization parameters, significantly improve the lift-to-drag ratio, reduce aerodynamic drag, thereby improving hovering efficiency, forward flight efficiency and overall flight performance (meeting the requirements of long-duration hovering observation, rapid forward flight transition and maneuvering response under sudden working conditions in power inspection tasks), and enhance flight stability and response sensitivity (providing anti-interference ability and precise controllability for UAVs in high-voltage electromagnetic interference environments or narrow inspection channels).

[0008] On the basis of obtaining a general rotor optimization design scheme, aimed at the actual needs of rotor optimization of coaxial twin-rotor plateau load-bearing UAV, the aerodynamic coupling effect and environmental adaptability between the upper and lower rotors of the coaxial twin-rotor were considered, and the phase difference angle of the upper and lower rotor blades was taken as a variable. The goal was to minimize the lift loss caused by aerodynamic interference, and the rotor design parameters were generated through a multi-objective optimization algorithm.

[0009] The present invention specifically adopts the following technical solutions: A method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV comprises the following steps: Determine the geometric and aerodynamic parameter ranges of the original rotor based on the aircraft parameters and generate basic rotor parameters; By combining the lift-torque dynamics equation with the free wake model, the aerodynamic load distribution under the low-density flow field is simulated, and the aerodynamic load distribution is used as the input data for the rotor shape constraint design; The temperature, humidity and altitude of the plateau environment are obtained, and a dynamic model is constructed to quantify the nonlinear relationship between air density and aerodynamic load under different altitude conditions, which is used to correct the aerodynamic shape parameter mapping rules in the rotor shape constraint design; the influence of altitude on the aerodynamic load distribution and the rotor power consumption under the target thrust are calculated by the Newton iteration method, and the influence law and power consumption are used as input parameters for multi-objective optimization; Based on the basic rotor parameters, the rotor shape constraint design is carried out: the plateau environmental parameters are mapped to the rotor twist angle, chord length distribution and airfoil profile parameters in the basic rotor parameters, and the transient aerodynamic response is analyzed by combining the time spectrum method and the multi-grid method; the comprehensive optimization objective function is defined according to the transient aerodynamic response results; Perform multi-objective optimization: Based on the comprehensive optimization objective function, a multi-objective optimization algorithm is used to generate rotor design parameters suitable for the plateau environment.

[0010] The generation of basic rotor parameters not only provides an initial design benchmark, but also constrains the dynamic adjustment range in plateau environments. It defines the initial design space and constraints for optimization, ensuring that the parameters are dynamically adjusted within a reasonable range in subsequent steps.

[0011] The aerodynamic load distribution binds aerodynamic performance and structural parameters through dynamic data to ensure that the optimization results meet the actual needs of the low-density flow field in the plateau. The subsequent optimization of the rotor twist angle, chord length distribution and airfoil profile parameters is combined with the rotor parameters themselves and the lift distribution, pressure distribution, torque distribution, etc. in the aerodynamic load distribution.

[0012] The influence law is a representation of the solution of the Newton iteration method, including the law of change of power with altitude; F is used to correct the aerodynamic efficiency term in multi-objective optimization. s / F ρ part.

[0013] Furthermore, generating basic rotor parameters includes: Determine the rotor radius, chord length distribution, airfoil series and number of blades based on the aircraft type and mission profile; Parameterize the design parameters of the forward-swept, backward-swept, and downward-reversed feature points to generate a geometrically sensitive space; A parameter combination is selected in the geometrically sensitive space to construct a basic propeller type.

[0014] Furthermore, the free wake model discretizes the blade tip vortex through a viscous vortex particle algorithm, and adopts a viscous vortex core empirical model to describe the distortion and dissipation of the vortex; the vortex particles are initialized according to the rotor speed and pitch angle, and the wake motion trajectory is tracked through a Lagrangian method; The construction of the free wake model includes: Based on the vorticity-velocity form of the incompressible Navier-Stokes equations, the vortex structure in the flow field is discretized into viscous vortex particles that carry vorticity, position and intensity information. The amount of attached vortex ring on the rotor surface is calculated by combining the lifting surface theory, and the newly generated vortex particles are released in real time according to the rotor movement to simulate the generation process of the blade tip vortex and the wake vortex. The generation process of the tip vortex and the wake vortex is coupled to output the free wake model.

[0015] Furthermore, the dynamic model is constructed based on the unsteady Navier-Stokes equations and free vortex theory. After the rotor aerodynamic load is input, the influence of the plateau low-density air on the drag attenuation of the aerodynamic load and the power consumption is output; the convergence condition of the Newton iteration method is the speed change threshold , where n is the rotor speed and m is the number of iterations; the rotor power consumption is calculated by the formula Calculate, where c is the power system efficiency coefficient; the air density Calculate, where For altitude The air density at is the air density at sea level, h is the altitude, and H is the attenuation height coefficient.

[0016] Furthermore, the analysis of transient aerodynamic response by combining the time spectrum method with the multi-grid method includes: Capturing the transient aerodynamic characteristics of rotor dynamic stall by using time spectrum method; Use multi-grid method to accelerate flow field solution to improve the prediction accuracy of aerodynamic shape parameters; The parameters of the rotor shape constraint include: Airfoil section shape parameters: Optimize leading edge radius, maximum camber position and trailing edge angle based on thin wing theory; Propeller tip geometric characteristic parameters: aerodynamic modification design for noise reduction; Blade span parameters: used for coupling optimization of half span and installation angle; The optimization of the airfoil section shape parameters includes dynamically adjusting the geometric shape under different Reynolds numbers.

[0017] Furthermore, the aerodynamic efficiency term is related to lift, power and drag, and the structure-stability term is related to blade pressure distribution and rotor solidity; the aerodynamic efficiency term is , the structural-stability term is ,in , P max The maximum power consumed by the rotor in a hovering state to generate the maximum hovering lift under different atmospheric densities is: is the rotor material performance coefficient, is the lift of the aircraft, The density of the atmosphere in which the aircraft is resistance, is the blade root pressure, is the blade tip pressure, is the pressure difference between the upper and lower surfaces of the blade.

[0018] Furthermore, the rotor design parameters adapted to the plateau environment are generated through a multi-objective optimization algorithm. Specifically, the multi-objective optimization design is carried out through the NSGA-II multi-objective optimization algorithm, and the rotor aerodynamic shape is iteratively optimized through selection, crossover, and mutation genetic operators to obtain the Pareto optimal solution set.

[0019] Furthermore, the rotor is a coaxial twin rotor, and the negative impact of aerodynamic interference on lift and energy consumption is suppressed by optimizing the phase difference angle and shape parameters of the coaxial twin rotor; the optimization design includes: The phase difference angle φ between the upper and lower rotors is taken as the design variable, and the influence of φ on the transient aerodynamic load is analyzed by combining the time spectrum method. The coupling effect of the velocity field induced by the upper and lower rotors is calculated based on the viscous vortex particle algorithm. By formula: To quantify, , They represent the circulation distribution of the upper and lower rotors respectively, , is the induced velocity field; R is the rotor radius, ρ is the air density; The phase difference angle φ and rotor shape parameters are collaboratively iteratively optimized through the NSGA-II multi-objective optimization algorithm to generate the Pareto optimal solution set.

[0020] And, an aircraft, characterized in that its rotor is obtained by optimizing the design according to the method described above.

[0021] And, a system for determining rotor design parameters of a coaxial dual-rotor high-altitude load-carrying UAV, comprising: A basic rotor modeling module is used to determine the geometric and aerodynamic parameter ranges of the original rotor based on the aircraft parameters and generate basic rotor parameters; The plateau flow field coupling module simulates the aerodynamic load distribution under low-density flow fields by combining the lift-torque dynamic equation with the free wake model. The aerodynamic load distribution is used as the input data for the rotor shape constraint design. The environmental parameter processing module is used to obtain the temperature, humidity and altitude of the plateau environment, build a dynamic model to quantify the nonlinear relationship between air density and aerodynamic load under different altitude conditions, and correct the aerodynamic shape parameter mapping rules in the rotor shape constraint design; calculate the influence of altitude on the aerodynamic load distribution and the rotor power consumption under the target thrust through the Newton iteration method, and the influence law and power consumption are used as input parameters for multi-objective optimization; A rotor shape constraint design module is used to perform rotor shape constraint design based on basic rotor parameters, map plateau environmental parameters to rotor twist angle, chord length distribution and airfoil profile parameters in the basic rotor parameters, analyze transient aerodynamic response by combining time spectrum method and multi-grid method, and define a comprehensive optimization objective function according to the transient aerodynamic response results; map plateau environmental parameters to rotor twist angle, chord length distribution and airfoil profile parameters, analyze transient aerodynamic response by combining time spectrum method and multi-grid method, and define a comprehensive optimization objective function according to the transient aerodynamic response results; The multi-objective optimization module is used to generate rotor design parameters adapted to the plateau environment through a multi-objective optimization algorithm based on the comprehensive optimization objective function.

[0022] And, an electronic device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the program.

[0023] A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that the computer program implements the steps of the above method when executed by a processor.

[0024] Compared with the prior art, the present invention and its preferred solution can improve the performance of the rotor in high altitude areas, reduce the drag loss, and improve the efficiency in hovering and forward flight states by introducing plateau environmental parameters to optimize the design of the rotor, which is especially suitable for the long-flight hovering observation and rapid transition requirements of power inspection UAVs in complex terrain in plateau mountains. By introducing plateau environmental parameters to optimize the design of the rotor, the rotor can better adapt to the high altitude, low pressure and low temperature environment (solve the problems of insufficient lift and weak crosswind resistance caused by low-density air in power inspection tasks), reduce the performance degradation caused by environmental changes, and ensure the stable operation of the rotor in high altitude areas (guarantee the attitude stability and safe obstacle avoidance of the UAV in the electromagnetic interference environment of the high-voltage transmission line corridor). By optimizing the blade shape and angle of attack design, more air can be pushed at the same speed, thereby reducing energy consumption and extending the flight time (meeting the dual requirements of power inspection tasks for endurance and maneuvering response to sudden working conditions). By combining the rotor aerodynamic basic model with the free wake model, the rotor aerodynamic model is obtained, which can accurately describe the flow field characteristics of the rotor under different flight conditions (for high-precision prediction of complex flow fields such as near-ground flight and gust disturbances during power inspection), significantly improve the accuracy of aerodynamic load prediction, and provide reliable data support for optimization design. The rotor aerodynamic model integrates aerodynamics, structural dynamics and flight mechanics parameters, supports the coordinated optimization of the rotor aerodynamic shape, structural strength and flight performance (the optimized rotor takes into account both anti-turbulence capability and control sensitivity in narrow inspection channels), and analyzes the aerodynamic performance in hovering and forward flight states through the free wake model, which can clarify the change law of the lift-to-drag ratio of the rotor type at different altitudes. Through the optimization parameters of the rotor torsion angle and the chord length distribution, the thrust and efficiency of the rotor in a low-density environment can be optimized, and the optimization parameters of the airfoil profile shape, the optimization parameters of the blade tip geometry and the blade span optimization parameters can be obtained. The geometric shape of each blade section can be dynamically adjusted through the optimization parameters of the airfoil section shape, so that it maintains a high lift-to-drag ratio at different Reynolds numbers (to meet the aerodynamic stability requirements of power inspection drones when flying across altitudes from low-altitude plains to plateau operating areas), ensuring the stability of aerodynamic performance within a wide Reynolds number range. The optimization parameters of the blade tip geometry can locally optimize the blade tip shape, reduce rotor noise while improving aerodynamic efficiency (reduce interference with acoustic detection of high-voltage equipment during drone inspections), and optimize the blade spanwise optimization parameters to optimize the blade half-span and installation angle coupling parameters, improve the lift-to-drag ratio and anti-interference capability of the rotor (enhance anti-interference and precise hovering capabilities in high-voltage electromagnetic field environments). By optimizing the rotor design through different optimization parameters, the lift-to-drag ratio can be significantly improved, aerodynamic drag can be reduced, and thus hovering efficiency, forward flight efficiency and overall flight performance can be improved (providing high-precision and high-reliability flight platform support for refined inspection of transmission lines). BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 The present invention is a flowchart of a method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV according to an embodiment of the present invention.

[0026] Figure 2 This is a comparison chart of the lift-to-drag ratio of the front and rear airfoils optimized in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] Hereinafter, the specific embodiments of the present application will be described in detail with reference to the accompanying drawings. According to these detailed descriptions, those skilled in the art can clearly understand the present application and can implement the present application. Without violating the principles of the present application, the features in the various embodiments can be combined to obtain new implementations, or certain features in certain embodiments can be replaced to obtain other preferred implementations.

[0028] In order to make the features and advantages of the present invention more clearly understood, the following embodiments are specifically described in detail with reference to the accompanying drawings: The embodiments of the present invention provide Figure 1 The specific process of the method for determining the rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV shown in the figure includes the following steps: S1: Obtain relevant parameters of the aircraft, determine the parameters of the original rotor according to the relevant parameters of the aircraft, and obtain the basic propeller type according to the original rotor parameters; As a preferred solution of this embodiment, the method for obtaining the original rotor parameters specifically includes: Parameterizing the original rotor to obtain the design parameter range of the rotor characteristic points, wherein the rotor characteristic points include: forward-sweep characteristic points, backward-sweep characteristic points, downward-reverse characteristic points and rotor aerodynamic parameters; Different parameters are selected within the design parameter range of the rotor feature points to construct the basic rotor of the aircraft. The rotor aerodynamic parameters are selected as follows:

[0029] Where T is the tension parameter, is the lift coefficient, is the air density, D is the rotor diameter, and n is the rotor speed; in, is the power parameter to overcome the resistance torque, is the power coefficient;

[0030]

[0031] in, is the efficiency parameter, J is the pitch ratio, reflecting the airflow angle at the blade tip, and V is the axial speed.

[0032] S2: Use the parameters of the basic propeller type obtained in S1 to build a rotor aerodynamic model, use the rotor aerodynamic model to simulate the aerodynamic performance of the basic rotor, and obtain the aerodynamic load of the rotor; As a preferred solution of this embodiment, the method of constructing a rotor aerodynamic model using the parameters of the original rotor specifically includes: Based on the rotor radius, rotor chord length and speed parameters, the dynamic equations of lift and torque are established, including the interaction between propellers and the effect of air resistance; The rotor force and moment are calculated by combining the rotor and fuselage with wind tunnel data, and the unsteady aerodynamic model is used to describe the change of the rotor's local aerodynamic load. Calculate the flow field disturbance during near-ground flight through the NS equation and correct the pull and torque coefficients; The basic rotor aerodynamic model is established using the dynamic equations of lift and torque, the change of local aerodynamic loads on the rotor, and the thrust and torque coefficients, as follows: The viscous vortex particle algorithm is used to spatially discretize the rotor tip vortex through line vortex discretization, and the viscous vortex core empirical model is used to reflect the distortion and dissipation of the blade tip vortex, and a free wake model is established. The rotor aerodynamic basic model and free wake model are integrated into the rotor aerodynamic model.

[0033] Establish a free wake model, including: Based on the vorticity-velocity form of the incompressible Navier-Stokes equations, the vortex structure in the flow field is discretized into viscous vortex particles, each of which carries vorticity, position and intensity information. The large-scale vortex in the rotor wake is discretized into small vortex elements, and the motion trajectory of the rotor wake is described by the Lagrangian method. Initialize the vortex particle distribution according to the rotor speed and pitch angle, set the initial vortex field and calculate the vortex particle transport process; The amount of attached vortex ring on the rotor surface is calculated by combining the lifting surface theory, and the newly generated vortex particles are released in real time according to the rotor movement to simulate the generation process of the blade tip vortex and the wake vortex. The generation process of the tip vortex and the wake vortex is coupled to obtain the free wake model, which is specifically expressed as follows: ‌ in, is the radial position of the vortex element on the blade The position vector at is the free velocity vector, is the azimuth, is the vortex age, is the wake distortion; In this step, the rotor aerodynamic model is obtained by combining the rotor aerodynamic basic model with the free wake model. The aerodynamic basic model can accurately describe the flow field characteristics of the rotor in different flight states, such as induced velocity distribution and aeroelastic coupling effect, by integrating free wake analysis, blade-vortex interference effect and nonlinear blade torsion distribution factors, significantly improving the accuracy of aerodynamic load prediction and providing reliable data support for optimized design. The rotor aerodynamic model integrates aerodynamics, structural dynamics and flight mechanics parameters, supports the coordinated optimization of the rotor aerodynamic shape, structural strength and flight performance, and can achieve rapid and high-precision simulation of the rotor flow field. By analyzing the aerodynamic performance in hovering and forward flight states through the free wake model, the change law of the lift-to-drag ratio of the rotor type at different altitudes can be clarified.

[0034] S3: Obtain the temperature, humidity and altitude of the plateau environment, quantify the environmental parameters under different altitude conditions, and calculate the influence of altitude on the aerodynamic load distribution and the rotor power consumption under the target thrust through the Newton iteration method; As a preferred solution of this embodiment, the influence of altitude on aerodynamic load distribution is determined by calculating through Newton iteration method, specifically including: A dynamic model is constructed based on the unsteady Navier-Stokes equations and free vortex theory, the aerodynamic load of the rotor is input into the dynamic model, and the influence of low-density air on the aerodynamic load of the rotor is output; The Newton iteration method is used to calculate the rotor power consumption under the target thrust due to altitude, as follows: in, is the tensile force value, are the rotor geometric parameters, is the rotor speed, For altitude The air density at is the target pulling force, is the air density at sea level, H is the attenuation height; Update the rule using Newton's iteration method: Convergence is judged when Stop iteration when ,; ‌Calculate power‌ and substitute the converged Value to power formula:

[0035] in, is the power system efficiency coefficient.

[0036] S4: Determine the design constraints and optimization objectives of the rotor shape based on the relevant parameters and mission profile of the aircraft, combined with environmental parameters under different altitude conditions and rotor power consumption under target thrust; As a preferred solution of this embodiment, determining the design constraints of the rotor shape specifically includes: Mapping plateau environmental parameters to rotor design parameters, and obtaining parameters for adjusting rotor twist angle and chord length distribution; When the rotor is in flight, the transient aerodynamic response analysis of the rotor is carried out by coupling the time spectrum method and the multi-grid method to obtain the aerodynamic shape parameters of the rotor. Based on the thin wing theory, the high lift-to-drag ratio airfoil in a wide Reynolds number range is determined, and the airfoil section shape parameters, blade tip geometric characteristic parameters and blade span parameters are obtained; As a preferred solution of this embodiment, determining the optimization target specifically includes:

[0037]

[0038] Where, P is the power consumption, P max The maximum power consumed by the rotor in a hovering state to generate the maximum hovering lift under different atmospheric densities is: is the atmospheric density, is the atmospheric density at altitude i, To optimize the goal, is the rotor material performance coefficient, is the lift of the aircraft, The density of the atmosphere in which the aircraft is resistance, is the blade root pressure, is the blade tip pressure, is the pressure difference between the upper and lower surfaces of the blade.

[0039] In this step, the thrust and efficiency of the rotor in a low-density environment can be optimized by optimizing the rotor twist angle and chord length distribution parameters, and the airfoil section shape optimization parameters, blade tip geometry optimization parameters, and blade span optimization parameters are obtained. The airfoil section shape optimization parameters can be used to dynamically adjust the geometry of each blade section so that it maintains a high lift-to-drag ratio at different Reynolds numbers and ensures the stability of aerodynamic performance within a wide Reynolds number range. The blade tip geometry optimization parameters can locally optimize the blade tip shape to reduce rotor noise while improving aerodynamic efficiency. The blade span optimization parameters can be used to optimize the blade semi-span and installation angle coupling parameters to improve the lift-to-drag ratio and anti-interference capability of the rotor. The optimization results are as follows: Figure 2as shown.

[0040] By "introducing plateau environmental parameters and optimizing the design of the rotor, the performance of the rotor in high altitude areas can be improved, the thrust loss can be reduced, the efficiency in hovering and forward flight can be improved, the rotor can better adapt to the high altitude, low pressure and low temperature environment, reduce the performance degradation caused by environmental changes, ensure the stable operation of the rotor in high altitude areas, push more air at the same speed, thereby reducing energy consumption and extending flight time" technical solution can achieve the technical effect of "reduced thrust and increased energy consumption of the rotor in plateau environment".

[0041] S5: Optimize the rotor design according to the design constraints and optimization objectives of the rotor shape; As a preferred solution of this embodiment, the design optimization of the rotor specifically includes: The multi-objective optimization design is carried out through the NSGA-II multi-objective optimization algorithm. The iterative optimization of the rotor aerodynamic shape is carried out through the selection, crossover and mutation genetic operators to obtain the Pareto optimal solution set. The iterative optimization of the rotor aerodynamic shape is carried out through the selection, crossover and mutation genetic operators, as follows:

[0042] ' is the fitness convergence threshold, is the maximum number of iterations, For the The optimal fitness value ‌ ; The Pareto optimal solution set is analyzed and processed to determine whether the optimization converges. If it converges, the result is output, and an optimal solution that meets the design requirements is selected and ended. Otherwise, a new optimal solution is selected as the new initial solution and NSGA-II is used again to carry out multi-objective optimization design.

[0043] As a preferred embodiment, in a plateau environment, the coordinated optimization of the coaxial twin rotors needs to comprehensively consider the aerodynamic coupling effect and environmental adaptability between the upper and lower rotors. By introducing the phase difference parameterization design, the phase difference angle of the upper and lower rotor blades is adjusted. As the key variable, the objective function is to minimize the lift loss caused by aerodynamic interference. ,in It is generated by the interaction of the induced velocity fields of the upper and lower rotor wakes, and its dynamic distribution is calculated by the viscous vortex particle algorithm: In the formula , They represent the circulation distribution of the upper and lower rotors respectively, , is the induced velocity field.

[0044] Combined with time spectrum analysis In order to study the influence of transient aerodynamic loads, the NSGA-II multi-objective optimization algorithm is used to realize the collaborative iterative optimization of phase difference and rotor shape parameters, and finally generate the Pareto optimal solution set.

[0045] Based on the same inventive concept, the present invention also provides a computer device, which includes: one or more processors, and a memory for storing one or more computer programs; the program includes program instructions, and the processor is used to execute the program instructions stored in the memory. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is used to implement one or more instructions, specifically used to load and execute one or more instructions in a computer storage medium to implement the above method.

[0046] It should be further explained that, based on the same inventive concept, the present invention also provides a computer storage medium, on which a computer program is stored, and the computer program is executed by the processor to execute the above method. The storage medium can adopt any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electrical, magnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present invention, a computer-readable storage medium can be any tangible medium containing or storing a program, which can be used by an instruction execution system, device or device or used in combination with it.

[0047] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0048] The above shows and describes the basic principles, main features and advantages of the present disclosure. Those skilled in the art should understand that the present disclosure is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present disclosure. Without departing from the spirit and scope of the present disclosure, the present disclosure may have various changes and improvements, and these changes and improvements fall within the scope of the present disclosure to be protected.

[0049] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of methods for determining rotor design parameters based on plateau environments under the inspiration of the present invention. All equal changes and modifications made within the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV, characterized in that: The following steps are involved: Determine the geometric and aerodynamic parameter ranges of the original rotor based on the aircraft parameters and generate basic rotor parameters; By combining the lift-torque dynamics equation with the free wake model, the aerodynamic load distribution in low-density flow fields is simulated; The temperature, humidity and altitude of the plateau environment are obtained, and a dynamic model is constructed to quantify the nonlinear relationship between air density and aerodynamic load under different altitude conditions, which is used to correct the aerodynamic shape parameter mapping rules in the rotor shape constraint design; the influence of altitude on the aerodynamic load distribution and the rotor power consumption under the target thrust are calculated by the Newton iteration method; Mapping plateau environmental parameters to the rotor twist angle, chord length distribution and airfoil profile parameters in the basic rotor parameters, analyzing transient aerodynamic response by combining time spectrum method and multi-grid method; defining a comprehensive optimization objective function according to the transient aerodynamic response results; Based on the comprehensive optimization objective function, rotor design parameters adapted to the plateau environment are generated through a multi-objective optimization algorithm.

2. The method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV according to claim 1 is characterized by: The generating basic rotor parameters comprises: Determine the rotor radius, chord length distribution, airfoil series, and number of blades based on the aircraft type and mission profile; Parameterize the design parameters of the forward-swept, backward-swept, and downward-reversed feature points to generate a geometrically sensitive space; A parameter combination is selected in the geometrically sensitive space to construct a basic propeller type.

3. The method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV according to claim 1 is characterized by: The free wake model discretizes the blade tip vortex through a viscous vortex particle algorithm, and uses a viscous vortex core empirical model to describe the distortion and dissipation of the vortex; the vortex particles are initialized according to the rotor speed and pitch angle, and the wake motion trajectory is tracked through a Lagrangian method; The construction of the free wake model includes: Based on the vorticity-velocity form of the incompressible Navier-Stokes equations, the vortex structure in the flow field is discretized into viscous vortex particles that carry vorticity, position and intensity information. The amount of attached vortex ring on the rotor surface is calculated by combining the lifting surface theory, and the newly generated vortex particles are released in real time according to the rotor movement to simulate the generation process of the blade tip vortex and the wake vortex. The generation process of the tip vortex and the wake vortex is coupled to output the free wake model.

4. The method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV according to claim 1 is characterized by: The dynamic model is constructed based on the unsteady Navier-Stokes equations and free vortex theory. After the rotor aerodynamic load is input, the influence of the plateau low-density air on the drag attenuation of the aerodynamic load and the power consumption is output; the convergence condition of the Newton iteration method is the speed change threshold , where n is the rotor speed and m is the number of iterations; the rotor power consumption is calculated by the formula Calculate, where c is the power system efficiency coefficient; the air density Calculate, where For altitude The air density at is the air density at sea level, h is the altitude, is the attenuation height coefficient.

5. The method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV according to claim 1 is characterized by: The analysis of transient aerodynamic response by combining the time spectrum method with the multi-grid method includes: Capturing the transient aerodynamic characteristics of rotor dynamic stall by using time spectrum method; Use multi-grid method to accelerate flow field solution to improve the prediction accuracy of aerodynamic shape parameters; The parameters of the rotor shape constraint include: Airfoil section shape parameters: Optimize leading edge radius, maximum camber position and trailing edge angle based on thin wing theory; Propeller tip geometric characteristic parameters: aerodynamic modification design for noise reduction; Blade span parameters: used for coupling optimization of half span and installation angle; The optimization of the airfoil section shape parameters includes dynamically adjusting the geometric shape under different Reynolds numbers.

6. The method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV according to claim 1 is characterized by: The comprehensive optimization objective function is composed of the addition of an aerodynamic efficiency term and a structural-stability term: the aerodynamic efficiency term is related to lift, power and drag, and the structural-stability term is related to blade pressure distribution and rotor solidity; the aerodynamic efficiency term is , the structural-stability term is ,in, The maximum power consumed by the rotor in a hovering state to generate the maximum hovering lift under different atmospheric densities is: is the rotor material performance coefficient, is the lift of the aircraft, The density of the atmosphere in which the aircraft is resistance, is the blade root pressure, is the blade tip pressure, is the pressure difference between the upper and lower surfaces of the blade.

7. The method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV according to claim 1 is characterized by: The rotor design parameters adapted to the plateau environment are generated through a multi-objective optimization algorithm. Specifically, the multi-objective optimization design is carried out through the NSGA-II multi-objective optimization algorithm, and the aerodynamic shape of the rotor is iteratively optimized through selection, crossover, and mutation genetic operators to obtain the Pareto optimal solution set.

8. The method for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV according to claim 1 is characterized by: The rotor is a coaxial twin rotor, and the optimized design includes: The phase difference angle φ between the upper and lower rotors is taken as the design variable, and the influence of φ on the transient aerodynamic load is analyzed by combining the time spectrum method. The coupling effect of the velocity field induced by the upper and lower rotors is calculated based on the viscous vortex particle algorithm. By formula: To quantify, , They represent the circulation distribution of the upper and lower rotors respectively, , is the induced velocity field; R is the rotor radius, ρ is the air density; The phase difference angle φ and rotor shape parameters are collaboratively iteratively optimized through the NSGA-II multi-objective optimization algorithm to generate the Pareto optimal solution set.

9. An aircraft, characterized in that: The rotor is obtained by optimizing the design according to any one of claims 1 to 8.

10. A system for determining rotor design parameters of a coaxial twin-rotor high-altitude load-bearing UAV, characterized in that: include: A basic rotor modeling module is used to determine the geometric and aerodynamic parameter ranges of the original rotor based on the aircraft parameters and generate basic rotor parameters; The plateau flow field coupling module simulates the aerodynamic load distribution under low-density flow fields by combining the lift-torque dynamics equation with the free wake model; Environmental parameter processing module, used to obtain the temperature, humidity and altitude of the plateau environment, build a dynamic model to quantify the nonlinear relationship between air density and aerodynamic load under different altitude conditions, and to correct the aerodynamic shape parameter mapping rules in the rotor shape constraint design; calculate the influence of altitude on aerodynamic load distribution and rotor power consumption under target thrust through Newton iteration method; The rotor shape constraint design module is used to perform rotor shape constraint design, map the plateau environmental parameters to the rotor twist angle, chord length distribution and airfoil profile parameters in the basic rotor parameters, analyze the transient aerodynamic response by combining the time spectrum method and the multi-grid method, and define the comprehensive optimization objective function according to the transient aerodynamic response results; The multi-objective optimization module is used to generate rotor design parameters adapted to the plateau environment through a multi-objective optimization algorithm based on the comprehensive optimization objective function.

11. The system for determining rotor design parameters of a coaxial twin-rotor high-altitude load-carrying UAV according to claim 10, characterized in that: The dynamic model is constructed based on the unsteady Navier-Stokes equations and free vortex theory. After the rotor aerodynamic load is input, the influence of the plateau low-density air on the drag attenuation of the aerodynamic load and the power consumption is output; the convergence condition of the Newton iteration method is the speed change threshold , where n is the rotor speed and m is the number of iterations; the rotor power consumption is calculated by the formula Calculate, where c is the power system efficiency coefficient; the air density Calculate, where For altitude The air density at is the air density at sea level, h is the altitude, is the attenuation height coefficient; The comprehensive optimization objective function is composed of the addition of an aerodynamic efficiency term and a structural-stability term: the aerodynamic efficiency term is related to lift, power and drag, and the structural-stability term is related to blade pressure distribution and rotor solidity; the aerodynamic efficiency term is , the structural-stability term is ,in , The maximum power consumed by the rotor in a hovering state to generate the maximum hovering lift under different atmospheric densities is: is the rotor material performance coefficient, is the lift of the aircraft, The density of the atmosphere in which the aircraft is The resistance is the pressure at the root of the blade, is the blade tip pressure, is the pressure difference between the upper and lower surfaces of the blade; The rotor is a coaxial twin rotor, and the optimized design includes: The phase difference angle φ between the upper and lower rotors is taken as the design variable, and the influence of φ on the transient aerodynamic load is analyzed by combining the time spectrum method. The coupling effect of the velocity field induced by the upper and lower rotors is calculated based on the viscous vortex particle algorithm. By formula: To quantify, , They represent the circulation distribution of the upper and lower rotors respectively, , is the induced velocity field; R is the rotor radius, ρ is the air density; The phase difference angle φ and rotor shape parameters are collaboratively iteratively optimized through the NSGA-II multi-objective optimization algorithm to generate the Pareto optimal solution set.

12. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the method according to any one of claims 1 to 8 are implemented.

13. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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