A distributed multi-rotor tiltwing aircraft and method of aerodynamic layout optimization

Abstract

The application provides a distributed multi-rotor tilting wing aircraft and an aerodynamic layout optimization method, which comprises the following steps: step 1, determining the layout optimization variables and their threshold ranges of the aircraft according to the layout characteristics of a reference distributed multi-rotor tilting wing aircraft and overall design requirements; step 2, establishing an aerodynamic interference calculation model of the reference distributed multi-rotor tilting wing aircraft; step 3, establishing an aerodynamic interference influence evaluation index, calculating the aerodynamic interference characteristics of the distributed multi-rotor tilting wing aircraft in the hovering and forward flight states, and determining the optimized state of the aircraft; step 4, determining the to-be-optimized variables according to the determined optimized state of the aircraft; step 5, analyzing the aerodynamic performance influence law of the to-be-optimized variables in the optimized state of the aircraft; and step 6, determining the value range of the to-be-optimized variables according to the aerodynamic performance influence law and in combination with the configuration parameter limits.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aircraft aerodynamic design, and particularly relates to a distributed multi-rotor tilting wing aircraft and an aerodynamic layout optimization method. BACKGROUND

[0002] The distributed multi-rotor tilting wing aircraft is a new type of rotor aircraft, which can realize vertical take-off and landing and high-speed flight. On the basis of the tilting wing, the distributed rotor layout is adopted, and multiple rotors are distributed on the leading edge of the wing and can tilt with the whole rotor. The multiple rotor units of this configuration can be designed as lift propeller units and screw propeller units. In the vertical take-off and landing state, all rotor units work together. In the high-speed forward flight state, the lift propeller units are folded, and the screw propeller provides forward flight power. The distributed multi-rotor tilting wing aircraft is one of the important development directions of future new type high-speed rotor aircraft.

[0003] The distributed multi-rotor tilting wing aircraft has complex interference between rotors, rotors / airfoils, and front and rear airfoils. The aerodynamic interference has an important influence on the aerodynamic characteristics of the whole aircraft. Therefore, the aerodynamic interference problem between components should be considered in the aerodynamic layout design of the distributed multi-rotor tilting wing aircraft.

[0004] The aeronautical industry 602 (patent application number 201911229120.8) proposes a distributed multi-rotor tilting wing aircraft, which refers to the distributed layout of high-cruise-speed fixed-wing aircraft and long-endurance VTOL aircraft. According to engineering experience, the design scheme preliminarily considers the influence of partial aerodynamic interference and makes relevant layout design, but there is still a large optimization design space.

[0005] The current distributed multi-rotor tilting wing aircraft design has the following deficiencies: the aerodynamic interference is usually considered according to design experience or simple engineering algorithm,

[0006] The influence of aerodynamic interference cannot be fully evaluated, resulting in that the designed aerodynamic layout cannot meet the requirements and delays the development progress. SUMMARY

[0007] The application proposes a distributed multi-rotor tilting wing aircraft and an aerodynamic layout optimization method, which can fully consider the influence of aerodynamic interference and improve the comprehensive performance of the aerodynamic layout.

[0008] TECHNICAL SCHEME

[0009] An aerodynamic layout optimization method of a distributed multi-rotor tilting wing aircraft, comprising the following steps:

[0010] Step 1: According to the layout characteristics of the reference distributed multi-rotor tilting wing aircraft and the overall design requirements, the layout optimization variables and their threshold ranges of the aircraft are determined;

[0011] Step 2: Establishing the aerodynamic interference calculation model of the baseline distributed multi-rotor tilt-wing aircraft;

[0012] Step 3: Establishing the aerodynamic interference impact evaluation index, calculating the aerodynamic interference characteristics of the distributed multi-rotor tilt-wing aircraft in hovering and forward flight states, and determining the aircraft to be optimized state;

[0013] Step 4: According to the determined aircraft to be optimized state, determining the to-be-optimized variables;

[0014] Step 5: Analyzing the aerodynamic performance influence law of the to-be-optimized variables in the aircraft to-be-optimized state;

[0015] Step 6: According to the aerodynamic performance influence law, combining the configuration parameter restrictions, determining the value range of the to-be-optimized variables.

[0016] Further, in the step 1, the baseline distributed multi-rotor tilt-wing aircraft includes: a front wing, a rear wing, and a rotor; the rotor includes: a lift propeller unit and a propeller unit;

[0017] In the hovering state, the front wing and the rear wing are both vertically upward, the lift propeller unit and the propeller unit work simultaneously, in the forward flight state, the front wing and the rear wing are both tilted to horizontal, the lift propeller unit is folded and stored, and the propeller unit works to provide forward flight power.

[0018] Further, the optimization variables and their threshold ranges are as follows:

[0019] The rotation of the rotor, the threshold range is the top view clockwise / counter-clockwise;

[0020] The propeller hub center distance from the wing tip spanwise distance L, the threshold range is 0≤L / R≤6.4, R is the propeller radius;

[0021] The vertical distance h between the front wing and the rear wing in the forward flight state, the threshold range is -1≤h / R≤1, and the rear wing is above the front wing;

[0022] The distance k between the lift propeller and the propeller disc plane, the threshold range is 0≤k / R≤0.2;

[0023] The hub center spanwise distance b of adjacent rotors, the threshold range is 2<b / R≤2.4;

[0024] The distance a of the hub center of the front and rear propellers in the vertical plane projection in the forward flight state, 0≤a / R≤2.

[0025] Further, in the step 2, the aerodynamic interference calculation model of the baseline distributed multi-rotor tilt-wing aircraft is established by the following process:

[0026] First, the baseline distributed multi-rotor tilt wing aircraft geometry model is simplified, and components not considered in aerodynamic layout optimization are removed, including: landing gear, airspeed tube;

[0027] The rotor calculation method can adopt one or more of the momentum source method, multiple coordinate system method, slip grid method and nested grid method;

[0028] Then, the simplified aircraft geometry model is meshed;

[0029] The mesh data is imported into the calculation software to obtain the aerodynamic interference calculation model of the baseline distributed multi-rotor tilt wing aircraft;

[0030] The boundary conditions of the aerodynamic interference calculation model are set.

[0031] Further, in step 3,

[0032] The aerodynamic interference characteristics of the distributed multi-rotor tilt wing aircraft in hover and forward flight states include: the aerodynamic characteristics of the whole machine and isolated components in hover and forward flight states;

[0033] The isolated components include isolated lift fans, isolated propellers, isolated front wings and isolated rear wings;

[0034] The aerodynamic performance parameters of the wing include lift, drag and lift-drag ratio;

[0035] The aerodynamic performance parameters of the lift fan and propeller include tension, power and efficiency; the hover state is the hover efficiency of the rotor, and the forward flight state is the propulsion efficiency of the rotor;

[0036] The aerodynamic interference influence evaluation index includes: component aerodynamic interference influence rate and whole machine aerodynamic interference influence rate;

[0037] The component aerodynamic interference influence rate = (the aerodynamic performance parameter of the component in the interference state - the aerodynamic performance parameter of the component in the isolated state) / the aerodynamic performance parameter of the component in the isolated state;

[0038] The whole machine aerodynamic interference influence rate:

[0039] The whole machine aerodynamic interference influence rate in hover state = the average value of the aerodynamic interference influence rates of all rotor hover efficiencies;

[0040] The whole machine aerodynamic interference influence rate in forward flight state = the sum of the lift-drag ratio aerodynamic interference influence rates of all wings / the number of wings * 0.8 + the sum of the propulsion efficiency aerodynamic interference influence rates of all rotors / the number of propellers * 0.2;

[0041] When the aerodynamic interference influence rate of the whole machine in the hovering state is less than the aerodynamic interference influence rate of the whole machine in the forward flight state, the hovering state is determined as the state to be optimized, otherwise the forward flight state is the state to be optimized.

[0042] Further, in the step 4, the aerodynamic interference values between two components are calculated for the determined state to be optimized, specifically including: calculating the aerodynamic interference characteristics between the front wing / rear wing, the front propeller / rear propeller, the front propeller / front wing and the rear propeller / rear wing;

[0043] The aerodynamic interference influence rates of the above four combinations are calculated.

[0044] The two combinations with the greatest influence are selected to determine the optimization parameters.

[0045] Further, in the step 5, the aerodynamic interference calculation model of the reference distributed multi-rotor tilt wing aircraft is established based on the aerodynamic interference calculation model of the reference distributed multi-rotor tilt wing aircraft.

[0046] Different values are set for the two optimization parameters respectively to obtain two curves of the aerodynamic interference influence rates changing with the optimization parameters;

[0047] According to the two curves of the aerodynamic interference influence rates changing with the optimization parameters.

[0048] Further, in the step 6, the value of the optimization parameter corresponding to the highest point of the curve is selected as the optimal value.

[0049] A distributed multi-rotor tilt wing aircraft, the aerodynamic layout of the aircraft is optimized by the method.

[0050] Beneficial effects: the application proposes a high-performance low-interference aerodynamic layout optimization method of distributed multi-rotor tilting wing aircraft, which can optimize the aerodynamic layout of the distributed multi-rotor tilting wing aircraft, and has certain application value for the design and development of the aerodynamic layout of the distributed multi-rotor tilting wing aircraft. The application proposes an aerodynamic layout optimization method for a certain distributed multi-rotor tilting wing aircraft, aiming to reduce the adverse effects of aerodynamic interference on the aircraft; the application establishes an aerodynamic interference calculation model of a certain benchmark distributed multi-rotor tilting wing aircraft based on the CFD method, which can efficiently calculate the aerodynamic interference characteristics of the distributed multi-rotor tilting wing aircraft, and determine that the main aerodynamic interference state is the forward flight state, and the main adverse aerodynamic interference in the forward flight state is the aerodynamic interference of the front wing on the rear wing and the aerodynamic interference of the rear propeller on the rear wing; the application analyzes the influence of the arrangement position of the rear propeller and the vertical distance between the front wing and the rear wing on the aerodynamic performance of the rear wing, obtains the relationship curve of the vertical distance between the front wing and the rear wing and the aerodynamic interference influence rate of the lift-drag ratio of the rear wing, determines the relationship curve of the installation position of the propeller and the lift-drag ratio of the rear wing, and finally improves the benchmark configuration according to the actual situation, obtains the optimized aerodynamic layout, and the lift-drag ratio of the optimized aircraft is increased, and at the same time, the rear propeller arranged closer to the inside of the wing is more conducive to the structural dynamics characteristics of the aircraft. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 A flow chart of the aerodynamic layout optimization method of the distributed multi-rotor tilting wing aircraft proposed by the application is shown in the figure;

[0052] Figure 2 A schematic diagram of the benchmark distributed multi-rotor tilting wing aircraft is shown in the figure;

[0053] Figure 3 A schematic diagram of the relative position of the front wing and the rear wing and the relative position of the rear propeller and the wing is shown in the figure;

[0054] Figure 4 A relationship curve of the aerodynamic interference influence rate of the lift-drag ratio of the rear wing and the dimensionless h (h / R) is shown in the figure;

[0055] Figure 5 A relationship curve of the aerodynamic interference influence rate of the lift-drag ratio of the wing and the dimensionless L (L / R) is shown in the figure. DETAILED DESCRIPTION

[0056] The present application determines the layout optimization variables and threshold range of the aircraft according to the layout characteristics and overall design requirements of the reference distributed multi-rotor tilt wing aircraft, analyzes the aerodynamic interference characteristics of the configuration by numerical simulation of the typical flight state of the reference distributed multi-rotor tilt wing aircraft, and establishes an aerodynamic layout optimization method for the distributed multi-rotor tilt wing aircraft. The method can obtain an aerodynamic layout of a distributed multi-rotor tilt wing aircraft with high performance and low interference, achieve the purpose of reducing aerodynamic interference and improving aerodynamic layout performance, and the flow chart of the aerodynamic layout optimization method for the distributed multi-rotor tilt wing aircraft is shown in Figure 1 .

[0057] The core idea of the present application is as follows: first, the layout optimization variables and threshold range of the aircraft are determined according to the layout characteristics and overall design requirements of the reference distributed multi-rotor tilt wing aircraft; then, numerical calculation is performed on the reference distributed multi-rotor tilt wing aircraft to obtain the aerodynamic interference characteristics in the hovering and forward flight states, and the main aerodynamic interference influence state is determined as the forward flight state; then, the influence of the state parameters and configuration parameters of the aircraft in the forward flight state on the aerodynamic layout performance is analyzed; finally, the design parameters are optimized to obtain the aerodynamic layout optimization scheme considering the configuration parameter constraints.

[0058] The present application adopts the following technical scheme: an aerodynamic layout optimization method for a distributed multi-rotor tilt wing aircraft, comprising the following design steps:

[0059] First, the layout optimization variables and threshold range of the aircraft are determined according to the layout characteristics and overall design requirements of the reference distributed multi-rotor tilt wing aircraft;

[0060] The specific method is as follows: the layout of the reference distributed multi-rotor tilt wing aircraft is shown in Figure 2 , which includes a front wing, a rear wing, a lift propeller unit (8) and a propeller unit (4), and other components. In the hovering state, the wing is vertically upward, the lift propeller unit and the propeller unit work simultaneously, in the forward flight state, the wing is tilted to the horizontal, the lift propeller unit is folded and stored, and the propeller unit works to provide forward flight power.

[0061] According to the layout characteristics and overall design requirements of the aircraft, the optimization variables and threshold range are determined as follows:

[0062] The direction of the rotor (clockwise / counterclockwise as viewed from above);

[0063] The distance L between the center of the propeller hub and the wing tip spanwise distance L (0≤L / R≤6.4, R is the propeller radius);

[0064] The vertical distance h between the front and rear wings in the forward flight state (-1≤h / R≤1, R is the propeller radius, and the rear wing is above the front wing for positive);

[0065] The distance k (0≤k / R≤0.2) between the lift propeller and the plane of the propeller disc is adjusted by changing the height of the propeller pod to meet the folding requirement of the lift propeller, and the length of the lift propeller pod is longer than that of the propeller pod, the length of the lift propeller pod is not changed, the length of the propeller pod is adjusted but cannot be longer than that of the lift propeller pod, and the distance between the two is adjusted by changing the height of the propeller pod;

[0066] The distance b (2<b / R≤2.4) between the centers of the adjacent rotor hubs in the spanwise direction;

[0067] The distance a (0≤a / R≤2) between the centers of the hub of the front and rear propellers in the vertical plane in the forward flight state.

[0068] Secondly, a CFD method is used to build a baseline distributed multi-rotor tilt-wing aircraft aerodynamic interference calculation model, and the calculation efficiency and accuracy are considered, and one or more of the momentum source method, multiple coordinate system method, sliding mesh method and nested grid method are used to simulate the rotor wake.

[0069] The specific method is as follows: firstly, the baseline distributed multi-rotor tilt-wing aircraft geometric model is processed, and components not considered in this aerodynamic optimization, such as landing gear and airspeed tube, are removed, and the processed geometric model is divided into grids, and one or more of the momentum source method, multiple coordinate system method, sliding mesh method and nested grid method can be used for rotor calculation. In order to speed up the calculation, only the momentum source method can be used to simulate the rotor, which uses the momentum source method to simulate the rotor, which does not need to divide the blade grid, only needs to encrypt the grid at the position of the propeller disc, and the grid size at the position of the propeller disc is 0.01R-0.02R, R is the radius of the rotor, the momentum source method can quickly calculate the rotor flow field, and is suitable for aerodynamic interference calculation and analysis of distributed multi-rotor tilt-wing aircraft, finally, the grid is imported into the calculation software, the Newton iteration method is used to set the rotor pitch, so that the rotor tension meets the set target value, the target value in the hovering state is that the total tension of all rotors is equal to the weight of the whole machine, the target value in the forward flight state is that the total tension of all rotors is equal to the drag of the whole machine, the boundary conditions of the calculation model are set, the far field boundary condition is the pressure far field type, the inflow velocity in the hovering state is set to 0, and the inflow velocity in the forward flight state is set to the cruising speed of the distributed multi-rotor tilt-wing aircraft, and the software used is self-compiled software or commercial software.

[0070] Thirdly, an aerodynamic interference evaluation index is established, and the aerodynamic interference characteristics of the distributed multi-rotor tilt-wing aircraft in the hovering and forward flight states are calculated and analyzed, and it is determined that the forward flight state is a strong aerodynamic interference state, and the aerodynamic interference has a great influence on the lift-drag characteristics of the aircraft in this state.

[0071] The specific analysis method is: calculating the aerodynamic characteristics of the whole machine and isolated components in hovering state and forward flight state, the isolated components including isolated lift propeller, isolated propeller, isolated front wing and isolated rear wing. The modeling process of isolated components is similar to the whole machine calculation modeling process, but in the modeling process of isolated components, the isolated component is meshed separately, and then imported into the calculation software. Except that the grid imported into the software is different, the setting parameters of isolated component calculation and whole machine calculation are consistent.

[0072] In hovering state, the lift propeller unit and the propeller unit work together, and in forward flight state, the lift propeller unit is folded and the propeller unit works.

[0073] The aerodynamic performance parameters of the wing, lift propeller unit and propeller unit are calculated.

[0074] The aerodynamic performance parameters of the wing include lift, drag and lift-drag ratio.

[0075] The aerodynamic performance parameters of the rotor (including lift propeller and propeller) include tension, power and efficiency (hovering efficiency of rotor in hovering state and propelling efficiency of rotor in forward flight state).

[0076] The aerodynamic interference influence rate of the component and the aerodynamic interference influence rate of the whole machine are defined, the component is determined by comparing the aerodynamic interference influence rate of the whole machine in hovering and forward flight states, and the forward flight state is affected by aerodynamic interference, so the optimization is carried out mainly for the forward flight state.

[0077] The aerodynamic interference influence rate of the component = (the aerodynamic performance parameter of the component in interference state - the aerodynamic performance parameter of the component in isolated state) / the aerodynamic performance parameter of the component in isolated state.

[0078] The aerodynamic interference influence rate of the whole machine:

[0079] The aerodynamic interference influence rate of the whole machine in hovering state = the average value of the aerodynamic interference influence rates of the hovering efficiencies of all rotors.

[0080] The aerodynamic interference influence rate of the whole machine in forward flight state = the sum of the aerodynamic interference influence rates of the lift-drag ratios of all wings and the logarithm of the number of wings * 0.8 + the aerodynamic interference influence rates of the propelling efficiencies of all rotors and the number of propellers * 0.2.

[0081] The calculation shows that the aerodynamic interference influence rate of the whole machine in hovering state is -0.04, and the aerodynamic interference influence rate of the whole machine in forward flight state is -0.12, so the aerodynamic interference influence rate in forward flight state is small, and the forward flight state is determined as the strong aerodynamic interference state.

[0082] Fourthly, the aerodynamic interference between the two components in the forward flight state is calculated. By reducing the number of analyzed aerodynamic components, the complexity of the aerodynamic interference characteristic analysis is reduced, and the aerodynamic interference mechanism of the whole aircraft is clarified. By analyzing the aerodynamic interference characteristics between the two components in the forward flight state, it is determined that the main adverse aerodynamic interference factors are the aerodynamic interference of the front wing on the rear wing and the aerodynamic interference of the rear propeller on the rear wing.

[0083] The specific analysis method is as follows: the aerodynamic interference characteristics between the front wing / rear wing, front propeller / rear propeller, front propeller / front wing, and rear propeller / rear wing are calculated respectively, the aerodynamic interference characteristics between the two components in the forward flight state are analyzed, and the main adverse aerodynamic interference factors are determined by comparing the aerodynamic interference influence rate of each component. The main adverse aerodynamic interference factors are the aerodynamic interference of the front wing on the rear wing and the aerodynamic interference of the rear propeller on the rear wing. Through flow field analysis, it is found that the wing tip vortex of the front wing has a downward washing effect on the rear wing, which reduces the effective angle of attack of the rear wing, thereby reducing the lift and lift-drag ratio of the rear wing. The rotation flow of the rear propeller is in the same direction as the wing tip vortex of the rear wing, which reduces the effective angle of attack of the rear wing, thereby reducing the lift and lift-drag ratio of the wing.

[0084] The calculation model of the front wing / rear wing shows that the lift-drag ratio aerodynamic interference influence rate of the rear wing is -0.28, and the lift-drag ratio aerodynamic interference influence rate of the front wing is -0.005. The calculation model of the front propeller / rear propeller shows that the propeller efficiency aerodynamic interference influence rate of the front propeller is -0.001, and the propeller efficiency aerodynamic interference influence rate of the rear propeller is -0.02. The calculation model of the front propeller / front wing shows that the propeller efficiency aerodynamic interference influence rate of the front propeller is 0.05, and the lift-drag ratio aerodynamic interference influence rate of the front wing is 0.1. The calculation model of the rear propeller / rear wing shows that the propeller efficiency aerodynamic interference influence rate of the rear propeller is 0.04, and the lift-drag ratio aerodynamic interference influence rate of the rear wing is -0.12.

[0085] It is found that the aerodynamic interference between the front propeller and the front wing improves the performance, the aerodynamic interference between the front propeller and the rear propeller has little effect, and the aerodynamic interference between the front wing and the rear wing and the rear propeller and the rear wing seriously degrades the performance of the rear wing. Therefore, it is determined that the adverse aerodynamic interference factors are the aerodynamic interference of the front wing on the rear wing and the aerodynamic interference of the rear propeller on the rear wing.

[0086] Fifthly, the influence of the vertical distance h between the front wing and the rear wing and the distance L between the hub center of the rear propeller and the wing tip span of the wing on the aerodynamic performance of the aircraft is analyzed according to the aircraft layout optimization variables and their threshold ranges that have been determined.

[0087] The specific analysis method is: based on the established aerodynamic interference calculation model, the vertical distance h of different front wings and rear wings and the distance L of the center of the rear propeller hub from the wing tip are calculated to obtain the aerodynamic characteristics of the aircraft, and the relative position of the front wing and the rear wing and the relative position of the rear propeller and the wing are shown in the schematic diagram as shown in Figure 3 The influence of the vertical distance h of the front wing and the rear wing on the aerodynamic characteristics of the rear wing is analyzed, and it is found that in the threshold range of the optimization variable, the lift-drag ratio of the rear wing changes greatly at the position of 1R above the front wing, and the lift-drag ratio of the rear wing is large. The relationship curve between the aerodynamic interference influence rate of the lift-drag ratio of the rear wing and the dimensionless h (h / R) is shown in Figure 4 The influence of the distance L of the center of the rear propeller hub from the wing tip on the aerodynamic characteristics of the wing is analyzed, and it is found that with the increase of L, the lift-drag ratio of the rear wing first increases and then remains basically unchanged, and when the distance between the propeller and the wing tip is greater than 2R, the adverse effect of the propeller on the wing is basically unchanged. The relationship curve between the aerodynamic interference influence rate of the lift-drag ratio of the rear wing and the distance L of the center of the rear propeller hub from the wing tip is shown in Figure 5 .

[0088] The sixth step is to move the rear propeller towards the inside of the wing according to the optimization analysis results and the configuration parameter limit, and to exchange the installation position of the rear propeller and the adjacent lift propeller. It is found through numerical calculation of the whole machine that the lift and the lift-drag ratio of the optimized layout aircraft are increased, and the arrangement of the propeller close to the inside of the wing is beneficial to the structural dynamics characteristics of the configuration.

Claims

1. An aerodynamic layout optimization method for a distributed multi-rotor tiltrotor aircraft, characterized in that the method... include: Step 1: Based on the layout characteristics and overall design requirements of the benchmark distributed multi-rotor tilt-wing aircraft, determine the layout optimization variables and their threshold ranges for the aircraft; Step 2: Establish a calculation model for the aerodynamic disturbances of a baseline distributed multi-rotor tiltrotor aircraft; Step 3: Establish aerodynamic interference impact evaluation index, calculate the aerodynamic interference characteristics of the distributed multi-rotor tilt-wing aircraft in hovering and forward flight states, and determine the aircraft's state to be optimized; Step 4: Based on the determined aircraft state to be optimized, determine the variables to be optimized; Step 5: Analyze the influence of the variable to be optimized on the aerodynamic performance of the aircraft under the state to be optimized; Step 6: Based on the influence of aerodynamic performance and the constraints of configuration parameters, determine the range of values ​​for the variables to be optimized.

2. The aerodynamic layout optimization method according to claim 1, characterized in that, In step 1, the reference distributed multi-rotor tilt-wing aircraft includes: a front wing, a rear wing, and a rotor; the rotor includes: a lift propeller unit and a propeller unit. In the hovering state, both the front and rear wings point vertically upwards, and the lift propeller unit and the propeller unit work simultaneously. In forward flight, both the front and rear wings tilt to the horizontal, the lift propeller unit folds and retracts, and the propeller unit works to provide forward flight power.

3. The aerodynamic layout optimization method according to claim 2, characterized in that, The optimization variables and their threshold ranges are determined as follows: The rotor's direction of rotation has a threshold range of clockwise / counterclockwise when viewed from above; The spanwise distance L from the center of the propeller hub to the wingtip has a threshold range of 0 ≤ L / R ≤ 6.4, where R is the propeller radius; The vertical distance h between the front and rear wings in forward flight mode has a threshold range of -1≤h / R≤1, with the rear wing being above the front wing as positive. The distance k between the lifting propeller and the propeller disk plane has a threshold range of 0 ≤ k / R ≤ 0.2; The spanwise distance b between the hub centers of adjacent rotors has a threshold range of 2 < b / R ≤ 2.4; The distance 'a' between the centers of the propeller hubs of the forward and rear propellers in forward flight mode and projected onto the vertical plane is 0 ≤ a / R ≤ 2.

4. The aerodynamic layout optimization method according to claim 3, characterized in that, In step 2, the aerodynamic disturbance calculation model of the benchmark distributed multi-rotor tilt-wing aircraft is established through the following process: First, the geometric model of the baseline distributed multi-rotor tilt-wing aircraft is simplified by removing components that are not considered in aerodynamic layout optimization, including: landing gear and pitot tube; Rotor calculation methods can employ one or more of the following: momentum source method, multi-coordinate system method, sliding mesh method, and nested mesh method; Then, the simplified aircraft geometry model is meshed. The divided grid data is imported into the calculation software to obtain the aerodynamic interference calculation model of the benchmark distributed multi-rotor tiltrotor aircraft. Set the boundary conditions for the aerodynamic disturbance calculation model.

5. The aerodynamic layout optimization method according to claim 4, characterized in that, In step 3 The aerodynamic interference characteristics of distributed multirotor tiltrotor aircraft in hovering and forward flight states include the aerodynamic characteristics of the whole aircraft and isolated components in hovering and forward flight states. Isolated components include isolated lift propeller, isolated propeller, isolated fore wing, and isolated rear wing; The aerodynamic performance parameters of an airfoil include lift, drag, and lift-to-drag ratio; The aerodynamic performance parameters of lift propellers and propellers include thrust, power, and efficiency; in hovering state, it is the hovering efficiency of the rotor, and in forward flight state, it is the propulsion efficiency of the rotor. The aerodynamic interference impact evaluation indicators include: component aerodynamic interference impact rate and overall machine aerodynamic interference impact rate; Component aerodynamic interference influence rate = (Aerodynamic performance parameters of the component in the interference state - Aerodynamic performance parameters of the component in the isolated state) / Aerodynamic performance parameters of the component in the isolated state; Overall aerodynamic interference impact rate: The overall aerodynamic interference impact rate during hovering is equal to the average aerodynamic interference impact rate of all rotor hovering efficiency. The overall aerodynamic interference impact rate in forward flight state = sum of the lift-to-drag ratio aerodynamic interference impact rates of all wings / number of wing pairs * 0.8 + sum of the propulsion efficiency aerodynamic interference impact rates of all rotors / number of propellers * 0.2; If the overall aerodynamic interference impact rate of the aircraft in hovering state is greater than that in forward flight state, then the hovering state is determined to be a state to be optimized; otherwise, the forward flight state is determined to be a state to be optimized.

6. The aerodynamic layout optimization method according to claim 5, characterized in that, In step 4, for the determined state to be optimized, the aerodynamic interference values ​​between the two components are calculated, specifically including: calculating the aerodynamic interference characteristics between the front wing / rear wing, the front propeller / rear propeller, the front propeller / front wing, and the rear propeller / rear wing. Calculate the aerodynamic interference rate of the above four combinations; Select the two combinations with the greatest impact and determine the parameters to be optimized.

7. The aerodynamic layout optimization method according to claim 6, characterized in that, In step 5, the aerodynamic interference calculation model of the established benchmark distributed multi-rotor tilt-wing aircraft is used. By setting different values ​​for the two parameters to be optimized, curves showing the change of the aerodynamic interference influence rate with the parameters to be optimized were obtained.

8. The aerodynamic layout optimization method according to claim 7, characterized in that, In step 6, the parameter to be optimized corresponding to the highest point of the curve is selected as the optimal value.

9. A distributed multi-rotor tilt-wing aircraft, characterized in that: The aerodynamic layout of the aircraft is optimized by the method described in any one of claims 1-8.

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