Overall design scheme of electric multi-rotor helicopter

Abstract

The invention belongs to the field of aviation, and discloses an overall design scheme of an electric multi-rotor helicopter. The design method of the electric multi-rotor helicopter sequentially comprises the steps of configuration analysis and total parameter selection, electric power system modeling, coaxial dual-rotor aerodynamic modeling, flight performance modeling and total parameter multi-objective optimization design, and the flight performance of the electric multi-rotor helicopter is calculated according to preliminarily selected total parameters. And then an objective function is selected to complete multi-objective optimization design of overall parameters, and optimization of flight performance such as hovering performance and climbing performance of the helicopter is achieved. The electric aircraft is low in noise, small in vibration, clean and free of pollution, and the provided design method is high in universality, high in practicability and extremely easy to implement.

Description

Technical Field

[0001] This invention belongs to the field of aviation and provides an overall design scheme for an electric multi-rotor helicopter. Background Technology

[0002] Compared to traditional helicopters, electric multirotor helicopters offer advantages such as lower noise, less vibration, and cleaner, pollution-free operation. Furthermore, using electric helicopter batteries as a power source saves fuel and reduces emissions, making them a promising new mode of transportation. In recent years, optimization design has become an important method for optimizing the overall parameters of helicopters; however, this has mainly focused on single-objective optimization design. Meanwhile, research on coaxial electric multirotor helicopters is relatively scarce. However, coaxial electric multirotors possess high aerodynamic efficiency, offering significant advantages and potentially increasing range. Therefore, this patent provides an overall design scheme for an electric multirotor helicopter. Summary of the Invention

[0003] This patent provides an overall design scheme for an electric multirotor helicopter and establishes a method for optimizing the overall parameters of an electric multirotor helicopter, which can realize the configuration selection and overall parameter optimization design of an electric multirotor light helicopter.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: an overall design scheme for an electric multi-rotor helicopter, including: configuration analysis and overall parameter selection, electric power system modeling, coaxial twin-rotor aerodynamic modeling, flight performance modeling, and multi-objective optimization design of overall parameters.

[0005] Furthermore, based on the mission profile of the electric multirotor helicopter, the configuration is selected; combining the quasi-design method and statistical analysis method, the preliminary overall parameters for the electric multirotor helicopter are selected.

[0006] Furthermore, based on the composition and structure of the electric power system, an equivalent circuit diagram of the electric power system is established, and the models of each component of the electric multi-rotor helicopter power system are completed; then, the selection of each component of the electric power system is carried out.

[0007] Furthermore, the helicopter employs a coaxial rotor, and using Leishman's momentum blade element method, an inflow model for the coaxial dual rotor was established.

[0008] Furthermore, referring to traditional helicopter flight performance calculation methods, the flight performance of the electric multirotor helicopter is calculated, including the vertical flight performance, horizontal flight performance, and climb performance of the designed electric multirotor helicopter.

[0009] Furthermore, an optimization model for the overall parameters of the electric multi-rotor helicopter was established. The design variables were the maximum takeoff weight of the helicopter, rotor disk load, blade chord length, and pitch. The flight time, hovering performance, and total system force efficiency were used as objective functions. The overall parameters were optimized using the NSGA-II optimization algorithm based on genetic algorithm to obtain a set of Pareto optimal solutions that meet the constraints. Then, the analytic hierarchy process was used to select the final scheme, and the flight performance and objective function value under the final scheme were determined.

[0010] In summary, this invention patent has the following beneficial effects:

[0011] 1. The electric multi-rotor helicopter of the present invention has low noise, low vibration, and is clean and pollution-free. The design method provided is highly versatile, practical and easy to implement.

[0012] 2. The optimization method for the overall parameters of the electric multi-rotor helicopter of the present invention can effectively improve the helicopter's endurance, hovering performance and overall system force efficiency, thereby maximizing energy utilization and improving endurance.

[0013] 3. The multi-objective optimization algorithm for electric multi-rotor helicopters of the present invention can solve the problems of insufficient selection of design constraints and insufficient range and number of optimization parameters, and realize multi-parameter system optimization. Attached Figure Description

[0014] Figure 1 Schematic diagram of an electric multi-rotor helicopter

[0015] Figure 2 Equivalent circuit diagram of the electronically controlled circuit

[0016] Figure 3 Equivalent circuit diagram of the motor

[0017] Figure 4 This is a schematic diagram of the NSGA-II optimization algorithm based on genetic algorithms.

[0018] Figure 5 A schematic diagram of the solution set of the genetic algorithm. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0020] First, preliminary overall parameters are selected: a mature aircraft model closely matching the design requirements is chosen as the prototype. Referring to the prototype's overall parameters and relevant data, and based on the designer's experience and existing conditions, suitable overall parameters are determined. Statistical analysis of parameters is then performed on all helicopters with the same configuration. Linear fitting is conducted using relevant software, and finally, a semi-empirical formula is obtained through regression algorithms to determine the helicopter's overall parameters. The external shape is as follows... Figure 1 As shown, the parameter results are shown in Table 1:

[0021] Table 1 Overall Parameters of Electric Multirotor Helicopters

[0022]

[0023]

[0024] A series of performance indicators of an electric multi-rotor helicopter are estimated, equivalent circuit diagrams are established for each electric power component, and the propeller, motor, ESC, and battery are modeled based on the basic parameters of each component. The results for the ESC and motor are as follows. Figure 2 , Figure 3 As shown in Table 2, the selected components are summarized below:

[0025] Table 2 Summary of Preliminary Overall Parameters of Electric Multirotor Helicopters

[0026]

[0027]

[0028] Using Leishman's momentum blade element method, an inflow model for a coaxial dual rotor was established, yielding the following results:

[0029] upper rotor

[0030]

[0031] Lower rotor

[0032]

[0033] The correction factor F is represented by the tip loss effect (i.e., the high induced local loss of the blade caused by the formation of tip vortices), and its specific expression is as follows:

[0034]

[0035] In the formula, f is a function of the number of blades k and the radius r, i.e.

[0036]

[0037] In the formula, φ is the inflow angle (equal to λ(r) / r under the small angle assumption). In practical applications, the Prandtl function modifies the above formula as follows:

[0038] dC T =4Fλλ u rdr

[0039] r is the dimensionless radial position, and λ is the dimensionless inflow velocity. u Let λ be the dimensionless induced velocity of the upper rotor, where λ = λ u +λ ∞ , λ ∞ The dimensionless incoming flow velocity is at infinity. k is the number of blades, r is the radial position of the blade element segment, and C... lα V is the slope of the airfoil profile lift coefficient, θ is the pitch angle, and V c V is the velocity of the incoming flow at infinity. i This represents the rotor induced velocity. The subscript 'u' represents the upper rotor, and the subscript 'l' represents the upper rotor.

[0040] Performance calculations were performed, including vertical flight performance, horizontal flight performance, and climb performance. At sea level, the electric multi-rotor helicopter has the highest vertical climb rate, approximately 15.95 m / s. The altitude corresponding to a vertical climb rate of 0 m / s is 3629 meters, meaning the theoretical hovering ceiling is approximately 3629 meters, and the hovering time is approximately 20.82 minutes. The electric multi-rotor helicopter has a maximum level flight speed of 130.7 km / h and a maximum endurance of approximately 0.48 hours, or 29.03 minutes. At sea level, the electric multi-rotor helicopter has the highest climb rate, 11.76 m / s. The altitude corresponding to a climb rate of 0 m / s is approximately 5336 meters, meaning the theoretical dynamic ceiling is approximately 5336 meters. The flight altitude corresponding to a climb rate of 0.5 m / s is 5101 meters, meaning the practical dynamic ceiling is approximately 5101 meters.

[0041] An optimization model for the overall parameters of an electric multirotor helicopter is calculated, including the NSGA-II optimization algorithm based on a genetic algorithm, as follows: Figure 4 As shown in Table 3, the range of values ​​for the design variables and the constraints are as follows:

[0042] Table 3. Range of Design Variables and Constraints

[0043]

[0044]

[0045] We selected three objective functions—system force efficiency, maximum flight time, and hovering ceiling—and took negative values ​​for them. The smaller the values, the better the objective function. Figure 5The optimized solution set shown is the final optimized solution in the Pareto solution set, which is the final "optimal solution". The optimized values ​​of its objective function and flight performance are compared with the previously calculated initial values. The comparison results are shown in Table 4.

[0046] Table 4 Comparison of optimization results before and after.

[0047]

[0048] As shown in Table 4, compared with the initial values ​​before optimization, hovering time increased by 10.8%, maximum vertical climb rate increased by 34.61%, hover ceiling without ground effect increased by 25.64%, practical dynamic ceiling increased by 14.76%, maximum slant climb rate increased by 26.7%, maximum level flight speed decreased by 1.56%, endurance increased by 8.13%, and overall system force efficiency increased by 2.02%. After optimization, except for a slight decrease in maximum level flight speed, all other flight performance characteristics of the electric multi-rotor helicopter have been improved.

Claims

1. A general design scheme for an electric multi-rotor helicopter, characterized in that, include: Configuration analysis and overall parameter selection, electric power system modeling, coaxial twin rotor aerodynamic modeling, flight performance modeling, and multi-objective optimization design of overall parameters.

2. The overall design scheme of the electric multi-rotor helicopter according to claim 1, characterized in that: Based on the mission profile of the electric multirotor helicopter, the configuration is selected; combining the original design method and statistical analysis method, the preliminary overall parameters for the electric multirotor helicopter are selected.

3. The overall design scheme of the electric multi-rotor helicopter according to claim 1, characterized in that: Based on the composition and structure of the electric power system, an equivalent circuit diagram of the electric power system was established, and the models of each component of the electric multi-rotor helicopter power system were completed; then, the selection of each component of the electric power system was carried out.

4. The overall design scheme of the electric multi-rotor helicopter according to claim 1, characterized in that: The electric multi-rotor helicopter uses a coaxial rotor. Using Leishman's momentum blade element method, an inflow model of the coaxial dual rotor was established.

5. The overall design scheme of the electric multi-rotor helicopter according to claims 1-4, characterized in that: Referring to traditional helicopter flight performance calculation methods, the flight performance of the electric multirotor helicopter is calculated, including the vertical flight performance, horizontal flight performance, and climb performance of the designed electric multirotor helicopter.

6. The overall design scheme of the electric multi-rotor helicopter according to claims 1-5, characterized in that: An optimization model for the overall parameters of an electric multirotor helicopter was established. The design variables were the maximum takeoff weight of the helicopter, rotor disk load, blade chord length, and pitch. The flight time, hovering performance, and total system force efficiency were used as objective functions. The overall parameters were optimized using the NSGA-II optimization algorithm based on a genetic algorithm to obtain a set of Pareto optimal solutions that met the constraints. Then, the analytic hierarchy process was used to select the final scheme, and the flight performance and objective function value under the final scheme were determined.

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