A method and implementation device for designing a propeller for a noise-controllable vertical takeoff and landing aircraft.

Abstract

This invention belongs to the field of vertical takeoff and landing (VTOL) aircraft technology, specifically relating to a noise-controllable VTOL aircraft propeller design method and implementation device. The design method includes steps such as selecting key positions in the blade spanwise direction and determining the basic airfoil, optimizing the airfoil at the key positions, constructing a preliminary propeller configuration, investigating the influence of chord length, negative torque, and blade number on noise, determining the basic propeller configuration and optimization range, and optimizing the propeller aerodynamic performance. This method starts with optimizing the airfoil at the key positions of the blade, gradually investigating the influence of chord length, negative torque, and blade number on propeller noise, determining the basic propeller configuration and optimization range with acceptable noise, and performing multi-objective aerodynamic optimization based on this. This improves the aerodynamic efficiency of the propeller, reduces the noise level, and reduces trial and error costs and time. It can provide a high-performance, low-noise propeller design scheme for VTOL aircraft, meeting their application needs in complex environments such as urban air traffic.

Description

Technical Field

[0001] This invention belongs to the field of vertical take-off and landing aircraft technology, specifically relating to a noise-controllable vertical take-off and landing aircraft propeller design method and implementation device. Background Technology

[0002] Vertical take-off and landing (VTOL) aircraft, capable of vertical take-off and landing without runway reliance, have broad application prospects in urban air traffic, search and rescue, and patrol, and are considered core vehicles for future urban low-altitude flight. However, during operation, the high-speed rotating propellers of VTOL aircraft generate significant noise due to airflow disturbances, vortex effects, and blade vibration. On the one hand, propeller noise propagates directly into the cabin, resulting in poor passenger comfort; on the other hand, VTOL aircraft are widely deployed in densely populated areas, and the shorter noise propagation distance in low-altitude flight scenarios exacerbates noise pollution in nearby residential areas. Therefore, propeller noise has become one of the bottlenecks restricting the further promotion and application of VTOL aircraft.

[0003] Traditional VTOL aircraft propeller design methods mostly focus on aerodynamic performance optimization, lacking a systematic consideration of noise control. This leads to excessive propeller noise in practical applications, or the need for passive noise reduction measures (such as sound insulation materials and structural shielding) to achieve noise reduction. However, these methods often increase structural weight, affecting the overall performance of the aircraft. Therefore, comprehensively considering aerodynamic performance and noise control during the VTOL propeller design phase is key to solving its noise problem.

[0004] Therefore, the present invention aims to provide a design method and implementation device for a vertical take-off and landing aircraft propeller with controllable noise. By systematically and comprehensively considering aerodynamic performance and noise control during the design stage, active noise control is achieved, thereby solving the problem of excessive propeller noise or increased structural weight due to passive noise reduction in the later stage in the prior art. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention provides a design method and implementation device for a vertical take-off and landing aircraft propeller with controllable noise, solving the problem of excessive propeller noise or structural weight increase caused by passive noise reduction in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for designing a propeller for a vertical takeoff and landing (VTOL) aircraft with controllable noise is provided, comprising the following steps:

[0008] S1: Select key locations along the blade span and determine the basic airfoil:

[0009] Based on the design requirements of the aircraft, key locations on the blade span were selected for subsequent airfoil optimization, and the basic airfoil for optimization was determined.

[0010] S2: Determine the optimization objectives and constraints for typical operating conditions, and optimize the airfoil at key locations along the blade span:

[0011] Based on typical hovering and cruising conditions, the maximum lift coefficient is used respectively. and minimize drag coefficient With the goal of optimizing the basic airfoil under constraints, the coordinate parameters of the optimized airfoil are determined.

[0012] S3: Initially arranges an optimized airfoil with equal chord length along the blade span:

[0013] The optimized airfoil is arranged along the spanwise direction, and a constant chord length design is adopted during the arrangement to form a preliminary propeller configuration;

[0014] S4: Based on a fixed negative torque value (Twist) and a specific number of blades, adjust the chord length value (C) to generate a test configuration set and determine the acceptable chord length range for noise. ;

[0015] S5: Based on a fixed chord length C and a specific number of blades, adjust the negative torque value Twist to generate a test configuration set and determine the acceptable negative torque range for noise. ;

[0016] S6: Based on a fixed chord length C and a fixed negative torsion value Twist, adjust the number of blades to generate a test configuration set and determine the acceptable range of blade numbers for noise. ;

[0017] S7: Determine the basic propeller configuration and optimization scope:

[0018] The optimization range for the chord length C is set as follows: The optimization range for negative torque Twist is: The optimization range for the number of blades is: The acceptable chord length range for noise determined from S4. A fixed value is selected from the acceptable negative torque range determined by S5. A fixed value is selected, along with the acceptable number of blades for noise determined from S6. A fixed value is selected from these values ​​to form a basic propeller configuration with acceptable noise.

[0019] S8: Optimized propeller configuration aerodynamic performance under corresponding operating conditions:

[0020] Under typical operating conditions, based on the basic configuration, multi-objective aerodynamic optimization is performed within the parameter range of chord length C, negative torsion Twist, and number of blades determined by S7.

[0021] The beneficial effects of adopting the above technical solution are as follows: Step S1, by selecting key positions in the blade spanwise direction and determining the basic airfoil, can not only determine the basic airfoil for subsequent optimization, providing a starting point and reference for subsequent airfoil optimization and avoiding blind exploration that deviates from the required characteristics, but also improve the positions that have the greatest impact on aircraft performance, thus improving the targeting of the optimization effect; Step S2, by determining the optimization objectives and constraints under typical operating conditions, optimizes the airfoil at key positions in the blade spanwise direction to maximize the lift coefficient. and minimize drag coefficient To achieve the goal of optimizing the basic airfoil under constraints, the optimized airfoil can exhibit better aerodynamic and flight performance under typical operating conditions such as hovering and cruise. Step S3 involves initially arranging optimized airfoils with equal chord lengths along the blade span, forming a preliminary propeller configuration that facilitates subsequent steps. Step S4 involves selecting specific negative torque values ​​and the number of blades, adjusting the chord length values ​​to generate a test configuration set, in order to explore the influence and range of chord length values ​​on propeller noise, and to clarify the acceptable chord length range for noise. This provides a clear range for subsequent parameter selection, avoiding ineffective exploration within unreasonable chord length ranges, and can screen out propeller configurations that meet noise requirements, helping to reduce the noise level of the propeller during operation. In step S5, based on the determined chord length value and number of blades, the negative torque value is adjusted to generate a test configuration set to explore the influence law and range of the negative torque value on propeller noise, and further determine the acceptable negative torque range for noise. This narrowed the optimization range of the negative torque value, further optimizing the propeller's noise performance. In step S6, based on the determined chord length and negative torque values, the number of blades was adjusted to generate a test configuration to explore the influence and range of the number of blades on propeller noise, and to determine the acceptable range of the number of blades for noise. This provides a basis for finally determining the number of blades in the basic propeller configuration, avoiding noise problems caused by unreasonable blade number selection. In step S7, a basic propeller configuration with acceptable noise is constructed by selecting chord length, negative torque, and blade number, providing a performance benchmark for subsequent aerodynamic performance optimization. In step S8, under typical operating conditions, multi-objective aerodynamic optimization is performed based on the basic configuration within the determined parameter range, comprehensively considering factors such as hovering efficiency, cruise efficiency, and thrust coefficient, so that the propeller has better aerodynamic performance while meeting noise requirements, thereby improving the overall performance of the aircraft.

[0022] This design method combines aerodynamic performance with noise control. By optimizing parameters such as propeller airfoil, chord length, negative torque, number of blades, and overall propeller configuration, the propeller's flight performance is improved while effectively controlling noise levels. Furthermore, the steps are interconnected and progressively advanced, enabling the rapid selection of propeller configurations that meet the requirements, thus improving design efficiency and shortening the development cycle.

[0023] Furthermore, in S1, key locations include the main lift section at 50%–90% of the blade span, the blade root, and the blade tip.

[0024] The beneficial effects of adopting the above technical solutions are as follows: The main lift section is located at 50% to 90% of the blade span, with a moderate angle of attack, low induced drag, and far from the blade hub interference, resulting in the highest aerodynamic efficiency. By selecting and optimizing an airfoil with good lift characteristics as the basic airfoil for the main lift section at 50% to 90% of the blade span, the overall aerodynamic efficiency under hovering and cruise conditions can be further improved. The blade root is selected as a basic airfoil with high strength and large thickness. The blade root has a small rotation radius and low linear velocity, but the mass is concentrated, requiring it to withstand the maximum centrifugal load while transmitting torque and thrust. Optimizing the airfoil at the blade root can alleviate the aerodynamic efficiency loss caused by the large thickness of the structure. The blade tip is selected as a basic airfoil with small maximum thickness, small leading edge radius, thin trailing edge, small camber, and high maximum lift coefficient. The blade tip has a high linear velocity, and vortex interference leads to a higher risk of airflow separation. Optimizing the blade tip airfoil can delay the occurrence of airflow separation.

[0025] Furthermore, in S2, the optimization objective and constraints in the hovering state are:

[0026]

[0027]

[0028] Where x is the airfoil parameterization vector, To optimize the airfoil lift coefficient in hovering mode, To optimize the airfoil drag coefficient during hovering, This represents the drag coefficient of the basic airfoil in hovering mode. To optimize the maximum thickness of the airfoil, UP is the maximum thickness of the base airfoil, LOW is the upper boundary of the optimized airfoil parameterization vector, and UP is the lower boundary of the optimized airfoil parameterization vector.

[0029] The optimization objective and constraints during cruise mode are as follows:

[0030]

[0031]

[0032] Where x is the airfoil parameterization vector, To optimize the airfoil drag coefficient during cruise, To optimize the airfoil lift coefficient during cruise, is the lift coefficient of the base airfoil in cruise mode, UP is the upper boundary of the optimized airfoil parameterization vector, and LOW is the lower boundary of the optimized airfoil parameterization vector.

[0033] The beneficial effect of adopting the above technical solution is that the optimization constraint in the hovering state is the drag coefficient. The drag coefficient should not exceed that of the basic airfoil. This ensures that the optimized airfoil has low drag during hovering, thereby reducing energy loss; and the maximum thickness of the optimized airfoil during hovering... and the maximum thickness of the basic airfoil Similarly, this ensures that the optimized airfoil maintains structural strength and meets loading requirements. Furthermore, by optimizing the upper boundary (UP) and lower boundary (LOW) of the airfoil's parametric vector, extreme changes in the airfoil shape can be avoided, ensuring the aircraft's performance stability under various operating conditions. The optimization constraint under cruise conditions is the lift coefficient. Lift coefficient higher than the basic airfoil This ensures high cruise efficiency during cruise mode; and the same maximum thickness constraint and upper and lower boundary restrictions of the optimized airfoil parameterization vector exist during cruise mode as during hovering mode, in order to ensure that the multi-design point optimization formed by the two states produces a unique optimization solution.

[0034] Furthermore, in S2, the coordinate parameters of the optimized airfoil are determined using the Hicks-Henne function. By applying a linear perturbation to the surface of the basic airfoil, the airfoil parameterization vector is transformed. The formula for converting to airfoil coordinate parameters is:

[0035]

[0036] in, The x-coordinate of the airfoil chord is... To optimize the longitudinal coordinates of the upper surface of the airfoil, To optimize the longitudinal coordinates of the lower surface of the airfoil, The ordinate of the upper surface of the basic airfoil. The lower surface ordinate of the basic airfoil. The disturbance component coefficient applied to the upper surface, The disturbance component coefficient applied to the lower surface, ;

[0037] The formula for the shape function is:

[0038]

[0039] in, , These are n-1 specific airfoil chord abscissas.

[0040] The beneficial effects of adopting the above technical solution are as follows: by applying linear perturbation to the surface of the basic airfoil using the Hicks-Henne function, the airfoil can be accurately optimized, increasing the controllability of the optimized airfoil.

[0041] Furthermore, in S3, the preliminary propeller configuration arrangement includes arranging the root optimized airfoil and the tip optimized airfoil at corresponding positions along the blade span, arranging the optimized airfoil of the main lift section within the corresponding blade span range, and smoothly connecting the middle sections of the three airfoils.

[0042] The beneficial effects of adopting the above technical solution are as follows: by optimizing the arrangement of the propeller root, the structural stability and aerodynamic efficiency of the propeller root area can be ensured; by optimizing the arrangement of the propeller tip, the airflow separation can be delayed and the aerodynamic efficiency of the tip can be improved; by optimizing the arrangement of the main lift section, the overall aerodynamic performance of the propeller can be further improved; and by adopting the design method of equal chord length to arrange the propeller, it is convenient to explore the factors and range of noise influence.

[0043] Furthermore, in S4, the fixed specific negative torque value Twist and the specific number of blades are empirical values ​​for propeller aerodynamic design; adjusting the chord length value C to generate a test configuration set is based on the empirical chord length value, selecting multiple discrete values ​​of chord length value C to form a test configuration set, which is used to explore the influence law and range of chord length value on propeller noise.

[0044] The beneficial effects of adopting the above technical solution are as follows: In step S4, the negative torque value Twist and the number of blades are fixed to verified aerodynamic design experience values, and several chord length values ​​C are discretely selected based on the chord length experience value to form a test configuration set. This can quickly lock the influence law of chord length on propeller noise and its acceptable range, which not only avoids blind testing, but also provides a clear noise boundary for subsequent multi-objective aerodynamic optimization of propeller configuration, effectively improving test efficiency.

[0045] Furthermore, in S5, the specific chord length value C is within the noise-acceptable chord length range determined in S4. In the process, the chord length value with the best hovering and cruising efficiency of the obtained propeller configuration is selected; the specific number of blades is the fixed specific number of blades in S4; the negative torque value Twist is adjusted to generate a test configuration set. Based on the fixed negative torque value Twist in S4, multiple discrete values ​​of negative torque value Twist are selected to form a test configuration set, which is used to explore the influence law and range of negative torque value on propeller noise.

[0046] The beneficial effects of adopting the above technical solution are as follows: In step S5, the chord length C is fixed to the best aerodynamic performance value within the acceptable chord length range of noise determined in S4, the number of blades is maintained at a specific value in S4, and multiple negative torque values ​​Twist are discretely selected based on the negative torque value Twist to form a test configuration set. Under the constraint of maintaining aerodynamic efficiency, the influence range of negative torque on propeller noise can be obtained, which is beneficial for subsequent optimization and avoids the problem of low efficiency caused by blind adjustment.

[0047] Furthermore, in S6, the specific chord length value C is the acceptable chord length range for noise determined in S4. In the process, the chord length value that yields the best hovering and cruising efficiency for the obtained propeller configuration is selected; the specific negative torque value Twist is the acceptable negative torque range for noise determined by S5. In the process, the negative torque value with the best hovering and cruise efficiency of the obtained propeller configuration is selected; the number of blades is adjusted to generate a test configuration set. Based on the fixed number of blades in S4 or S5, multiple discrete values ​​of the number of blades are selected to form a test configuration set, which is used to explore the influence law and range of the number of blades on propeller noise.

[0048] The beneficial effects of adopting the above technical solution are as follows: In step S6, based on the chord length value C verified in S5 and the negative torque value Twist in S5 which has acceptable noise and the best aerodynamic performance, multiple blade values ​​are discretely sampled with a predetermined number of blades as the reference to form a test configuration set, thereby quickly locking the range of influence of blade number change on propeller noise within a local optimal range.

[0049] Furthermore, in S8, the mathematical description of propeller aerodynamic performance optimization is as follows:

[0050]

[0051]

[0052] Where FM is hovering efficiency, ETA is cruise efficiency, CT is thrust coefficient, and R is propeller radius. Optimize the airfoil's initial position for the main lift stage. The airfoil's ending position is optimized for the main lift phase, with Twist representing a negative torque value. This represents the lower boundary of the acceptable negative torque value for noise, as determined in S5. This represents the upper boundary of the acceptable negative torque value for noise, as determined in S5. The average chord length of the blade, This represents the lower boundary of the acceptable chord length value for noise, as determined in S4. The upper boundary of the acceptable chord length value for noise, as determined in S4, is where Blade is the number of blades. This represents the lower boundary of the acceptable number of blades for noise, as determined in S6. This represents the upper boundary of the acceptable number of blades for noise, as determined in S6. This refers to the blade sweep position. The lower boundary of the swept position. The upper boundary of the swept position, The blade sweep angle, The lower boundary of the sweep angle. This is the upper boundary of the sweep angle.

[0053] The beneficial effects of adopting the above technical solution are: it mainly optimizes three aerodynamic performance indicators, namely hovering efficiency (FM), cruise efficiency (ETA), and thrust coefficient (CT), and the optimization process is subject to the negative torque value range that is acceptable to the noise level. ), chord length interval ( ), blade number range ( ) and the range of sweep position and sweep angle ( , By addressing the constraints of [unclear], this multi-objective optimization can simultaneously improve the aerodynamic performance of the propeller in hovering and cruise states, ensuring that the aircraft can achieve better flight efficiency in different flight modes, while also keeping noise within an acceptable range and avoiding restrictions on aircraft use caused by noise issues.

[0054] The present invention provides a propeller design device for vertical take-off and landing aircraft that achieves the above-mentioned noise controllability, including an aerodynamic optimization module, an aerodynamic evaluation module and a noise evaluation module. The aerodynamic evaluation module and the aerodynamic optimization module are bidirectionally connected. The output end of the aerodynamic evaluation module is connected to the input end of the noise evaluation module, and the output end of the noise evaluation module is connected to the input end of the aerodynamic optimization module.

[0055] The aerodynamic optimization module is used to maximize the lift coefficient under typical hovering and cruising conditions. and minimize drag coefficient For the objective and constrained optimization of the basic airfoil, it receives the aerodynamic data of the evaluated intermediate airfoil as a reference for the optimization process and to guide the direction of airfoil optimization; it is used for typical operating conditions based on a noise-acceptable propeller configuration with a defined chord length. Negative torque value and number of blades Multi-objective aerodynamic optimization within the parameter range, receiving the evaluated intermediate propeller configuration aerodynamic data as a reference for the optimization process and guiding the direction of propeller configuration optimization;

[0056] The aerodynamic evaluation module receives intermediate airfoil parameters for key positions under typical hovering and cruise conditions generated by the aerodynamic optimization module, performs two-dimensional coordinate calculations and aerodynamic numerical simulations of the intermediate airfoil parameters, and transmits the aerodynamic data to the aerodynamic optimization module. It also performs three-dimensional coordinate calculations and aerodynamic numerical simulations of the propeller test configuration set during the determination of the propeller's basic configuration and optimization range, and transmits the propeller surface pressure distribution data to the noise evaluation module as the basis for determining the propeller's basic configuration and optimization range. Furthermore, it receives intermediate propeller configuration parameters for multi-objective aerodynamic optimization based on the propeller's basic configuration under typical conditions generated by the aerodynamic optimization module, performs three-dimensional coordinate calculations and aerodynamic numerical simulations of the intermediate propeller configuration parameters, and transmits the aerodynamic data to the aerodynamic optimization module.

[0057] The noise assessment module receives surface pressure distribution data of the propeller test configuration set output by the aerodynamic assessment module during the propeller basic configuration and optimization range determination stage, performs acoustic numerical simulation, and finally selects the chord length C, negative torque Twist, and number of blades to form a noise-acceptable propeller basic configuration, and determines the noise-acceptable chord length range. Negative torque range and blade number range The data is then sent to the aerodynamic optimization module for propeller configuration optimization.

[0058] The beneficial effects of adopting the above technical solution are as follows: The aerodynamic optimization module is used to perform airfoil parameter optimization and propeller configuration optimization. It can perform multi-objective aerodynamic optimization based on the aerodynamic data provided by the aerodynamic evaluation module and the basic configuration and optimization range provided by the noise evaluation module. The aerodynamic evaluation module can evaluate the aerodynamic performance of the blade airfoil and propeller configuration, providing aerodynamic data for the aerodynamic optimization module. The noise evaluation module can evaluate the noise level of different propeller configurations, determine the acceptable design parameter range for noise, and provide noise control constraints for the aerodynamic optimization module. Moreover, through the feedback from the noise evaluation module, the aerodynamic optimization module can consider noise control while meeting aerodynamic performance requirements, achieving a balance between aerodynamic performance and noise level. In addition, the bidirectional data connection between the aerodynamic evaluation module and the aerodynamic optimization module ensures information flow and data updates during the design process, improving the accuracy and iteration efficiency of the design.

[0059] In summary, the noise-controllable vertical takeoff and landing aircraft propeller design method and implementation device provided by this invention have the following beneficial effects:

[0060] (1) The noise controllable vertical take-off and landing aircraft propeller design method in this invention adopts the method of "first reducing the noise boundary and then improving aerodynamics", which advances the noise control to the aerodynamic design stage, so that there is no need to add sound insulation structure or shielding device in the later stage of aircraft development, which significantly avoids the weight, complexity and cost of passive noise reduction.

[0061] (2) The noise-controllable vertical take-off and landing aircraft propeller design method in this invention starts with the optimization of airfoil at the key position of the blade. By optimizing the airfoil of the main lift section, the root and tip of the blade, a high-performance airfoil that balances hovering efficiency and cruise efficiency is quickly obtained. On this basis, the single variable method is used to lock the influence law of chord length, negative torque and blade number on propeller noise in turn, and then quickly determine the acceptable parameter range of noise. This not only narrows the scope of subsequent multi-objective aerodynamic optimization, but also avoids a large number of time-consuming noise calculations in the continuous design range, effectively reducing the trial and error cost. Finally, multi-objective aerodynamic optimization is carried out within the determined noise constraint range, so that the propeller can meet the low noise requirements of complex scenarios such as urban air traffic while maintaining the optimal hovering efficiency and cruise efficiency. Thus, a high-performance, low-noise, and rapidly iterative propeller design scheme is provided for vertical take-off and landing aircraft.

[0062] (3) The implementation device of the noise-controllable vertical take-off and landing aircraft propeller design method in this invention integrates an aerodynamic optimization module, an aerodynamic evaluation module and a noise evaluation module to form a highly efficient and collaborative closed-loop optimization system. The aerodynamic optimization module is used to perform airfoil parameter optimization and propeller configuration optimization. It can perform multi-objective aerodynamic optimization based on the aerodynamic data provided by the aerodynamic evaluation module and the basic configuration and optimization range provided by the noise evaluation module. The aerodynamic evaluation module can evaluate the aerodynamic performance of the blade airfoil and propeller configuration and provide aerodynamic data for the aerodynamic optimization module. The noise evaluation module can evaluate the noise level of different propeller configurations, determine the acceptable range of design parameters for noise, and provide noise control constraints for the aerodynamic optimization module. Through the feedback of the noise evaluation module, the aerodynamic optimization module can consider noise control while meeting the aerodynamic performance requirements, and achieve a balance between aerodynamic performance and noise level. This not only improves the automation of the design process, but also ensures the reliability of the design results.

[0063] (4) The implementation device of the noise controllable vertical take-off and landing aircraft propeller design method in this invention can flexibly set typical working conditions according to different vertical take-off and landing aircraft usage scenarios, and can also set the corresponding noise acceptableness according to different standards to adjust the propeller configuration optimization range, meet diverse design requirements, and realize efficient noise reduction and aerodynamic performance synergistic optimization in a wide range of scenarios. Attached Figure Description

[0064] Figure 1 This is a flowchart of the design method of the present invention;

[0065] Figure 2 This is a schematic diagram showing the composition and input / output relationships of the devices of the present invention; Detailed Implementation

[0066] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0067] Example 1

[0068] like Figure 1 As shown, the present invention provides a noise-controllable vertical takeoff and landing aircraft propeller design method, which includes the following steps:

[0069] S1: Select key locations along the blade span and determine the basic airfoil:

[0070] Based on the design requirements of the aircraft, key locations on the blade span were selected for subsequent airfoil optimization, and the basic airfoil for optimization was determined.

[0071] S2: Determine the optimization objectives and constraints for typical operating conditions, and optimize the airfoil at key locations along the blade span:

[0072] Based on typical hovering and cruising conditions, the maximum lift coefficient is used respectively. and minimize drag coefficient With the goal of optimizing the basic airfoil under constraints, the coordinate parameters of the optimized airfoil are determined.

[0073] S3: Initially arranges an optimized airfoil with equal chord length along the blade span:

[0074] The optimized airfoil is arranged along the spanwise direction, and a constant chord length design is adopted during the arrangement to form a preliminary propeller configuration;

[0075] S4: Based on a fixed negative torque value (Twist) and a specific number of blades, adjust the chord length value (C) to generate a test configuration set and determine the acceptable chord length range for noise. ;

[0076] S5: Based on a fixed chord length C and a specific number of blades, adjust the negative torque value Twist to generate a test configuration set and determine the acceptable negative torque range for noise. ;

[0077] S6: Based on a fixed chord length C and a fixed negative torsion value Twist, adjust the number of blades to generate a test configuration set and determine the acceptable range of blade numbers for noise. ;

[0078] S7: Determine the basic propeller configuration and optimization scope:

[0079] The optimization range for the chord length C is set as follows: The optimization range for negative torque Twist is: The optimization range for the number of blades is: The acceptable chord length range for noise determined from S4. A fixed value is selected from the acceptable negative torque range determined by S5. A fixed value is selected, along with the acceptable number of blades for noise determined from S6. A fixed value is selected from these values ​​to form a basic propeller configuration with acceptable noise.

[0080] S8: Optimized propeller configuration aerodynamic performance under corresponding operating conditions:

[0081] Under typical operating conditions, based on the basic configuration, multi-objective aerodynamic optimization is performed within the parameter range of chord length C, negative torsion Twist, and number of blades determined by S7.

[0082] In step S1, key locations include the main lift section at 50%–90% of the blade span, the high-strength blade root, and the high-speed blade tip. The main lift section has a moderate angle of attack, low induced drag, and is far from the blade hub, resulting in the highest aerodynamic efficiency. By selecting and optimizing an airfoil with good lift characteristics as the base airfoil for the main lift section at 50%–90% of the blade span, the overall aerodynamic performance of the propeller can be further improved, thereby increasing the efficiency and economy of the aircraft. The blade root is selected as a base airfoil with high strength and large thickness. The blade root has a small rotation radius and low linear velocity, but the mass is concentrated, requiring it to withstand the maximum centrifugal load while transmitting torque and thrust. Optimizing the airfoil at the blade root can alleviate the aerodynamic efficiency loss caused by the large structural thickness. The blade tip is selected as a base airfoil with small maximum thickness, small leading edge radius, thin trailing edge, small camber, and high maximum lift coefficient. The blade tip has a high linear velocity, and vortex interference leads to a higher risk of airflow separation. Optimizing the blade tip airfoil can delay the occurrence of airflow separation.

[0083] In step S2, the optimization objective and constraints in the hovering state are:

[0084]

[0085]

[0086] Where x is the airfoil parameterization vector, To optimize the airfoil lift coefficient in hovering mode, To optimize the airfoil drag coefficient during hovering, This represents the drag coefficient of the basic airfoil in hovering mode. To optimize the maximum thickness of the airfoil, UP is the maximum thickness of the base airfoil, LOW is the upper boundary of the optimized airfoil parameterization vector, and UP is the lower boundary of the optimized airfoil parameterization vector.

[0087] The optimization objective and constraints during cruise mode are as follows:

[0088]

[0089]

[0090] Where x is the airfoil parameterization vector, To optimize the airfoil drag coefficient during cruise, To optimize the airfoil lift coefficient during cruise, is the lift coefficient of the base airfoil in cruise mode, UP is the upper boundary of the optimized airfoil parameterization vector, and LOW is the lower boundary of the optimized airfoil parameterization vector.

[0091] The coordinate parameters of the optimized airfoil are determined using the Hicks-Henne function. This is achieved by applying a linear perturbation to the surface of the base airfoil, transforming the airfoil parameterized vector. The formula for converting to airfoil coordinate parameters is:

[0092]

[0093] in, The x-coordinate of the airfoil chord is... To optimize the longitudinal coordinates of the upper surface of the airfoil, To optimize the longitudinal coordinates of the lower surface of the airfoil, The ordinate of the upper surface of the basic airfoil. The lower surface ordinate of the basic airfoil. The disturbance component coefficient applied to the upper surface, The disturbance component coefficient applied to the lower surface, ;

[0094] The formula for the shape function is:

[0095]

[0096] in, , These are n-1 specific airfoil chord abscissas.

[0097] The optimization constraint in hovering mode is the drag coefficient. The drag coefficient should not exceed that of the basic airfoil. This ensures that the optimized airfoil has low drag during hovering, thereby reducing energy loss; and the maximum thickness of the optimized airfoil during hovering... and the maximum thickness of the basic airfoil Similarly, this ensures that the optimized airfoil maintains structural strength and meets loading requirements. Furthermore, by optimizing the upper boundary (UP) and lower boundary (LOW) of the airfoil's parametric vector, extreme changes in the airfoil shape can be avoided, ensuring the aircraft's performance stability under various operating conditions. The optimization constraint under cruise conditions is the lift coefficient. Lift coefficient higher than the basic airfoil This ensures high cruise efficiency during cruise mode; and the same maximum thickness constraint and upper and lower boundary restrictions of the optimized airfoil parameterization vector exist during cruise mode as during hovering mode, in order to ensure that the multi-design point optimization formed by the two states produces a unique optimization solution.

[0098] In step S3, the preliminary propeller configuration arrangement includes arranging the optimized root airfoil and the optimized tip airfoil at corresponding positions along the blade span, and initially arranging the optimized airfoil of the main lift section within the corresponding blade span range. The middle sections of the three airfoils are smoothly connected. By optimizing the arrangement of the root, the structural stability and aerodynamic efficiency of the root region can be ensured. By optimizing the arrangement of the tip, airflow separation can be delayed and the aerodynamic efficiency of the tip can be improved. By optimizing the arrangement of the main lift section, the overall aerodynamic performance of the propeller can be further improved. Furthermore, the propeller configuration arrangement using a constant chord length design method facilitates the investigation of noise influencing factors and their range.

[0099] In step S4, the fixed specific negative torque value Twist and the specific number of blades are empirical values ​​for propeller aerodynamic design. The test configuration set is generated by adjusting the chord length value C based on the empirical chord length value, selecting discrete values ​​of multiple chord length values ​​C to form a test configuration set. This set is used to explore the influence and range of the chord length value on propeller noise. By fixing the negative torque value Twist and the number of blades to verified empirical aerodynamic design values, and discretely selecting several chord length values ​​C based on the empirical chord length value to form a test configuration set, the influence of the chord length on propeller noise and its acceptable range can be quickly identified. This avoids blind testing and provides a clear noise boundary for subsequent multi-objective aerodynamic optimization of propeller configuration, effectively improving testing efficiency.

[0100] In step S5, the specific chord length value C is the acceptable chord length range for noise determined in S4. In this study, the chord length value with the best hovering and cruise efficiency for the obtained propeller configuration was selected; the specific number of blades was the fixed number of blades in S4; the negative torque value Twist was adjusted to generate a test configuration set. Based on the fixed negative torque value Twist in S4, multiple discrete values ​​of negative torque Twist were selected to form a test configuration set, which was used to explore the influence law and range of negative torque on propeller noise. By fixing the chord length value C to the aerodynamically best value within the acceptable noise chord length range determined in S4, maintaining the specific number of blades in S4, and then discretely selecting multiple negative torque values ​​Twist based on the negative torque value Twist to form a test configuration set, the influence range of negative torque on propeller noise can be obtained while maintaining aerodynamic efficiency constraints. This is beneficial for subsequent optimization and avoids the inefficiency problem caused by blind adjustments.

[0101] In step S6, the specific chord length value C is the noise-acceptable chord length range determined in S4. In the process, the chord length value that yields the best hovering and cruising efficiency for the obtained propeller configuration is selected; the specific negative torque value Twist is the acceptable negative torque range for noise determined by S5. In the process, the negative torque value with the best hovering and cruising efficiency of the obtained propeller configuration is selected; the number of blades is adjusted to generate a test configuration set. Based on the fixed number of blades in S4 or S5, multiple discrete values ​​of the number of blades are selected to form a test configuration set, which is used to explore the influence law and range of the number of blades on propeller noise, so as to quickly lock the influence range of the number of blades on propeller noise within a local optimal range.

[0102] In step S7, the optimization range of the chord length value C is set to... The optimization range for negative torque Twist is: The optimization range for the number of blades is: The acceptable chord length range for noise determined from S4. A fixed value is selected, and the acceptable negative torque range for noise is determined from S5. A fixed value is selected, along with the acceptable number of blades for noise determined from S6. Fixed values ​​are selected to form a basic propeller configuration with acceptable noise, providing a performance benchmark for subsequent aerodynamic performance optimization.

[0103] In step S8, under typical operating conditions, based on the basic configuration, multi-objective aerodynamic optimization of the propeller is performed within a defined parameter range. The mathematical description of the propeller aerodynamic performance optimization is as follows:

[0104]

[0105]

[0106] Where FM is hovering efficiency, ETA is cruise efficiency, CT is thrust coefficient, and R is propeller radius. Optimize the airfoil's initial position for the main lift stage. The airfoil's ending position is optimized for the main lift phase, with Twist representing a negative torque value. This represents the lower boundary of the acceptable negative torque value for noise, as determined in S5. This represents the upper boundary of the acceptable negative torque value for noise, as determined in S5. The average chord length of the blade, This represents the lower boundary of the acceptable chord length value for noise, as determined in S4. The upper boundary of the acceptable chord length value for noise, as determined in S4, is where Blade is the number of blades. This represents the lower boundary of the acceptable number of blades for noise, as determined in S6. This represents the upper boundary of the acceptable number of blades for noise, as determined in S6. This refers to the blade sweep position. The lower boundary of the swept position. The upper boundary of the swept position, The blade sweep angle, The lower boundary of the sweep angle. This is the upper boundary of the sweep angle.

[0107] In step S8, the main focus is on optimizing three aerodynamic performance indicators: hovering efficiency (FM), cruise efficiency (ETA), and thrust coefficient (CT). The optimization process is subject to the acceptable range of negative torque values ​​for noise. ), chord length interval ( ), blade number range ( ) and the range of sweep position and sweep angle ( , By addressing the constraints of [unclear], this multi-objective optimization can simultaneously improve the aerodynamic performance of the propeller in hovering and cruise states, ensuring that the aircraft can achieve better flight efficiency in different flight modes, while also keeping noise within an acceptable range and avoiding restrictions on aircraft use caused by noise issues.

[0108] The noise-controllable propeller design method for vertical takeoff and landing aircraft provided by this invention starts with airfoil optimization at key positions of the blades, gradually exploring the influence of chord length, negative torque value, and blade number on propeller noise, determining the basic propeller configuration and optimization range with acceptable noise, and performing multi-objective aerodynamic optimization based on this. This not only improves the aerodynamic efficiency of the propeller but also significantly reduces the noise level, while reducing the trial and error costs and time in the design process. At the same time, it can provide a high-performance, low-noise propeller design scheme for vertical takeoff and landing aircraft, meeting their application requirements in complex environments such as urban air traffic.

[0109] Example 2

[0110] like Figure 2 As shown, in order to implement the above design method, the present invention provides an implementation device for a noise-controllable vertical take-off and landing aircraft propeller design method, including an aerodynamic optimization module, an aerodynamic evaluation module and a noise evaluation module. The aerodynamic evaluation module and the aerodynamic optimization module are bidirectionally connected. The output end of the aerodynamic evaluation module is connected to the input end of the noise evaluation module, and the output end of the noise evaluation module is connected to the input end of the aerodynamic optimization module.

[0111] Among them, the aerodynamic optimization module is used to maximize the lift coefficient under typical hovering and cruising conditions. and minimize drag coefficient For the objective and constrained optimization of the basic airfoil, it receives the aerodynamic data of the evaluated intermediate airfoil as a reference for the optimization process and to guide the direction of airfoil optimization; it is used for typical operating conditions based on a noise-acceptable propeller configuration with a defined chord length. Negative torque value and number of blades Multi-objective aerodynamic optimization within the parameter range, receiving the evaluated intermediate propeller configuration aerodynamic data as a reference for the optimization process and guiding the direction of propeller configuration optimization;

[0112] The aerodynamic evaluation module receives intermediate airfoil parameters for key positions under typical hovering and cruise conditions generated by the aerodynamic optimization module, performs two-dimensional coordinate calculations and aerodynamic numerical simulations of the intermediate airfoil parameters, and transmits the aerodynamic data to the aerodynamic optimization module. It also performs three-dimensional coordinate calculations and aerodynamic numerical simulations of the propeller test configuration set during the determination of the propeller's basic configuration and optimization range, and transmits the propeller surface pressure distribution data to the noise evaluation module as the basis for determining the propeller's basic configuration and optimization range. Furthermore, it receives intermediate propeller configuration parameters for multi-objective aerodynamic optimization based on the propeller's basic configuration under typical conditions generated by the aerodynamic optimization module, performs three-dimensional coordinate calculations and aerodynamic numerical simulations of the intermediate propeller configuration parameters, and transmits the aerodynamic data to the aerodynamic optimization module.

[0113] The noise assessment module receives surface pressure distribution data of the propeller test configuration set output by the aerodynamic assessment module during the propeller basic configuration and optimization range determination stage, performs acoustic numerical simulation, and finally selects the chord length C, negative torque Twist, and number of blades to form a noise-acceptable propeller basic configuration, and determines the noise-acceptable chord length range. Negative torque range and blade number range The data is then sent to the aerodynamic optimization module for propeller configuration optimization.

[0114] The implementation device for the noise-controllable vertical takeoff and landing (VTOL) aircraft propeller design method of this invention integrates an aerodynamic optimization module, an aerodynamic evaluation module, and a noise evaluation module to form a highly efficient and collaborative closed-loop optimization system. The aerodynamic optimization module performs airfoil parameter optimization and propeller configuration optimization, and can perform multi-objective aerodynamic optimization based on the aerodynamic data provided by the aerodynamic evaluation module and the basic configuration and optimization range provided by the noise evaluation module. The aerodynamic evaluation module can evaluate the aerodynamic performance of the blade airfoil and propeller configuration, providing aerodynamic data for the aerodynamic optimization module. The noise evaluation module can evaluate the noise level of different propeller configurations, determine the acceptable design parameter range for noise, and provide noise control constraints for the aerodynamic optimization module. Furthermore, through feedback from the noise evaluation module, the aerodynamic optimization module can consider noise control while meeting aerodynamic performance requirements, achieving a balance between aerodynamic performance and noise level. This not only improves the automation level of the design process but also ensures the reliability of the design results.

[0115] In summary, the noise-controllable vertical takeoff and landing (VTOL) aircraft propeller design method and implementation device provided by this invention achieves active noise control by systematically and comprehensively considering aerodynamic performance and noise control during the design phase, ensuring that the designed propeller achieves the optimal balance between aerodynamic performance and noise control. Furthermore, the efficient collaboration of the device provides strong support for the implementation of this method. The combination of the design method and the implementation device not only improves design efficiency and reduces R&D costs, but also enhances the overall performance and environmental friendliness of the aircraft, reduces noise pollution, and provides important technical support and guarantees for the future development of urban low-altitude flight.

Claims

1. A method of designing a vertical take-off and landing aircraft propeller with controllable noise, characterized in that, The method comprises the following steps: S1: selecting key positions in the blade span direction and determining a basic airfoil: According to the design requirements of the aircraft, the key positions in the blade span direction are selected for subsequent airfoil optimization, and the basic airfoil for optimization is determined; S2: determining optimization objectives and constraint conditions of typical working conditions, and optimizing the airfoil of the key positions in the blade span direction: According to the typical working conditions of hovering and cruising, the coordinate parameters of the optimized airfoil are determined by optimizing the basic airfoil under the constraint condition, respectively taking the maximum lift coefficient and the minimum drag coefficient as the target. S3: preliminarily arranging the optimization airfoil with equal chord length along the blade span direction: The optimized airfoil is arranged along the span direction, and the equal chord length design is adopted in the arrangement to form a preliminary propeller configuration; S4: According to the fixed specific negative twist value Twist and specific blade number, adjust the chord length value C to generate a test configuration set, determine the chord length interval acceptable for noise ; S5: According to the fixed specific chord length value C and specific blade number, adjust the negative twist value Twist to generate a test configuration set, determine the noise acceptable negative twist interval ; S6: According to the fixed specific chord length value C and specific negative twist value Twist, adjust the blade number generation test configuration set to determine the noise acceptable blade number interval ; S7: determining a propeller basic configuration and an optimization range: The optimization range of the chord length value C is set as The optimization range of the negative twist value Twist is set as The optimization range of the number of blades is set as ; The noise-acceptable chord interval determined from S4 The noise-acceptable negative twist interval determined from S5 The noise-acceptable number of blades interval determined from S6 Together with the fixed values selected in S3, S4, and S5, the noise-acceptable propeller base configuration S8: optimizing the aerodynamic performance of the propeller configuration under corresponding working conditions: Under typical working conditions, based on the basic configuration, multi-objective aerodynamic optimization is performed within the parameter range of the chord length value C, the negative twist value Twist and the number of blades determined in S7.

2. The method of claim 1, wherein: In S1, the key positions include a main lift section at 50% to 90% of the blade span length, a blade root and a blade tip.

3. The method of claim 1, wherein: In S2, the optimization objectives and constraint conditions under the hovering state are: where x is the airfoil parameterization vector, CLO is the optimized airfoil lift coefficient in hover, CRO is the optimized airfoil drag coefficient in hover, CRO is the optimized airfoil drag coefficient in hover, TMAX is the maximum thickness of the optimized airfoil, TMAX is the maximum thickness of the optimized airfoil, UP is the upper bound of the optimized airfoil parameterization vector, and LOW is the lower bound of the optimized airfoil parameterization vector. The optimization objectives and constraint conditions under the cruising state are: where x is the airfoil parameterization vector, is the optimized airfoil drag coefficient in cruise, is the optimized airfoil lift coefficient in cruise, is the lift coefficient of the base airfoil in cruise, UP is the upper bound of the optimized airfoil parameterization vector, and LOW is the lower bound of the optimized airfoil parameterization vector.

4. The method of claim 1, wherein: In the S2, the coordinate parameters of the optimized airfoil are determined by using the Hicks-Henne function. The airfoil parameterization vector is converted into the airfoil coordinate parameters by applying linear perturbations on the surface of the base airfoil, and the formula is as follows: The conversion of the airfoil parameterization vector into the airfoil coordinate parameters is shown in the following formula: wherein is the chord-wise transverse coordinate of the airfoil, is the upper surface longitudinal coordinate of the optimized airfoil, is the lower surface longitudinal coordinate of the optimized airfoil, is the upper surface longitudinal coordinate of the base airfoil, is the lower surface longitudinal coordinate of the base airfoil, is the perturbation component coefficient applied to the upper surface, is the perturbation component coefficient applied to the lower surface, ; The shape function formula is: wherein , are n-1 specific airfoil chord-wise abscissas.

5. The method of claim 1, wherein: In S3, the preliminary propeller configuration arrangement includes arranging the blade root optimization airfoil and the blade tip optimization airfoil at the corresponding positions in the blade span direction, preliminarily arranging the optimization airfoil of the main lift section within the corresponding blade span direction range, and smoothly connecting the middle sections of the three airfoils.

6. The noise-controllable vertical take-off and landing aircraft propeller design method according to claim 1, wherein in S4, the fixed specific negative twist value Twist and the specific number of blades are empirical values for propeller aerodynamic design; and adjusting the chord length value C to generate a test configuration set is to select a plurality of discrete values of the chord length value C based on the empirical value of the chord length, to form a test configuration set for exploring the influence law and range of the chord length value on the propeller noise.

7. The method of claim 1, wherein: In S5, the specific chord length value C is the noise acceptable chord length interval determined in S4 In S5, the specific chord length value C is the noise acceptable chord length interval determined in S4 In S5, the specific chord length value C is the noise acceptable chord length interval determined in S4 8. The method of claim 1, wherein: In the S6, the specific chord length value C is the noise acceptable chord length interval determined in S4 In the S6, the specific chord length value C is the noise acceptable chord length interval determined in S4 In the S6, the specific chord length value C is the noise acceptable chord length interval determined in S4 In the S6, the specific chord length value C is the noise acceptable chord length interval determined in S4 9. The method of claim 1, wherein: In S8, the mathematical description of the optimization of the aerodynamic performance of the propeller is: where FM is the hover efficiency, ETA is the cruise efficiency, CT is the thrust coefficient, and R is the propeller radius, is the optimized airfoil start position for the main lift segment, is the optimized airfoil end position for the main lift segment, and Twist is the negative twist value, is the lower boundary of the noise acceptable negative twist value determined in S5, is the upper boundary of the noise acceptable negative twist value determined in S5, is the average chord length of the blades, is the lower boundary of the noise acceptable chord length value determined in S4, is the upper boundary of the noise acceptable chord length value determined in S4, and Blade is the number of blades, is the lower boundary of the noise acceptable number of blades determined in S6, is the upper boundary of the noise acceptable number of blades determined in S6, is the sweepback position of the blades, is the lower boundary of the sweepback position, is the upper boundary of the sweepback position, is the sweepback angle of the blades, is the lower boundary of the sweepback angle, is the upper boundary of the sweepback angle.

10. An implementation apparatus of a noise-controllable VTOL aircraft propeller design method, characterized by: The system comprises an aerodynamic optimization module, an aerodynamic evaluation module and a noise evaluation module, the aerodynamic evaluation module is bidirectionally connected with the aerodynamic optimization module, the output end of the aerodynamic evaluation module is connected with the input end of the noise evaluation module, and the output end of the noise evaluation module is connected with the input end of the aerodynamic optimization module; The aerodynamic optimization module is configured to maximize the lift coefficient and minimize the drag coefficient under the constraint conditions in the hovering and cruising typical working conditions, respectively, and to receive the evaluated intermediate airfoil aerodynamic data as a reference for the optimization process and to guide the airfoil optimization direction. The multi-objective aerodynamic optimization is configured to receive the evaluated intermediate propeller configuration aerodynamic data as a reference for the optimization process and to guide the propeller configuration optimization direction in the parameter range of the determined chord length value , negative torsion value and number of blades. The aerodynamic evaluation module is used for receiving the intermediate airfoil parameters of the key position airfoil optimization under the hovering and cruising typical working conditions generated by the aerodynamic optimization module, realizing two-dimensional coordinate calculation and aerodynamic numerical simulation of the intermediate airfoil parameters, and delivering the aerodynamic data to the aerodynamic optimization module; is used for realizing three-dimensional coordinate calculation and aerodynamic numerical simulation of the propeller test configuration set in the propeller basic configuration and optimization range determination stage, delivering the propeller surface pressure distribution data to the noise evaluation module as a basis for determining the propeller basic configuration and the optimization range; and is used for receiving the intermediate propeller configuration parameters of the multi-objective aerodynamic optimization based on the propeller basic configuration under the typical working conditions generated by the aerodynamic optimization module, realizing three-dimensional coordinate calculation and aerodynamic numerical simulation of the intermediate propeller configuration parameters, and delivering the aerodynamic data to the aerodynamic optimization module; The noise evaluation module is configured to receive the surface pressure distribution data of the propeller test configuration set output by the aerodynamic evaluation module in the propeller basic configuration and optimization range determination stage, to realize acoustic numerical simulation, and finally to select the chord length value C, the negative twist value Twist and the number of blades to form a noise-acceptable propeller basic configuration, and to determine a noise-acceptable chord length interval , a negative twist interval and a number of blades interval , and to deliver the same to the aerodynamic optimization module for propeller configuration optimization.

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