A method of designing a hollow propeller

Abstract

The application discloses a hollow propeller design method, and belongs to the technical field of unmanned aerial vehicle power structures. The method comprises the following steps: setting basic geometric parameters based on unmanned aerial vehicle working conditions and loads, obtaining a three-dimensional shape and aerodynamic pressure distribution through fluid mechanics simulation optimization; performing coupling finite element analysis on aerodynamic loads and centrifugal force, determining a high stress area, and constructing a specific range of solid transition sections; designing a variable wall thickness internal cavity guided by stress distribution, and realizing accurate matching of stress and wall thickness; arranging longitudinal reinforcing ribs to construct a torsion-resistant box section; and integrally forming through additive manufacturing. The application integrates aerodynamic simulation, structural analysis and manufacturing constraints to form a closed-loop design. The longitudinal reinforcing ribs can improve torsional stiffness and suppress buckling. The variable wall thickness design eliminates redundant weight. Integrally forming eliminates the defects of the bonding interface, effectively solves the pain points of the traditional scheme, has high design flexibility and engineering application value, and significantly improves the power-to-weight ratio and endurance potential of the unmanned aerial vehicle.

Description

Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle (UAV) propulsion structure technology, specifically a hollow propeller design method. Background Technology

[0002] With the deep integration of aerodynamics, microelectromechanical systems (MEMS), and advanced materials science, unmanned aerial vehicle (UAV) technology has achieved leapfrog development in many key fields such as geographic mapping, environmental monitoring, logistics distribution, and emergency rescue. As the core kinetic energy conversion component of the UAV propulsion system, the aerodynamic efficiency and structural mass distribution of the propeller directly determine the power-to-weight ratio, endurance, and maneuverability of the aircraft. Under the current technological trend of pursuing extreme flight performance, how to achieve extreme lightweighting of the propeller through structural innovation while ensuring its mechanical reliability under complex dynamic conditions has become one of the research focuses in the field of aerospace engineering.

[0003] Currently, most mainstream high-performance UAV propellers use high-strength carbon fiber composites or lightweight aluminum alloys as the base material, and their manufacturing process still relies primarily on traditional subtractive manufacturing technologies such as CNC milling. While this process can ensure high surface finish and dimensional tolerance accuracy thanks to mature cutting mechanisms, it has inherent limitations in material utilization, especially for expensive special aerospace materials, where the cutting process often results in significant resource waste. A more profound technical challenge lies in the fact that, limited by the accessibility of machining tools and the physical constraints of the mechanical motion envelope, traditional subtractive manufacturing processes struggle to process propeller models with complex internal cavities or non-uniform topology optimization structures. This results in existing propellers mostly exhibiting solid structures. Although solid designs possess strong static compressive strength, during high-speed rotation, their large mass generates severe centrifugal loads. This internal stress caused by "self-weight" often accounts for a significant proportion of the total stress, thus restricting further increases in rotational speed and energy efficiency.

[0004] To overcome the weight bottleneck of solid structures, the industry has attempted a split-type adhesive bonding solution, where the propeller is molded into two separate shells, each filled with lightweight foam or structural adhesive for bonding. However, this approach has revealed serious reliability issues in practical applications. Specifically, the adhesive interface, as a heterogeneous weak layer in the structure, is highly susceptible to stress concentration under the combined effects of alternating aerodynamic loads and centrifugal forces generated by high-speed rotation, leading to interface delamination or the initiation of microcracks. Furthermore, due to the randomness of the filler material distribution and the discrete nature of the bonding process, the propeller's center of gravity can easily deviate from its axis, resulting in a catastrophic decline in dynamic balance performance. This dynamic imbalance caused by manufacturing defects can not only induce severe fuselage vibration and damage the lifespan of motor bearings, but may also trigger structural fatigue failure near the resonance point.

[0005] The underlying cause lies in a severe logical disconnect between existing propeller design and manufacturing systems. On one hand, existing structural solutions often rely on static load assumptions, lacking detailed consideration of the multi-physics coupling effects such as aerodynamic pressure distribution, centrifugal loads, and rotational elastic deformation within the flight envelope. This results in material arrangement failing to follow the actual load transfer path, frequently leading to a coexistence of stiffness redundancy or localized strength in high-stress areas such as the blade root and airfoil leading edge. On the other hand, traditional design methods have failed to fully exploit the digital potential of additive manufacturing (3D printing) in shaping complex forms, resulting in cavity designs often being limited to simple, uniformly thick shells, unable to achieve dynamic wall thickness optimization based on stress gradient distribution. Due to a lack of in-depth research on the synergistic evolution relationship between the distribution of internal longitudinal stiffeners and the aerodynamic characteristics of the airfoil section, existing hollow structures often fall short when facing complex torsional and shear resistance requirements.

[0006] In summary, in the current industrial application context, how to construct a fully integrated design scheme that deeply couples aerodynamic load and structural strength, can accurately guide the spatial distribution of materials, and takes into account the characteristics of additive manufacturing processes for the unique working conditions of UAV propellers, in order to solve the inherent technical contradiction between lightweight requirements and high reliability and high dynamic stability, has become a key challenge and an urgent technical problem to be solved in the research and development of aerospace propulsion components. Summary of the Invention

[0007] The purpose of this invention is to provide a hollow propeller design method to solve the following technical problems mentioned in the background art:

[0008] The existing drone propellers suffer from technical problems such as insufficient structural strength, limited manufacturing processes, and disconnect from actual load conditions during the lightweighting process.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0010] A hollow propeller design method includes the following steps:

[0011] S1. Based on the flight envelope conditions and preset load requirements of the target UAV, the basic geometric parameters of the propeller are set, and the basic geometric parameters are verified and optimized by computational fluid dynamics simulation to obtain the three-dimensional geometric shape and surface aerodynamic pressure distribution that meet the performance indicators.

[0012] S2, based on the three-dimensional geometric shape and surface aerodynamic pressure distribution, combined with the rotating centrifugal force load, multi-physics field coupled finite element analysis is performed to obtain the equivalent stress distribution of the blade.

[0013] Based on the equivalent stress distribution, the region extending from the rotor hub to the point where the equivalent stress decreases to 50% of the peak value is determined as the high stress region. A solid transition section is constructed extending from the rotor hub to the point where the stress decreases to 50% of the peak value. The cross-section of this section is a complete solid airfoil.

[0014] S3, with equivalent stress distribution as the topology guide, designs an internal cavity that runs continuously along the span in the blade region outside the solid transition section.

[0015] The wall thickness of the internal cavity is mapped according to the magnitude of local equivalent stress, so as to achieve a continuous change in wall thickness, which increases in high stress area and decreases in low stress area.

[0016] S4, based on the surface aerodynamic pressure distribution and equivalent stress distribution, arranges at least one longitudinal stiffener along the spanwise direction in the internal cavity. The longitudinal stiffener is used to form an anti-torsion box section structure extending from the end of the solid transition section to the blade tip region.

[0017] The S5 will be an integrated 3D model of the completed design, including the hub, solid transition section, variable thickness internal cavity and longitudinal reinforcing ribs, which will be integrally formed using additive manufacturing process.

[0018] Furthermore, the basic geometric parameters include at least the number of blades, diameter, pitch ratio, chord length distribution curve, airfoil family, and installation angle.

[0019] Furthermore, the wall thickness of the internal cavity is dynamically mapped according to local strength requirements, and the basic value of the internal cavity wall thickness is defined as 10% of the maximum thickness of the corresponding airfoil section; the local wall thickness is increased according to the linear proportional relationship between the local equivalent stress and the maximum equivalent stress of the entire blade, and the core formula for linear thickening is:

[0020]

[0021] in, Where is the local wall thickness, and k is the linear scaling factor adapted for engineering applications. It is set according to the allowable stress of the molded substrate and ranges from 0.1 to 0.15. This is the basic value for wall thickness. For local equivalent stress, This represents the maximum equivalent stress.

[0022] Furthermore, the computational fluid dynamics simulation in step S1 uses the steady Navier-Stokes equations based on a multi-block structured grid. During the grid generation process, the leading edge, trailing edge, and tip vortex region of the airfoil are refined, and the height of the first layer of the grid makes the dimensionless wall distance y+ approach 1. By adjusting the combination of inflow wind speed and rotational speed, the complete curves of thrust coefficient Ct, power coefficient Cp, and efficiency η as a function of advance ratio J are obtained. During the simulation verification process, the absolute value of the aerodynamic performance deviation between the positive and negative propellers is made less than 2%.

[0023] Furthermore, in step S2, the multiphysics coupled finite element analysis includes two stages:

[0024] The first stage simulates the centrifugal tensile stress field of the propeller at its rated maximum speed.

[0025] In the second stage, the deformation displacement of the first stage is used as the initial condition, and the non-uniform aerodynamic pressure distribution derived in step S1 is superimposed to perform nonlinear deformation analysis.

[0026] The length of the solid transition section must be determined to ensure that, under maximum working conditions, the maximum shear stress at the root section is less than 60% of the allowable stress of the material.

[0027] Furthermore, in step S3, the wall thickness increase amount Through formula Calculated; or obtained through the wall thickness distribution function. Determine the shell wall thickness at any spanwise position r, where The basic wall thickness of the cross section is given by , and k is the thickening factor with a value ranging from 0.1 to 0.15. The inner surface of the internal cavity is fitted with a non-uniform rational B-spline NURBS surface.

[0028] Furthermore, in step S4, the longitudinal stiffeners are positioned near the pressure center at 20% or 30% of the chord length of the airfoil's leading edge; the cross-sectional shape of the longitudinal stiffeners is set to a rectangular cross-section, an I-shaped variable cross-section structure, or an I-shaped variable cross-section structure according to the local shear flow distribution; at the junction of the solid transition section and the internal cavity, a bifurcated transition structure is used to achieve a smooth distribution of the load from the solid transition section to the longitudinal stiffeners.

[0029] Furthermore, it also includes smoothing all geometric abrupt changes inside the internal cavity; and uniformly setting rounded chamfers at the four corners where the longitudinal stiffeners connect to the inner wall of the internal cavity, the inner confluence point of the front and rear edges of the internal cavity, and the boundary step at the junction of the solid transition section and the starting end of the internal cavity. The radius R of the rounded chamfer ranges from 1.0 to 2.5 mm.

[0030] Furthermore, the molding substrate is a polymer material; during the additive manufacturing process, the path algorithm of the printing nozzle is adjusted so that the fiber arrangement direction is consistent with the direction of the main stress line of the blade; when using the fused deposition modeling (FDM) process, the shell filling rate is set to 100%, the longitudinal reinforcing rib filling rate is not less than 90%, and the temperature of the constant temperature chamber is kept 50℃-80℃ above the ambient temperature.

[0031] Furthermore, the process includes surface polishing and degreasing of the molded propeller body; covering the outer surface of the molded propeller body with a layer of high-modulus carbon fiber fabric with a thickness of 0.5mm to 1.0mm to form an outer reinforcing layer; vacuum-assisted impregnation with epoxy resin and curing for 2 to 4 hours in a gradient temperature environment of 80℃ to 120℃.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] This invention effectively constructs a torsional closed box segment by scientifically arranging longitudinal stiffeners inside the cavity and setting a specific width-to-chord length ratio. This not only improves the overall torsional stiffness of the blade and suppresses aeroelastic instability, but also provides internal support for the thin-walled skin, preventing local buckling deformation under high-speed airflow pressure.

[0034] The method described in this invention deeply integrates aerodynamic performance simulation, structural dynamics analysis, and additive manufacturing process constraints, forming a closed-loop design flow. Compared to traditional subtractive manufacturing schemes that rely on empirical formulas, this invention can customize the internal topology for different flight conditions, offering design flexibility and engineering application value.

[0035] This invention directly links wall thickness to local equivalent stress, ensuring the strength of high-stress areas such as the blade root and leading edge while greatly eliminating redundant weight in the blade tip and belly area, thus significantly improving the power-to-weight ratio and endurance potential of the UAV.

[0036] This invention utilizes the integrated molding capabilities of additive manufacturing to eliminate the adhesive interface found in traditional hollow propeller designs. This seamless connection structure fundamentally solves the technical problem of shell delamination caused by alternating stress generated during high-speed rotation, significantly enhancing the structural reliability and fatigue life of the propeller under extreme maneuvering conditions. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating a hollow propeller design method according to the present invention.

[0038] Figure 2 This is a schematic diagram of the blade structure of the present invention;

[0039] Figure 3 This is a schematic diagram of the internal cavity structure of the blade of the present invention;

[0040] Figure 4 This is a schematic diagram of the overall structure of the blade of the present invention;

[0041] Figure 5 This is a partial cross-sectional view of the blade of the present invention;

[0042] Figure 6This is a schematic diagram of the blade stress distribution of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1:

[0045] A hollow propeller design method, such as Figure 1 As shown, it includes the following steps:

[0046] S1, based on the target UAV's full flight envelope conditions and preset load requirements, sets the basic geometric parameters of the propeller. In this stage, the basic geometric parameters of the propeller are systematically set, encompassing the number of blades, diameter, pitch ratio, chord length distribution curve, airfoil family, and installation angle. To verify the effectiveness of these initial designs, this invention uses high-fidelity fluid dynamics CFD simulation to verify and iteratively optimize the basic geometric parameters, establishing a three-dimensional fluid domain model. In the construction of the simulation environment, the three-dimensional fluid domain model is divided into a rotating region and a far-field stationary region, with data exchange between the two through a sliding mesh interface. For mesh generation, this embodiment uses multiple structured meshes, especially for the leading and trailing edges of the airfoil and the tip region where strong lift-induced vortices may be generated, implementing fine-grained meshing. In the boundary layer region, the mesh growth rate is strictly controlled between 1.1 and 1.2, and the height of the first layer mesh is calculated based on the estimated Reynolds number to ensure that the dimensionless wall distance y+ is close to 1. The core of the simulation process lies in using the SSTk-ω turbulence model as a closed-loop equation. This model, by combining the robustness of the k-ω model in near-wall treatment with the accuracy of the k-ε model in far-field calculations, can accurately simulate boundary layer flow separation and adverse pressure gradient effects that may occur under high advance ratio or high load conditions. Steady and unsteady simulations were performed for hovering and maximum forward flight conditions, respectively, to obtain the propeller's thrust coefficient, power coefficient, and aerodynamic efficiency curves at different speeds. By adjusting the airfoil circulation distribution and torsion gradient, the design goal is to ensure that the propeller's aerodynamic characteristics at its rated operating point fully meet the preset specifications, and that the absolute value of the aerodynamic performance deviation between the forward and reverse propellers is statistically less than 2%, thus providing a symmetrical and stable physical basis for the flight control algorithm of the multi-rotor platform. Finally, the three-dimensional geometry and surface aerodynamic pressure distribution that meet the performance specifications are obtained.

[0047] S2, after the aerodynamic shape is locked through computational fluid dynamics simulation, proceeds to the construction of the solid transition section structure. Based on the three-dimensional geometry and surface aerodynamic pressure distribution, multiphysics coupled finite element analysis is performed in conjunction with rotating centrifugal force loads to obtain the equivalent stress distribution of the blade. This analysis aims to obtain the complete equivalent stress distribution and shear stress distribution of the blade under all operating conditions. According to the equivalent stress distribution, the region extending from the hub to the point where the equivalent stress decays to 50% of the peak value is identified as the high-stress region. The stress concentration region at the blade root and its attenuation law along the span can be clearly identified, thereby constructing a transition section corresponding to this high-stress region. The cross-section of this section is a complete solid airfoil, and the length of this section typically accounts for 15% to 25% of the total blade span to bear and transmit the main loads.

[0048] The theoretical basis for this step lies in identifying the stress distribution field of the blade under extreme dynamic loads through multiphysics coupled simulation. The simulation model not only considers the strong centrifugal force load caused by high rotational speed, but also extracts the non-uniform surface aerodynamic pressure load obtained in the aforementioned aerodynamic simulation. Using the finite element method, rotational velocity boundary conditions and surface pressure mapping are applied to the three-dimensional model to calculate the equivalent stress gradient extending from the blade root to the blade tip. The study found significant stress concentration at the connection between the blade root and the blade hub, which is the result of the combined superposition of axial tensile stress accumulated at the root section by the rotating centrifugal force and the maximum bending moment generated at the root by aerodynamic lift. Figure 3 as well as Figure 5 As shown, to ensure structural integrity, this invention establishes a solid transition section between the rotor hub and the subsequently designed internal cavity. The length of this transition section is not subjectively set, but scientifically determined by the stress attenuation law; that is, it covers the physical position where the stress value attenuates to 50% of the peak value, starting from the point of maximum equivalent stress at the blade root and extending towards the blade tip. Specifically, as shown... Figure 6 As shown. In the specific execution of geometric constraints, this length is set to 15% to 25% of the total blade span. Within this range, the blade remains a complete solid airfoil structure without any cavities or weight-reducing holes, so as to utilize the high continuity characteristics of solid materials to achieve smooth load transfer from the rotation axis to the blade body, and completely eliminate the root stress singularity induced by abrupt changes in cross-sectional stiffness.

[0049] S3, guided by the equivalent stress distribution, designs a continuous internal cavity along the span in the blade region outside the solid transition section; the wall thickness of the internal cavity is mapped according to the magnitude of the local equivalent stress, realizing a continuous change in wall thickness, which increases in the high stress area and decreases in the low stress area.

[0050] This step utilizes the equivalent stress distribution obtained in the preceding steps as a guide for topology optimization, forming a hollow cavity with varying thickness in the region following the solid transition section. The geometric topology of the internal cavity is not a simple shell with uniform wall thickness, but rather achieves dynamic, on-demand material distribution through a wall thickness distribution function. The basic wall thickness of the internal cavity is defined as 10% of the maximum thickness of the corresponding airfoil section. The increase in local wall thickness is directly linked to the local stress level. Specifically, the increase is calculated based on the linear proportional relationship between the local equivalent stress and the maximum equivalent stress of the entire blade. Alternatively, it can be calculated using a preset wall thickness distribution function. To determine the shell thickness at an arbitrary spanwise position r, where, Let r be the shell thickness at position r. This is the foundation wall thickness of the cross section. The stress at position r, The maximum stress is given by k, which is a thickening factor ranging from 0.1 to 0.15. This design ensures that the wall thickness exhibits a continuous and smooth variation in the spanwise direction, and that the wall thickness remains relatively large in areas with high stress, such as near the blade root, gradually thinning towards the blade tip. To further eliminate stress fluctuations, the inner surface of the internal cavity is mathematically fitted using a non-uniform rational B-spline surface, ensuring that the wall thickness variation achieves second-order continuity (G2 continuity) in both the spanwise and chordwise directions. This high degree of geometric smoothness effectively avoids the possibility of local high-frequency stress oscillations under dynamic vibration modes.

[0051] S4, based on the surface aerodynamic pressure distribution and equivalent stress distribution, arranges at least one longitudinal stiffener along the spanwise direction in the internal cavity. The longitudinal stiffener is used to form an anti-torsion box section structure extending from the end of the solid transition section to the blade tip region.

[0052] Considering the risk of shell buckling during high-speed rotation and torsional deformation under complex aerodynamic loads, this invention incorporates longitudinal stiffeners within the internal cavity. The design of these longitudinal stiffeners is based on the pressure difference distribution characteristics between the pressure and suction surfaces obtained in step S1, and the shear stress concentration areas identified in step S2. The longitudinal stiffeners completely fill the cavity along the cross-sectional height, transforming the original thin-walled hollow structure into a box-section structure with torsional resistance. A strict proportional constraint exists between the width b of the longitudinal stiffener and the chord length c of its cross-section, satisfying the relationship b = k × c, where the proportionality coefficient k ranges from 0.15 to 0.25. Spatially, the longitudinal stiffeners are located within 20% or 30% of the airfoil's leading edge chord length. This location typically coincides with the pressure center of a typical low Reynolds number airfoil, allowing the longitudinal stiffeners to directly bear the majority of the aerodynamic lift and effectively suppress blade torsion around the elastic axis. The longitudinal stiffeners begin at the end of the solid transition section and extend continuously to a position 10% of the blade tip's span. In this way, at the junction of the solid transition section and the hollow section, the load flows smoothly from the solid body to the shell and longitudinal stiffeners through a bifurcated transition structure.

[0053] S5 will complete the integrated 3D model of the design, including the hub, solid transition section, variable thickness internal cavity, and longitudinal reinforcing ribs, as shown below. Figure 4 As shown, the part is integrally formed using additive manufacturing. After manufacturing, supports are removed, the surface is smoothed, and necessary post-curing treatments are performed to ensure that the part achieves its final design performance.

[0054] After the digital model is constructed, it is imported into the additive manufacturing system for integrated molding. In this embodiment, the molding substrate is a high-performance long-fiber reinforced composite material, such as carbon fiber reinforced nylon or polyetheretherketone (PEEK). The specific execution parameters of the additive manufacturing process have been finely optimized to adapt to the complex internal cavity structure of this invention. The printing layer thickness is set within the range of 0.05 mm to 0.2 mm; a smaller layer thickness is beneficial for improving interlayer bonding strength and surface roughness. The scanning spacing is set to no more than 0.15 mm to ensure the airtightness of the cavity walls. For the case of using fused deposition modeling (FDM), the movement path of the printing nozzle is adjusted to align the fiber arrangement direction with the blades as much as possible along the principal stress line. The fill rate of the outer shell is set to 100%, and the fill rate of the internal longitudinal reinforcing ribs is no less than 90%. Simultaneously, to reduce the accumulation of thermal stress during the cooling process of large-sized parts, the ambient temperature chamber of the molding equipment is maintained at a level 20°C to 40°C lower than the glass transition temperature of the substrate, such as 50°C to 80°C for PA-CF materials, thereby suppressing warping deformation and ensuring accurate geometric reproduction. The formed blades are like Figures 2 to 5 As shown.

[0055] The molded propeller can be selectively surface-strengthened. First, the main body surface is physically polished and degreased. Then, a layer of high-modulus carbon fiber fabric with a thickness of 0.5mm to 1.0mm is applied to its outer surface using an automated lay-up process. Vacuum-assisted impregnation with epoxy resin is then performed, following a specific gradient temperature curing curve, such as holding at 80℃ for 1 hour, followed by curing at 120℃ for 3 hours. This outer strengthening layer, chemically bonded to the internal 3D-printed main body through the resin matrix, constitutes a multi-scale composite structure, significantly improving the propeller's impact resistance and environmental weather resistance.

[0056] Further optimization involves defining the fundamental geometric parameters, including at least the number of blades, diameter, pitch ratio, chord length distribution curve, airfoil family, and installation angle. The primary function of these fundamental geometric parameters is to anchor the hollow propeller to the core geometric baseline required for adapting to the target UAV's full flight envelope and pre-set load conditions. This lays a suitable and targeted initial geometric framework for subsequent aerodynamic simulation optimization, structural stress analysis, hollow topology design, and integrated additive manufacturing. This baseline directly determines the propeller's fundamental aerodynamic performance boundaries (such as the initial ranges of thrust, power, and aerodynamic efficiency) and the geometric constraints of the structural design. It ensures that all subsequent CFD simulation iterations, multiphysics coupling analysis, and topology design of variable-thickness cavities and longitudinal stiffeners are all geared towards meeting the actual flight requirements of the target UAV, preventing subsequent designs from deviating from core load and operating condition requirements. It serves as the underlying geometric basis for the entire hollow propeller design scheme.

[0057] Further optimized, the wall thickness of the internal cavity is dynamically mapped according to local strength requirements, and the basic value of the internal cavity wall thickness is defined as 10% of the maximum thickness of the corresponding airfoil section; the local wall thickness is increased according to the linear proportional relationship between the local equivalent stress and the maximum equivalent stress of the entire blade, and the core formula for linear thickening is:

[0058]

[0059] in, Where is the local wall thickness, and k is the linear scaling factor adapted for engineering applications. It is set according to the allowable stress of the molded substrate and ranges from 0.1 to 0.15. This is the basic value for wall thickness. For local equivalent stress, This represents the maximum equivalent stress.

[0060] By directly linking local wall thickness to local equivalent stress, high-stress areas (such as load-concentrated areas near solid transition sections) automatically thicken to withstand greater loads, while low-stress areas (such as blade tips with weaker loads) maintain a thinner base wall thickness. This design avoids the weight redundancy caused by overall thick walls and prevents structural failure in high-stress areas due to insufficient wall thickness. Ultimately, it achieves a balance between the core contradictions of strength and safety and lightweight design, directly improving the drone's endurance, payload performance, and flight stability.

[0061] Further optimized, the computational fluid dynamics simulation in step S1 employs a steady Navier-Stokes equations solution based on a multi-block structured grid. During mesh generation, the leading edge, trailing edge, and tip vortex regions of the airfoil are refined, and the height of the first mesh layer ensures that the dimensionless wall distance y+ approaches 1, for example, between 0.8 and 1.2. By adjusting the combination of inflow velocity and rotational speed, complete curves of thrust coefficient Ct, power coefficient Cp, and efficiency η as a function of advance ratio J are obtained. During simulation verification, the absolute value of the aerodynamic performance deviation between the propellers is kept below 2%. Through high-fidelity multi-block structured grids, fine processing of near-wall y+≈1, and the SSTk-ω turbulence model, the simulation can accurately predict the thrust coefficient, power coefficient, and efficiency curves of the propeller across the entire flight envelope (hovering, forward flight, etc.), providing accurate aerodynamic load input for subsequent structural stress analysis and hollow topology design, ensuring complete matching between structural design and aerodynamic performance. The requirement that the absolute value of the aerodynamic performance deviation between the propellers be less than 2% is a core requirement for multi-rotor UAVs. Attitude control of multi-rotor platforms relies on the symmetrical thrust output of multiple rotors, both positive and negative. If the performance deviation between the rotors is too large, the flight control algorithm needs to continuously compensate for attitude disturbances, which can lead to increased energy loss, flight jitter, or even loss of control. This constraint ensures a high degree of symmetry in the aerodynamic characteristics of the rotors, enabling the flight control system to control the UAV more stably and efficiently, which is a key prerequisite for ensuring the safety and performance of multi-rotor flight.

[0062] Further optimized, in step S2, the multiphysics coupled finite element analysis includes two stages: the first stage, simulating the centrifugal tensile stress field of the propeller at the rated maximum speed; the second stage, using the deformation displacement of the first stage as the initial condition, superimposing the non-uniform aerodynamic pressure distribution derived in step S1, and performing nonlinear deformation analysis; the length of the solid transition section must be determined to ensure that, under the maximum working condition, the maximum shear stress of the root section is less than 60% of the allowable stress of the material.

[0063] First, the centrifugal tensile stress field under high-speed rotation is simulated separately, and then aerodynamic pressure is superimposed for nonlinear deformation analysis. This process restores the actual stress and deformation of the propeller under the combined action of high-speed rotation and aerodynamic loads. Because in actual flight, the blade deformation caused by aerodynamic loads will in turn change the stress distribution, nonlinear analysis avoids the errors caused by linear assumptions, ensuring the accuracy of stress calculations and providing a reliable mechanical basis for the subsequent design of the solid transition section. Requiring the maximum shear stress at the root to be less than 60% of the material's allowable stress is a typical fatigue safety margin design. The propeller is a high-frequency rotating moving component; under long-term cyclic loading, even if the static stress is lower than the allowable stress, fatigue cracks may still occur. The 60% margin not only meets the static strength requirements, but more importantly, it provides sufficient fatigue life redundancy for high-frequency cyclic loading, effectively preventing fatigue cracks or direct fracture at the root of the hollow structure due to stress concentration. Root failure is one of the most fatal failures of multi-rotor UAVs. This design, through scientific stress analysis and conservative safety constraints, allows the solid transition section to smoothly transfer loads, avoiding stress abrupt changes that are prone to occur in hollow structures, and providing a core guarantee for the balance between lightweight and safety of the entire propeller.

[0064] Further optimized, in step S3, the wall thickness increase amount Through formula Calculated; or obtained through the wall thickness distribution function. Determine the shell wall thickness at any spanwise position r, where The basic wall thickness of the cross section is given by , and k is the thickening factor with a value ranging from 0.1 to 0.15. The inner surface of the internal cavity is fitted with a non-uniform rational B-spline NURBS surface.

[0065] By leveraging the linear proportional relationship between local equivalent stress and the maximum equivalent stress across the entire blade, the wall thickness increase in each region is dynamically calculated, ensuring that the wall thickness at each location perfectly matches the local strength requirements. High-stress areas (such as load-concentrated areas near the solid transition section) are automatically thickened to withstand greater loads, while low-stress areas (such as the blade tip) maintain the basic wall thickness. This avoids redundant weight from a thick wall across the entire blade and prevents structural failure in high-stress areas due to insufficient wall thickness. (Basic wall thickness) The minimum wall thickness (10% of the maximum thickness of the corresponding airfoil) ensures structural rigidity, while the thickening factor k (0.1~0.15) provides a controllable engineering margin, which can be flexibly adjusted according to different materials and working conditions, allowing the design to conform to mechanical theory while also possessing the flexibility for engineering implementation. Non-uniform rational B-spline (NURBS) surfaces achieve second-order continuity (G2 continuity) of wall thickness variation in the spanwise and chordwise directions, avoiding local stress peaks caused by abrupt changes in wall thickness. Under the dynamic load of high-speed propeller rotation, this highly smooth inner surface can effectively suppress local high-frequency stress oscillations, significantly improving fatigue life. The mathematical continuity of NURBS surfaces makes additive manufacturing path planning smoother, reduces printing defects, ensures the geometric accuracy and airtightness of the hollow cavity, and avoids stress concentration or structural failure caused by manufacturing errors.

[0066] Further optimized, in step S4, the longitudinal stiffeners are positioned near the pressure center at 20% or 30% of the chord length of the airfoil's leading edge; the cross-sectional shape of the longitudinal stiffeners is set to a rectangular cross-section, an I-shaped variable cross-section structure, or an I-shaped variable cross-section structure according to the local shear flow distribution; at the junction of the solid transition section and the internal cavity, a bifurcated transition structure is used to achieve a smooth distribution of the load from the solid transition section to the longitudinal stiffeners. The specific function of this design is to maximize torsional stiffness and structural stability within the lightweight framework of a hollow propeller through precise structural layout and detailed optimization, while ensuring smooth load transfer and uniform stress distribution. The longitudinal stiffeners, positioned near the pressure center at 20% or 30% of the airfoil's leading edge chord length, directly bear the main load of aerodynamic lift, effectively suppressing torsional deformation of the blades around the elastic axis and preventing buckling failure of the thin-walled hollow structure under high-speed rotation and complex aerodynamic loads. The cross-sectional shape, using rectangular, I-shaped, or I-shaped variable sections based on local shear flow distribution, precisely matches the requirements for local shear stress transfer, maximizing shear and torsional efficiency while reducing weight. The bifurcated transition structure at the junction of the solid transition section and the internal cavity allows the load to be smoothly diverted from the solid transition section to the shell and longitudinal stiffeners of the hollow cavity, completely eliminating the risk of stress concentration at the solid-hollow junction area. This ensures the structural integrity and fatigue life of the entire propeller under dynamic cyclic loads, ultimately achieving the optimal balance between lightweight and high structural performance in the hollow propeller.

[0067] Further optimization includes smoothing all geometric abrupt changes inside the internal cavity; uniformly setting rounded chamfers at the four corners where the longitudinal stiffeners connect to the inner wall of the internal cavity, the inner confluence point of the leading and trailing edges of the internal cavity, and the boundary step at the junction of the solid transition section and the starting end of the internal cavity, with the radius R of the rounded chamfer ranging from 1.0 to 2.5 mm. By setting 1.0-2.5mm rounded chamfers at all geometric abrupt changes, the risk of various stress concentrations inside the hollow propeller is systematically eliminated. Under high-speed rotating dynamic cyclic loads, the local stress peak is significantly reduced, avoiding fatigue cracks or instantaneous fractures caused by sharp corners or steps. At the same time, the smooth rounded transition can optimize the forming path of additive manufacturing, reduce interlayer defects and uneven material accumulation at sharp corners, ensure the airtightness and structural continuity of the hollow cavity, and make the load transfer from the solid transition section to the hollow section, and from the longitudinal stiffeners to the shell more uniform and smooth. Ultimately, under the premise of lightweight design, the structural integrity, fatigue life and manufacturing reliability of the entire hollow propeller are further improved.

[0068] Further optimized, the molding substrate is a polymer material such as polyetheretherketone (PEEK) or a composite material such as carbon fiber reinforced nylon (PA-CF). During additive manufacturing, the path algorithm of the printing nozzle is adjusted to ensure that the fiber arrangement direction is consistent with the principal stress line direction of the blade. The principal stress line direction is extracted through multiphysics coupled finite element analysis in step S2, specifically the direction of the maximum principal stress trace of the equivalent stress field. When using fused deposition modeling (FDM) technology, the shell fill rate is set to 100%, the longitudinal reinforcing rib fill rate is not less than 90%, and the temperature of the constant temperature chamber is maintained at 50℃-80℃ above the ambient temperature. By selecting high-performance substrates such as carbon fiber reinforced nylon PA-CF or polyetheretherketone (PEEK), which combine high strength, lightweight, and fatigue resistance, and by optimizing the precise process in additive manufacturing, the structural reliability and lightweight goal of the hollow propeller are guaranteed from the perspectives of material performance and manufacturing quality. Adjusting the printing nozzle path to align the fiber arrangement direction with the principal stress line of the blade allows for precise matching of the high strength characteristics of carbon fiber with the load transfer direction, maximizing structural load-bearing efficiency and avoiding waste of material mechanical properties. Setting the outer shell to 100% fill rate ensures the airtightness and surface structural rigidity of the hollow cavity, while the longitudinal reinforcing ribs have a fill rate of no less than 90%, ensuring torsional load-bearing capacity under the premise of lightweighting. Maintaining the constant temperature chamber temperature at 50℃-80℃ above the ambient temperature effectively suppresses thermal stress accumulation and warping deformation caused by temperature differences during fused deposition modeling, improves interlayer bonding strength and geometric forming accuracy of complex hollow structures, and ultimately manufactures an integrated hollow propeller that combines lightweight, high strength, high aerodynamic efficiency, and long fatigue life.

[0069] Further optimizations include surface polishing and degreasing of the molded propeller body; covering the outer surface of the molded propeller body with a layer of high-modulus carbon fiber fabric with a thickness of 0.5mm to 1.0mm to form an outer reinforcing layer; vacuum-assisted impregnation with epoxy resin and curing for 2 to 4 hours in a gradient temperature environment of 80°C to 120°C. By polishing and degreasing the surface of the molded propeller, residual support marks and surface impurities from additive manufacturing are removed, improving surface cleanliness and roughness, and providing a reliable interface foundation for the subsequent bonding of the outer reinforcement layer. By covering the outer surface with 0.5mm to 1.0mm high-modulus carbon fiber fabric and using epoxy resin vacuum-assisted impregnation, a dense multi-scale composite reinforcement layer can be formed on the outer surface of the propeller, significantly improving the propeller's impact resistance, fatigue strength, and environmental weather resistance. The gradient temperature curing process from 80℃ to 120℃ ensures that the epoxy resin fully impregnates the carbon fiber fabric and cures uniformly, avoiding the accumulation of thermal stress. This allows the outer reinforcement layer and the 3D printed body to form a strong chemical bond through the resin matrix, optimizing the smoothness of the aerodynamic surface to improve aerodynamic efficiency and further enhancing the overall structural load-bearing capacity and service life. Ultimately, this allows the propeller to achieve superior reliability and environmental adaptability while maintaining a lightweight design.

[0070] To demonstrate the superiority of the hollow propeller design method of this invention, the following is a data-driven comparison and demonstration through specific embodiments and comparative examples.

[0071] Example 2:

[0072] This invention presents a design scheme. The target propeller diameter is set at 22 inches (558.8 mm), and the rated speed is 7500 RPM. PA12-CF30 material is used, and the length of the solid transition section is set to 20% (55.8 mm) of the blade span. The internal cavity wall thickness is determined according to stress field mapping, with a base wall thickness of 0.8 mm. The longitudinal stiffeners are located at 25% chord length, and the width coefficient k is set to 0.2. A 2.0 mm rounded chamfer is provided. FDM technology is used for integrated printing.

[0073] Comparative Example 1: A conventional solid propeller. Its external parameters are completely identical to those of Example 2, and it is made of the same solid material (PA12-CF30) without any internal cavity.

[0074] Comparative Example 2: Hollow propeller with uniform wall thickness (no longitudinal stiffeners). The external parameters are the same as those of Example 2. It has a hollow cavity inside, but the wall thickness is a constant 1.2 mm, and there are no longitudinal stiffeners inside. It has no chamfered design, and the upper and lower propeller surfaces are joined together using an adhesive bonding process.

[0075] Static tension test, mass weighing test, dynamic balance test and fatigue strength test were conducted on the above three sets of propellers. The experimental results are shown in Table 1 below.

[0076] Table 1

[0077]

[0078] Analysis of the data in Table 1 shows that, while achieving a significant weight reduction (approximately 49.7% lighter than a solid paddle), Embodiment 2 of the present invention maintains its maximum equivalent stress within a safe range and is far lower than that of Comparative Example 2. In terms of the key structural efficiency indicator, the present invention achieves 0.82 N / g, significantly superior to the traditional solid design. Furthermore, due to the synergistic effect of the longitudinal stiffeners and variable thickness design, the torsional stiffness of Embodiment 1 is largely preserved, decreasing only slightly compared to a solid paddle, and far exceeding that of the unstiffened Comparative Example 2, effectively ensuring the stability of aerodynamic performance. In fatigue testing, thanks to the rounded chamfers and integrated molding eliminating the risk of adhesive interfaces, the present invention achieves a strength retention rate of 92% after 1 million cycles, demonstrating its high reliability under long-term dynamic loads.

[0079] Furthermore, in the specific engineering implementation, the computational fluid dynamics simulation described in step S1 is not limited to basic thrust calculation, but also includes capturing the evolution of the tip vortex. Through fine mesh generation, this scheme can identify the induced drag distribution caused by the blade tip shape, thereby further reducing unnecessary material at the blade tip location and decreasing the moment of inertia by optimizing the variable thickness parameters in step S3. This deep synergy between aerodynamics and structure ensures that the aerodynamic center does not shift while reducing weight.

[0080] As a refined embodiment of the present invention, the two-stage structural mechanics simulation in step S2 demonstrates extremely high engineering accuracy. The first stage of static centrifugal load analysis aims to simulate the centrifugal prestress field of the propeller at its rated maximum speed (e.g., 10000 RPM); the second stage introduces a geometric nonlinear switch, using the prestrain generated in the first stage as the initial value and superimposing transient aerodynamic loads from the CFD. Through this bidirectional or unidirectional coupled analysis, the load stiffening effect of the blade during rotation can be identified. The design of the solid transition section is based on the results of this nonlinear analysis, ensuring that under maximum operating conditions, the maximum shear stress at the root section is always less than 60% of the allowable stress of the material, thereby providing stable mechanical support for the propeller root during extreme maneuvers, such as rapid climbs or large overload turns.

[0081] In step S3, the internal surface mapping algorithm for the cavity is crucial for achieving lightweight design. Specifically, the nodal stress values ​​obtained from finite element analysis are transformed into a spatially continuous scalar field. The design system automatically generates a geometric entity with variable wall thickness by running a gradient-based wall thickness optimization algorithm on this scalar field. In regions with drastic stress changes, the second derivative of the wall thickness function is constrained within a preset threshold to ensure that the manufactured cavity wall is not only mechanically optimized but also geometrically printable. This method abandons the traditional manual setting of segmented wall thicknesses, achieving true topological optimization of the material distribution.

[0082] Regarding the longitudinal stiffener design in step S4, this invention particularly emphasizes its spatial alignment with the aerodynamic load axis. Since the UAV propeller experiences periodic flapping moments during operation, the placement of the longitudinal stiffeners (20%-30% of the chord length) precisely utilizes the maximum geometric moment of inertia provided by the thickest part of the airfoil, thereby achieving the maximum increase in bending stiffness with minimal mass increase. The cross-sectional shape of the longitudinal stiffeners is not limited to a simple rectangle in practical applications. In a variant of this embodiment, an I-shaped variable cross-section design is adopted, which further utilizes the principle of material distribution away from the neutral axis, reducing the stiffener weight by another 15% while maintaining torsional performance.

[0083] In step S5, controlling the diffusion of high-performance polymer molecular chains is crucial to determining the airtightness and strength of the cavity structure. When using FDM, the overlap between adjacent paths is set to 15% to 25%, ensuring that the molten filaments are fully integrated when forming each layer of variable-thickness shell. For PA-CF material, the printhead temperature is maintained at 260°C to 280°C. This high temperature induces the long fibers to align along the nozzle movement direction during extrusion. This microscopic fiber orientation aligns with the macroscopic principal stress direction, causing the hollow blades to exhibit high specific strength characteristics similar to anisotropic composite materials when subjected to tensile loads.

[0084] In the post-processing stage, the surface strengthening layer not only enhances the structure but also eliminates potential microporosity in additively manufactured parts through the tight wrapping of carbon fiber fabric. Vacuum-assisted impregnation ensures that epoxy resin can penetrate into the tiny gaps between the 3D printed layers, forming a microscopic anchoring effect. Experimental data shows that the propeller treated with S7 exhibits a 40% increase in surface hardness and a reduction in moisture absorption rate of over 85%. This allows the hollow propeller to operate for extended periods in harsh environments such as salt spray and high humidity without structural failure due to material degradation.

[0085] Specifically, the design method described in this invention is applicable not only to conventional fixed-wing propellers but also to propellers for high-maneuverability multi-rotor platforms. Because the cavity structure significantly reduces the rotational inertia of the blades, the dynamic response speed of the motor when adjusting its speed is improved by 20% to 30%. This data is crucial for improving the attitude control bandwidth of UAVs. In actual flight tests, UAVs equipped with propellers of this invention showed approximately 0.5 seconds shorter attitude recovery time when encountering sudden crosswinds compared to models equipped with solid propellers of the same specifications, fully demonstrating the synergistic advantages of this invention in aerodynamics, structure, and system control.

[0086] Furthermore, this invention considers the strain rate sensitivity of the material when setting the chamfer radius R. Under high-speed rotation, the material is in a high-frequency vibration state. By setting the R value above 1.0 mm, the reflection intensity of stress waves at the structural connection is effectively minimized, suppressing local overload phenomena caused by stress wave superposition. This detailed engineering treatment, combined with the integrated characteristics of additive manufacturing, allows the propeller's failure mode to change from the original root brittle fracture to controlled shell buckling in destructive tests at speeds exceeding the rated speed of up to 12000 RPM, greatly improving the system's safety and fault tolerance.

[0087] In summary, this invention provides a hollow propeller design scheme that is highly reliable in mechanical performance and extremely lightweight in mass through a complete engineering process, from aerodynamic load extraction to stress field topology mapping, and then to integrated additive manufacturing and surface strengthening. This invention not only solves the failure problem of traditional hollow structures at the adhesive interface, but also optimizes material utilization through the scientific configuration of variable-thickness walls and internal longitudinal stiffeners. This stress-driven dynamic wall thickness adjustment mechanism, combined with the integrated printing process of high-performance fiber-reinforced composite materials, represents the technological path for UAV power components to transition from experience-based design to data-driven design, possessing extremely high engineering application value and industrialization prospects. The organic combination of all the above technical features constitutes a logically rigorous, data-rich, and repeatable engineering technology system, laying a solid material foundation for the development of a new generation of high-performance UAV propellers.

[0088] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A hollow propeller design method, characterized in that, Includes the following steps: S1. Based on the flight envelope conditions and preset load requirements of the target UAV, the basic geometric parameters of the propeller are set, and the basic geometric parameters are verified and optimized by computational fluid dynamics simulation to obtain the three-dimensional geometric shape and surface aerodynamic pressure distribution that meet the performance indicators. S2, based on the three-dimensional geometric shape and surface aerodynamic pressure distribution, combined with the rotating centrifugal force load, multi-physics field coupled finite element analysis is performed to obtain the equivalent stress distribution of the blade. Based on the equivalent stress distribution, the region starting from the root of the blade hub and extending towards the blade tip until the equivalent stress decays to 50% of its peak value is identified as the high stress region. A solid transition section corresponding to the high stress region is constructed. S3, with equivalent stress distribution as the topology guide, designs a continuous internal cavity along the span in the blade region outside the solid transition section; the wall thickness of the internal cavity is mapped according to the magnitude of local equivalent stress. S4, based on the surface aerodynamic pressure distribution and equivalent stress distribution, arranges at least one longitudinal stiffener along the spanwise direction in the internal cavity. The longitudinal stiffener is used to form an anti-torsion box section structure extending from the end of the solid transition section to the blade tip region. The S5 will be an integrated 3D model of the completed design, including the hub, solid transition section, variable thickness internal cavity and longitudinal reinforcing ribs, which will be integrally formed using additive manufacturing process.

2. The hollow propeller design method according to claim 1, characterized in that: The basic geometric parameters include at least the number of blades, diameter, pitch ratio, chord length distribution curve, airfoil family, and installation angle.

3. The hollow propeller design method according to claim 1, characterized in that: The wall thickness of the internal cavity is dynamically mapped according to local strength requirements. The basic value of the internal cavity wall thickness is defined as 10% of the maximum thickness of the corresponding airfoil section. The local wall thickness is increased according to the linear proportional relationship between the local equivalent stress and the maximum equivalent stress of the entire blade. The core formula for linear thickening is: in, Where is the local wall thickness, and k is the linear scaling factor adapted for engineering applications. It is set according to the allowable stress of the molded substrate and ranges from 0.1 to 0.

15. This is the basic value for wall thickness. For local equivalent stress, This represents the maximum equivalent stress.

4. The hollow propeller design method according to claim 1, characterized in that: The computational fluid dynamics simulation in step S1 uses the steady Navier-Stokes equations based on a multi-block structured grid. During the grid generation process, the leading edge, trailing edge, and tip vortex region of the airfoil are refined, and the height of the first layer of the grid makes the dimensionless wall distance y+ approach 1. By adjusting the combination of inflow wind speed and rotational speed, the complete curves of thrust coefficient Ct, power coefficient Cp, and efficiency η as a function of advance ratio J are obtained. During the simulation verification process, the absolute value of the aerodynamic performance deviation between the positive and negative propellers is kept less than 2%.

5. The hollow propeller design method according to claim 1, characterized in that: In step S2, the multiphysics coupled finite element analysis includes two stages: The first stage simulates the centrifugal tensile stress field at the rated maximum speed of the propeller. In the second stage, the deformation displacement of the first stage is used as the initial condition, and the non-uniform aerodynamic pressure distribution derived in step S1 is superimposed to perform nonlinear deformation analysis. The length of the solid transition section is determined such that, under maximum working conditions, the maximum shear stress at the root section is less than 60% of the allowable stress of the material.

6. The hollow propeller design method according to claim 1, characterized in that: In step S3, the wall thickness increase amount Through formula Calculated; or obtained through the wall thickness distribution function. Determine the shell wall thickness at any spanwise position r, where The basic wall thickness of the cross section is given by , and k is the thickening factor with a value ranging from 0.1 to 0.

15. The inner surface of the internal cavity is fitted with a non-uniform rational B-spline NURBS surface.

7. The hollow propeller design method according to claim 1, characterized in that: In step S4, the longitudinal stiffeners are positioned near the pressure center at 20% or 30% of the chord length of the airfoil's leading edge; the cross-sectional shape of the longitudinal stiffeners is set to a rectangular cross-section, an I-shaped variable cross-section structure, or an I-shaped variable cross-section structure according to the local shear flow distribution; at the junction of the solid transition section and the internal cavity, a bifurcated transition structure is used to achieve a smooth distribution of the load from the solid transition section to the longitudinal stiffeners.

8. The hollow propeller design method according to claim 1, characterized in that: It also includes smoothing all geometric abrupt changes inside the internal cavity; and uniformly setting rounded chamfers at the four corners where the longitudinal stiffeners connect to the inner wall of the internal cavity, the inner confluence point of the front and rear edges of the internal cavity, and the boundary step at the junction of the solid transition section and the starting end of the internal cavity. The radius R of the rounded chamfer ranges from 1.0 to 2.5 mm.

9. A hollow propeller design method according to claim 1, characterized in that: The substrate is a polymer material. During the additive manufacturing process, the path algorithm of the printing nozzle is adjusted so that the fiber arrangement direction is consistent with the principal stress line direction of the blade. When using the fused deposition modeling (FDM) process, the shell fill rate is set to 100%, the longitudinal reinforcing rib fill rate is not less than 90%, and the temperature of the constant temperature chamber is kept 50℃-80℃ higher than the ambient temperature.

10. A hollow propeller design method according to claim 1, characterized in that: It also includes surface polishing and degreasing of the molded propeller body; covering the outer surface of the molded propeller body with a layer of carbon fiber fabric with a thickness of 0.5mm to 1.0mm to form an outer reinforcement layer; vacuum-assisted impregnation with epoxy resin and curing for 2 to 4 hours in a gradient temperature environment of 80℃ to 120℃.

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