Paddle tip blowing method for lift augmentation of unmanned rotorcraft

Abstract

The invention discloses a blade tip blowing method for lift augmentation of a rotor unmanned aerial vehicle, belongs to the technical field of lift augmentation of rotor unmanned aerial vehicles, and aims to solve the problem of insufficient lift force caused by vortex induced resistance generated by a blade tip vortex of a traditional rotor unmanned aerial vehicle. Transverse distributed jet flow is arranged on the 25% c-75% c section of the blade end face airfoil profile (the jet flow is blown out at the double blade tip speed, the two blades symmetrically apply the jet flow, and the jet flow is conveyed through a titanium alloy guide pipe). During design, jet parameters are simulated and optimized through pneumatic modeling (multiple reference coordinate systems and SST k-omega turbulence models), working conditions are dynamically adapted, and vorticity analysis and lift comparison verification are combined. According to the scheme, blade tip vortexes can be damaged, resistance is reduced, lift force is improved, meanwhile, flight stability is guaranteed, and multiple flight working conditions are adapted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rotor unmanned aerial vehicle lift enhancement, and particularly relates to a rotor unmanned aerial vehicle lift enhancement method. BACKGROUND

[0002] During hovering or flight, the tip region of the rotor blade is prone to form a high-intensity tip vortex due to the pressure difference between the upper and lower surfaces of the blade, which is a vortex formed by the rolling up of airflow at the tip. The tip vortex produces significant vortex-induced drag, directly offsetting the lift contribution of the rotor, resulting in insufficient rotor lift, and further affecting the load capacity, hovering stability and flight efficiency of the unmanned aerial vehicle. Meanwhile, in the traditional rotor design, the lift distribution of the blade is prone to be uneven due to vortex interference, and lacks dynamic adjustment means for different flight conditions, making it difficult to balance between "lift enhancement", "energy consumption control" and "structural stability". These problems have become the key to restricting the performance improvement of the rotor unmanned aerial vehicle.

[0003] Therefore, a rotor unmanned aerial vehicle lift enhancement method is provided. SUMMARY

[0004] The present application provides a rotor unmanned aerial vehicle lift enhancement method to solve the problems in the background art.

[0005] The specific technical solutions are as follows: A rotor unmanned aerial vehicle lift enhancement method is provided, which adopts a rotor unmanned aerial vehicle with a large aspect ratio straight wing. The airfoil of the rotor unmanned aerial vehicle is NACA0012, and the chord length c is 170 mm. A transversely distributed jet is arranged on the 25%c-75%c segment of the blade end face airfoil. The jet is an airflow blown along the blade span direction at twice the tip speed. The jet breaks the tip vortex and reduces the vortex-induced drag to improve the rotor lift.

[0006] As a preferred embodiment of the present application, the transversely distributed jet is realized by arranging 6 flow control holes with a diameter of 0.5%c at equal intervals on the 25%c-75%c segment of the blade end face airfoil. The jet airflow is blown along the blade span direction at twice the tip speed through the flow control holes.

[0007] As a preferred embodiment of the present application, the flow control hole is a circular hole with a hole diameter of 0.85 mm. The tip spanwise position corresponding to the flow control hole is controlled at 0.95R-0.99R, where R is the rotor half-span length.

[0008] As a preferred embodiment of the present application, the jet airflow is transported through an airflow duct arranged inside the blade. The material of the airflow duct is selected from high-strength materials such as titanium alloy to withstand the tensile force and bending moment generated by the rotation of the blade.

[0009] As a preferred embodiment of the present invention, the transversely distributed jet is applied symmetrically on the two blades to ensure that the torques on both sides cancel each other out and to make the lift of each blade uniform and stable.

[0010] As a preferred embodiment of the present invention, the rotary-wing UAV adopts a Caradonna two-bladed rotor. The blades are rectangular in plan, without twist or sharp edges, with a rotor disk radius of 1.143m, an aspect ratio of 6, and a total pitch of 8°.

[0011] As a preferred embodiment of the present invention, the design steps of the method include: S1, destroying the tip vortex generated when the rotor is hovering by using a laterally distributed jet at the blade tip to reduce vortex-induced drag; S2, establishing an aerodynamic model of the hovering rotor and performing numerical simulation using the multiple reference coordinate system method and the SST k-omega turbulence model; S3, setting the boundary condition of the flow control orifice as a velocity inlet, with the jet velocity being twice the blade tip velocity; S4, obtaining the original lift and the lift after blowing through simulation, and optimizing the jet parameters; S5, repeatedly optimizing according to different flight conditions to obtain the optimal design parameters.

[0012] As a preferred embodiment of the present invention, the lift force in the method is calculated using the following formula: in, For hovering lift, This is the rotor lift coefficient. air density, The area of ​​the disk formed by the rotor's rotation. The rotor angular velocity, This is the radius of a single rotor.

[0013] As a preferred embodiment of the present invention, the method further includes a dynamic optimization step based on flight conditions: adjusting the jet parameters for different hovering states or flight speeds using numerical simulation methods, the jet parameters including the number, diameter, and jet intensity of flow control holes; employing feedback optimization design, repeating aerodynamic modeling and simulation steps to obtain the maximum lift enhancement effect; the optimization objective is to ensure that the lift enhancement rate is not less than 5%, while ensuring a balance between jet energy consumption and structural stability.

[0014] As a preferred embodiment of the present invention, the method further includes a lift enhancement effect verification step based on numerical simulation: aerodynamic simulation is performed using the Multiple Reference Frame (MRF) method and the SST k-omega turbulence model to simulate the flow field characteristics of the rotor in a hovering state with a tip velocity of 100 m / s; the lift enhancement effect is verified by comparing lift data under no-jet control and with jet control, wherein the lift without jet is 205.42 N, and the lift with jet increases to 216.58 N, with a lift enhancement rate of not less than 5%; vorticity analysis (such as the Q criterion) is used to evaluate the tip vortex destruction effect to ensure that the jet effectively reduces vortex-induced drag. The present invention has the following beneficial effects: 1. Highly efficient rotor lift enhancement: By setting a high-speed lateral distributed jet in the key area of ​​the rotor tip, the generation of the rotor tip vortex is directly destroyed, reducing vortex-induced drag from the root. After the drag is reduced, the rotor's lift contribution is no longer excessively offset, thus achieving an effective increase in lift. Moreover, the jet parameters (velocity, position, distribution) are optimized through simulation and can be precisely applied to the rotor tip vortex core, further enhancing the efficiency of lift enhancement.

[0015] 2. Ensure flight stability: The symmetrical jet design allows the torque of the two blades to cancel each other out, preventing the drone from yawing or swaying due to torque imbalance; at the same time, the rectangular blades without twisting or sharp edges reduce airflow turbulence, and the uniform jet distribution ensures consistent lift output from each blade, improving the stability and controllability of the drone during hovering and flight.

[0016] 3. Adaptable to multiple flight conditions: By "dynamically optimizing parameters for different flight conditions", the jet parameters (number of holes, diameter, intensity) can be adjusted according to changes in hovering state and flight speed. This avoids the problem of "insufficient effect" or "excessive energy consumption" of a single parameter under multiple flight conditions, making the method applicable to diverse flight scenarios and improving its versatility.

[0017] 4. Balancing structural safety and low energy consumption: The titanium alloy airflow duct can withstand the rotational load of the blades, avoiding jet interruption or blade structure failure caused by duct damage, thus ensuring the flight safety of the UAV; at the same time, the optimization process takes into account both "jet energy consumption" and "structural stability", avoiding blindly pursuing lift and excessively increasing the jet intensity, achieving a balance between "lift, energy consumption, and safety" to ensure the practicality of the method.

[0018] 5. Verifiable and reliable results: The verification scheme of "comparing lift through aerodynamic simulation and evaluating vortex damage through vortex analysis" can directly confirm whether the lift increase is due to tip vortex damage (rather than other interfering factors), ensuring that the effectiveness of the method has a clear basis and enhancing its credibility in practical applications. Attached Figure Description

[0019] Figure 1Lift generated by a hovering rotor under jet-free flow control; Figure 2 The tip vorticity diagram for a hovering rotor with Q=20 under jetless flow control. Figure 3 A slice of vorticity along the X=0 plane under jetless flow control for a hovering rotor; Figure 4 A slice of vorticity along the Y=0 plane under jetless flow control for a hovering rotor; Figure 5 A schematic diagram of the setup for hovering rotor tip blowing technology; Figure 6 A schematic diagram of the jet effect of a hovering rotor under the control of airflow at the blade tip; Figure 7 The lift generated by the hovering rotor under the control of the airflow at the rotor tip; Figure 8 The tip vorticity diagram for a hovering rotor with Q=20 under tip blowing flow control; Figure 9 A slice of vorticity along the X=0 plane for a hovering rotor under the control of tip airflow. Figure 10 This is a slice of vorticity along the Y=0 plane for a hovering rotor under the control of tip airflow. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0022] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0023] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Example: Refer to Figures 1 to 10 ,in, Figure 1 This figure illustrates the baseline lift of the rotor without tip blowing technology. Through numerical simulation (SST k-omega turbulence model), the lift is 205.42 N under hovering conditions with a tip velocity of 100 m / s. This figure serves as a benchmark, highlighting the aerodynamic limitations of the original rotor and providing a basis for subsequent lift enhancement evaluation. It verifies the insufficient lift of the rotor under uncontrolled conditions, emphasizing the necessity of this invention to address endurance and payload capabilities. Figure 2 The tip vortex structure without jet control was visualized using the Q criterion (Q=20), showing the strong tip vortex generated when the rotor is hovering. The vorticity diagram shows that the vortex core is intact and the spiral trajectory is clear in the original operating condition, resulting in high vortex-induced drag, which limits lift. This diagram reveals the key source of rotor aerodynamic losses and provides theoretical support for the jet-induced vortex core destruction in this embodiment. Figure 3 The vorticity distribution under uncontrolled conditions is shown in the X=0 plane (i.e., the longitudinal section of the rotor rotation center). The slice diagram clearly shows the spatial expansion and intensity of the tip vortex, illustrating the evolution of the vortex structure in the vertical direction, which leads to energy loss. This figure supplements the three-dimensional flow field information, highlighting the severity of airflow separation under uncontrolled conditions, and providing a basis for targeted intervention in the tip region in this embodiment. Figure 4 The figure shows the vortex distribution without control from the Y=0 plane (i.e., the transverse section at the rotor rotation center). It reveals the symmetry and intensity of the tip vortex in the horizontal direction, further verifying the negative impact of vortex-induced drag on lift. This figure is consistent with... Figure 3 Together, they constructed a complete view of the uncontrolled flow field, emphasizing the optimization space of the original design; Figure 5 The diagram visually illustrates the arrangement of the tip blowing device. The position of the jet flow control holes in the 25%c-75%c section of the airfoil on the blade end face (6 equally spaced circular holes) and the direction of the airflow blowing out along the spanwise direction are marked. This diagram concretizes the technical solution, helps to understand the symmetrical distribution and structural integration of the jet holes, and highlights the simplicity and engineering feasibility of the method. Figure 6This diagram schematically illustrates the flow field changes after the application of a blowing technique, such as the interaction between the jet airflow and the tip vortex. It demonstrates the process of the jet disrupting the vortex core, visually illustrating how the airflow replenishes boundary layer momentum and suppresses separation. Figure 5 The dynamic extension verifies the design concept of "precise intervention in the tip region" in this application; Figure 7 contrast Figure 1 The figure shows the lift results after applying the tip-blowing technology. Numerical simulation shows that the lift increased from 205.42N to 216.58N, an increase of 5.43%, which directly proves the validity of this application. This figure highlights the improvement of the UAV's payload and endurance due to the increased lift, and is used to verify the conclusion that the lift increase effect is significant. Figure 8 and Figure 2 The comparison shows the destructive effect of the tip vortex after blowing air. The vorticity diagram with Q=20 shows that the vortex core fractures and deforms, indicating that the jet effectively reduces the vortex intensity and induced drag. Figure 9 The distribution of vorticity after blowing air is shown on the X=0 plane, and... Figure 3 In contrast, the slice diagram shows the local dissipation of the vortex structure, confirming the suppressive effect of the jet on airflow separation. This diagram provides longitudinal flow field evidence to illustrate how the present invention improves the flow near the blade tip region and enhances stability through precise control. Figure 10 The change in vorticity after blowing air is presented from the Y=0 plane, and Figure 4 The complementary nature of the figure shows a reduction in horizontal vortex intensity, verifying the counteracting effect of the symmetrical jet on torque. This figure enhances the robustness of the method, demonstrates its adaptability in complex flow fields, and provides support for improving the wind resistance performance of UAVs.

[0025] The tip-blowing method for enhancing the lift of a rotorcraft UAV provided in this embodiment employs a rotorcraft UAV with a high aspect ratio straight wing. The airfoil of the rotorcraft UAV is NACA0012, and the chord length c is 170mm. A laterally distributed jet is set in the 25%c-75%c section of the airfoil on the blade tip. The jet is an airflow blown out along the blade span at twice the tip velocity. By destroying the tip vortex through the jet, the vortex-induced drag is reduced, thereby increasing the rotor lift.

[0026] The proposed solution first defines the basic structural parameters of the rotorcraft UAV (high aspect ratio straight wing, NACA0012 airfoil, chord length 170mm) to provide a suitable aerodynamic carrier for jet action. Then, by setting a lateral distributed jet with twice the tip velocity in the 25%c-75%c section of the airfoil at the blade tip, it directly intervenes in the flow field of the blade tip region. The technical effect is that by actively disrupting the tip vortex generated by the rotor through the jet, vortex-induced drag is reduced from the source of the flow field, thereby increasing rotor lift and providing the UAV with superior lift performance.

[0027] Specifically, in this embodiment, the lateral distributed jet is achieved by arranging six flow control holes with a diameter of 0.5%c at equal intervals along the 25%c-75%c section of the airfoil on the blade end face. The blowing airflow is expelled along the blade spanwise at twice the tip velocity through the flow control holes. This scheme concretizes the lateral distributed jet as "arranging six flow control holes with a diameter of 0.5%c at equal intervals," clearly defining the output mode and distribution form of the jet. Its technical effect is that the equally spaced and specific diameter flow control holes allow the jet to uniformly cover the 25%c-75%c section of the blade, avoiding situations where the jet is too strong or too weak in some areas, ensuring that the destructive effect of the jet on the tip vortex is stable and consistent, thereby making the lift enhancement effect more stable and avoiding lift fluctuations caused by uneven jet distribution.

[0028] Specifically, in this embodiment, the flow control orifice is a circular orifice with a diameter of 0.85 mm. The spanwise position of the corresponding blade tip is controlled between 0.95R and 0.99R, where R is the rotor's half-span. This scheme further refines the parameters of the flow control orifice (circular orifice shape, 0.85 mm diameter, and spanwise position between 0.95R and 0.99R), precisely positioning the jet's point of action near the blade tip region of the rotor's half-span. The technical effect is that the blade tip vortex is mainly generated in the near-blade tip region. The circular orifice with a specific shape, diameter, and position allows the jet to precisely act on the core generation region of the blade tip vortex, enhancing the jet's ability to break up the blade tip vortex and more efficiently reducing vortex-induced drag, thereby making the lift increase more efficient and effective.

[0029] Specifically, in this embodiment, the blowing airflow is delivered through an airflow duct arranged inside the propeller blade. The airflow duct is made of high-strength materials such as titanium alloy to withstand the tension and bending moment generated by the blade rotation. This solution explicitly uses high-strength materials such as titanium alloy for the airflow delivery carrier (the airflow duct inside the propeller blade). The technical effect is as follows: the propeller blade generates significant tension and bending moment during rotation. The duct made of high-strength material can resist these mechanical loads, preventing the duct from being damaged by stress and interrupting the airflow delivery, ensuring a continuous and stable jet supply, and thus making the drag reduction and lift increase effect continue to be effective. At the same time, the structural stability of the duct also ensures the overall structural safety of the propeller blade, preventing the flight safety of the UAV from being affected by duct failure.

[0030] Specifically, in this embodiment, the lateral distributed jet is applied symmetrically to the two propeller blades to ensure that the torques on both sides cancel each other out and that the lift of each blade is uniform and stable. This solution proposes a method of "symmetrically applying a lateral distributed jet to the two propeller blades," focusing on the balancing effect of the jet among multiple blades. Its technical effects are: the symmetrically applied jet allows the torques generated by the two propeller blades to cancel each other out, avoiding problems such as yaw and attitude instability caused by torque imbalance in the UAV; simultaneously, the symmetrical jet also ensures that the lift output of the two propeller blades is uniform and consistent, guaranteeing a balanced overall lift distribution for the UAV and improving stability and controllability during flight.

[0031] Specifically, in this embodiment, the rotary-wing UAV adopts a Caradonna two-bladed rotor with rectangular blades that are free from twist and sharp edges. The rotor disk radius is 1.143m, the aspect ratio is 6, and the collective pitch is 8°. This design clearly defines the specific rotor parameters of the rotary-wing UAV (Caradonna two-bladed rotor, rectangular blades, no twist or sharp edges, specific rotor disk radius / aspect ratio / collective pitch), providing a suitable rotor structure basis for jet action. Its technical effects are: the rectangular blades, free from twist and sharp edges, reduce airflow turbulence during rotor rotation; the specific rotor disk radius, aspect ratio, and collective pitch allow the rotor to maintain stable aerodynamic performance, providing a stable aerodynamic environment for the jet to disrupt the tip vortex, reduce drag, and increase lift. This avoids the impact of rotor structural defects on the jet's effectiveness, ensuring the stability of lift enhancement.

[0032] Specifically, in this embodiment, the design steps of the method include: S1, disrupting the tip vortex generated during rotor hovering by using a laterally distributed jet at the blade tip to reduce vortex-induced drag; S2, establishing an aerodynamic model of the hovering rotor and performing numerical simulation using a multi-reference coordinate system method and an SST k-omega turbulence model; S3, setting the boundary condition of the flow control orifice as a velocity inlet, with the jet velocity being twice the blade tip velocity; S4, obtaining the original lift and the lift after blowing through simulation, and optimizing the jet parameters; S5, repeatedly optimizing according to different flight conditions to obtain the optimal design parameters. This scheme proposes design steps for the blade tip blowing method (disrupting the tip vortex → establishing an aerodynamic model for simulation → setting jet boundary conditions → simulation optimization of parameters → adapting to different flight conditions), forming a systematic design process. Its technical effects are as follows: First, the core direction of drag reduction and lift enhancement is clarified through jet flow. Then, professional aerodynamic simulation methods (multiple reference coordinate systems, SST k-omega turbulence model) are used to ensure the accuracy of the model. The optimal jet parameters are found through simulation optimization. Finally, it is adapted to different flight conditions to ensure that the designed propeller tip blowing method can effectively play the role of drag reduction and lift enhancement in various scenarios, thereby improving the versatility and practicality of the method.

[0033] Specifically, in this embodiment, the lift is calculated using the following formula: in, For hovering lift, This is the rotor lift coefficient. air density, The area of ​​the disk formed by the rotor's rotation. The rotor angular velocity, This is the radius of a single rotor.

[0034] This solution provides a specific formula for lift calculation, clarifying the quantitative relationship between lift and parameters such as lift coefficient, air density, and rotor disk area. Its technical benefits are as follows: the formula allows for accurate calculation of hovering lift, providing a quantitative basis for evaluating lift changes in "no-jet" and "with-jet" states, facilitating the determination of whether the jet's drag reduction and lift enhancement effects meet standards; simultaneously, the quantitative calculation also provides data support for subsequent adjustments to jet parameters (such as velocity and number of orifices), avoiding blind optimization and improving the accuracy of parameter adjustments.

[0035] Specifically, in this embodiment, the method further includes a dynamic optimization step based on flight conditions: using numerical simulation, the jet parameters are adjusted for different hovering states or flight speeds. These jet parameters include the number, diameter, and jet intensity of flow control orifices. Feedback optimization design is employed, repeatedly performing aerodynamic modeling and simulation steps to achieve the maximum lift increase. The optimization objective is to ensure a lift increase rate of no less than 5%, while maintaining a balance between jet energy consumption and structural stability. This scheme adds a dynamic optimization step based on flight conditions (adjusting jet parameters → feedback optimization simulation → balancing lift, energy consumption, and structural stability), focusing on the adaptability and overall performance of the method under different conditions. Its technical effects are: adjusting jet parameters for different hovering states or flight speeds allows the method to adapt to diverse flight scenarios, ensuring the lift increase target is achieved under various conditions; the feedback optimization process can continuously iterate parameters to achieve the maximum lift increase; and it simultaneously considers jet energy consumption and structural stability, avoiding excessive energy consumption or structural damage due to excessive pursuit of lift, thus ensuring the practicality and safety of the method.

[0036] Specifically, in this embodiment, the method further includes a lift enhancement effect verification step based on numerical simulation: aerodynamic simulation is performed using the Multiple Reference Frame (MRF) method and the SST k-omega turbulence model to simulate the flow field characteristics of the rotor in a hovering state with a tip velocity of 100 m / s; the lift enhancement effect is verified by comparing lift data under no-jet control and with jet control, where the lift without jet is 205.42 N, and the lift with jet increases to 216.58 N, with a lift enhancement rate of not less than 5%; vorticity analysis (such as the Q criterion) is used to evaluate the tip vortex destruction effect, ensuring that the jet effectively reduces vortex-induced drag. This scheme proposes a lift enhancement effect verification step (aerodynamic simulation of the flow field → comparison of lift data → vorticity analysis to evaluate the vortex destruction effect), providing a verification basis for the effectiveness of the method. Its technical effects are as follows: professional aerodynamic simulation can simulate the real flow field of the rotor, and the lift data with and without jet can be compared to intuitively determine whether the lift has been improved; vorticity analysis (such as the Q criterion) can verify from the essence of the flow field whether the tip vortex has been effectively destroyed, ensuring that the lift improvement is indeed due to the reduction of vortex-induced drag, rather than other factors, providing reliable verification of the effectiveness of the tip blowing method and enhancing the credibility of the method.

[0037] In summary, this tip-blowing method actively intervenes in the tip flow field through jet injection, disrupting the generation and development of tip vortices, thereby reducing vortex-induced drag at its source and ultimately increasing lift. The specific principle can be divided into three parts: 1. Core of Flow Field Intervention: Based on the basic structure of rotary-wing UAVs (NACA0012 airfoil, high aspect ratio straight wing, Caradonna two-bladed rotor, etc.), a lateral distributed jet is set in the 25%c-75%c section of the airfoil at the blade tip (critical region near the blade tip). The jet is blown out along the spanwise direction at twice the blade tip velocity, directly acting on the source of blade tip vortex generation. The high-speed jet can disrupt the flow structure of the vortex, weaken or even break the blade tip vortex, reduce the offsetting effect of vortex-induced drag on lift, and achieve lift enhancement.

[0038] 2. Structural and Flow Field Adaptation: The jet effect is enhanced through specific structural design: First, the flow control orifice is precisely positioned in the near-tip region of 0.95R~0.99R (R is the rotor half-span) to ensure that the jet directly hits the core of the tip vortex; second, a symmetrical jet design is adopted (the jet is applied symmetrically to the two blades) to offset the torque on both sides and avoid uneven lift caused by vortex interference; third, a titanium alloy duct is used to deliver the airflow to ensure continuous and stable airflow during rotation and to avoid jet interruption affecting the flow field intervention effect.

[0039] 3. Simulation and Optimization Support: By establishing a hovering rotor aerodynamic model (using the multi-reference coordinate system method and SSTk-omega turbulence model), the real flow field environment is simulated. The flow control orifice is set as the velocity inlet (the jet velocity is twice the tip velocity). The lift difference between "no jet" and "with jet" is simulated and compared to optimize the jet parameters (number of orifices, diameter, jet intensity). At the same time, the parameters are dynamically adjusted for different flight conditions. Through feedback iteration, the balance between "maximum lift increase" and "energy consumption and structural stability" is achieved to ensure the effectiveness of the principle in practice.

[0040] The use of this method must follow the process of "structural adaptation → system installation → parameter setting → optimization verification", and the specific steps are as follows: 1. Select a suitable rotorcraft UAV basic structure: Select a high aspect ratio straight-wing UAV with an airfoil of NACA0012 (chord length 170mm). The rotor adopts the Caradonna two-blade type (rectangular blades, no twist and no sharp edges, disk radius 1.143m, aspect ratio 6, collective pitch 8°) to provide a stable aerodynamic carrier for jet action.

[0041] 2. Install the jet delivery and output system: On the airfoil section of the blade end face from 25%c to 75%c, machine six circular flow control holes with a diameter of 0.85mm at equal intervals (corresponding to the spanwise positions of 0.95R to 0.99R); Arrange titanium alloy airflow ducts inside the blade, with one end connected to the air source and the other end connected to the flow control holes, to ensure that the ducts can withstand the tension and bending moment generated by the blade rotation and avoid interruption of airflow delivery.

[0042] 3. Set the basic parameters of the jet: Adjust the air source output so that the blowing airflow is blown out along the blade span at "twice the blade tip speed" through the flow control hole; at the same time, ensure that the jets of the two blades are applied symmetrically to avoid torque imbalance.

[0043] 4. Parameter optimization through simulation: Establish a hovering rotor aerodynamic model, and use multiple reference coordinate systems and SST k-omega turbulence model for numerical simulation to obtain lift data for "no jet" and "with jet", and adjust jet parameters (such as number of holes, diameter, and jet intensity); for different hovering states or flight speeds, repeat the feedback optimization process of "modeling → simulation → adjustment" to determine the optimal parameters under the condition.

[0044] 5. Verify the effect: Simulate the rotor flow field characteristics through aerodynamic simulation, compare the difference in lift with and without jet, and evaluate the tip vortex destruction effect using vorticity analysis (such as Q criterion) to confirm that the lift increase is due to the reduction of vortex-induced drag. After the verification is qualified, the UAV can be put into actual flight. If the flight conditions are changed, repeat step 4 to adjust the parameters.

[0045] In summary, the specific technical effects of this propeller tip blowing method are as follows: 1. Highly efficient rotor lift enhancement: By setting a high-speed lateral distributed jet in the key area of ​​the rotor tip, the generation of the rotor tip vortex is directly destroyed, reducing vortex-induced drag from the root. After the drag is reduced, the rotor's lift contribution is no longer excessively offset, thus achieving an effective increase in lift. Moreover, the jet parameters (velocity, position, distribution) are optimized through simulation and can be precisely applied to the rotor tip vortex core, further enhancing the efficiency of lift enhancement.

[0046] 2. Ensure flight stability: The symmetrical jet design allows the torque of the two blades to cancel each other out, preventing the drone from yawing or swaying due to torque imbalance; at the same time, the rectangular blades without twisting or sharp edges reduce airflow turbulence, and the uniform jet distribution ensures consistent lift output from each blade, improving the stability and controllability of the drone during hovering and flight.

[0047] 3. Adaptable to multiple flight conditions: By "dynamically optimizing parameters for different flight conditions", the jet parameters (number of holes, diameter, intensity) can be adjusted according to changes in hovering state and flight speed. This avoids the problem of "insufficient effect" or "excessive energy consumption" of a single parameter under multiple flight conditions, making the method applicable to diverse flight scenarios and improving its versatility.

[0048] 4. Balancing structural safety and low energy consumption: The titanium alloy airflow duct can withstand the rotational load of the blades, avoiding jet interruption or blade structure failure caused by duct damage, thus ensuring the flight safety of the UAV; at the same time, the optimization process takes into account both "jet energy consumption" and "structural stability", avoiding blindly pursuing lift and excessively increasing the jet intensity, achieving a balance between "lift, energy consumption, and safety" to ensure the practicality of the method.

[0049] 5. Verifiable and reliable results: The verification scheme of "comparing lift through aerodynamic simulation and evaluating vortex damage through vortex analysis" can directly confirm whether the lift increase is due to tip vortex damage (rather than other interfering factors), ensuring that the effectiveness of the method has a clear basis and enhancing its credibility in practical applications.

[0050] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for propeller tip blowing to enhance lift in a rotary-wing unmanned aerial vehicle, characterized in that, A rotorcraft unmanned aerial vehicle (UAV) with a high aspect ratio straight wing has an airfoil of NACA0012 and a chord length c of 170 mm. A lateral distributed jet is set in the 25%c-75%c section of the airfoil on the blade tip. The jet is an airflow blown out along the blade span at twice the blade tip velocity. The jet disrupts the blade tip vortex, reduces vortex-induced drag, and improves rotor lift.

2. The tip-blowing method for enhancing the lift of a rotary-wing unmanned aerial vehicle according to claim 1, characterized in that, The lateral distributed jet is achieved by arranging six flow control holes with a diameter of 0.5%c at equal intervals in the 25%c-75%c section of the airfoil on the blade end face. The blowing airflow is blown out along the blade spanwise at twice the blade tip speed through the flow control holes.

3. The tip-blowing method for enhancing the lift of a rotary-wing unmanned aerial vehicle according to claim 2, characterized in that, The flow control orifice is a circular orifice with a diameter of 0.85 mm. The spanwise position of the blade tip corresponding to the flow control orifice is controlled between 0.95R and 0.99R, where R is the rotor half-span.

4. The tip-blowing method for enhancing the lift of a rotary-wing unmanned aerial vehicle according to claim 2, characterized in that, The blowing airflow is delivered through airflow ducts arranged inside the blades. The airflow ducts are made of high-strength titanium alloy to withstand the tension and bending moment generated by the rotation of the blades.

5. The tip-blowing method for enhancing the lift of a rotary-wing unmanned aerial vehicle according to claim 1, characterized in that, The lateral distributed jet is applied symmetrically to the two blades to ensure that the torques on both sides cancel each other out and that the lift of each blade is uniform and stable.

6. The tip-blowing method for enhancing the lift of a rotary-wing unmanned aerial vehicle according to claim 1, characterized in that, The rotorcraft UAV uses a Caradonna two-bladed rotor. The blades are rectangular in plan, without twist or sharp edges, with a rotor disk radius of 1.143m, an aspect ratio of 6, and a collective pitch of 8°.

7. The tip-blowing method for enhancing the lift of a rotary-wing unmanned aerial vehicle according to claim 1, characterized in that, The design steps of the method include: S1, disrupting the tip vortex generated when the rotor is hovering by using a laterally distributed jet at the rotor tip to reduce vortex-induced drag; S2, establishing an aerodynamic model of the hovering rotor and performing numerical simulation using the multiple reference coordinate system method and the SST k-omega turbulence model; S3, setting the boundary condition of the flow control orifice as a velocity inlet, with the jet velocity being twice the tip velocity; S4, obtaining the original lift and the lift after blowing through simulation, and optimizing the jet parameters; S5, repeatedly optimizing according to different flight conditions to obtain the optimal design parameters.

8. The tip-blowing method for enhancing the lift of a rotary-wing unmanned aerial vehicle according to claim 7, characterized in that, The lift force is calculated using the following formula: in, For hovering lift, This is the rotor lift coefficient. air density, The area of ​​the disk formed by the rotor's rotation. The rotor angular velocity, This is the radius of a single rotor.

9. The tip-blowing method for enhancing the lift of a rotary-wing unmanned aerial vehicle according to claim 7, characterized in that, The method also includes a dynamic optimization step based on flight conditions: by using numerical simulation, the jet parameters are adjusted for different hovering states or flight speeds, including the number, diameter, and jet intensity of flow control holes; feedback optimization design is adopted, and the aerodynamic modeling and simulation steps are repeated to obtain the maximum lift enhancement effect; the optimization goal is to ensure that the lift enhancement rate is not less than 5%, while ensuring a balance between jet energy consumption and structural stability.

10. The tip-blowing method for enhancing the lift of a rotary-wing unmanned aerial vehicle according to claim 7, characterized in that, The method also includes a lift enhancement verification step based on numerical simulation: aerodynamic simulation is performed using the multi-reference coordinate system method and the SST k-omega turbulence model to simulate the flow field characteristics of the rotor in a hovering state with a tip velocity of 100 m / s; the lift enhancement effect is verified by comparing the lift data under no-jet control and with jet control, where the lift is 205.42 N without jet and increases to 216.58 N with jet, with a lift enhancement rate of not less than 5%; the tip vortex destruction effect is evaluated using vortex analysis to ensure that the jet effectively reduces vortex-induced drag.

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