Ducted unmanned aerial vehicle

Abstract

The invention discloses a ducted unmanned aerial vehicle, and relates to the technical field of electric vertical take-off and landing aircrafts, the ducted unmanned aerial vehicle comprises a fuselage and a propulsion assembly, the front side and the rear side of the fuselage are provided with a front battery bin and a rear battery bin respectively, the propulsion assembly comprises ducts arranged on the left side and the right side of the fuselage, and motors are arranged at the bottoms of propellers; the motors are electrically connected with batteries in the front battery bin and the rear battery bin through wires, the motors are connected with a flight control system, and the flight control system is used for controlling the rotating speed of all the motors and the thrust direction of all the propelling assemblies. According to the duct type unmanned aerial vehicle, the duct serves as a natural sound barrier, noise generated by the propeller can be reduced, the duct directly radiates noise outwards by restraining blade tip vortex, wake flow is smoothly restrained to reduce turbulence noise, and the multiple blades and the small diameter of the propeller are matched with an acoustic liner to absorb noise in the high-frequency range; therefore, the noise pollution problem of the unmanned aerial vehicle is obviously improved in multiple modes.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vertical take-off and landing aircraft, in particular to a ducted UAV. Background Art

[0002] Currently, the field of electric vertical take-off and landing aircraft, or eVTOL, has formed three major mainstream technical configurations: multi-rotor, composite wing and tilt-rotor. Each configuration has its own characteristics in terms of aerodynamic characteristics, propulsion system and applicable scenarios. Multi-rotor eVTOL adopts a wingless design and relies entirely on the power output of multiple rotors to provide all lift and forward motion; composite wing eVTOL adopts a separate system design with independent vertical lift system and horizontal propulsion system; the tilt-rotor configuration realizes the change of power unit direction through a mechanical tilt mechanism, and the rotor provides both lift and cruise thrust.

[0003] At present, noise pollution is one of the most prominent shortcomings facing traditional eVTOLs. Open propeller eVTOLs usually generate a noise level of 85-95 decibels during the vertical take-off and landing phase, which is equivalent to the operating noise of heavy trucks, severely limiting their application in densely populated urban areas. This high-decibel noise mainly comes from the broadband noise generated by the propeller and the propeller-vortex interference effect, which can easily cause noise pollution in community environments and arouse public resistance. In addition, open propellers usually use a 2-4 blade design, and the low-frequency noise generated has a long transmission distance and can easily penetrate buildings. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a ducted UAV that solves the problems raised in the above background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a ducted UAV, comprising a fuselage and a propulsion assembly, wherein a front battery compartment and a rear battery compartment are respectively provided on the front and rear sides of the fuselage, and the fuselage is made of carbon fiber composite material and has a streamlined structure, the propulsion assembly comprises ducts arranged on the left and right sides of the fuselage, and a propeller is provided inside the duct, the inner wall of the duct is paved with an acoustic pad, and a lip is provided at the edge of the duct, a motor is provided at the bottom of the propeller, and the motor is electrically connected to the batteries inside the front battery compartment and the rear battery compartment through a wire, and the motor is connected to a flight control system, and the flight control system is used to control the speed of each motor and the thrust direction of each propulsion assembly.

[0006] Furthermore, the ducts are ring-shaped, and the ducts are symmetrically distributed about the central axis of the fuselage.

[0007] Furthermore, the gap between the duct and the propeller is controlled within the range of 1-5% of the propeller diameter.

[0008] Furthermore, the blade speed of the propeller is set within the range of 20-100 Hz through frequency control.

[0009] Furthermore, the acoustic pad is a porous sound-absorbing material or a resonance cavity structure.

[0010] Furthermore, the porous sound-absorbing material includes but is not limited to glass fiber and foam metal.

[0011] Furthermore, the lip is in an arc shape, and is used to smoothly introduce external airflow.

[0012] Furthermore, doors are provided in the middle of the left and right sides of the fuselage, and a glass window is provided at the front end of the fuselage on one side of the front battery compartment.

[0013] Furthermore, a skid-type landing gear is provided at the bottom of the fuselage, and two skid-type landing gears are provided.

[0014] The present invention provides a ducted UAV, which has the following beneficial effects:

[0015] 1. The ducted UAV acts as a natural sound barrier, reducing the noise generated by the propeller. The duct suppresses the noise radiated directly outward by the tip vortex, reduces turbulent noise by smoothing and constraining the wake, and absorbs high-frequency noise with the propeller's multi-blade and small diameter combined with acoustic pads. This significantly improves the noise pollution problem of UAVs through multiple methods.

[0016] 2. The ducted UAV completely wraps the high-speed rotating propeller, effectively preventing people or objects from accidentally contacting the rotating parts. The airflow generated by the high-speed rotation of the propeller must pass through the duct before it can be discharged. The duct can also constrain and guide the airflow, reduce the interference of ground vortex effects, and improve flight stability.

[0017] 3. The ducted structure of this ducted UAV can constrain and guide airflow, reducing the problem of airflow interference in a multi-rotor layout, enabling the UAV to adopt a denser power layout, providing greater flexibility for aircraft design. The duct can generate the same lift with a smaller overall size, making the overall design more compact and convenient for deployment in small urban spaces. The duct can also smooth the incoming airflow and reduce the impact of crosswinds, allowing the aircraft to remain stable in strong wind conditions, thereby achieving more precise thrust control and position maintenance, and improving hovering accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic top-down perspective structural diagram of a ducted UAV according to the present invention;

[0019] Figure 2 This is a schematic diagram of the upward-looking three-dimensional structure of a ducted UAV according to the present invention;

[0020] Figure 3 The following is a table showing the comparison of parameters between an embodiment of a ducted UAV of the present invention and a conventional aircraft.

[0021] In the figure: 1. Fuselage; 2. Front battery compartment; 3. Rear battery compartment; 4. Propulsion assembly; 401. Duct; 402. Propeller; 403. Acoustic pad; 404. Lip; 5. Door; 6. Glass window; 7. Skid-type landing gear. DETAILED DESCRIPTION

[0022] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0023] like Figure 1-Figure 3 As shown, the present invention provides a technical solution: a ducted UAV, including a fuselage 1 and a propulsion assembly 4, wherein a front battery compartment 2 and a rear battery compartment 3 are respectively provided on the front and rear sides of the fuselage 1, and the fuselage 1 is made of carbon fiber composite material and has a streamlined structure, the propulsion assembly 4 includes a duct 401 provided on the left and right sides of the fuselage 1, and a propeller 402 is provided inside the duct 401, an acoustic pad 403 is laid on the inner wall of the duct 401, and a lip 404 is provided at the edge of the duct 401, a motor is provided at the bottom of the propeller 402, and the motor is electrically connected to the batteries inside the front battery compartment 2 and the rear battery compartment 3 through a wire, and the motor is connected to A flight control system is used to control the speed of each motor and the thrust direction of each propulsion assembly 4. The ducts 401 are ring-shaped and symmetrically distributed about the central axis of the fuselage 1. The gap between the ducts 401 and the propeller 402 is controlled within a range of 1-5% of the diameter of the propeller 402. The blade speed of the propeller 402 is set within a high frequency range of 2000-5000 Hz through frequency control. The acoustic liner 403 is a porous sound-absorbing material or a resonant cavity structure. The porous sound-absorbing material includes but is not limited to glass fiber and foam metal. The lip 404 is arc-shaped and is used to smoothly introduce external airflow.

[0024] The specific operation is as follows: the inner wall of the duct 401 is designed as a smooth curved surface to reduce the additional noise generated by airflow turbulence, and the lip 404 is arc-shaped to smoothly introduce external airflow, reduce airflow separation and turbulence, and reduce noise and energy loss. The smooth introduction of external airflow can suppress the formation of spirals;

[0025] Furthermore, the propeller 402 uses a multi-blade, small-diameter design to push the main noise frequency to a high-frequency range that is more easily attenuated in the atmosphere. The acoustic pad 403, composed of a porous sound-absorbing material or a resonant cavity structure, specifically absorbs noise in this high-frequency range, thereby reducing the impact on distant observers and better complying with urban environmental noise regulations.

[0026] Furthermore, the duct 401 acts as a natural sound barrier, reducing the noise generated by the propeller 402. The duct 401 suppresses the noise radiated directly outward by the blade tip vortex, and smoothes and constrains the wake to reduce turbulent noise. Furthermore, the propeller 402 has multiple blades and a small diameter, and the acoustic pad 403 absorbs high-frequency noise. These multiple approaches work together to significantly improve drone noise pollution.

[0027] In addition, the duct 401 completely encloses the high-speed rotating propeller 402, effectively preventing people or objects from accidentally contacting the rotating parts, improving ground operation safety, and reducing the risk of collision with birds during flight. The airflow generated by the high-speed rotation of the propeller 402 must pass through the duct 401 before it can be discharged. Therefore, the duct 401 can also constrain and guide the airflow, reduce interference from ground vortex effects, and improve flight stability.

[0028] Secondly, the low-pressure suction generated by the leading edge of duct 401 provides additional thrust contribution. In the hovering state, duct 401 can generate significant wing-shaped lift, which improves thrust output. Under the same power and disc area, the static thrust of duct 401 and propeller 402 is significantly higher than that of open blades. Under the same thrust, power consumption is significantly reduced. During the transition flight phase, the thrust direction is smoothly adjusted through vector control technology, maintaining a high energy conversion efficiency and improving the aircraft's range.

[0029] The Duct 401 structure can constrain and guide airflow, reduce the problem of airflow interference in multi-rotor layouts, enable the UAV to adopt a denser power layout, and provide greater flexibility for aircraft design. The Duct 401 can generate the same lift with a smaller overall size, making the overall design more compact and convenient for deployment in small spaces in cities. Moreover, the Duct 401 can smooth the incoming flow and reduce the impact of crosswinds, allowing the aircraft to remain stable under strong wind conditions, thereby achieving more precise thrust control and position maintenance, improving hovering accuracy, and is particularly suitable for application scenarios that require precise positioning.

[0030] Example 1: The fuselage 1 is made of carbon fiber composite material and has a streamlined shape. Eight propulsion assemblies 4 are evenly distributed below the fuselage 1. The inner diameter of the duct 401 of each propulsion assembly 4 is 300 mm, and the diameter of the propeller 402 is 290 mm. The gap between the duct 401 and the propeller 402 is 10 mm, which is 3.4% of the diameter of the propeller 402. The inner wall of the duct 401 is a smooth curved surface, and the lip 404 adopts an arc-shaped flow guide design. The inner wall of the duct 401 is paved with a 10 mm thick glass fiber sound-absorbing material as an acoustic pad 403. The propeller 402 uses a carbon fiber blade with a diameter of 290 mm. The blade passing frequency is controlled to be around 3000 Hz through aerodynamic computational fluid dynamics simulation optimization.

[0031] Each propeller 402 is driven by a brushless motor with a rated power of 50kW, which is powered by a lithium battery pack. The flight control system adopts a redundant design, including multiple inertial measurement units and satellite navigation modules, for accurately controlling the motor speed and thrust direction of the propulsion assembly 4;

[0032] Performance test: Noise testing was conducted at a distance of 10 meters from the aircraft. The noise level during vertical takeoff and landing was 75 decibels, which is about 20 decibels lower than that of traditional open-blade drones. Flight tests were conducted under wind conditions of level 6. The aircraft's attitude was stable, and the hovering accuracy error was controlled within 0.5 meters. The range test showed that the drone has a range of 300 kilometers at cruising speed.

[0033] Example 2: The fuselage 1 is made of carbon fiber composite material and has a streamlined shape. Eight propulsion assemblies 4 are evenly distributed below the fuselage 1. The inner diameter of the duct 401 is 250 mm, the diameter of the propeller 402 is 240 mm, and the clearance is 10 mm, which is 4.2% of the diameter of the propeller 402. The inner wall of the duct 401 is a smooth curved surface, and the lip 404 adopts an arc-shaped flow guide design. The inner wall of the duct 401 is paved with a composite acoustic pad 403 composed of glass fiber sound-absorbing material with a thickness of 15 mm. The propeller 402 uses carbon fiber blades with a diameter of 240 mm, and the blade passing frequency is controlled at approximately 4000 Hz.

[0034] Performance test: At a distance of 10 meters from the aircraft, the noise level during vertical take-off and landing was 70 decibels. Hovering and positioning tests were conducted in a complex urban environment. The aircraft was able to maintain stability under strong wind conditions, with the hovering accuracy error controlled within 0.3 meters.

[0035] Based on the performance test results of Examples 1 and 2, the results were compared with those of a traditional open propeller aircraft under the same test conditions. The traditional open propeller aircraft selected the EH216-S aircraft. Figure 3 As shown, it can be seen that the ducted UAV of the present invention has the advantages of better noise reduction effect, higher safety, stronger wind resistance, and more compact structure.

[0036] like Figure 1-Figure 3 As shown, doors 5 are provided in the middle of the left and right sides of the fuselage 1, and a glass window 6 is provided at the front end of the fuselage 1 on one side of the front battery compartment 2. Skid-type landing gears 7 are provided at the bottom of the fuselage 1, and two skid-type landing gears 7 are provided;

[0037] The specific operation is as follows: the skid-type landing gear 7 provides support when the UAV lands, and by opening the cabin door 5, various accessories inside the fuselage 1 can be inspected and repaired, and the glass window 6 is used to protect the detection ends of various sensors such as cameras and infrared sensors without affecting the normal operation of the sensors.

[0038] In summary, when the ducted UAV is in use, first, during flight, the propeller 402, which uses a multi-blade, small-diameter design, pushes the main noise frequency to a high-frequency range that is more easily attenuated in the atmosphere. The acoustic pad 403, composed of a porous sound-absorbing material or a resonant cavity structure, specifically absorbs the noise in this high-frequency range. Together with the duct 401, which acts as a natural sound barrier, it can reduce the noise generated by the propeller 402. The duct 401 also suppresses the tip vortex from directly radiating noise outward and smoothes and constrains the wake to reduce turbulent noise. Thus, through multiple methods working together, the noise pollution problem of the UAV is significantly improved.

[0039] Furthermore, the duct 401 completely encloses the high-speed rotating propeller 402, effectively preventing people or objects from accidentally contacting the rotating parts, improving ground operation safety, and reducing the risk of collision with birds during flight. Furthermore, the airflow generated by the high-speed rotation of the propeller 402 must pass through the duct 401 before it can be discharged. Thus, the duct 401 can also constrain and guide the airflow, reducing interference from ground vortex effects and improving flight stability.

[0040] Secondly, the low-pressure suction generated by the leading edge of duct 401 provides additional thrust contribution. In the hovering state, duct 401 can generate significant wing-shaped lift, which improves thrust output. Under the same power and disc area, the static thrust of duct 401 and propeller 402 is significantly higher than that of open blades. Under the same thrust, power consumption is significantly reduced. During the transition flight phase, the thrust direction is smoothly adjusted through vector control technology, maintaining a high energy conversion efficiency and improving the aircraft's range.

[0041] The Duct 401 structure can constrain and guide airflow, reduce the problem of airflow interference in multi-rotor layouts, enable the UAV to adopt a denser power layout, and provide greater flexibility for aircraft design. The Duct 401 can generate the same lift with a smaller overall size, making the overall design more compact and convenient for deployment in small spaces in cities. Moreover, the Duct 401 can smooth the incoming flow and reduce the impact of crosswinds, allowing the aircraft to remain stable under strong wind conditions, thereby achieving more precise thrust control and position maintenance, improving hovering accuracy, and is particularly suitable for application scenarios that require precise positioning.

[0042] The embodiments of the present invention are presented for purposes of illustration and description and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are chosen and described in order to better illustrate the principles of the invention and its practical application and to enable those skilled in the art to understand the invention and design various embodiments with various modifications as suited for specific applications.

Claims

1. A ducted UAV comprising a fuselage (1) and a propulsion assembly (4), characterized in that: The front and rear sides of the fuselage (1) are respectively provided with a front battery compartment (2) and a rear battery compartment (3), and the fuselage (1) is made of carbon fiber composite material and has a streamlined structure. The propulsion assembly (4) includes a duct (401) provided on the left and right sides of the fuselage (1), and a propeller (402) is provided inside the duct (401). The inner wall of the duct (401) is paved with an acoustic pad (403), and a lip (404) is provided at the edge of the duct (401). A motor is provided at the bottom of the propeller (402), and the motor is electrically connected to the batteries inside the front battery compartment (2) and the rear battery compartment (3) through a wire. The motor is connected to a flight control system, and the flight control system is used to control the rotation speed of each motor and the thrust direction of each propulsion assembly (4).

2. The ducted UAV according to claim 1, characterized in that: The ducts (401) are ring-shaped, and the ducts (401) are symmetrically distributed about the central axis of the fuselage (1).

3. The ducted UAV according to claim 1, characterized in that: The gap between the duct (401) and the propeller (402) is controlled within the range of 1-5% of the diameter of the propeller (402).

4. The ducted UAV according to claim 1, characterized in that: The blade rotation speed of the propeller (402) is set within the range of 20-100 Hz through frequency control.

5. The ducted UAV according to claim 4, characterized in that: The acoustic pad (403) is a porous sound-absorbing material or a resonance cavity structure.

6. The ducted UAV according to claim 1, characterized in that: The porous sound-absorbing material includes but is not limited to glass fiber and foam metal.

7. The ducted UAV according to claim 1, characterized in that: The lip (404) is in an arc shape, and the lip (404) is used to smoothly introduce external airflow.

8. The ducted UAV according to claim 1, characterized in that: Doors (5) are provided in the middle of the left and right sides of the fuselage (1), and a glass window (6) is provided at the front end of the fuselage (1) on one side of the front battery compartment (2).

9. The ducted UAV according to claim 1, characterized in that: The bottom of the fuselage (1) is provided with a skid-type landing gear (7), and two skid-type landing gears (7) are provided.

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