Ducted fan unit

Abstract

A ducted fan unit (1). The ducted fan unit (1) is mounted on an aircraft wing (3); a duct (11) is formed inside the ducted fan unit (1); the duct (11) is sequentially provided with a duct air intake section (111), a duct middle section (112) and a duct exhaust section (113) in an airflow direction; a fan (12) is provided in the duct air intake section (111), and the fan (12) is connected to a power unit (13) so as to guide air from the outside into the duct (11); the air from the outside enters the duct (11) from the duct air intake section (111), passes through the duct middle section (112) and then flows out of the duct (11) via the duct exhaust section (113); and the cross sections of the duct sections of the duct (11) are shaped as a rounded rectangle or a circle. The efficiency of the fan in the ducted fan units (1) is improved, and a stable lift augmentation effect is provided.

Description

Ducted fan unit Technical Field

[0001] The present invention relates to a ducted fan unit, and more particularly, to a ducted fan unit suitable for the field of aviation aircraft. Background Art

[0002] With the development of the aviation industry, environmental issues such as harmful gas pollution and fuel consumption generated during aircraft operation have gradually attracted attention. Currently, large civil aircraft primarily utilize a low-wing, multiple high-bypass turbofan engines, and a low-lying tail. The aerodynamic layout of mainstream civil aircraft powered by high-bypass turbofan engines has essentially reached its optimal design, making it difficult to significantly improve aerodynamic performance and efficiency, making it difficult to meet the public's demand for environmental protection, high efficiency, and low fuel consumption.

[0003] To develop green and environmentally friendly aviation, distributed electric propulsion technology has gradually become a key development direction. Distributed ducted fan electric propulsion is an important form of distributed electric propulsion and is attracting increasing attention.

[0004] For example, patent document CN115489716A proposes a wing integrated with a distributed fan. The wing is attached to the fuselage and is provided with a fan power group, wherein the fan power group is arranged on the inner wing of the wing and arranged above the wing to form an integral part with the wing. The inner wing includes an inner wing flap, which is a movable component that can move between a first extended position and a first retracted position. When in the first extended position, the inner wing flap is extended relative to the inner wing and arranged close to the trailing edge of the fan power group. When in the first retracted position, the inner wing flap is retracted relative to the inner wing. In this way, the inner wing flap can be extended rearward and deflected when needed. The airflow ejected by the fan generates a low-pressure area and a high-pressure area between the upper surface and the lower surface of the inner wing flap under the action of the Coanda effect, thereby achieving the effect of increasing the lift of the wing.

[0005] However, in this invention, the cross-sectional shape of the duct outlet is designed to be a right-angled rectangle, while the cross-sectional shape of the fan is circular, so that the cross-sectional area of ​​the duct cannot be controlled to be smaller, resulting in reduced fan efficiency.

[0006] In addition, during the outflow process, the cross-sectional shape occupied by the flowing airflow changes dramatically, which can easily cause flow separation, increase the aircraft's resistance, and affect the stable operation of the fan.

[0007] Furthermore, the flaps used in this invention remain in close contact with the fan's trailing edge during movement, relying primarily on the Coanda effect to deflect the fan jet and increase lift. However, if the flaps remain in close contact with the fan's trailing edge without openings when the fan is operating in a low-power range, the lift-enhancing effect will be severely reduced.

[0008] In addition, patent document CN114954899A proposes a wing assembly equipped with an engine. The wing assembly is used for an aircraft having a fuselage and at least one pair of wings, and is configured to generate lift for the aircraft relative to the flow direction. The wing assembly includes: a main section configured to be fixedly mounted to the fuselage so as to extend from the fuselage in the direction of extension of the wing; and a plurality of flap sections, each having a main body and pivotally mounted to the main section so as to be pivotable about a pivot axis via a pivot device in a plurality of angular orientations, including horizontal and vertical orientations. In the horizontal orientation, the main body of the flap section is generally aligned with the main section to form an elongated and substantially continuous cross-section; in the vertical orientation, the flap section is angled downward relative to the main section. The invention also relates to an aircraft equipped with at least one pair of such wing assemblies.

[0009] However, the engine of the above-mentioned wing assembly is fixed on the flap, and the corresponding function is achieved by pivoting the flap and the engine as a whole around the pivot axis. In addition, ducted fans are arranged on the horizontal tail and outer wing sections of the aircraft, which increases the difficulty of system integration and safety analysis.

[0010] In summary, although aircraft with distributed ducted fans already exist in the prior art, they also have corresponding disadvantages.

[0011] Therefore, how to provide a ducted fan unit that can improve fan efficiency and provide a stable lift-increasing effect has become a technical problem that needs to be solved urgently.

[0012] Prior art literature

[0013] Patent Literature

[0014] Patent Document 1: Chinese Patent Publication CN115489716A

[0015] Patent Document 2: Chinese Patent Publication CN114954899A Summary of the Invention

[0016] The present disclosure is made to solve the above-mentioned technical problems, and its purpose is to provide a ducted fan unit, which can reduce the operating resistance of the internal fan and keep the airflow in the internal duct stable, so that the fan can operate stably.

[0017] In order to achieve the purpose of the present disclosure, a ducted fan unit is provided, which is installed on an aircraft wing, wherein the ducted fan unit is formed with a duct inside, and the duct is sequentially formed into a duct intake section, a duct middle section and a duct exhaust section along the airflow direction, and a fan is arranged in the duct intake section. The fan is connected to a power unit to guide air from the outside into the duct, and the air from the outside enters the duct from the duct intake section, and after passing through the duct middle section, flows out of the duct through the duct exhaust section, and the cross-section of each duct section of the duct is formed into a rounded rectangle or a circle.

[0018] According to the structure described above, since the cross-section of each duct segment of the duct is formed into a rounded rectangle or circle that is roughly the same as the cross-section of the fan, the cross-section of the space occupied by the airflow flowing in the duct will not change significantly, and the airflow in the duct can be kept stable, thereby enabling the fan to operate stably.

[0019] Preferably, a central tail cone is arranged in the above-mentioned ducted exhaust section, and the above-mentioned central tail cone is connected to the rear end of the fan hub and extends rearward beyond the rearmost edge of the above-mentioned ducted fan unit.

[0020] According to the above configuration, by arranging the center tail cone in the duct exhaust section, the airflow flowing in the duct can be guided and regulated by the center tail cone, thereby making the airflow more stable.

[0021] Preferably, the cross-sectional area of ​​the central tail cone is formed to vary with the cross-sectional area of ​​the ducted exhaust section, so that the cross-sectional area of ​​the air flow passage for flowing in the ducted exhaust section decreases monotonically along the flow direction of the air flow.

[0022] According to the above configuration, the cross-sectional area of ​​the center tail cone can be adjusted to adjust the passage area for the air flow, thereby controlling the flow rate of the air flow flowing out through the ducted exhaust section.

[0023] Preferably, the ducted fan unit further comprises a ducted movable portion, and the ducted movable portion is capable of deflecting between a stowed position and a deployed position.

[0024] Preferably, when the above-mentioned ducted movable part is in the retracted position, the upper surface of the above-mentioned ducted movable part is in close contact with the rear edge of the above-mentioned ducted bottom of the above-mentioned ducted fan unit; when the above-mentioned ducted movable part is in the deployed position, a gap is formed between the lower surface of the above-mentioned ducted movable part and the above-mentioned ducted bottom.

[0025] According to the structure as described above, by adjusting the movable part of the duct to the expanded position, a gap is formed between the movable part of the duct and the bottom of the duct. The airflow flowing along the bottom of the duct can flow into the duct through the gap, thereby ensuring the lift-increasing effect when the fan runs at a lower power.

[0026] Preferably, an edge tail cone is arranged between two adjacent ducted fan units to fill the gap formed between the two adjacent ducted fan units.

[0027] Preferably, the edge cone is formed in a tapered shape extending toward the rear of the aircraft wing.

[0028] According to the above configuration, the airflow flowing along the outer periphery of the ducted fan unit can be rectified by the edge vertebra.

[0029] Preferably, a plurality of the ducted fan units are arranged on the aircraft wing.

[0030] Preferably, the duct bottom of each of the plurality of ducted fan units is fixedly connected to the upper surface of the aircraft wing, thereby forming an integral body with the aircraft wing.

[0031] According to the above configuration, by integrating the plurality of ducted fan units with the aircraft wing, the aircraft can be propelled to take off using the lift force provided by the plurality of ducted fan units.

[0032] Preferably, all fans of the plurality of ducted fan units are driven by a single power unit.

[0033] According to the above-described structure, a single power unit is used to drive multiple ducted fan units fixed to the wings of an aircraft, which can simplify the structure, reduce the overall mass, and improve the power operation efficiency of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] With reference to the above purposes, the technical features of the present invention are clearly described in the following technical solutions, and its advantages are apparent from the following detailed description with reference to the accompanying drawings, which illustrate preferred embodiments of the present invention by way of example without limiting the scope of the inventive concept.

[0035] FIG1 is a schematic diagram of a ducted fan unit according to the present invention when the ducted movable portion is in a retracted position.

[0036] FIG2 is a schematic diagram of the ducted fan unit of the present invention when the ducted movable portion is in the deployed position.

[0037] FIG3 is a schematic diagram of the state where the ducted fan units of the present invention are arranged along the wing surface of an aircraft.

[0038] 1 Ducted fan unit; 11 Duct; 111 Ducted air intake section; 112 Ducted middle section; 113 Ducted exhaust section; 12 Fan; 13 Power unit; 14 Support; 15 Center tail cone; 16 Duct top; 17 Duct bottom; 18 Ducted movable part; 2 Edge tail cone; 3 Aircraft wing. DETAILED DESCRIPTION

[0039] Various embodiments of the present invention will now be described in detail, examples of which are illustrated in the accompanying drawings. Although the present invention is described in conjunction with exemplary embodiments, it should be appreciated that this description is not intended to limit the invention to the exemplary embodiments described below. On the contrary, the present invention is intended to cover not only these exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the invention as defined by the appended claims.

[0040] The structure of the ducted fan unit 1 of the present invention will be described below with reference to Fig. 1. Fig. 1 shows the overall structure of the ducted fan unit 1 of the present invention.

[0041] As shown in FIG. 1 , the ducted fan unit 1 of the present invention mainly includes a duct 11 , a fan 12 , a power unit 13 , a support 14 , a central tail cone 15 , a duct top 16 , a duct bottom 17 and a duct movable portion 18 .

[0042] The duct 11 includes a duct intake section 111 , a duct middle section 112 and a duct exhaust section 113 in sequence along the airflow direction, and the cross section of each duct section is formed into a rounded rectangular shape with a substantially constant area.

[0043] The airflow from the outside enters the duct 11 from the duct intake section 111 , and after passing through the duct middle section 112 , flows out of the duct 11 through the duct exhaust section 113 .

[0044] In addition, the "front" and "rear" used in this article are relative to the direction of airflow. For example, the direction of airflow inflow is called "front", and the direction of airflow outflow is called "rear".

[0045] As described above, since the cross-section of each duct section is formed into a rounded rectangular shape with a substantially constant area, after the airflow from the outside flows into each duct section through the circular cross-section fan, the shape of the flow passage cross-section through which the airflow flows does not change drastically, and the cross-sectional area of ​​the flow passage changes gradually, thereby reducing the overall pressure loss, reducing the risk of boundary layer separation, and providing the aircraft with stable flight power.

[0046] A fan 12, a power unit 13 and a support member 14 are arranged in the above-mentioned duct middle section 112. The above-mentioned fan 12 is connected to the output shaft of the power unit 13. The above-mentioned power unit 13 is preferably an electric motor, which drives the fan 12 to rotate after being powered on, thereby generating the propulsion force required for the aircraft to fly.

[0047] The support member 14 supports the fan 12 and the power unit 13 , and its upper end is fixedly connected to the duct top 16 , and its lower end is fixedly connected to the duct bottom 17 .

[0048] The duct top 16 and the duct bottom 17 are respectively the top and bottom of the outer shell of the engine nacelle, and are supported by the support member 14 to form a duct 11 for airflow.

[0049] A ducted exhaust section 113 is formed on the downstream side of the ducted middle section 112 in the airflow direction. The ducted exhaust section 113 is formed so that the cross-sectional area gradually decreases along the airflow direction, thereby accelerating the jet airflow.

[0050] In addition, a central tail cone 15 is arranged in the above-mentioned ducted exhaust section 113. The above-mentioned central tail cone 15 is connected to the rear end of the fan hub, and its cross-sectional area varies with the cross-sectional area of ​​the ducted exhaust section 113, so that the cross-sectional area of ​​the airflow channel flowing between the ducted exhaust section 113 and the central tail cone 15 decreases monotonically along the flow direction of the airflow, thereby causing the airflow to accelerate monotonically, which can avoid boundary layer separation on the ducted exhaust section 113 and the central tail cone 15.

[0051] As described above, since a central tail cone 15 is arranged in the above-mentioned ducted exhaust section 113, the air flow rate flowing out through the above-mentioned ducted exhaust section 113 can be controlled by designing the cross-sectional area 0 of the central tail cone 15 at the outlet of the ducted exhaust section 113, so as to optimize the air flow rate required for the efficient operation of the fan 12.

[0052] The ducted movable portion 18 generally also serves as a flap of the aircraft and is capable of deflecting between a stowed position and a deployed position.

[0053] Figure 1 shows the ducted fan unit 1 of the present invention with the ducted movable portion 18 in the retracted position. As shown in Figure 1 , when the ducted movable portion 18 is in the retracted position, its upper surface is in close contact with the rear edge of the ducted bottom portion 17 of the ducted fan unit 1. In other words, there is no gap between the leading edge of the ducted movable portion 18 and the rear edge of the ducted bottom portion 17.

[0054] In this way, when the above-mentioned duct movable part 18 is in the retracted position, the lower surface of the duct movable part 18 is in contact with the above-mentioned duct bottom 17. Therefore, according to Bernoulli's principle, due to the airflow ejected from the fan in the duct 11, the airflow velocity on the upper surface of the duct movable part 18 is greater than the airflow velocity below, and a low-pressure area is formed on the upper surface of the above-mentioned duct movable part 18, and a high-pressure area is formed on the lower surface, which can play a role in lifting the aircraft.

[0055] However, when the fan is running at a lower power, if the duct movable portion 18 is always in close contact with the trailing edge of the fan without any gaps, the lift-increasing effect will be seriously weakened.

[0056] Therefore, the ducted fan unit 1 of the present invention is designed to enable the ducted movable portion 18 to be deployed and slit relative to the ducted bottom 17. Figure 2 shows the ducted fan unit 1 of the present invention when the ducted movable portion 18 is in the deployed position.

[0057] As shown in Figure 2, when the above-mentioned duct movable part 18 is in the expanded position, the duct movable part 18 deflects in the clockwise direction, and a gap is formed between the lower surface of the duct movable part 18 and the duct bottom 17. The airflow flowing along the lower surface of the duct bottom 17 can flow into the duct 11 through the gap, and flow backward and downward along the shape of the duct movable part 18, so that the duct movable part 18 obtains an upward reaction force, that is, a lift-increasing effect is generated.

[0058] In addition, the airflow flowing in the duct 11 will also be attracted by the duct active part 18, causing the flow direction to be deflected downward, thereby increasing the lift that the duct active part 18 can obtain. Therefore, when the fan runs at a higher power, the lift-increasing effect generated by the deflection of the duct active part 18 becomes better.

[0059] 3, the arrangement of the ducted fan unit 1 of the present invention on the wing surface of the aircraft wing 3 will be described. FIG3 shows the arrangement of the ducted fan unit 1 of the present invention along the wing surface of the aircraft wing 3.

[0060] As shown in Figure 3, a plurality of ducted fan units 1 of the present invention are arranged along the wing surface of the aircraft wing 3, and the duct bottom 17 of each of the above-mentioned multiple ducted fan units 1 is fixedly connected to the wing support structure of the aircraft wing 3, thereby forming an integral body with the aircraft wing 3.

[0061] Furthermore, since the duct top portion 16 and the duct bottom portion 17 of the ducted fan unit 1 are formed in a substantially triangular shape, a non-contacting triangular region is formed between two adjacent ducted fan units 1 .

[0062] To this end, the present invention arranges an edge tail cone 2 between two adjacent ducted fan units 1 to fill the gap formed between the two adjacent ducted fan units 1 .

[0063] The edge tail cone 2 is formed in a tapered shape extending toward the rear of the ducted fan unit 1 , and can rectify the airflow flowing around the periphery of the ducted fan unit 1 , thereby improving the working efficiency of the fan.

[0064] The ducted movable portion 18 is specifically an inner flap of the aircraft, which is connected to the rear end of the aircraft wing 3 and can be deflected between a stowed position and a deployed position.

[0065] Although the structure and operating principles of the present invention have been described above in conjunction with preferred embodiments, those skilled in the art will recognize that the above examples are for illustrative purposes only and do not limit the present invention. The present invention may be modified and varied within the spirit of the claims, and such modifications and variations shall fall within the scope of protection of the present invention.

[0066] For example, in the present invention, an example is shown in which the cross-section of each duct segment of the above-mentioned duct 11 is formed into a rounded rectangular shape with a roughly constant area, but the present invention is not limited to this. The cross-section of each duct segment of the above-mentioned duct 11 can also be formed into other shapes such as a circle, as long as the cross-sectional shape occupied by the flowing airflow does not change drastically.

[0067] For example, in the present invention, an example is shown in which the above-mentioned multiple ducted fan units 1 each include a power unit 13 and the power unit 13 drives their respective fans 12, but the present invention is not limited to this. All fans 12 in the above-mentioned multiple ducted fan units 1 can also be driven by a single power unit 13, thereby simplifying the overall structure and reducing the structural weight.

Claims

1. A ducted fan unit (1), which is installed on an aircraft wing (3), wherein, the ducted fan unit (1) forms a duct (11) inside, and the duct (11) is successively formed into a duct intake section (111), a duct middle section (112), and a duct exhaust section (113) along the air flow direction, a fan (12) is arranged in the duct intake section (111), and the fan (12) is connected to a power unit (13) to guide the air from the outside into the duct (11), the air from the outside enters the duct (11) from the duct intake section (111), and flows out of the duct (11) through the duct exhaust section (113) after passing through the duct middle section (112), the cross-section of each duct section of the duct (11) is formed into a rounded rectangle or a circle.

2. The ducted fan unit (1) according to claim 1, characterized in that, a central tail cone (15) is arranged in the duct exhaust section (113), the central tail cone (15) is connected to the rear end of the fan hub, and extends rearward beyond the position of the trailing edge of the ducted fan unit (1).

3. The ducted fan unit (1) according to claim 2, characterized in that, the cross-sectional area of the central tail cone (15) is formed to change with the cross-sectional area of the duct exhaust section (113), so that the cross-sectional area of the air flow channel flowing in the duct exhaust section (113) monotonically decreases along the air flow direction.

4. The ducted fan unit (1) according to claim 3, characterized in that, the ducted fan unit (1) further includes a duct movable part (18), and the duct movable part (18) can deflect between a retracted position and a deployed position.

5. The ducted fan unit (1) according to claim 4, characterized in that, when the duct movable part (18) is in the retracted position, the upper surface of the duct movable part (18) is in close contact with the trailing edge of the duct bottom (17) of the ducted fan unit (1); when the duct movable part (18) is in the deployed position, a gap is formed between the lower surface of the duct movable part (18) and the duct bottom (17).

6. The ducted fan unit (1) according to any one of claims 1 to 5, characterized in that, an edge tail cone (2) is arranged between two adjacent ducted fan units (1) to fill the gap formed between two adjacent ducted fan units (1).

7. The ducted fan unit (1) according to claim 6, characterized in that, the edge tail cone (2) is formed into a conical shape extending rearward toward the aircraft wing (3).

8. The ducted fan unit (1) according to claim 1, characterized in that, a plurality of the ducted fan units (1) are arranged in a row on the aircraft wing (3).

9. The ducted fan unit (1) according to claim 8, characterized in that, The bottom of the duct of each of the plurality of ducted fan units (1) is fixedly connected to the upper surface of the aircraft wing (3), so as to be integrated with the aircraft wing (3).

10. The ducted fan unit (1) according to claim 8 or 9, characterized in that all the fans (12) of the plurality of ducted fan units (1) are driven by a single power unit (13).

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