Ducted fan unit, wing assembly and aircraft equipped with such wing assembly

Abstract

The invention relates to a ducted fan unit comprising: a duct (13) having a starting end (13a) and a terminating end (13b); a fan assembly (2) arranged within the duct through which an airflow passes in an airflow flow direction (F); and a central cone (10) mounted downstream of the fan assembly, the central cone extending in the direction of flow of the air flow beyond the terminating end of the duct and having a varying cross-section, the central cone forming a maximum cross-section (10a) of the central cone at the terminating end, a control system is arranged on a maximum cross-section of the central cone that transitions between an original configuration having an original size and an expanded configuration having a cross-sectional size greater than the original size. Through the structure, the area of the spray pipe can be actively adjusted, and the problem that the fan efficiency is reduced is solved. In addition, the invention further relates to a wing assembly composed of the ducted fan unit and a wing, and an aircraft provided with the wing assembly.

Description

Technical Field

[0001] The present invention relates to a ducted fan unit, and more specifically, to a ducted fan unit with an actively adjustable nozzle area. On the other hand, the present invention also relates to a wing assembly consisting of the ducted fan unit and a wing, and an aircraft equipped with the wing assembly. Background Art

[0002] With the development of the aviation industry, environmental issues such as harmful gas pollution and fuel consumption generated by aircraft operation have gradually attracted attention. At present, mainstream large civil aircraft usually adopt the aircraft aerodynamic layout form of low single wing, multi-engine high bypass ratio turbofan engine and low horizontal tail. In order to achieve the goals of high thrust, low fuel consumption, high thrust-to-weight ratio, and take into account the use requirements such as high reliability, the performance of the engine has been optimized to the extreme, resulting in its composition structure is very complex and the process is difficult to achieve. Therefore, the aerodynamic layout form of mainstream civil aircraft using high bypass ratio turbofan engine as the power system has basically tended to the optimal solution, and its aerodynamic performance and efficiency are difficult to significantly improve, and it is difficult to meet people's requirements for its green environmental protection, high efficiency and low consumption.

[0003] In order to develop green aviation, distributed electric propulsion technology has gradually become a key development direction for various countries. Distributed ducted fan electric propulsion is an important form of distributed electric propulsion and is attracting more and more attention. Distributed ducted fans can improve the equivalent bypass ratio, and deep coupling with the wing can improve the lift-to-drag ratio during the climb and cruise phases. Multiple power units achieve safety redundancy, and the power difference can be used to adjust the flight attitude and other advantages.

[0004] In Chinese invention patent CN115489716B filed by the applicant of the present invention on September 22, 2022, a wing integrated with a distributed fan is disclosed. This wing is attached to the fuselage and is provided with a fan power group, wherein the fan power group is arranged on the inner section wing of the wing and is arranged above the wing to be integrated with the wing. The inner section wing includes an inner section wing flap, which is movable between a first extended position and a first retracted position, and wherein the inner section wing flap is extended relative to the inner section wing when in the first extended position and is arranged close to the trailing edge of the fan power group, and the inner section wing flap is retracted relative to the inner section wing when in the first retracted position.

[0005] Since the inner wing flap is a movable part, it can be extended backward and deflected when needed. The airflow ejected by the fan creates low-pressure and high-pressure areas on the upper and lower surfaces of the inner wing flap respectively under the Coanda effect, thereby achieving the effect of increasing the lift of the wing.

[0006] However, since the nozzle outlet area of ​​the ducted fan in the above-mentioned invention patent is a fixed value, technical personnel in this field are unable to adjust it, resulting in the fan being unable to always maintain a high fan efficiency under a wide range of incoming wind speeds and fan speeds, posing risks to the reduction of ducted fan thrust and stable fan operation, and the reduction in fan efficiency will also reduce the aircraft's range.

[0007] In order to adjust the nozzle outlet area of ​​the ducted fan, technical personnel in this field have proposed various improvement schemes.

[0008] For example, in Chinese patent application CN115009523A filed by Lily Aviation Co., Ltd. on March 2, 2022, an aircraft engine including a variable area discharge nozzle is disclosed. The aircraft engine is configured to be movable between a hovering position for takeoff and landing and a cruising position for forward flight relative to an aircraft component of the aircraft, wherein the engine includes an aerodynamic component having at least one aerodynamic element, the aerodynamic element being movable between a first position according to a first operating state of the aircraft and a second position according to a second operating state of the aircraft, the aerodynamic element defining an aerodynamic surface in contact with an airflow passing through the engine.

[0009] The above patent application adjusts the nozzle area by tilting and rotating the duct fan mechanism to control the nozzle surface to open or close, thereby achieving flow control. However, the control mechanism that enables the nozzle surface to open and close will have discontinuous curved surfaces in the flow channel during the opening process, which will in turn enhance the flow separation phenomenon, which is very unfavorable for flow control.

[0010] For another example, in the Chinese invention patent application CN117644969A also filed by the applicant of the present invention on January 19, 2024, a ducted fan unit installed on an aircraft wing is disclosed. This ducted fan unit has a duct formed 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. A fan is arranged in the duct intake section, and the fan is connected to the power unit to guide the air from the outside into the duct. The air from the outside enters the duct from the duct intake section, and after passing through the duct middle section, it flows out of the duct through the duct exhaust section. The cross-section of each duct section of the duct is formed into a rounded rectangle or a circle.

[0011] The above patent application adjusts the nozzle area by flap deflection, but its adjustable range is relatively small and cannot be actively adjusted, which cannot fully meet the needs of technical personnel in this field. Although the patent application also arranges a central tail cone in the ducted exhaust section so that the cross-sectional area of ​​the airflow channel flowing in the ducted exhaust section decreases monotonically along the airflow flow direction, such a design cannot actively adjust the nozzle outlet area of ​​the ducted fan, and has great limitations when facing complex flight conditions.

[0012] To this end, those skilled in the art also hope to design a ducted fan unit that can actively adjust the nozzle area, thereby achieving a wide range of control over the flow rate. Summary of the invention

[0013] An object of the present invention is to provide a ducted fan unit capable of actively adjusting the nozzle area.

[0014] A first aspect of the present invention relates to a ducted fan unit comprising:

[0015] A duct, the duct comprising a starting end and a terminating end;

[0016] a fan assembly disposed in the duct, the fan assembly driving air flow through the duct along the air flow direction; and

[0017] A central cone is installed downstream of the fan assembly, the central cone extends along the airflow direction and exceeds the terminal end of the duct, and has a variable cross section, wherein the central cone forms the maximum cross section of the central cone at the terminal end,

[0018] A control system is arranged on the maximum cross-section of the central cone to convert the maximum cross-section of the central cone between an original configuration and an expanded configuration. In the original configuration, the cross-section of the central cone has an original size, and in the expanded configuration, the cross-section of the central cone has a size larger than the original size.

[0019] The so-called "starting end" and "terminating end" refer to the two ends of the duct formed between the upper part of the nacelle of the aircraft engine and the wing. A fan assembly is installed at the starting end of the duct, and the fan blades of the fan assembly rotate around the central axis of the fan hub to suck the airflow into the duct. After entering the duct, the airflow passes through the duct along the flow direction of the airflow. The trailing edge of the inner surface of the wing and the upper part of the nacelle is the terminating end of the duct, and the airflow in the duct leaves the duct from the terminating end.

[0020] The reference of the term "downstream" is the above-mentioned airflow direction. Since the airflow flows from upstream to downstream in the duct along the airflow direction, the positional relationship between the components arranged in the duct can be determined with reference to the above-mentioned direction.

[0021] The center cone is usually designed so that the cross-sectional area of ​​the airflow channel between the duct and the center cone decreases monotonically along the direction of airflow flow, so that the airflow in the airflow channel is accelerated and boundary layer separation of the airflow is avoided. In other words, when the cross-sectional area of ​​the duct remains basically unchanged, the cross-sectional area of ​​the center cone extending in the duct usually increases monotonically along the direction of airflow flow, and thus the maximum cross-sectional area of ​​the center cone is obtained at the terminal end of the duct. This cross-sectional area is also called the nozzle outlet cross-sectional area. In special cases, due to the excessively rapid contraction of the inner profile of the nozzle, it may also be necessary to achieve a monotonic reduction in the cross-sectional area of ​​the airflow channel through a non-monotonic design of the cross-sectional area of ​​the center cone.

[0022] The maximum cross section of the central cone can be switched between the original configuration and the expanded configuration by the control system. In other words, the control system can further increase the maximum cross section of the central cone on the basis of the original size. In this way, the nozzle area and the flow channel shape can be actively adjusted, thereby realizing active control of the flow rate.

[0023] Preferably, the central cone can be mounted to the tail or rear end of the fan assembly by means of a base, and a central cone bracket is connected to the base and supports the central cone.

[0024] Through the above structure, the central cone bracket can support the basic configuration of the central cone, providing more stable support for the control system to control the cross section of the central cone.

[0025] More preferably, the control system may include: at least one driving source; at least one skin shape conforming member, which maintains the original shape of the skin of the center cone; and at least one skin limit point, which uses power from the driving source to drive the skin shape conforming member to convert between the original configuration and the expanded configuration.

[0026] In the above technical solution, the term "skin shape conforming member" refers to a planar component that occupies a certain amount of space, while the term "skin limiting point" refers to a point-shaped component that occupies a much smaller amount of space than the former. Through the above structure, the skin limiting point and the skin shape conforming member realize the joint movement between the two in the form of point-to-surface movement, thereby making the driving effect of the driving source more stable and efficient.

[0027] In the above preferred embodiment, the driving source can be an actuator or a linear motor or other equipment that provides an energy source.

[0028] The skin shape conforming member can be made of a rigid material, while the skin is made of a stretchable material. In this way, in the entire cross section constituting the central cone, the skin covered by the skin shape conforming member maintains the original configuration and size, while the skin not covered by the skin shape conforming member or the skin between the skin shape conforming members is stretched to increase the cross-sectional size of the central cone.

[0029] The term "stretchable material" refers to a material that has a certain degree of external stiffness and is able to withstand certain aerodynamic forces.

[0030] The skin stop point can be a movable block or a clamping plate associated with the skin shape conforming member. The use of a block or a clamping plate can make the engagement between the skin stop point and the skin shape conforming member more secure.

[0031] Preferably, the controller may further include a control element receiving power from a driving source to move the skin limiting point.

[0032] More preferably, the control elements may include: two longitudinal control elements arranged along the longitudinal direction of the maximum cross-section of the central cone, the longitudinal control elements controlling the movement of the skin limit point along the longitudinal direction; and two transverse control elements arranged along the transverse direction of the maximum cross-section of the central cone, the transverse control elements controlling the movement of the skin limit point along the transverse direction.

[0033] In the above technical solution, the terms "longitudinal" and "lateral" are determined with reference to the embodiment shown in the accompanying drawings. Of course, for those skilled in the art, the embodiment can also be rotated 90°. In this case, the terms "longitudinal" and "lateral" can be interchanged without any impact on the protection scope of the present invention. The rotation angle can also be flexibly adjusted according to the actual conditions of installation.

[0034] Through the above structure, the control element is decomposed into four elements, two of which are arranged in the longitudinal direction of the maximum cross section of the central cone, and the other two are arranged in the transverse direction of the maximum cross section of the central cone. Each of these elements can be a group composed of the previously mentioned driving source, the skin shape conforming member and the skin limit point, receiving power from the driving source, and driving the skin limit point to drive the skin shape conforming member to move together in the longitudinal or transverse direction, thereby actively adjusting the size of the maximum cross section of the central cone.

[0035] In the above preferred embodiment, the control element may be a linear rod or a threaded rod that can be reciprocated under the drive of the driving source. Accordingly, the skin limit point may cooperate with the control element, and in the maximum cross section of the central cone, the skin limit point moves relative to the control element in a predetermined direction by rotation or translation.

[0036] Through the above structure, the skin limit point can be moved relative to the control element along the arrangement direction of the control element by rotation or translation, thereby achieving the purpose of actively adjusting the maximum cross-section of the central cone.

[0037] At least one set of control systems is also arranged upstream of the central cone at its largest cross section, which switches the other cross sections of the central cone between the original configuration and the expanded configuration.

[0038] Through the above structure, the central cone can also adjust the sizes of one or more other cross sections other than its largest cross section, thereby strengthening the shape control of the flow channel and further improving the active control of the flow rate.

[0039] A second aspect of the present invention relates to a wing assembly, comprising a wing and a ducted fan unit as described above, wherein the ducted fan unit is arranged above the wing.

[0040] A third aspect of the invention relates to an aircraft equipped with a wing assembly as described above.

[0041] In summary, the ducted fan unit according to the present invention can achieve the following advantages:

[0042] (i) By providing a center cone with a variable cross-section in the ducted fan unit, the problem of reduced fan efficiency due to the wide speed range and rotation speed range faced by the fan unit during aircraft takeoff, cruising, approach and landing is solved;

[0043] (ii) The shape of the central cone is controlled by controlling the size of the cross-sectional shape, thereby controlling the nozzle area of ​​the ducted fan. The central cone has a ductile skin so that changes in the shape of the central cone will not cause significant flow separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to further illustrate the structure of the ducted fan unit according to the present invention and its technical effects, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, wherein:

[0045] Figure 1 is a schematic diagram of a ducted fan unit installed inside a nacelle according to the present invention;

[0046] Figure 2 yes Figure 1 A schematic diagram of the central cone of the ducted fan unit shown in FIG. 1 is a diagram showing the change between the original configuration and the expanded configuration, wherein the original configuration of the central cone is shown by a solid line, and the expanded configuration of the central cone is shown by a dotted line;

[0047] Figure 3 A first embodiment of a ducted fan unit according to the present invention is shown, which is a side view taken along the maximum cross section of a central cone of the ducted fan unit; and

[0048] Figure 4 A second embodiment of a ducted fan unit according to the present invention is shown, and the figure is a side view taken along the maximum cross section of a central cone of the ducted fan unit.

[0049] Reference numerals

[0050] 1 Wing

[0051] 2 Fan assembly

[0052] 3 Nacelle upper part

[0053] 4 Inner surface

[0054] 5.5' Skin

[0055] 6. Drive source

[0056] 7 Center cone bracket

[0057] 8, 8' skin limit point

[0058] 9, 9' skin shape retaining parts

[0059] 10 Center cone

[0060] 10a Maximum cross section of the central cone

[0061] 10b Other cross sections of the central cone

[0062] 11a Lateral control element

[0063] 11b Longitudinal control element

[0064] 12 Base

[0065] 13 Duct

[0066] 13a Starting point

[0067] 13b Termination

[0068] F Air flow direction DETAILED DESCRIPTION

[0069] The structure, working principle and technical effects of the ducted fan unit according to the present invention are described below with reference to the accompanying drawings.

[0070] It should be clear that the embodiments described in this specification only cover some embodiments of the present invention, not all embodiments. Based on the embodiments recorded in the specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0072] For example, the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned accompanying drawings are intended to cover non-exclusive inclusions. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0073] For another example, in the specification of the present invention, the terms "first" and "second" are only used to distinguish the same devices or elements, and do not indicate or imply that the devices or elements referred to must have a specific arrangement order, or must be arranged and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In fact, if the names of the above devices or elements are interchanged, it will not cause any undesirable limitation to the protection scope of the present invention.

[0074] In addition, based on the same understanding of orientation, in the specification of the present invention, the orientations or positional relationships indicated by terms such as "upstream", "downstream", "longitudinal", "lateral", "inside" and "outside" are based on the orientations or positional relationships shown in the accompanying 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, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0075] Figure 1 FIG. 1 is a schematic diagram of a ducted fan unit according to the present invention being installed inside a nacelle. Figure 1 As shown, a ducted fan unit is provided between the wing 1 and the upper part 3 of the nacelle of the aircraft. The ducted fan unit comprises: a duct 13, which has a starting end 13a and a terminal end 13b; a fan assembly 2 arranged in the duct 13, the fan assembly 2 comprising a fan hub and a plurality of fan blades rotating around the fan hub, with the rotation of the fan blades, the air flow is sucked into the fan assembly 2 at the starting end 13a and passes through the duct 13 along the air flow direction F, and finally discharged from the duct 13 from the terminal end 13b; and a center cone 10 installed downstream of the fan assembly 2, the center cone 10 extends along the air flow direction F and exceeds the terminal end 13b of the duct 13.

[0076] The center cone 10 is usually designed so that the cross-sectional area of ​​the airflow passage between the duct 13 and the center cone 10 decreases monotonically along the airflow flow direction F, so that the airflow in the airflow passage is accelerated and boundary layer separation of the airflow is avoided. In other words, when the cross-sectional area of ​​the duct remains basically unchanged, the cross-sectional area of ​​the center cone 10 extending in the duct 13 usually increases monotonically along the airflow flow direction F, and thus the maximum cross-sectional area 10a of the center cone 13 is obtained at the terminal end 13b of the duct 13. At this position, the airflow passage can obtain the minimum cross-sectional area by subtracting the cross-sectional area of ​​the center cone 13 from the cross-sectional area of ​​the duct. Even in special cases, the cross-sectional area of ​​the airflow passage is no more than 105% of the minimum cross-sectional area of ​​the airflow passage.

[0077] A control system is arranged on the largest cross section 10a of the central cone 10, i.e., the nozzle outlet, which can switch the central cone 10 between an original configuration with an original size and an expanded configuration with a cross-sectional size larger than the original size. Through the above structure, the nozzle area can be actively adjusted, solving the problem of reduced fan efficiency.

[0078] The central cone 10 is mounted to the tail of the fan assembly 2 by means of the base 12. In other words, the central cone 10 is mounted downstream of the fan assembly 2 by means of the base 12 relative to the airflow direction F. The central cone bracket 7 is connected to the base 12 and extends downstream along the airflow direction F, thereby supporting the central cone 10 so that each cross section thereof along the airflow direction F maintains the original size.

[0079] Continue to see Figure 1 The control system includes: at least one, preferably four, driving sources 6; at least one, preferably four, skin shape conforming members 9, which maintain the original shape of the skin 5 of the central cone 10; at least one, preferably four, skin limit points 8; and at least one, preferably four, control elements, each of which receives power from a corresponding driving source 6 and applies it to a corresponding skin limit point 8, and the skin limit point 8 moves using the power and drives the skin shape conforming member 9 to switch between the original configuration and the expanded configuration of the central cone 10. Figure 2 As shown, the original configuration of the central cone 10 is shown by solid lines, while the expanded configuration of the central cone 10 is shown by dashed lines.

[0080] In the above embodiment, the driving source 6 is preferably an actuator or a linear motor so as to output power to the skin limit point 8. Of course, those skilled in the art should understand that the driving source 6 is not limited to the actuator or the linear motor, and other types of driving sources should also fall within the protection scope of the present invention.

[0081] In the above embodiment, the skin shape retaining member 9 is made of a rigid material, for example, at least one of various metals, rigid plastics, composite carbon fiber, and cardboard, or a combination thereof. The skin 5 is made of a stretchable material, for example, at least one of various natural rubbers, synthetic rubbers, and dielectric elastomers, or a combination thereof. Of course, those skilled in the art should understand that the skin shape retaining member 9 and the skin 5 are not limited to being made of the above materials, and other types of materials should also fall within the scope of protection of the present invention.

[0082] The skin limit point 8 is interrelated with the skin shape conforming part 9, wherein the skin limit point 8 is a point-like component, such as a moving block or a splint, which occupies a smaller amount of space; the skin shape conforming part 9 is a plane component, and the skin limit point 8 realizes the common movement with the skin shape conforming part 9 in the form of point-to-plane.

[0083] The skin shape conforming member 9 is pressed against the skin 5 of the center cone 10 from the inside of the center cone 10, so that at least some of the skin 5 is covered on the skin shape conforming member 9. Since the skin shape conforming member 9 is made of a hard material, if the skin shape conforming member 9 is made into at least a part of the predetermined cross-sectional shape of the center cone in advance, the skin 5 covered on the skin shape conforming member 9 will always maintain the predetermined cross-sectional shape of the center cone during the movement. That is to say, in the process of the center cone 10 being converted from the original configuration to the expanded configuration, the increase in the cross-sectional size is mainly attributed to the stretching effect of the skin 5 not covered on the skin shape conforming member 9 or the skin 5 between the skin shape conforming members 9.

[0084] The control elements include: two longitudinal control elements 11b arranged along the longitudinal direction on the nozzle outlet of the central cone 10, each longitudinal control element 11b controls the longitudinal movement of the corresponding skin limit point 8; and two lateral control elements 11a arranged along the lateral direction on the nozzle outlet of the central cone 10, each lateral control element 11a controls the lateral movement of the skin limit point 8.

[0085] In the above embodiment, the control element is a linear rod (such as a slotted rod) or a threaded rod that can be moved back and forth under the drive of the driving source 6. In the case where the control element is a slotted rod, the skin limit point 8 moves relative to the control element in the maximum cross-section 10a of the center cone 10 by translating in the groove of the slotted rod, such as in the longitudinal or transverse direction. In the case where the control element is a threaded rod, the skin limit point 8 moves relative to the control element in the maximum cross-section 10a of the center cone 10 by rotating the thread of the threaded rod, such as in the longitudinal or transverse direction. The skin limit point 8 drives the skin shape retaining member 9 to move in the longitudinal or transverse direction, thereby realizing the conversion between the original configuration and the expanded configuration of the center cone 10.

[0086] In addition, the central cone 10 is also provided with at least one control system upstream of its nozzle outlet to switch other cross sections 10b of the central cone 10 between the original configuration and the expanded configuration. The composition of the control system is completely consistent with the control system described above and will not be repeated here.

[0087] Figure 3 and 4 A first embodiment and a second embodiment of a ducted fan unit according to the present invention are shown respectively, wherein the original configuration of the central cone 10 is shown by a solid line and the expanded configuration of the central cone 10 is shown by a dotted line.

[0088] like Figure 3 As shown, the four skin shape conforming members 9 form a closed circle in the original configuration of the central cone 10, as shown by the solid line in the figure. If the center of the original configuration of the central cone 10 is used as the origin and the longitudinal and transverse directions of the original configuration of the central cone 10 are used as coordinate axes to establish coordinates, then one of the skin shape conforming members 9 with an arc shape can be within the range of +45° to -45° of the transverse axis, and the other skin shape conforming members 9 are similar.

[0089] As the driving source 6 outputs power, the control elements 11a and 11b control the corresponding skin limit points 8 and the skin limit points 8 drive the skin shape conforming parts 9 to move longitudinally or transversely until the nozzle outlet of the center cone 10 changes from the original configuration to the expanded configuration. In this process, the skin 5 covering the skin shape conforming parts 9 always maintains the predetermined cross-sectional shape of the center cone, while the skin 5 between the skin shape conforming parts 9 is stretched, so that the nozzle outlet of the center cone 10 is further enlarged. Figure 3 As shown, the skin 5, skin limit point 8 and skin shape retaining member 9 in the original configuration eventually become the skin 5', skin limit point 8' and skin shape retaining member 9' in the expanded configuration (shown by dotted lines), realizing the transformation of the maximum cross-section 10a of the central cone 10 from the original configuration to the expanded configuration.

[0090] In other cross sections 10 b of the central cone 10 , the skin 5 , the skin limiting points 8 and the skin shape retaining members 9 move in a similar manner, which will not be described in detail herein.

[0091] and Figure 3 similar, Figure 4 Another embodiment of a ducted fan unit is shown. Different from the previous embodiment, Figure 4The four skin shape conforming members 9 in the original configuration of the central cone 10 form a non-closed substantially square, as shown by the solid line in the figure. If the center of the original configuration of the central cone 10 is taken as the origin and the longitudinal and transverse directions of the original configuration of the central cone 10 are taken as the coordinate axes to establish the coordinates, then one of the skin shape conforming members 9 having a straight line shape can be within the range of +45° to -45° of the transverse axis, and the other skin shape conforming members 9 are similarly deduced.

[0092] As the driving source 6 outputs power, the control elements 11a and 11b control the corresponding skin limit points 8 and the skin limit points 8 drive the skin shape conforming parts 9 to move longitudinally or transversely until the maximum cross-section 10a of the center cone 10 changes from the original configuration to the expanded configuration. In this process, the skin 5 covering the skin shape conforming parts 9 always maintains the predetermined cross-sectional shape of the center cone, while the skin 5 between the skin shape conforming parts 9 is stretched, so that the maximum cross-section 10a of the center cone 10 is further increased. Figure 4 As shown, the skin 5, skin limit point 8 and skin shape retaining member 9 in the original configuration eventually become the skin 5', skin limit point 8' and skin shape retaining member 9' in the expanded configuration (shown by dotted lines), realizing the transformation of the maximum cross-section 10a of the central cone 10 from the original configuration to the expanded configuration.

[0093] In other cross sections 10 b of the central cone 10 , the skin 5 , the skin limiting points 8 and the skin shape retaining members 9 move in a similar manner, which will not be described in detail herein.

[0094] Although the structure, connection process and technical effects of the ducted fan unit according to the present invention are described above in combination with the preferred embodiments and the accompanying drawings, it should be recognized by those skilled in the art that the above examples are only for illustration and cannot be used as limitations on the present invention. For example, the cross section of the central cone can be divided into six, eight or more regions, and each region can be equipped with a corresponding control system to expand the cross section of the central cone, etc. Therefore, the present invention can be modified and varied within the spirit of the claims, and these modifications and variations will fall within the scope required by the claims of the present invention.

Claims

1. A ducted fan unit, comprising: A duct (13), wherein the duct (13) comprises a starting end (13a) and a terminating end (13b); a fan assembly (2) arranged in the duct (13), the fan assembly (2) driving the air flow through the duct (13) along the air flow direction (F); and a central cone (10) installed downstream of the fan assembly (2), the central cone (10) extending along the airflow direction (F) and beyond the terminal end (13b) of the duct (13), and having a variable cross section, wherein the central cone (10) forms a maximum cross section (10a) of the central cone (10) at the terminal end (13b), A control system is arranged on the maximum cross-section (10a) of the central cone (10) to convert the maximum cross-section (10a) of the central cone (10) between an original configuration and an expanded configuration. In the original configuration, the cross-section of the central cone (10) has an original size. In the expanded configuration, the cross-section of the central cone (10) has a size larger than the original size.

2. The ducted fan unit according to claim 1, wherein: The central cone (10) is mounted on the rear of the fan assembly (2) by means of a base (12), and a central cone bracket (7) is connected to the base (12) and supports the central cone (10).

3. The ducted fan unit according to claim 1, wherein: The control system comprises: at least one driving source (6); at least one skin shape conforming member (9), the skin shape conforming member (9) maintaining the original shape of the skin (5) of the central cone (10); and At least one skin limiting point (8), wherein the skin limiting point (8) utilizes power from the driving source (6) to drive the skin shape retaining member (9) to switch between the original configuration and the expanded configuration.

4. The ducted fan unit according to claim 3, wherein: The driving source (6) is an actuator or a linear motor; and / or The skin outer shape retaining member (9) is made of a rigid material, and the skin (5) is made of a stretchable material; and / or The skin limiting point (8) is a moving block or a clamping plate associated with the skin shape retaining member (9).

5. The ducted fan unit according to claim 3, wherein: The controller also includes a control element that receives power from the drive source (6) to move the skin limit point (8).

6. The ducted fan unit according to claim 5, wherein: The control element comprises: Two longitudinal control elements (11b) are arranged in the longitudinal direction on the maximum cross section (10a) of the central cone (10), and the longitudinal control elements (11b) control the movement of the skin limit point (8) in the longitudinal direction; and Two lateral control elements (11a) are arranged in the lateral direction on the maximum cross section (10a) of the central cone (10), and the lateral control elements (11a) control the lateral movement of the skin limiting point (8).

7. The ducted fan unit according to claim 5, wherein: The control element is a linear rod or a threaded rod that can move back and forth under the drive of the drive source (6).

8. The ducted fan unit according to claim 5, wherein: The skin limiting point (8) cooperates with the control element, and in the maximum cross section (10a) of the central cone (10), the skin limiting point (8) moves along a predetermined direction relative to the control element by means of rotation or translation.

9. The ducted fan unit according to any one of claims 1 to 8, wherein: The central cone (10) is also provided with at least one set of control systems upstream of its largest cross section (10a) for switching other cross sections (10b) of the central cone (10) between an original configuration and an expanded configuration.

10. A wing assembly, comprising a wing (1) and a ducted fan unit according to any one of claims 1 to 9, wherein the ducted fan unit is arranged above the wing (1).

11. An aircraft equipped with a wing assembly according to claim 10.

Images