Micro-hole array based ducted passive air-breathing structure and aircraft

Abstract

This invention provides a ducted passive air bleed structure and aircraft based on a micro-pore array, relating to the field of aircraft technology. The ducted passive air bleed structure includes a duct body and a downstream nozzle section; an air bleed channel is provided within the duct wall, connecting an array of inlet micro-pores at the lip to an array of outlet micro-pores offset towards the inner side of the nozzle in the nozzle junction area. This structure is purely passive, with no moving parts and zero power consumption, relying on the natural airflow redistribution driven by the pressure difference inside and outside the duct under flight conditions: during hovering / takeoff, it enhances lip suction to suppress backflow and separation; during cruise, it improves boundary layer control and jet mixing inside the nozzle, enhancing thrust vector efficiency and total pressure recovery. The micro-pore array design significantly enhances pressure difference response sensitivity, stress dispersion, acoustic vibration suppression, and improves tolerance tolerance and mass production consistency; the fully rigid structure completely avoids jamming risks, significantly improving long-term reliability and flight safety margins, and achieving a balanced optimization between propulsion efficiency, aerodynamic stability, lightweight design, and operational economy.

Description

Technical Field

[0001] This invention relates to the field of aircraft technology, and in particular to a ducted passive air intake structure based on a micro-pore array and an aircraft thereof. Background Technology

[0002] In existing technologies, to adapt to the differentiated requirements of duct exhaust area for various operating conditions (hovering / takeoff / climb / cruise) of VTOL aircraft, mainstream area adjustment schemes rely on active actuators (such as hydraulic / electric adjustment valves, sliding sleeves) or passive structures with movable parts (such as elastic lips, pressure-driven flaps). This leads to fundamental contradictions such as high structural complexity, large system weight, non-negligible power consumption, high maintenance costs, easy wear and jamming of moving parts, poor mass production consistency, and insufficient flight safety redundancy. On the other hand, if a purely passive bleed air scheme only uses conventional through holes, it is prone to problems such as backflow of external duct airflow, aggravated local flow separation at the lip, uncontrollable bleed air direction and flow rate, and low effective bleed air efficiency under low-speed conditions. This results in deterioration of intake stability, a decrease in propulsion efficiency instead of an increase, and even induces unsteady aerodynamic loads, making it impossible to achieve true condition-adaptive exhaust area adjustment. Summary of the Invention

[0003] The purpose of this invention is to provide a ducted passive air intake structure and aircraft based on a micro-pore array, which achieves adaptive duct exhaust area under various operating conditions without introducing any moving parts or increasing energy consumption and complexity, so as to balance propulsion efficiency, aerodynamic stability and structural reliability under multiple operating conditions such as takeoff / hovering and cruise.

[0004] In a first aspect, the duct passive air intake structure based on micropore array provided by the present invention includes: a duct body surrounding and forming a duct cavity, and a nozzle section disposed at the downstream end of the duct body; The duct body has an air intake channel in its wall, which extends from the air intake inlet located at the lip of the duct body to the air intake outlet located in the area where the duct body connects with the nozzle and is biased towards the inside of the nozzle of the nozzle. The air intake is configured with multiple inlet micropores arranged in an array, and the air outlet is configured with multiple outlet micropores arranged in an array.

[0005] In conjunction with the first aspect, the present invention provides a first possible implementation of the first aspect, wherein the inlet micro-orifice extends axially from the leading edge surface of the lip of the duct body along the duct body and communicates with the air intake channel.

[0006] In conjunction with the first possible implementation of the first aspect, the present invention provides a second possible implementation of the first aspect, wherein the inlet micro-orifice is located at the orifice edge of the leading edge surface of the duct body lip and has a chamfer.

[0007] In conjunction with the first aspect, the present invention provides a third possible implementation of the first aspect, wherein the inlet micropores and / or the outlet micropores have gradually narrowed diameters along the airflow direction.

[0008] In conjunction with the first aspect, the present invention provides a fourth possible implementation of the first aspect, wherein the air intake channel extends along the axial direction of the duct body, and multiple air intake channels are provided; Multiple air intake channels are arranged at circumferential intervals along the duct body.

[0009] In conjunction with the first aspect, the present invention provides a fifth possible implementation of the first aspect, wherein the air intake channel includes a straight extension section extending downstream from the air intake inlet and parallel to the axis of the duct body, and an inclined section extending from the straight extension section to the air intake outlet and inclined toward the axis of the nozzle section.

[0010] In conjunction with the fifth possible implementation of the first aspect, the present invention provides a sixth possible implementation of the first aspect, wherein the inclined section gradually narrows in diameter along the airflow direction.

[0011] In conjunction with the first aspect, the present invention provides a seventh possible implementation of the first aspect, wherein the apertures of the plurality of inlet micropores and the plurality of outlet micropores are respectively configured to be from 0.5 mm to 3 mm.

[0012] In conjunction with the first aspect, the present invention provides an eighth possible implementation of the first aspect, wherein the interior of the wall of the duct body is hollow, and a support beam is connected between the side wall of the air intake channel and the wall of the duct body.

[0013] Secondly, the aircraft provided by the present invention is equipped with the ducted passive air bleed structure described in the first aspect.

[0014] The embodiments of this invention bring the following beneficial effects: By setting an array of inlet micropores at the lip of the duct body and arranging an array of outlet micropores biased towards the inside of the nozzle in the duct-nozzle connection area, combined with the air intake channel set in the wall, a purely passive, non-moving, zero-power airflow redistribution mechanism is constructed. Without introducing hydraulic or electric actuation mechanisms or elastic movable structures, the natural changes in the pressure difference inside and outside the duct under different flight conditions are utilized—for example, the negative pressure outside the lip is significant during hovering or takeoff, and the static pressure downstream of the nozzle decreases and the velocity gradient increases during cruise. This drives the airflow to be autonomously and directionally drawn out from the lip region (high pressure / high energy region) through the micropore array and injected into the inner boundary layer of the nozzle along a preset path, thereby dynamically adjusting the equivalent exhaust area and outflow angle distribution: enhancing the lip suction effect under low-speed conditions and suppressing backflow and flow separation; strengthening the inner boundary layer control and jet mixing under high-speed conditions, improving thrust vector efficiency and total pressure recovery. This enables adaptive and coordinated control of exhaust area and bleed air behavior under multiple operating conditions, breaking through the fundamental trade-off between structural complexity, weight, reliability and adaptive capability in traditional active or passive bleed air schemes.

[0015] The use of a micro-pore array design (rather than a single large through-hole) gives this structure multiple engineering advantages: on the one hand, the micro-pore size (typically on the millimeter scale) significantly improves the Reynolds number sensitivity and differential pressure response sensitivity of local flow, making bleed air start-up and shutdown smoother and flow rate more controllable; on the other hand, the array layout effectively disperses stress concentration, suppresses acoustic resonance, and greatly improves manufacturing tolerances and mass production consistency; in addition, the all-rigid structure with no wear parts completely avoids moving part jamming, sealing failure, and redundant design burden, significantly improving the long-term service reliability and flight safety margin of the system, and achieving a balanced improvement in propulsion efficiency, aerodynamic stability, lightweighting, and maintenance economy.

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a cross-sectional view of the passive air duct structure provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a duct passive air intake structure provided in an embodiment of the present invention.

[0019] Icons: 1-Duct body; 2-Nozzle section; 3-Air intake channel; 31-Straight extension section; 32-Inclined section; 4-Air intake outlet; 5-Duct lip; 6-Air intake inlet; 7-Inlet micro-orifice; 8-Support beam; 9-Power shaft; 10-Blade; 11-Outlet micro-orifice. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used only to describe differences in name and should not be construed as indicating or implying relative importance. Physical quantities in formulas, unless otherwise specified, should be understood as basic quantities in the International System of Units (SI), or derived quantities derived from basic quantities through mathematical operations such as multiplication, division, differentiation, or integration.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] like Figure 1 and Figure 2As shown, the duct passive air intake structure based on a micropore array provided in this embodiment of the invention includes: a duct body 1, which encloses a duct cavity through which the main airflow passes, and the upstream end of the duct body 1 has a duct lip with a forward / backward or symmetrical curvature design; a nozzle 2, which is fixedly connected to the downstream end of the duct body 1 and extends axially, with its nozzle facing the rear of the aircraft, for discharging the airflow and air intake mixing flow inside the duct; and an air intake channel 3, which is located inside the wall of the duct body 1 and is a through-type hollow channel, with one end being an air intake inlet 6 located on the leading edge surface of the lip of the duct body 1; and the other end being an air intake outlet 4. Located in the junction area between the duct body 1 and the nozzle section 2, and biased towards the inner side of the nozzle section 2 (i.e., closer to the nozzle axis, rather than the outer wall surface), so that the air jet can cut into the inner boundary layer of the nozzle and enhance momentum mixing; the inlet micro-hole 7 is a plurality of through holes distributed in an array, opened on the leading edge surface of the lip of the duct body 1, and connected to the air inlet 6; each inlet micro-hole 7 extends inward along the axial direction of the duct body 1 and eventually merges into the air intake channel 3; the outlet micro-hole 11 is a plurality of through holes distributed in an array, opened on the inner surface of the junction area between the duct body 1 and the nozzle section 2, and connected to the air intake outlet 4.

[0024] During cruise (e.g., flight altitude 10km, Mach number 0.8): the total pressure at the duct inlet is approximately 60kPa, and the static pressure outside the nozzle is approximately 30kPa, creating a positive pressure difference of approximately 30kPa. This pressure difference drives the airflow at the duct lip 5 through the inlet micro-orifice 7, the bleed air passage 3, and the outlet micro-orifice 11 into the inner region of the nozzle section 2. The exhaust flow rate of the nozzle section 2 is reduced by approximately 8% compared to when there is no bleed air passage 3, effectively reducing the exhaust area of ​​the nozzle by approximately 8%. CFD simulations show that this adjustment improves cruise propulsion efficiency by 12%.

[0025] During takeoff or hovering (such as at high angle of attack during takeoff): the pressure difference between the inside and outside of the duct body 1 is less than 100 Pa, and there is no significant flow in the micropores (inlet micropore 7 and outlet micropore 11); CFD simulation results show that the intake distortion index variable is small and has no significant impact on the inlet airflow quality of the duct.

[0026] Furthermore, the inlet micro-orifice 7 extends axially from the leading edge surface of the lip of the duct body 1 and communicates with the air intake channel 3. Specifically, the inlet micro-orifice 7 starts from the leading edge surface of the lip of the duct body 1 and extends inward along the axial direction of the duct body 1 (i.e., perpendicular to the lip tangent plane, pointing towards the inner side of the duct cavity), with its axis nearly parallel to the central axis of the duct body 1. This axial arrangement avoids the weakening of the lip structure and stress concentration caused by oblique perforations, while ensuring that the momentum direction of the airflow entering the air intake channel 3 is consistent with the mainstream, reducing local disturbances.

[0027] Furthermore, the inlet micro-orifice 7 has a chamfer (rounded or beveled) at the edge of the orifice on the leading edge surface of the duct body 1 lip, with a rounded radius ≥ 0.2 mm. This reduces the risk of flow separation, lowers the sensitivity to local adverse pressure gradients caused by the inlet micro-orifice 7 under low-speed conditions, effectively suppresses the development of secondary separation vortices at the edge of the inlet micro-orifice 7, and ensures intake stability. The chamfering is performed using laser finishing or micro-abrasive blasting to ensure geometric consistency at the edge.

[0028] Furthermore, the inlet micro-orifice 7 and / or the outlet micro-orifice 11 have a gradually decreasing diameter along the airflow direction. Specifically, either the inlet micro-orifice 7 or the outlet micro-orifice 11 has a gradually decreasing diameter along the airflow direction, or both the inlet micro-orifice 7 and the outlet micro-orifice 11 have a gradually decreasing diameter along the airflow direction. This gradually decreasing design utilizes the Venturi effect to enhance local flow velocity and improve pressure differential driving efficiency. More importantly, under reverse flow conditions, the decreasing section creates a sudden change in flow resistance, increasing the critical Reynolds number for reverse flow by more than 30%, significantly suppressing unfavorable backflow during takeoff / hovering.

[0029] In this embodiment, the air intake channel 3 extends along the axial direction of the duct body 1, and multiple air intake channels 3 are provided; the multiple air intake channels 3 are arranged at intervals along the circumference of the duct body 1. The layout of multiple air intake channels 3 takes into account both the uniformity of air intake coverage and the redundancy of structural stiffness: on the one hand, it avoids the local thermal stress concentration and acoustic mode coupling caused by a single large channel; on the other hand, when a certain air intake channel 3 fails due to blockage by foreign objects or microcracks, the remaining air intake channels 3 can still maintain the air intake capacity.

[0030] In an optional embodiment, the bleed air channel 3 includes a straight extension section 31 extending downstream from the bleed air inlet 6 and parallel to the axis of the duct body 1, and an inclined section 32 extending from the straight extension section 31 to the bleed air outlet 4 and inclined towards the axis of the nozzle section 2. This segmented structure allows the bleed airflow to be directionally adjusted before entering the nozzle section 2, ensuring that the jet axis forms an angle (approximately 5° to 20°) with the main jet flow. This avoids energy loss caused by forward impact and prevents excessive deflection from causing jet stripping, which is beneficial for improving the thrust vector adjustment sensitivity.

[0031] Furthermore, the diameter of the inclined section 32 gradually decreases along the airflow direction, which can significantly enhance the penetration depth and mixing intensity of the air jet; at the same time, the radial pressure gradient generated by the tapered section can suppress boundary layer separation.

[0032] In an optional embodiment, the apertures of the plurality of inlet micropores 7 and the plurality of outlet micropores 11 are configured to be from 0.5 mm to 3 mm. The apertures of the inlet micropores 7 and the outlet micropores 11 can be independently configured to 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm or 3.0 mm, etc., and multiple apertures of inlet micropores 7 and outlet micropores 11 can be configured for the same air intake channel 3. In addition, the plurality of inlet micropores 7 and the plurality of outlet micropores 11 can be arranged in a non-uniform distribution to adapt to different incoming flow conditions.

[0033] Based on any of the aforementioned embodiments, the duct body 1 has a hollow interior wall, and a support beam 8 connects the side wall of the air intake channel 3 to the wall of the duct body 1. The wall of the duct body 1 is a hollow sandwich structure, with the support beam 8 positioned between its inner and outer walls. The support beam 8 is integrally formed or welded to the side wall of the air intake channel 3. This structure ensures the bending stiffness of the air intake channel 3 while limiting the thermal deformation deflection of the micropore array region, preventing pressure difference response drift caused by micropore misalignment under high-temperature conditions, and meeting the service stability requirements across the entire operating temperature range.

[0034] The aircraft provided in this embodiment of the invention is equipped with the ducted passive air intake structure described in the above embodiments. This aircraft can be a tiltrotor aircraft, a compound-wing unmanned aerial vehicle, or an eVTOL urban air transport vehicle. The ducted passive air intake structure is integrated into the main propulsion duct or lift duct. The duct body 1 surrounds the outside of the rotor blade 10 and is driven by the power shaft 9 to generate propulsive airflow. This aircraft possesses the technical advantages of the aforementioned ducted passive air intake structure, which will not be elaborated further here.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ducted passive air intake structure based on a micropore array, characterized in that, include: The duct body (1) that forms the duct cavity, and the nozzle section (2) located at the downstream end of the duct body (1). The duct body (1) has an air intake channel (3) in its wall. The air intake channel (3) extends from the air intake inlet (6) located at the lip of the duct body (1) to the air intake outlet (4) located in the area where the duct body (1) connects with the nozzle section (2) and is biased towards the inside of the nozzle of the nozzle section (2). The air intake (6) is provided with a plurality of inlet micropores (7) arranged in an array, and the air outlet (4) is provided with a plurality of outlet micropores (11) arranged in an array.

2. The ducted passive air intake structure based on a micropore array according to claim 1, characterized in that, The inlet micro-hole (7) extends from the leading edge surface of the lip of the duct body (1) along the axial direction of the duct body (1) and communicates with the air intake channel (3).

3. The ducted passive air intake structure based on a micropore array according to claim 2, characterized in that, The inlet micro-hole (7) is located on the lip front edge surface of the duct body (1) and has a chamfered edge.

4. The ducted passive air intake structure based on a micropore array according to any one of claims 1 to 3, characterized in that, The inlet micropore (7) and / or the outlet micropore (11) have gradually reduced diameters along the airflow direction.

5. The ducted passive air intake structure based on a micropore array according to claim 1, characterized in that, The air intake channel (3) extends along the axial direction of the duct body (1), and multiple air intake channels (3) are provided; Multiple air intake channels (3) are arranged at circumferential intervals along the duct body (1).

6. The ducted passive air intake structure based on a micropore array according to claim 1, characterized in that, The air intake channel (3) includes a straight extension section (31) extending downstream from the air intake inlet (6) and parallel to the axis of the duct body (1), and an inclined section (32) extending from the straight extension section (31) to the air intake outlet (4) and inclined toward the axis of the nozzle section (2).

7. The ducted passive air intake structure based on a micropore array according to claim 6, characterized in that, The inclined section (32) gradually narrows in diameter along the airflow direction.

8. The ducted passive air intake structure based on a micropore array according to claim 1, characterized in that, The apertures of the plurality of inlet micropores (7) and the plurality of outlet micropores (11) are respectively configured to be from 0.5 mm to 3 mm.

9. The ducted passive air intake structure based on a micropore array according to claim 1, characterized in that, The duct body (1) has a hollow interior wall, and a support beam (8) connects the side wall of the air intake channel (3) to the wall of the duct body (1).

10. An aircraft, characterized in that, The aircraft is equipped with a ducted passive air bleed structure as described in any one of claims 1 to 9.

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