Axisymmetric air intake and low-energy fluid control method

Abstract

The present invention relates to an axisymmetric air inlet and a low-energy fluid control method, which belongs to the field of aircraft technology. The axisymmetric air inlet includes a hollow two-stage central cone, a diffuser section connected thereto, and a lip cover arranged on its periphery. The two-stage central cone is axially divided into a first-stage central cone and a second-stage central cone. The first-stage central cone is the head of the central cone, and the end of its inner cone surface extends a lap joint in the direction of the generatrix. A discharge groove is circumferentially provided on the lap joint. The second-stage central cone is a conical sleeve, and its small-diameter end is sealably connected to the end of the first-stage central cone, and its large-diameter end is connected to the diffuser section. The diffuser section is controlled by a drive assembly and can expand radially outward, while driving the second-stage central cone to slide along the generatrix of the lap joint surface to complete the on-off control of the discharge groove. The present invention can improve the internal flow field of a wide-speed air inlet and timely control the low-energy fluid generated in the air inlet due to the mutual interference of shock wave boundary layers.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft, and in particular relates to an axisymmetric air inlet and a low-energy fluid control method. Background Art

[0002] For supersonic inlets flying in large airspaces and wide speed ranges, the difficulty in designing the inlet lies in taking into account both the performance at low altitude and low speed and the performance at high altitude and high speed. At low altitudes and low speeds, the inlet's overall contraction ratio is typically designed to be small, and the throat area to be large to meet high flow demands. At high altitudes and high speeds, to maximize engine thrust performance, the inlet's compression efficiency needs to be improved, requiring a smaller throat area. This contradiction becomes more pronounced as the inlet's operating range widens. Conventional fixed geometry inlets typically employ a compromise design approach, resulting in a decrease in overall inlet performance. Managing this contradiction is a pressing issue for achieving inlet operation over a wide Mach number range. Furthermore, the bleeder slot is an integral component of a wide-speed inlet. During supersonic flight, high backpressure can cause inlet actuation failures. This is primarily due to the interaction of the rapidly developing boundary layer with shock waves, which cause the shock wave to enter the inlet's contraction section, leading to flow separation, blockage, and reduced flow capture. This leads to instability in the inlet flow field and the resulting actuation failure. In other words, the rapid development of the boundary layer is a key factor in inlet actuation failures.

[0003] Existing methods for adjusting the throat area include using a movable center body to move axially to change the turbine duct opening; using protrusions on a memory alloy plate to change the throat height; using a drive to control the movement of a throttle cone along the incoming flow direction to change the throat cross-section; and using a movable throat plate to adjust the incoming flow in the intake duct. These technologies only disclose methods for adjusting the throat area or height, but fail to extract the rapidly developing boundary layer from the intake duct. This increases the interaction between the boundary layer and shock waves, affecting the intake duct's ability to withstand backpressure. Therefore, how to design a system that can both change the intake duct's contraction ratio and enable the opening and closing of the discharge duct in different speed ranges while meeting the overall engine performance requirements has become a major concern for researchers. Summary of the Invention

[0004] Technical issues to be solved:

[0005] In order to avoid the shortcomings of the existing technology, the present invention provides an axisymmetric air inlet and a low-energy fluid control method. The air inlet adopts a center cone with a split sealing structure, combined with the characteristics of the controllable axial linear motion of the second-stage center cone, which can meet the throat area requirements of the wide-speed range air inlet; and the discharge groove is coupled to the split center cone. While adjusting the throat area, the "opening" and "closing" of the discharge groove can be controlled to meet the large flow requirements of the engine under low inflow Mach number and to achieve the discharge of low-energy fluid in the air inlet under high inflow Mach number; the present invention can improve the internal flow field of the wide-speed range air inlet, timely control the low-energy fluid generated in the air inlet due to the mutual interference of the shock wave boundary layer, and improve the total pressure recovery coefficient of the air inlet, laying a technical foundation for the engineering application of the wide-speed range air inlet and even the development of advanced aircraft.

[0006] The technical solution of the present invention is: an axisymmetric air inlet, comprising a hollow two-stage central cone, a diffuser section connected thereto, and a lip cover arranged on the periphery thereof;

[0007] The two-stage center cone is divided into a first-stage center cone and a second-stage center cone along the axial direction; the first-stage center cone is the head of the center cone, and the end of its inner cone surface extends into a lap joint along the generatrix direction; a discharge groove is opened along the circumferential direction of the lap joint; the second-stage center cone is a conical sleeve, the small-diameter end of which is sealably connected to the end of the first-stage center cone, and the large-diameter end is connected to the diffuser section;

[0008] The diffuser section is controlled by a driving assembly and can expand radially outward, while driving the second-stage center cone to slide along the generatrix direction of the overlap surface to complete the on-off control of the discharge groove.

[0009] A further technical solution of the present invention is: a sealing ring is provided on the inner conical surface of the second-stage center cone, which is used for sealing the connection between the small diameter end of the second-stage center cone and the overlapping surface of the first-stage center cone; when the small diameter end of the second-stage center cone is in contact with the end of the first-stage center cone, the leakage groove on the overlapping surface is closed by the sealing ring; when the second-stage center cone slides along the overlapping surface toward the lip cover, the leakage groove on the overlapping surface is exposed, that is, the leakage groove is opened, and the sealing ring is sealed and connected to the outer edge of the overlapping surface.

[0010] A further technical solution of the present invention is: the second-stage central cone and the diffuser section are coaxially fixedly connected, and both are made of memory alloy; in the heated state, the diffuser section is expanded radially outward by the outward expansion force of the driving component, while driving the large diameter end of the second-stage central cone to expand, thereby changing the throat height.

[0011] A further technical solution of the present invention is that the drain grooves are two semicircular ring grooves symmetrically arranged on the overlapping surface, or a plurality of through holes evenly distributed along the circumference of the overlapping surface.

[0012] A further technical solution of the present invention is that the distance between the lip mask and the large-diameter end of the second-stage central cone, that is, the height H of the throat th , is determined by the flight altitude and flight Mach number during aircraft cruise; the area calculation formula of the throat is as follows:

[0013]

[0014] where A0 is the capture area of the inlet, σ is the total pressure recovery coefficient of the inlet after the oblique shock wave, q(λ0) and q(λ th ) are solved according to the incoming flow Mach number; the throat height of the inlet can be calculated from the calculated throat area.

[0015] A further technical solution of the present invention is that when the incoming flow Mach number 0 < Ma < 2.0, the half-cone angle α of the first-stage central cone is 10°.

[0016] A further technical solution of the present invention is that the thickness of the sealing ring is less than the thickness of the inclined plate of the second-stage central cone, so that the influence of adding the sealing ring on the flow field can be ignored.

[0017] A further technical solution of the present invention is that the sealing ring is made of an elastic material. To ensure the sealing performance of the second-stage central cone during movement, the diameter d1 of the sealing ring ≥ the inner diameter d2 of the overlapping surface of the first-stage central cone; the compression amount of the sealing ring in the initial state is Δl, and Δl increases during movement, ensuring the sealing performance during movement.

[0018] A further technical solution of the present invention is that the drive assembly includes a first connecting rod, a second connecting rod and a driver; the first connecting rod is arranged along the axial direction of the diffuser section, its inner end is connected to the driver, and its outer end is circumferentially hinged to one end of a plurality of second connecting rods, and the other ends of the plurality of second connecting rods are respectively circumferentially hinged to the inner wall of the diffuser section; by controlling the first connecting rod to linearly move along the axial direction of the diffuser by the driver, while带动多个第二连杆的一端沿扩压器轴向运动,进而对扩压器壁面施加拉力或压力。

[0019] A low-energy fluid control method for an axisymmetric inlet is as follows:

[0020] When the incoming flow Mach number increases, the drive assembly带动扩压段沿径向外扩,同时带动第二级中心锥、密封圈沿第一级中心锥搭接面的母线向外移动,随着第二级中心锥的移动,喉道面积减小,泄流槽由“关闭”状态变为“打开”状态;

[0021] When the incoming flow Mach number decreases, the drive assembly drives the diffuser section to converge radially, and at the same time drives the second-stage center cone and the sealing ring to move inward along the generatrix of the overlap surface of the first-stage center cone. As the second-stage center cone moves, the throat area increases, and the discharge groove changes from an "open" state to a "closed" state.

[0022] Beneficial effects

[0023] The beneficial effects of the present invention are as follows: the axisymmetric air inlet with adjustable throat area provided by the present invention changes the throat area by adjusting the position of the second-stage central cone to meet the performance requirements of the air inlet at different Mach numbers. At low incoming flow Mach numbers, the flow demand of the engine is large. If a leakage groove is added at this time, part of the fluid will flow out and the flow demand will not be met. At this time, the leakage groove is closed by moving the second-stage central cone toward the direction of the first-stage central cone; at high incoming flow Mach numbers, the flow demand of the engine is small, and low-energy fluid will be generated in the air inlet due to mutual interference of shock wave boundary layers under high back pressure. At this time, the leakage groove is opened by moving the second-stage central cone away from the first-stage central cone.

[0024] The second-stage center cone and the diffuser section of the present invention both use memory alloys. The phase transition temperature of conventional memory alloys is below 150°C, which falls within the range of low-temperature shape memory alloys. The flight conditions of the air inlet of the present invention are 0-11 km, Ma is 0-2, and the temperature is below 117°C, which meets the deformation range of the memory alloy.

[0025] When the incoming flow Mach number is greater than the design point Mach number, the inlet outlet must meet the subsonic condition. At this time, back pressure must be applied at the inlet outlet. As the back pressure is applied, low-energy fluid will be generated in the inlet, causing the inlet's ability to resist back pressure to be insufficient, and ultimately leading to the inlet's inability to start normally. The drain groove can promptly discharge the low-energy fluid in the inlet, thereby increasing the inlet's ability to resist back pressure and improving the inlet's aerodynamic performance. Figure 1 The figure shows a performance comparison between a supersonic inlet with and without drain grooves. As can be seen from the figure, the addition of drain grooves can promptly discharge low-energy fluid from the inlet, improving the inlet's backpressure resistance and total pressure recovery coefficient. Table 1 shows the aerodynamic performance of the inlet with and without drain grooves.

[0026] Table 1 Aerodynamic performance with / without discharge groove

[0027] With / without drain trough Ma Pressure ratio Total pressure recovery coefficient none 1.8 4.45 Bow shock launch have 1.8 4.45 95.38％ BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Comparison of the aerodynamic performance of the Ma1.8 inlet; (a) Ma1.8 with a pressure ratio of 4.45 and no bleeder slots, (b) Ma1.8 with a pressure ratio of 4.45 and with bleeder slots;

[0029] Figure 2 It is an axisymmetric inlet with adjustable throat area and discharge slots at low inflow Mach numbers.

[0030] Figure 3 It is an axisymmetric inlet with adjustable throat area and discharge slots at high inflow Mach numbers.

[0031] Explanation of the reference numerals: 1. First-stage center cone; 2. Second-stage center cone; 3. Sealing ring; 4. Axially symmetrical inlet diffuser section; 5. Discharge groove; 6. Lip cover; 7. Connecting rod; 8. Hinge; 9. Driver. DETAILED DESCRIPTION

[0032] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0034] In view of the problem that the existing technology cannot extract the rapidly developing boundary layer out of the air inlet, thereby increasing the interaction between the boundary layer and the shock wave and affecting the anti-backpressure capability of the air inlet, the present invention designs an axisymmetric air inlet, which adopts a center cone with a split sealing structure, combined with the controllable axial linear motion characteristics of the second-stage center cone, and can meet the throat area requirements of the air inlet in a wide speed range; and couples the discharge groove to the split center cone, and while adjusting the throat area, it can control the "opening" and "closing" of the discharge groove to meet the large flow requirement of the engine under low inflow Mach number and realize the discharge of low-energy fluid in the air inlet under high inflow Mach number.

[0035] In this embodiment, an axisymmetric air inlet duct includes a hollow two-stage central cone, a diffuser section connected thereto, and a lip cover arranged on the periphery thereof; the two-stage central cone is divided into a first-stage central cone and a second-stage central cone along the axial direction; the first-stage central cone is the head of the central cone, and the end of its inner cone surface extends a lap surface along the busbar direction; a leakage groove is circumferentially opened on the lap surface; the second-stage central cone is a conical sleeve, the small-diameter end of which is sealably connected to the end of the first-stage central cone, and the large-diameter end is connected to the diffuser section; the diffuser section is controlled by a drive assembly and can expand radially outward, while driving the second-stage central cone to slide along the busbar direction of the lap surface to complete the on-off control of the leakage groove.

[0036] The inner conical surface of the second-stage center cone is provided with a sealing ring for sealing the connection between the smaller diameter end of the second-stage center cone and the lap joint surface of the first-stage center cone. When the smaller diameter end of the second-stage center cone is in contact with the end of the first-stage center cone, the sealing ring closes the drainage groove on the lap joint surface. When the second-stage center cone slides along the lap joint surface toward the lip shield, the drainage groove on the lap joint surface is exposed, i.e., the drainage groove is opened, and the sealing ring is sealed to the outer edge of the lap joint surface. The drainage groove is symmetrically arranged on the lap joint surface, or a plurality of through holes evenly distributed along the circumference of the lap joint surface.

[0037] The second-stage center cone and the diffuser section are coaxially fixedly connected, and both are made of memory alloy; when heated, the outward expansion force of the driving component causes the diffuser section to expand radially outward, while driving the large diameter end of the second-stage center cone to expand, thereby changing the throat height.

[0038] The drive assembly includes a first connecting rod, a second connecting rod and a driver; the first connecting rod is arranged along the axial direction of the diffuser section, the inner end of the first connecting rod is connected to the driver, and the outer end of the first connecting rod is hinged to one end of multiple second connecting rods along the circumferential direction, and the other ends of the multiple second connecting rods are respectively hinged to the inner wall of the diffuser section along the circumferential direction; the driver controls the first connecting rod to move linearly along the axial direction of the diffuser, and at the same time drives one end of the multiple second connecting rods to move along the axial direction of the diffuser, thereby applying tension or pressure to the diffuser wall.

[0039] Preferably, an arc-shaped plate is provided at the hinge of the inner wall of the diffuser section, which converts the force point applied by the second connecting rod into a force surface, so that the diffuser section is evenly stressed. The pressure of the second connecting rod enables the diffuser section to expand evenly in the circumferential direction, and the tension of the second connecting rod can suppress the outward expansion of the diffuser section in the circumferential direction.

[0040] The present invention can improve the internal flow field of the wide-speed range air inlet, timely control the low-energy fluid generated in the air inlet due to the mutual interference of the shock wave boundary layer, and improve the total pressure recovery coefficient of the air inlet, laying a technical foundation for the engineering application of the wide-speed range air inlet and even the development of advanced aircraft.

[0041] Example:

[0042] like Figure 2 As shown, the present invention provides an axisymmetric air inlet with an adjustable throat area and a drain groove, comprising a first-stage central cone 1, a second-stage central cone 2, a sealing ring 3, an axisymmetric air inlet diffuser 4, a drain groove 5, a lip cover 6, a connecting rod 7, a hinge 8, and a driver 9. The connecting rod 7 includes a first connecting rod and a second connecting rod. The second-stage central cone 2 is fixedly connected to the diffuser 4, the second-stage central cone 3 is fixedly connected to the sealing ring 3, and the driver 9 is fixedly connected to the first connecting rod and located inside the central cone. The driver 9 controls the convergence and expansion of the diffuser 4, driving the second-stage central cone 2 and the sealing ring 3 to move along the direction of the first-stage central cone. In this process, the requirements for high flow rate at low inflow Mach numbers and high contraction ratio and high performance at high inflow Mach numbers are met, and the air inlet maintains high aerodynamic performance over a wide speed range.

[0043] Preferably, the thickness of the sealing ring 3 is less than the thickness of the second-stage central cone inclined plate, so that the effect of the addition of the sealing ring on the flow field can be ignored.

[0044] Preferably, the sealing ring 3 is made of an elastic material. To ensure the sealing performance of the center cone during movement, the diameter of the sealing ring d1 is greater than the inner diameter d2 of the first-stage center cone. The sealing ring is compressed by Δl in its initial state, and Δl increases during movement, ensuring the sealing performance during movement.

[0045] Preferably, the second-stage center cone and the diffuser section are fixedly connected, and the materials of both are memory alloys. Generally speaking, the phase change temperature of conventional memory alloys is below 150°C, which belongs to the range of low-temperature shape memory alloys. The flight conditions of the air inlet of the present invention are 0-11 km, Ma is 0-2, and the temperature is below 117°C, which meets the deformation range of the memory alloy.

[0046] The length of the second-stage central cone 2 is determined by the throat height H th To determine the throat height H th The throat height H is determined by the flight altitude and flight Mach number of the aircraft during cruising. th , the throat height is based on the flow conservation formula:

[0047]

[0048] Where: K is a constant, P * is the total pressure, T * is the total temperature, A0 is the capture area of ​​the inlet duct, A th is the inlet throat area, q(λ) is the flow function, and σ is the total pressure recovery coefficient after the inlet passes through the oblique shock wave.

[0049] Eliminate the same physical quantities on both sides, then:

[0050]

[0051] Where A0 is the capture area of ​​the inlet, σ is the total pressure recovery coefficient of the inlet after the oblique shock wave, q(λ0) and q(λ th ) According to the incoming flow Mach number, the throat area of ​​the inlet can be obtained, and then the throat height of the inlet can be obtained.

[0052] The axisymmetric air inlet with adjustable throat area and drain groove has the following structures: the first-stage central cone, the second-stage central cone, the sealing ring, the diffuser section, and the drain groove. Figure 2 As shown, the angle between the first-stage center cone and the horizontal plane is α. Under the design point Mach number, through the shock wave sealing principle and the throat height H th The starting position of the lip mask can be obtained.

[0053] A low-energy fluid control method for an axisymmetric intake duct in this embodiment is as follows:

[0054] When the incoming Mach number is low (Ma<1.2), the inlet requires a smaller contraction ratio. At this time, the throat height H th At its maximum value, under high back pressure conditions, the shock wave / boundary layer interference at low Mach numbers is relatively weak, and the small diameter end of the second-stage center cone fits closely with the end of the first-stage center cone. At this time, the discharge slot is in the "closed" state;

[0055] As the incoming flow Mach number increases, in order to fully utilize the thrust performance of the engine, it is necessary to improve the compression efficiency of the inlet duct. The required throat area is usually smaller. At this time, the driver 9 is controlled to drive the diffuser section 4 to expand radially outward, while driving the second-stage center cone 2 and the sealing ring 3 to move outward along the generatrix of the overlap surface of the first-stage center cone 1. As the second-stage center cone moves, the sealing ring 3 is always in a compressed state, ensuring the sealing performance inside the inlet duct, and the angle γ between the connecting rods increases. In the process of adjusting the actuating mechanism, the throat height of the inlet duct is reduced (such as Figure 3 (as shown), meeting the demand for a large contraction ratio. Furthermore, due to the increase in the incoming Mach number, under high backpressure conditions, shock wave / boundary layer interference becomes severe, resulting in a large amount of low-energy fluid within the inlet duct. During the adjustment process, the drain groove 3 changes from a "closed" state to an "open" state, enabling the timely discharge of low-energy fluid within the inlet duct, preventing the inlet duct from stalling and effectively buffering aerodynamic heat. Through the adjustment of the adjustable mechanism, the inlet duct can meet the intake requirements at different Mach numbers. Under high backpressure conditions, it can discharge low-energy fluid generated by the mutual interference of shock wave and boundary layers, significantly improving the aerodynamic performance of the inlet duct and the overall performance of the engine.

[0056] Specifically, the axisymmetric inlet with adjustable throat area and drain groove is an inlet with an adjustment mechanism added to the traditional non-adjustable axisymmetric inlet, which is easy to design. By controlling the driver, it not only meets the throat area requirements of the inlet under wide-speed flight range, but also solves the problem of low-energy fluid in the inlet under high back pressure conditions, greatly improves the total pressure recovery coefficient of the inlet, and better meets the overall performance requirements of the engine.

[0057] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. An axisymmetric air intake duct, characterized in that: It includes a hollow two-stage central cone, a diffuser section connected thereto, and a lip shroud disposed around it; The two-stage central cone is axially divided into a first-stage central cone and a second-stage central cone; the first-stage central cone is the head of the central cone, and a lapping surface extends along the generatrix direction at the end of its inner conical surface. Drainage grooves are circumferentially formed on the lapping surface; the second-stage central cone is a conical sleeve, the small-diameter end of which is hermetically connected to the end of the first-stage central cone, and the large-diameter end is connected to the diffuser section; The diffuser section is controlled by a driving component and can expand radially outward, and at the same time带动 the second-stage central cone to slide along the generatrix direction of the lapping surface to complete the on-off control of the drainage groove.

2. The axisymmetric air intake duct according to claim 1, characterized in that: A sealing ring is provided on the inner conical surface of the second-stage central cone for the sealing connection between the small-diameter end of the second-stage central cone and the lapping surface of the first-stage central cone; when the small-diameter end of the second-stage central cone fits with the end of the first-stage central cone, the drainage groove on the lapping surface is closed by the sealing ring; when the second-stage central cone slides along the lapping surface towards the lip shroud, the drainage groove on the lapping surface is exposed, that is, the drainage groove is opened, and the sealing ring is hermetically connected to the outer edge of the lapping surface.

3. The axisymmetric air intake duct according to claim 2, characterized in that: The thickness of the sealing ring is less than the thickness of the inclined plate of the second-stage central cone, so that the influence of adding the sealing ring on the flow field can be ignored.

4. The axisymmetric air intake duct according to claim 3, characterized in that: The sealing ring is made of an elastic material. To ensure the sealing performance during the movement of the second-stage central cone, the diameter d1 of the sealing ring ≥ the inner diameter d2 of the lapping surface of the first-stage central cone; the compression amount of the sealing ring in the initial state is Δl, and Δl increases during the movement, ensuring the sealing performance during the movement.

5. The axisymmetric air intake according to claim 1, characterized in that: The second-stage central cone and the diffuser section are coaxially and fixedly connected, and both are made of shape memory alloy; in the heating state, the outward expansion force of the driving component causes the diffuser section to expand radially outward, and at the same time带动 the large-diameter end of the second-stage central cone to expand, thereby changing the throat height.

6. The axisymmetric air intake duct according to claim 1, characterized in that: The drainage grooves are two semi-circular through grooves symmetrically arranged on the lapping surface, or a plurality of through holes circumferentially distributed along the circumferential surface of the lapping surface.

7. The axisymmetric air intake according to claim 1, characterized in that: The distance between the lip mask and the large diameter end of the second-stage center cone, that is, the height of the throat H th , determined by the flight altitude and flight Mach number of the aircraft during cruising; the throat area calculation formula is as follows: Where A0 is the capture area of ​​the inlet, σ is the total pressure recovery coefficient of the inlet after the oblique shock wave, q(λ0) and q(λ th ) is solved according to the incoming flow Mach number; the throat height of the inlet can be calculated by calculating the throat area.

8. The axisymmetric air intake duct according to claim 1, characterized in that: When the incoming flow Mach number 0 < Ma < 2.0, the half-cone angle α of the first-stage central cone is 10°.

9. The axisymmetric air intake according to claim 1, characterized in that: The driving component includes a first connecting rod, a second connecting rod and a driver; the first connecting rod is arranged along the axis of the diffuser section, the inner end of which is connected to the driver, and the outer end of which is circumferentially hinged to one end of a plurality of second connecting rods, and the other ends of the plurality of second connecting rods are respectively circumferentially hinged to the inner wall of the diffuser section; by controlling the first connecting rod to linearly move along the axis of the diffuser by the driver, and at the same time带动 one end of the plurality of second connecting rods to move along the axis of the diffuser, thereby applying a pulling force or a pressure to the wall surface of the diffuser.

10. A low-energy fluid control method for the axisymmetric inlet described in any one of claims 1-9, characterized in that: When the incoming flow Mach number increases, the driving component带动 the diffuser section to expand radially outward, and at the same time带动 the second-stage central cone and the sealing ring to move outward along the generatrix of the lapping surface of the first-stage central cone. As the second-stage central cone moves, the throat area decreases, and the drainage groove changes from the "closed" state to the "open" state; When the incoming flow Mach number decreases, the drive assembly drives the diffuser to converge radially, while simultaneously driving the second-stage center cone and the sealing ring to move inward along the generatrix of the first-stage center cone's overlapping surface. As the second-stage center cone moves, the throat area increases, and the discharge groove changes from an "open" state to a "closed" state.

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