An embedded air inlet with a slidable opening and closing door

Abstract

The application discloses a buried air inlet with a slidable opening and closing door, which comprises a first aircraft fuselage section, an air inlet entrance, a second aircraft fuselage section, the air inlet entrance is located between the first aircraft fuselage section and the second aircraft fuselage section, and the air inlet entrance is lower than the first aircraft fuselage section, further comprising an opening and closing door and a driver, the driver is installed in the second aircraft fuselage section, the opening and closing door is slidably installed on the second aircraft fuselage section, and the driver is used for driving the opening and closing door to move; a groove matched with the shape of the opening and closing door is further arranged on the second aircraft fuselage section; the opening and closing door is driven by the driver to slide along the second aircraft fuselage section in the axial direction to realize the opening and closing of the air inlet entrance; when the air inlet entrance is opened, the opening and closing door is located in the groove; when the air inlet entrance is closed, the opening and closing door covers the air inlet entrance, and one end of the opening and closing door is in contact with the first aircraft fuselage section to form a closed state.

Description

Technical Field

[0001] This invention relates to the field of aircraft engine air intake technology, and in particular to an embedded air intake with a sliding door. Background Technology

[0002] With technological advancements, increasingly higher demands are being placed on the comprehensive performance of aircraft, including aerodynamics and stealth. Embedded air intakes, because they do not protrude from the aircraft surface and do not generate additional frontal area, not only effectively reduce radar cross-section but also lower the aircraft's drag. They are a type of aero-engine air intake that balances aerodynamic and stealth performance.

[0003] Aircraft employing embedded air intakes typically use boosters for power before the aero-engine ignites. During boost, a detachable cover seals the air intake to prevent foreign objects from entering the engine and damaging components such as engine blades. This also reduces the adverse effects of the air intake on the overall external airflow, lowering aerodynamic drag during the boost phase. However, once the aero-engine needs to start operating, the cover sealing the air intake is blasted away from the aircraft body, making it impossible to close the intake again. If the aircraft subsequently enters a gliding phase without power or flies into a sandstorm environment, the air intake cannot be resealed, which is detrimental to the aircraft's stealth, aerodynamic drag, and engine lifespan.

[0004] Therefore, it is necessary to develop a new type of embedded air intake with a sliding door that can be opened and closed repeatedly, while ensuring that the door does not protrude from the overall fuselage envelope of the aircraft. Summary of the Invention

[0005] Purpose of the invention: To address the above-mentioned shortcomings, the present invention provides an embedded air intake duct with a sliding door.

[0006] Technical Solution: To solve the above problems, the present invention employs an embedded air intake with a sliding door, comprising a first fuselage section of an aircraft, an air intake inlet, and a second fuselage section of the aircraft. The air intake inlet is located between the first and second fuselage sections of the aircraft, and is lower than the first fuselage section. The invention also includes a door, a rack, and a actuator. The actuator is installed within the second fuselage section of the aircraft, and a gear is provided at the output end of the actuator. The second fuselage section of the aircraft has an opening for the gear to protrude. The opening and closing door is slidably installed on the second fuselage section of the aircraft, and a rack is installed on the side of the opening and closing door, with the gear meshing with the rack; the second fuselage section of the aircraft is also provided with a groove that matches the shape of the opening and closing door; the opening and closing door is driven by a driver to slide along the axial direction of the second fuselage section of the aircraft to realize the opening and closing of the air intake inlet. When the air intake inlet is open, the opening and closing door is located in the groove; when the air intake inlet is closed, the opening and closing door covers the air intake inlet and one end of the opening and closing door contacts the first fuselage section of the aircraft to form a closed state.

[0007] Furthermore, a groove is provided on the side of the air intake inlet, and a guide surface is provided inside the air intake inlet. The front end of the groove is connected to the guide surface through a transition step. A lip is provided on the guide surface, and an inner flow channel is connected to one side of the lip. An air intake outlet is provided at the end of the inner flow channel. When the air intake inlet is closed, one end of the opening and closing door covers the transition step.

[0008] Furthermore, the front vertex of the transition step is located at the center of the span of the first fuselage section of the aircraft, and the transition step gradually expands from this vertex from front to back and to both sides, and the transition step is symmetrically arranged along the axis of the first fuselage section of the aircraft.

[0009] Furthermore, the upper surface of the transition step is flush with the bottom surface of the chute, and the upper surface of the transition step is connected to the guide surface through the side surface of the transition step, which is perpendicular to the guide surface.

[0010] Furthermore, the cross-section of the transition step is two symmetrically arranged triangles, the angle α between the side of the transition step and the axis of the first fuselage section of the aircraft is 36±15°, and the distance between the guide surface and the upper surface of the first fuselage section of the aircraft is 20±15mm.

[0011] Furthermore, the second fuselage section of the aircraft is provided with a cavity, which is located on the side of the air intake and communicates with the air intake through an opening located on a slide. The drive is installed in the cavity, and the gear extends out of the cavity through the opening.

[0012] Furthermore, the depth of the groove and the recess are equal to the thickness of the opening and closing door; when the opening and closing door contacts the first fuselage section of the aircraft and forms a closed state, the opening and closing door and the outer surface of the first fuselage section of the aircraft together form a continuous and complete arc surface.

[0013] Furthermore, the lower surfaces of the gear, rack, and door are flush with each other, the upper surface of the rack is higher than the upper surface of the gear, and the upper surface of the rack is lower than the upper surface of the door.

[0014] Furthermore, a vortex generator is provided on the wall of the inner flow channel. The vortex generator is a flat thin sheet, and the plane on which the vortex generator is located is perpendicular to its mounting surface.

[0015] Furthermore, the vortex generator includes three sets of flat thin plates, two of which are located at the front end of the inner flow channel and one of which is located in the middle of the inner flow channel.

[0016] Beneficial effects: Compared with the prior art, the significant advantages of this invention are (1) by adding a repeatable opening and closing mechanism, the aircraft can simultaneously close the air intake to protect the downstream engine when the engine is off; (2) the design of the transition step structure can realize the discharge of low energy flow in the upstream boundary layer of the transition step, which can avoid performance deterioration in the air intake; (3) multiple vortex generators are added in the air intake, which effectively improves the performance of the air intake. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural diagram of the semi-mold configuration of the embedded air intake of the present invention in the open state.

[0018] Figure 2 This is a three-dimensional structural diagram of the embedded air intake duct semi-mold configuration of the present invention in the closed state;

[0019] Figure 3 This is an enlarged structural diagram of the air intake inlet of the present invention;

[0020] Figure 4 This is a schematic diagram of the cavity structure of the present invention;

[0021] Figure 5 This is a schematic diagram of the driving structure of the present invention;

[0022] Figure 6 This is a front view of the embedded airway opening and closing door drive device of the present invention.

[0023] Figure 7 This is a front view of the embedded airway opening and closing door drive device of the present invention in the closed state.

[0024] Figure 8 This is a bottom view of the fully-configured projectile of the present invention in the open state;

[0025] Figure 9 This is a bottom view of the projectile body in its fully-configured state in the closed position.

[0026] Figure 10 This is a graph of the total pressure recovery coefficient at the intake outlet obtained through simulation in this invention. Detailed Implementation

[0027] like Figure 1 and Figure 2 As shown, this embodiment of an embedded air intake with a sliding door includes a first fuselage section 1, a second fuselage section, an air intake inlet disposed between the first fuselage section 1 and the second fuselage section, a door 5, a rack 12, and a drive motor 13. The air intake inlet is lower than the first fuselage section 1. A groove 3 is provided on the side of the air intake inlet, and a guide surface 6 is provided inside the air intake inlet. The front end of the groove 3 is connected to the guide surface 6 through a transition step 2.

[0028] like Figure 3 As shown, the front vertex of the transition step 2 is located at the center of the spanwise width of the first fuselage section 1 of the aircraft. The transition step 2 gradually expands from this vertex from front to back and to both sides, and is symmetrically arranged along the axis of the first fuselage section of the aircraft. Its cross-section consists of two symmetrically arranged triangles, which appear as a "<" shaped indentation in the top view. The upper surface of the transition step 2 is flush with the bottom surface of the slide 3. The upper surface of the transition step 2 is connected to the guide surface 6 through the side surface 15 of the transition step. The side surface 15 of the transition step is perpendicular to the guide surface 6, and the angle α between the side surface 15 of the transition step and the axis of the first fuselage section 1 of the aircraft is 36±15°. In order to keep the air intake in the high-performance range, the thickness of the transition step should be 15±10mm, and the minimum distance from the intersection of the side edges of the "<" shaped transition step to the air intake lip should be ≥150mm.

[0029] A lip 4 is provided on the guide surface 6, and an inner flow channel 9 is connected to one side of the lip 4. An air intake outlet 10 is located at the end of the inner flow channel 9. The spanwise width of the guide surface 6 is greater than the spanwise width of the arc-shaped lip 4 at the air intake inlet. The guide surface 6 intersects with the inner flow channel 9, and the intersection line formed by their intersection is rounded off with a variable radius to obtain the air intake lip 4. The inner flow channel 9 gradually expands and deforms from its "U" shape at the inlet along the flow direction, transitioning to the circular shape of the air intake outlet 10. The inner flow channel 9 is formed by the S-curve air intake intersecting with the aircraft fuselage.

[0030] like Figure 4 As shown, a cavity 11 is provided within the second fuselage section of the aircraft. The cavity 11 is located on one side of the air intake and communicates with the air intake through a square opening. This opening is located on the slide rail 3. The height of the square opening is greater than the thickness of the gear 131, and the length of the opening is the same as the length of the cavity 11 region. Figure 5As shown, the drive motor 13 is installed inside the cavity 11, and the gear 131 extends out of the cavity through an opening. The opening / closing door 5 is slidably mounted on the aircraft fuselage. A mounting groove is formed on the lower part of the side wall of the opening / closing door 5, and the rack 12 is installed in this groove to prevent the rack from being exposed on the upper surface of the opening / closing door 5, thus avoiding adverse effects on the airflow above the opening / closing door 5. The gear 131 meshes with the rack 12. To ensure that the opening / closing door 5 can fully accommodate the rack 12, the door thickness should be ≥5mm. Simultaneously, to ensure that the rack tooth thickness provides sufficient shear stress to drive the opening / closing door back and forth, the rack thickness should be ≥3mm.

[0031] The lower surfaces of gear 131, rack 12, and door 5 are flush with each other. The upper surface of rack 12 is higher than the upper surface of gear 131, with a distance of ≥0.5mm between them. The upper surface of rack 12 is lower than the upper surface of door 5, with a distance of ≥0.5mm between them. The door 5 is axially slid along the aircraft fuselage 1 by drive motor 13 to open and close the air intake. This embodiment has two drive motors and two gears, as shown below. Figure 6 As shown, when the door opens, the door rack meshes with the drive gear of the drive motor behind it. Figure 7 As shown, when the gate is closed, the gate rack engages with the drive gear of the front drive motor. When the gate is in operation and the gate is moving, the rack will engage with the drive gears of both drive motors to provide greater thrust.

[0032] To ensure that the opening / closing door 5 does not affect the flight process, a groove 14 matching the shape of the opening / closing door 5 is provided on the upper surface of the second fuselage section of the aircraft, behind the air intake. The depth of both the slide groove 3 and the groove 14 is equal to the thickness of the opening / closing door 5. When the air intake is open, the opening / closing door 5 is placed in the groove 14, such as... Figure 8 As shown. When the air intake is closed, the opening / closing door 5 moves forward, positioned directly above the air intake inlet, and completely covers all structures at the air intake inlet. The opening / closing door (5) and the outer surface of the first fuselage section (1) of the aircraft together form a continuous and complete arc surface, as shown. Figure 9 As shown. Regardless of whether the air intake is closed or open, the upper surface of the opening / closing door 5 is flush with the surface of the aircraft fuselage. When viewed from the nose along the direction of the incoming airflow, there are no additional protruding units, and the drag on the aircraft from the incoming airflow does not change significantly compared to the open state.

[0033] It is important to note that when airflow passes near the fuselage of a long aircraft, the fluid near the fuselage surface gradually slows down, eventually reaching zero at the wall. This results in the formation of a low-energy flow layer near the wall, commonly known as the boundary layer. This boundary layer grows continuously along the flow direction near the wall, accumulating into a mass of low-energy flow before the air intake. When the aircraft's inlet / outlet mechanism is open, this low-energy flow is drawn into the air intake, significantly and adversely affecting its performance.

[0034] In this invention, the fluid develops a relatively thick low-energy flow before flowing through the transition step 2. However, as the fluid flows through the transition step 2, the height difference between the upper surface of the step and the guide surface 6 forms two sets of symmetrical vortices that run in the same direction as the side edges of the transition step 2. The vortices develop continuously from the apex of the transition step to both sides, carrying the upstream low-energy fluid outwards with the vortices. At this time, the low-energy flow mainly flows over the upper surface of the first fuselage section 1 of the aircraft, near the slide 3.

[0035] Meanwhile, in order to prevent the low-energy flow that has been discharged by the vortex that has been rolled up by the transition step 2 from being sucked back into the air intake, the bottom guide surface 6 needs to be a certain distance from the upper surface of the fuselage, that is, a depth of 20±15mm.

[0036] Furthermore, the side ridge of the intake duct inlet will also cause side ridge vortices, which, together with the descending step structure composed of the chute 3, transition step 2, and guide surface 6, will have an adverse effect on the intake duct. In order to improve the flow field inside the intake duct and ensure that the intake duct can still maintain a high total pressure recovery performance when the descending step exists, the present invention arranges a vortex generator on the intake duct profile.

[0037] Vortex generators 7 are mounted on the wall of the inner flow channel 9. The vortex generators are flat, thin plates, also known as turbulence deflectors, and can be made of copper or iron. Their plane is perpendicular to the mounting surface. Three sets of vortex generators are installed, two plates per set, symmetrically arranged. Two sets are located at the front end of the inner flow channel 9, and one set is located in the middle of the inner flow channel 9. A third set of vortex generators is located 100±20mm downstream of the second set along the flow direction, while the third set is approximately 30±20mm away from the first set along the flow direction. The angle between the bottom of the three sets of vortex generators and the intersection line of the inner flow channel 9 and the plane of symmetry is 25±10°. Each vortex generator is approximately 7–25mm long and 2–10mm high. The two sets of vortex generators closest to the lip are approximately 55±15mm from the plane of symmetry, and the third set is approximately 20±10mm from the plane of symmetry. The first set of vortex generators, located near the rear edge of the lip 4, generates vortices that run in the opposite direction to the side ridge vortices of the transition step. These vortices are amplified by the adjacent downstream second set of vortex generators, allowing them to merge with the side ridge vortices and partially offset the adverse effects of the side ridge vortices on the distortion within the duct. The third set of vortex generators, located further downstream within the intake duct, serves a rectifying function.

[0038] In this embodiment, the step thickness is 20mm, the distance from the intersection of the side edges of the "<"-shaped step to the inlet lip is 200mm, and the angle between the side edge of the transition step and the plane of symmetry α is 36°. The angle between the intersection line of the bottom of the three vortex generator and the inner surface 9 of the inlet and the plane of symmetry is 20°, with a length of approximately 12mm and a height of approximately 8mm. Numerical simulation is performed on a model with an inlet area of ​​21200mm² and an outlet diameter of 150mm. The numerical simulation shows that with an incoming Mach number of 0.7, an angle of attack of 2°, and an outlet Mach number of 0.4, the inlet outlet pattern is as follows. Figure 10 As shown, the total pressure recovery coefficient of the air intake reaches 0.94, which is close to the general performance of a typical embedded air intake without an opening and closing mechanism. This proves that after adding a reusable opening and closing mechanism to the aircraft, the adverse effects of the opening and closing mechanism can be ignored.

[0039] In summary, this invention, by adding a repeatable opening and closing mechanism, enables the aircraft to simultaneously shut down the air intake to protect the downstream engine when the engine is off. The designed transition step structure allows for the discharge of low-energy flow from the upstream boundary layer, preventing performance degradation within the air intake. The addition of multiple vortex generators within the air intake effectively improves its performance.

Claims

1. An embedded air intake with a sliding door, comprising a first fuselage section (1) of an aircraft, an air intake inlet, and a second fuselage section of the aircraft, wherein the air intake inlet is located between the first fuselage section (1) and the second fuselage section, and the air intake inlet is lower than the first fuselage section (1), characterized in that, It also includes an opening and closing door (5), a rack (12), and a driver (13). The driver (13) is installed inside the second fuselage section of the aircraft. The output end of the driver (13) is provided with a gear (131). The second fuselage section of the aircraft is provided with an opening for the gear (131) to be exposed. The opening and closing door (5) is slidably installed on the second fuselage section of the aircraft. The rack (12) is installed on the side of the opening and closing door (5), and the gear (131) meshes with the rack (12). The second fuselage section of the aircraft is also provided with a groove (14) that matches the shape of the opening and closing door (5). The driver (13) drives the opening and closing door (5) to slide along the axial direction of the second fuselage section of the aircraft to realize the opening and closing of the air intake. When the air intake is open, the opening and closing door (5) is located in the groove (14). When the air intake is closed, the opening and closing door (5) covers the air intake and one end of the opening and closing door (5) contacts the first fuselage section (1) of the aircraft and forms a closed state. The side of the air intake inlet is provided with a groove (3), and the air intake inlet is provided with a guide surface (6). The front end of the groove (3) is connected to the guide surface (6) through a transition step (2). The guide surface (6) is provided with a lip (4). One side of the lip (4) is connected to an inner flow channel (9). The end of the inner flow channel (9) is provided with an air intake outlet (10). When the air intake inlet is closed, one end of the opening and closing door (5) covers the transition step (2). The front vertex of the transition step (2) is located at the center of the span of the first fuselage section (1) of the aircraft. The transition step (2) gradually expands from the vertex from front to back and to both sides. The transition step (2) is symmetrically arranged along the axis of the first fuselage section (1) of the aircraft.

2. The embedded air intake duct with a sliding door as described in claim 1, characterized in that, The upper surface of the transition step (2) is flush with the bottom surface of the chute (3). The upper surface of the transition step (2) is connected to the guide surface (6) through the side surface of the transition step (15). The side surface of the transition step (15) is perpendicular to the guide surface (6).

3. The embedded air intake duct with a sliding door as described in claim 2, characterized in that, The cross-section of the transition step (2) is two symmetrically arranged triangles. The angle α between the side (15) of the transition step and the axis of the first fuselage section (1) of the aircraft is 36±15°. The distance between the guide surface (6) and the upper surface of the first fuselage section (1) of the aircraft is 20±15mm.

4. The embedded air intake duct with a sliding door as described in claim 1, characterized in that, The second fuselage section of the aircraft is provided with a cavity (11). The cavity (11) is located on the side of the air intake inlet and is connected to the air intake inlet through an opening. The opening is located on the slide (3). The driver (13) is installed in the cavity (11), and the gear (131) extends out of the cavity through the opening.

5. The embedded air intake duct with a sliding door as described in claim 1, characterized in that, The depth of the groove (3) and the groove (14) is equal to the thickness of the opening and closing door (5); when the opening and closing door (5) contacts the first fuselage section (1) of the aircraft and forms a closed state, the opening and closing door (5) and the outer surface of the first fuselage section (1) of the aircraft together form a continuous and complete arc surface.

6. The embedded air intake duct with a sliding door as described in claim 1, characterized in that, The lower surfaces of the gear (131), the rack (12), and the door (5) are flush with each other. The upper surface of the rack (12) is higher than the upper surface of the gear (131), and the upper surface of the rack (12) is lower than the upper surface of the door (5).

7. The embedded air intake duct with a sliding door as described in claim 1, characterized in that, The inner flow channel (9) is also provided with a vortex generator (7), which is a flat thin sheet and the plane where the vortex generator (7) is located is perpendicular to its mounting surface.

8. The embedded air intake duct with a sliding door as described in claim 7, characterized in that, The vortex generator (7) includes three sets of flat thin plates, two of which are located at the front end of the inner flow channel (9) and one of which is located at the middle end of the inner flow channel (9).

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