A two-dimensional supersonic variable geometry inlet with lip mask translation

Abstract

A dual-stage inlet with a horizontally movable lip shield comprises an inlet body with a compression surface, an inlet lip shield mounted on the outside of the inlet body, and an inlet expansion section mounted on the same side of the inlet lip shield at the rear of the inlet lip shield. An inner inlet passage is defined between the inlet body, the inlet lip shield mounted on the same side of the inlet body, and the inlet expansion section, and the inner passage is provided with a throat. The throat is inclined to increase the throat height as the lip shield moves forward. The inlet lip shield moves horizontally with changes in the incoming flow Mach number to meet the inlet's operating performance at different incoming flow Mach numbers, namely, the inlet flow coefficient, throat Mach number, and total pressure recovery coefficient meet design requirements at different incoming flow Mach numbers. The present invention achieves changes in the inlet throat area by moving the inlet lip shield. Compared with other variable geometry inlets, the present invention has a simple structure and the advantages of high reliability and strong feasibility.

Description

Technical Field

[0001] The present invention relates to the field of air-breathing supersonic aircraft design, and in particular to a dual supersonic variable geometry air inlet with a lip mask that translates. Background Art

[0002] The aircraft engine, the heart and power source of an aircraft, is a crucial component of the engine. The air inlet, a crucial component of the engine, pre-compresses the captured airflow, providing the necessary flow field for the compressor. Its performance and the quality of the flow field it provides determine the proper functioning and performance of the engine. Therefore, air inlet design is a critical element of aircraft engine design.

[0003] Just like aircraft flight, the main operating states of an air intake can be divided into stationary or takeoff state, climbing state, level flight state (cruise state), and dive state. The air intake must be able to operate normally in all four states. When designing an air intake, level flight state is generally selected as the design point. This requires that the overall performance of the air intake is at the optimal state at this design point. In other states, the air intake performance may be slightly reduced, but it must still be able to operate normally. According to the book "Principles of Inlets", a supersonic fixed-geometry inlet with a single profile cannot meet the requirements of normal operation at all incoming flow Mach numbers; this is because the throat area of a fixed-geometry inlet is fixed, and when the incoming flow Mach number is subsonic or low supersonic, the inlet must have a larger throat area to ensure smooth airflow passage and prevent congestion at the inlet throat, which would prevent the inlet from operating normally; and when the incoming flow Mach number is higher supersonic, the inlet needs to have a smaller throat area to ensure the ability to compress the airflow; this contradiction cannot be reconciled under a fixed-geometry inlet, so most existing supersonic inlets use a variable geometry method to broaden the working range of the inlet.

[0004] Currently, the main methods for variable geometry in supersonic inlets include lip rotation and adjustable wedges. While these methods can broaden the inlet's operating range, they present challenges in practical engineering applications, such as structural complexity, difficult processing, and poor feasibility and reliability. Therefore, to ensure that the inlet functions properly under all aircraft conditions, a design solution with simple geometric deformation and reliable structure is needed to address these issues. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention proposes a binary supersonic variable geometry inlet with a lip mask that moves horizontally, aiming to solve the problems of the variable geometry method of the existing supersonic inlet, such as complex structure, difficult processing, poor feasibility and reliability.

[0006] The present invention proposes the following technical solutions to solve the technical problems:

[0007] A binary supersonic variable geometry inlet with a lip shield that moves horizontally is enclosed by four sides: upper, lower, front, and rear. The lower side is an inlet body 1-1 with a compression surface located at the bottom of the inlet. The front and rear sides are inlet front side panels 1-2 and inlet rear side panels 1-3 vertically mounted on either side of the inlet body 1-1. The upper side is an inlet lip shield 2 located at the top of the inlet and opposite to the inlet body 1-1, and an inlet expansion section 3 mounted on the same side at the rear of the inlet lip shield 2. An inner inlet passage 4 is formed between the inlet body 1-1, the inlet front side panels 1-2, the inlet rear side panels 1-3, the inlet lip shield 2, and the inlet expansion section 3. The inner inlet passage 4 is provided with a throat 4-1. The invention is characterized in that:

[0008] The throat 4-1 is tilted so that the height of the throat 4-1 increases as the lip shield moves forward; the inlet lip shield 2 moves horizontally as the incoming flow Mach number changes to meet the working performance of the inlet at different incoming flow Mach numbers, that is, the inlet flow coefficient, throat Mach number, and total pressure recovery coefficient meet the design requirements at different incoming flow Mach numbers; the throat is formed by the inclined portion of the lip shield 2 and the parallel portion of the inlet body 1-1, and the throat length is determined by the shortest distance between parallel lines at the parallel portions.

[0009] Furthermore, the compression surface of the air inlet main body 1 - 1 is composed of an isentropic compression surface 8 , and the wedge plate 6 thereafter is tangent to the isentropic compression surface 8 , and the wedge plate 6 is provided with overflow holes of a certain number and size.

[0010] The inlet lip cover 2 moves in the horizontal direction as the incoming flow Mach number changes. The specific movement method is: when the incoming flow Mach number is subsonic or low supersonic, the inlet lip cover 2 is located at the forefront 7-1, and within this incoming flow range, the position of the inlet lip cover 2 remains unchanged; when the incoming flow Mach number gradually increases until it is greater than the Mach number setting value, the inlet lip cover 2 gradually moves backward; when the incoming flow Mach number reaches the inlet design point, the inlet lip cover 2 moves to the design position 7-2 and no longer moves thereafter; the Mach number setting value is determined at the beginning of the design.

[0011] Furthermore, the operating range of the air inlet is Ma0-3.0, the flight altitude is between 0-26km, and the flight Mach number Ma=3.0 and the flight altitude 24km are selected as the air inlet design points.

[0012] Furthermore, the distance that the air inlet lip cover 2 moves forward in the horizontal direction does not exceed the front end of the wedge plate 6 .

[0013] Furthermore, the throat is inclined, specifically: the throat direction is parallel to the front wedge plate 6, the inclination angle of the throat is the same as the total deflection angle of the airflow, which is a balanced angle that takes into account the change in throat height and the absence of throat congestion.

[0014] Furthermore, the entrance height of the binary air inlet is 91.7 mm, the internal compression angle and the total airflow deflection angle are both 13°, the maximum forward movement distance of the lip mask is 25 mm, the height of the throat at the air inlet design point is 26.1 mm, the height of the overflow hole is 5 mm, and the width is 2 mm.

[0015] Furthermore, there is a gap 5 at a certain distance between the air inlet lip mask 2 and the inlet of the expansion section 3. The height of the gap 5 is 1.3 mm. The gap 5 is used to facilitate the horizontal movement of the lip mask 2 without causing other geometric structures to move, and is conducive to self-adjustment when the back pressure at the air inlet outlet changes.

[0016] Furthermore, when the incoming flow Mach number is between 0 and 1.6, the position of the lip shield moves forward by 25 mm compared with the position at the design point; when the incoming flow Mach number is greater than 1.6, the air inlet gradually moves backward, and when the incoming flow Mach number is 2.1, the position of the lip shield moves forward by 15 mm compared with the position at the design point; when the incoming flow Mach number is 2.5, the position of the lip shield moves forward by 9 mm compared with the position at the design point; when the incoming flow Mach number is 3.0, the lip shield is at the design position and no longer moves, at which time the air inlet reaches the rated working state; when the lip shield position moves forward by 25 mm, the height of the throat 4-1 is greater than the height of the throat 4-1 when the lip shield position moves forward by 15 mm, and the height of the throat 4-1 when the lip shield position moves forward by 9 mm.

[0017] Advantages and effects of the present invention

[0018] 1. The present invention achieves a change in the throat area of the inlet by setting an inclined throat and horizontally moving the inlet lip, thereby widening the stable operating range of the supersonic inlet and allowing the inlet to operate normally in any state within the design range of the aircraft. Compared with fixed geometry inlets, this inlet can take into account both subsonic and low supersonic incoming flow ranges; compared with other variable geometry inlets, the lip translation scheme does not require changing the shape of the structure and has a simple structure; the impact on the flow field structure during movement is small, and it has the advantages of high reliability and strong feasibility. As the incoming flow Mach number increases, the lip gradually moves backward, which not only ensures the inlet's ability to compress the airflow, but also ensures that the engine has sufficient airflow to a certain extent.

[0019] 2. The present invention creates an inclined throat by providing a specially shaped lip shield. When the lip shield moves horizontally, the throat area changes with its movement. Both the inclined throat and the horizontal movement of the lip shield are essential. If only the inclined throat is provided but the lip shield cannot move horizontally, the throat area cannot adapt to changes in the incoming flow Mach number. If only the lip shield moves horizontally but the throat is horizontal, the throat area will not change with the horizontal movement of the lip shield. Only when the two are combined and support each other can the new effects be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1-1 It is a two-dimensional cross-sectional diagram of a binary supersonic inlet;

[0021] Figure 1-2 This is a three-dimensional structural diagram of the binary supersonic inlet without the front side panel;

[0022] Figure 1-3 It is a three-dimensional structural diagram of a binary supersonic inlet;

[0023] Figure 2 This is the dimension diagram of the two-dimensional cross-section calculation model of the dual-element air intake;

[0024] Figure 3 This is the Mach number cloud diagram when the downflow Mach number of profile Case 4 is 0.6;

[0025] Figure 4 This is the Mach number cloud diagram when the downflow Mach number of profile Case 4 is 0.8;

[0026] Figure 5 This is the Mach number cloud diagram when the downflow Mach number of profile Case 4 is 1.1;

[0027] Figure 6 This is the Mach number cloud diagram when the downflow Mach number of profile Case 4 is 1.6;

[0028] Figure 7 This is the Mach number cloud diagram when the downflow Mach number of profile Case 3 is 2.1;

[0029] Figure 8 This is the Mach number cloud diagram when the downflow Mach number of profile Case 2 is 2.5;

[0030] Figure 9 This is the Mach number cloud diagram when the downflow Mach number of profile Case 1 is 3.0;

[0031] Figure 10 This is a throat Mach number curve at different lip mask positions and different incoming flow Mach numbers;

[0032] Figure 11This is a flow coefficient curve diagram at different lip mask positions and different incoming flow Mach numbers;

[0033] Figure 12 This is a graph of the throat total pressure recovery coefficient at different lip mask positions and different incoming flow Mach numbers;

[0034] In the figure: 1-1: air intake main body; 1-2: air intake front side panel; 1-3: air intake rear side panel;

[0035] 2: Inlet lip; 3: Inlet expansion section; 4: Inlet passage; 4-1: Throat; 5: Slit; 6: Wedge; 6-1: Overflow hole; 7-1: Leading edge; 7-2: Design point position; DETAILED DESCRIPTION

[0036] Design principle of the present invention

[0037] 1. The innovation of the present invention lies in the inclination of the throat and the horizontal movement of the lip mask. The throat of the prior art is generally in a horizontal state rather than an inclined state. When the throat is in a horizontal state, the horizontal movement of the lip mask will not change the height and area of the throat. The throat 4-1 of the present invention adopts an inclined manner, and the lip mask is a curved plate with different heights and streamlined transitions at both ends. The throat is composed of the inclined part of the lip mask 2 and the parallel part of the air inlet main body 1-1, and the length of the throat is determined by the shortest distance between the parallel lines at the parallel parts. Figure 2 As can be seen from the cross-sectional view, when the lip mask 2 is located at the design point 7-2, that is, at the cut-off point of its backward movement, the height and area of the throat are the smallest; when the lip mask moves forward to the front end (25 mm from the design point), the height and area of the throat are the largest; as the lip mask moves forward, the inclination angle of the inclined portion of the lip mask remains unchanged, and this inclination angle is always the same as the inclination angle of the wedge plate during the translation process of the lip mask and remains parallel to the wedge plate.

[0038] 2. The inclination angle of the throat takes into account the balance between the change in the throat height and the prevention of throat congestion. If the inclination angle of the throat is too steep, although the steep inclination angle can easily cause the height of the throat to change, the resistance of the inlet will also increase greatly, which is not conducive to the flight of the aircraft. If the inclination angle of the throat is too gentle, the forward movement path of the lip shield will be lengthened, and the lengthened forward movement path will cause the front edge of the lip shield to exceed the front end of the wedge plate, which will cause the compression ratio in the inlet to increase, which is not conducive to the self-starting of the inlet, and the forebody shock wave will penetrate into the lip shield, causing flow separation near the lip, reducing the working performance of the inlet. Therefore, the inclination angle of the throat cannot be too small. The present invention sets the inclination angle of the throat to be in the range of 10° to 30°.

[0039] The present invention will be further explained below with reference to the accompanying drawings:

[0040] A binary supersonic variable geometry inlet with a lip shield that moves horizontally is enclosed by four sides: upper, lower, front, and rear. The lower side is an inlet body 1-1 with a compression surface located at the bottom of the inlet. The front and rear sides are inlet front side panels 1-2 and inlet rear side panels 1-3 vertically mounted on either side of the inlet body 1-1. The upper side is an inlet lip shield 2 located at the top of the inlet and opposite to the inlet body 1-1, and an inlet expansion section 3 mounted on the same side at the rear of the inlet lip shield 2. An inner inlet passage 4 is formed between the inlet body 1-1, the inlet front side panels 1-2, the inlet rear side panels 1-3, the inlet lip shield 2, and the inlet expansion section 3. The inner inlet passage 4 is provided with a throat 4-1. The invention is characterized in that:

[0041] The throat 4-1 is inclined so that the height of the throat 4-1 increases when the lip shield moves forward; the inlet lip shield 2 moves in the horizontal direction as the incoming flow Mach number changes to meet the working performance of the inlet under different incoming flow Mach numbers, that is, the inlet flow coefficient, throat Mach number, and total pressure recovery coefficient under different incoming flow Mach numbers meet the design requirements. The throat is formed by the inclined portion of the lip shield 2 and the parallel portion of the inlet body 1-1, and the throat length is determined by the shortest distance between parallel lines at the parallel portions.

[0042] The compression surface of the air inlet main body 1 - 1 is composed of an isentropic compression surface 8 , and the wedge plate 6 thereafter is tangent to the isentropic compression surface 8 , and a certain number and size of overflow holes are arranged on the wedge plate 6 .

[0043] Supplementary Note 1: The isentropic compression of the inlet compression surface is intended to reduce shock wave losses while decelerating and expanding the airflow, thereby increasing the total pressure recovery coefficient of the inlet. Overflow hole 6-1 is designed, on the one hand, to curb the development of the boundary layer on the compression surface, preventing shock wave boundary layer interference from causing the inlet to fail to start; on the other hand, it can also overflow excess airflow captured by the inlet, increasing the inlet flow capacity and facilitating the inlet's rapid self-start.

[0044] As shown by the dotted line in Figure 1, the inlet lip cover 2 moves in the horizontal direction as the incoming flow Mach number changes. The specific movement method is: when the incoming flow Mach number is subsonic or low supersonic, the inlet lip cover 2 is located at the forefront 7-1, and in this incoming flow range, the position of the inlet lip cover 2 remains unchanged; when the incoming flow Mach number gradually increases until it is greater than the Mach number setting value, the inlet lip cover 2 gradually moves backward; when the incoming flow Mach number reaches the inlet design point, the inlet lip cover 2 moves to the design position 7-2 and no longer moves thereafter; the Mach number setting value is determined at the beginning of the design.

[0045] Supplementary Note 2: The lip cover 2 gradually moves backward as the incoming flow Mach number increases. On the one hand, it can reduce the internal contraction ratio of the inlet duct, which is more conducive to the self-starting of the inlet duct; on the other hand, the throat area of the inlet duct is also gradually reduced, which improves the compression ability of the inlet duct on the airflow and ensures that the throat Mach number is within the normal range.

[0046] The operating range of the air inlet is Ma0-3.0, and the flight altitude is between 0-26 km. The flight Mach number Ma=3.0 and the flight altitude 24 km are selected as the air inlet design points.

[0047] The distance that the air intake lip cover 2 moves forward in the horizontal direction does not exceed the front end of the wedge plate 6.

[0048] The throat is tilted, specifically: the throat direction is parallel to the front wedge plate 6, and the tilt angle of the throat is the same as the total airflow deflection angle. This angle is a balanced angle that takes into account the change in throat height and the absence of throat congestion.

[0049] like Figure 2 As shown, the entrance height of the binary air inlet is 91.7 mm, the internal compression angle and the total airflow deflection angle are both 13°, the maximum forward movement distance of the lip mask is 25 mm, the height of the throat at the air inlet design point is 26.1 mm, the height of the overflow hole is 5 mm, and the width is 2 mm.

[0050] As shown in FIG1 , there is a gap 5 at a certain distance between the air inlet lip shield 2 and the inlet of the expansion section 3. The height of the gap 5 is 1.3 mm. The gap 5 is used to facilitate the horizontal movement of the lip shield 2 without causing other geometric structures to move, and is conducive to self-adjustment of the air inlet.

[0051] Supplementary Note 3: When the required flow rate at the inlet outlet decreases, the "excess" airflow can overflow from the gap, thereby adjusting the flow rate without destroying the shock wave structure and maintaining stable operation of the inlet.

[0052] When the incoming Mach number is between 0 and 1.6, the lip guard moves forward 25mm compared to its design position. When the incoming Mach number exceeds 1.6, the inlet gradually shifts backward. At an incoming Mach number of 2.1, the lip guard moves forward 15mm compared to its design position. At an incoming Mach number of 2.5, the lip guard moves forward 9mm compared to its design position. At an incoming Mach number of 3.0, the lip guard remains in its design position and no longer moves, at which point the inlet reaches its rated operating state. The height of the throat 4-1 when the lip guard moves forward 25mm is greater than the height of the throat 4-1 when the lip guard moves forward 15mm, which is greater than the height of the throat 4-1 when the lip guard moves forward 9mm.

[0053] Supplementary Note 4: For the convenience of description, the profile when the lip mask is located at the design point is defined as Case 1, the profile when the lip mask is moved forward 9mm is defined as Case 2, the profile when the lip mask is moved forward 15mm is defined as Case 3, and the profile when the lip mask is moved forward 25mm is defined as Case 4.

[0054] Supplementary Note 5: Inlet flow field structure at different lip mask positions and different incoming flow Mach numbers

[0055] like Figure 3-Figure 9 As shown in the figure, in order to explore the inlet flow field structure under different lip cover positions and different incoming flow Mach numbers, the design surface is numerically simulated. Since the expansion section is not the focus of this study, it is omitted to reduce the amount of calculation and only the section from the forebody to the throat is studied. This is also a common practice in studying supersonic inlets. Figure 3-Figure 9 As shown in the figure, the calculated incoming flow Mach numbers are 0.6, 0.8, 1.1, 1.6, 2.5, and 3.0, a total of six cases. Among them, the flight altitude of Mach numbers 0.6, 0.8, and 1.1 is 12km, and the flight altitude of Mach numbers 1.6, 2.5, and 3.0 is 24km.

[0056] Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 This diagram shows the effects of the present invention when the incoming airflow is at subsonic or low supersonic Mach numbers between 0.6 and 1.6. When the incoming airflow is at subsonic or low supersonic Mach numbers between 0.6 and 1.6, the inlet must have a large throat area to ensure smooth airflow and prevent congestion at the inlet throat, which could cause the inlet to malfunction.

[0057] Figure 3 、 Figure 4 This is the Mach number cloud diagram when the downflow Mach numbers of Case 4 are 0.6 and 0.8 respectively. Figure 2 The middle lip mask 2 moves forward to the front end 7-1 and the height and area of the throat 4-1 reach the maximum. Figure 3 、 Figure 4 It can be seen from the figure that the flow velocity at the throat of the inlet is greater than the incoming flow velocity. This is because the overall shape of the inlet is a contracting surface. When the incoming flow is subsonic, it has an accelerating and depressurizing effect on the airflow. It can be seen from the streamlines in the figure that the airflow can pass through the inlet smoothly without congestion.

[0058] Figure 5 This is the Mach number cloud diagram when the downflow Mach number of Case 4 is 1.1. Figure 2 The middle lip mask 2 moves forward to the front end 7-1 and the height and area of the throat 4-1 reach the maximum. Figure 5 It can be seen from the figure that there is a weak positive shock wave at the front of the air inlet, and the airflow behind the wave is subsonic. The subsequent flow conditions are similar to those at Mach numbers 0.6 and 0.8, and the airflow can flow smoothly through the throat.

[0059] Figure 6 This is the Mach number cloud diagram when the downflow Mach number of Case 4 is 1.6. Figure 2 The middle lip mask 2 moves forward to the front end 7-1 and the height and area of the throat 4-1 reach the maximum. Figure 6 It can be seen from the figure that the forebody shock wave system has been initially established, and there is a positive shock wave in front of the lip mask inlet, which further decelerates and expands the airflow entering the lip, and the airflow flows smoothly through the throat.

[0060] Figure 7 、 Figure 8 、 Figure 9 This is a rendering of the present invention under supersonic conditions with an incoming Mach number of 2.1 to 3.0. When the incoming Mach number is a relatively high supersonic speed, the air inlet needs to have a smaller throat area to ensure the airflow compression capability.

[0061] Figure 7 This is the Mach number cloud diagram for Case 3 when the downflow Mach number is 2.1. Figure 2 The middle lip cover 2 moves backward from the front end 25 mm. As the lip cover 2 moves backward, the height and area of the throat 4-1 also decrease and decrease accordingly. When the incoming flow Mach number is a higher supersonic speed of 2.1, the throat area is reduced to ensure the compression capability of the airflow.

[0062] Figure 8 This is the Mach number cloud diagram of Case 3 when the incoming flow Mach number is 2.5. At this time, the lip cover 2 continues to move backward from the front end 15 mm. As the lip cover 2 moves backward, the height and area of the throat 4-1 also decrease and decrease accordingly. When the incoming flow Mach number is a higher supersonic speed of 2.5, the throat area is reduced to ensure the compression capacity of the airflow.

[0063] from Figure 7 、 Figure 8 It can be seen from the two figures that at this time the inlet shock wave system has been fully established and the inlet is working normally.

[0064] Figure 9 This is a Mach number contour plot for Case 1, when the incoming flow reaches Mach 3.0. At this point, the lip 2 continues to move backward from the front 9mm to the design point. At the design point, the throat height is minimum, 26.1mm, and the throat area is also minimum. When the incoming flow reaches a higher supersonic speed of Mach 3.0, the throat area is reduced to ensure airflow compression. As can be seen from the figure, the inlet shock wave strikes the lip exactly, indicating rated operation.

[0065] Supplementary Note 6: The effect of lip mask movement on inlet performance (throat Mach number, flow coefficient, throat total pressure recovery coefficient).

[0066] Figure 10The horizontal coordinates 1 to 4 represent the positions of the lip masks in Case 1, Case 2, Case 3, and Case 4, and the vertical coordinates 0.8 to 1.6 represent the Mach number of the throat; the Mach numbers 1.6 to 3.0 in the diagram box in the upper right corner represent the Mach number of the inlet flow.

[0067] Figure 11 The horizontal axes 1 to 4 represent the positions of the lip masks in Case 1, Case 2, Case 3, and Case 4, and the vertical axes 0.4 to 0.8 represent the flow coefficients; the Mach numbers 1.6 to 3.0 in the diagram box in the upper right corner represent the Mach numbers of the inlet flow.

[0068] Figure 12 The horizontal axes 1 to 4 represent the positions of the lip masks in Case 1, Case 2, Case 3, and Case 4, and the vertical axes 0.85 to 0.95 represent the throat total pressure recovery coefficient; the Mach numbers 1.6 to 3.0 in the diagram box in the upper right corner represent the Mach numbers of the inlet flow.

[0069] The inlet lip cover 2 moves along the horizontal direction with the change of the incoming flow Mach number to meet the working performance of the inlet under different incoming flow Mach numbers, that is, to meet the design requirements of the inlet throat Mach number under different incoming flow Mach numbers, such as Figure 10 As shown in the figure: when the incoming flow Mach number is 1.6, 2.1, 2.5, and 3.0, the vertical axis is the throat Mach number curve of profiles Case 1 to Case 4. Among them, when the incoming flow Mach number is 1.6 to 2.5, the throat Mach number of profile Case 4 is less than 1, and is between 0.8 and 1; this is mainly because the lip cover is positioned relatively forward, causing the forebody shock wave to hit the lip cover, and the lip shock wave moves backward. Its reflected wave causes severe flow separation at the throat, thereby resulting in a decrease in the throat Mach number.

[0070] The inlet lip cover 2 moves along the horizontal direction as the incoming flow Mach number changes to meet the working performance of the inlet under different incoming flow Mach numbers, that is, to meet the design requirements of the inlet flow coefficient under different incoming flow Mach numbers, such as Figure 11 As shown in the figure, when the incoming flow Mach number is 1.6, 2.1, 2.5, and 3.0, the vertical axis is the inlet flow coefficient at different lip mask positions; when the inlet is at the same incoming flow Mach number of 3.0, the flow coefficient when the profile is Case 4 is the smallest, which cannot meet the engine's demand for airflow.

[0071] The inlet lip cover 2 moves along the horizontal direction as the incoming flow Mach number changes to meet the working performance of the inlet under different incoming flow Mach numbers, that is, to meet the design requirements of the throat total pressure recovery coefficient under different incoming flow Mach numbers, such as Figure 12As shown in the figure, when the incoming flow Mach number is 1.6, 2.1, 2.5, and 3.0, the vertical axis is the total pressure recovery coefficient of the inlet throat at different lip mask positions. When the inlet is at the same incoming flow Mach number of 3.0, the total pressure recovery coefficient of the throat when the profile is Case 4 is the smallest.

[0072] As can be seen, when the lip guard remains in the forward position (Case 4), at high inflow Mach numbers, the forebody shock wave impinges on the lip guard, and the lip shock wave reflection causes flow separation at the throat, severely degrading inlet performance. Therefore, at high inflow Mach numbers, the position of the inlet lip guard 2 needs to be moved rearward from Case 4. When the inlet is operating at subsonic or low supersonic speeds, the flow coefficient is minimized when the lip guard is at the design point (Case 1), failing to meet the engine's airflow requirements. Therefore, when the inlet is operating at subsonic or low supersonic speeds, the position of the inlet lip guard 2 needs to be moved forward from Case 1 to ensure the inlet remains in normal operation and achieves optimal performance.

[0073] It should be emphasized that the above specific embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the above embodiments as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A binary supersonic variable geometry air inlet with a lip mask that moves horizontally, the air inlet being enclosed by four sides: upper, lower, front, and rear. The lower side is an air inlet body (1-1) with a compression surface located at the bottom of the air inlet. The front and rear sides are air inlet front side panels (1-2) and air inlet rear side panels (1-3) vertically mounted on both sides of the air inlet body (1-1). The upper side is an air inlet lip mask (2) located at the top of the air inlet and arranged opposite to the air inlet body (1-1), and an air inlet expansion section (3) mounted on the same side at the tail of the air inlet lip mask (2). An air inlet inner channel (4) is formed between the air inlet body (1-1), the air inlet front side panels (1-2), the air inlet rear side panels (1-3), the air inlet lip mask (2), and the air inlet expansion section (3). The inner channel (4) is provided with a throat (4-1). The invention is characterized in that: The throat (4-1) is tilted so that the height of the throat (4-1) increases when the lip shield moves forward; the inlet lip shield (2) moves in the horizontal direction as the incoming flow Mach number changes, so as to meet the working performance of the inlet at different incoming flow Mach numbers, that is, the inlet flow coefficient, throat Mach number, and throat total pressure recovery coefficient meet the design requirements at different incoming flow Mach numbers; the throat is such that: the tilted portion of the lip shield (2) is parallel to the corresponding portion of the inlet body (1-1), and the throat length is determined by the shortest distance between parallel lines at the parallel portions; The throat is tilted, specifically: the throat direction is parallel to the front wedge plate (6), and the tilt angle of the throat is the same as the total deflection angle of the airflow. This angle is an angle that balances the change in throat height and the absence of throat obstruction.

2. The dual supersonic variable geometry inlet with a lip mask translation according to claim 1, characterized in that: The compression surface of the air inlet main body (1-1) is composed of an isentropic compression surface (8), and the wedge plate (6) behind it is tangent to the isentropic compression surface (8), and overflow holes of a certain number and size are arranged on the wedge plate (6).

3. The dual supersonic variable geometry inlet with lip mask translation according to claim 1, characterized in that: The inlet lip cover (2) moves along the horizontal direction as the incoming flow Mach number changes, and the specific movement method is: when the incoming flow Mach number is subsonic or low supersonic, the inlet lip cover (2) is located at the leading edge (7-1), and in this incoming flow range, the position of the inlet lip cover (2) remains unchanged; when the incoming flow Mach number gradually increases until it is greater than the Mach number setting value, the inlet lip cover (2) gradually moves backward; when the incoming flow Mach number reaches the inlet design point, the inlet lip cover (2) moves to the design point position (7-2), and no longer moves thereafter; the Mach number setting value is determined at the beginning of the design.

4. The dual supersonic variable geometry inlet with a lip mask translation according to claim 3, characterized in that: The operating range of the inlet is Ma0~3.0, and the flight altitude is between 0-26km. The flight Mach number Ma=3.0 and the flight altitude 24km are selected as the inlet design points.

5. The dual supersonic variable geometry inlet with lip mask translation according to claim 1, characterized in that: The distance that the air inlet lip cover (2) moves forward in the horizontal direction does not exceed the front end of the wedge plate (6).

6. The dual supersonic variable geometry inlet with lip mask translation according to claim 1, characterized in that: The inlet height of the binary supersonic variable geometry inlet is 91.7 mm, the internal compression angle and the total airflow deflection angle are both 13°, the maximum forward movement distance of the lip cover is 25 mm, the height of the throat at the inlet design point is 26.1 mm, the height of the overflow hole is 5 mm, and the width is 2 mm.

7. The dual supersonic variable geometry inlet with a lip mask translation according to claim 1, characterized in that: A gap (5) is provided at a certain distance between the inlet lip shield (2) and the inlet of the expansion section (3). The height of the gap (5) is 1.3 mm. The gap (5) is used to facilitate the horizontal movement of the lip shield (2) without causing other geometric structures to move, and is conducive to self-regulation when the back pressure at the outlet of the inlet changes.

8. The dual supersonic variable geometry inlet with lip mask translation according to claim 1, characterized in that: When the incoming flow Mach number is between 0 and 1.6, the lip cover position moves forward 25 mm compared with the position at the design point; when the incoming flow Mach number is greater than 1.6, the air inlet gradually moves backward. When the incoming flow Mach number is 2.1, the lip cover position moves forward 15 mm compared with the position at the design point; when the incoming flow Mach number is 2.5, the lip cover position moves forward 9 mm compared with the position at the design point; when the incoming flow Mach number is 3.0, the lip cover is at the design position and no longer moves. At this time, the air inlet reaches the rated working state; when the lip cover position moves forward 25 mm, the height of the throat (4-1) is greater than the height of the throat (4-1) when the lip cover position moves forward 15 mm, and the height of the throat (4-1) when the lip cover position moves forward 9 mm.

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