Single / dual flowpath switching binary hypersonic variable geometry inlet and switching method thereof

Abstract

The application discloses a single-double-flow switching type binary hypersonic variable-geometry inlet and a switching method thereof. The inlet comprises an outer compression section, an inner compression section, a splitter plate and a divergent section. The splitter plate is arranged between a lip cover and a lower surface of the divergent section, is parallel to the lower end surface of the lip cover, has a length equal to that of the divergent section, and divides the divergent section into two splitter flow channels. The lower surface of the inner compression section is rotationally connected to one end of the surface of the outer compression section located downstream. A locking device is arranged on a rotating shaft. During operation, the lower surface of the inner compression section and the surface of the outer compression section are locked when the lower surface of the inner compression section is smoothly connected to the lower surface of the divergent section or the splitter plate downstream, so that the two surfaces cannot rotate relative to each other. The single-double-flow switching type binary hypersonic variable-geometry inlet is matched with two different working modes of a downstream ramjet and a scramjet, the height of a throat of the inlet can be controlled, and the inlet designed at a high Mach number can be smoothly started at a low Mach number.

Description

Technical Field

[0001] This invention relates to the field of variable geometry design for hypersonic wide-range inlets, and particularly to a single / dual-channel switching type two-dimensional hypersonic variable geometry inlet and its switching method. Background Technology

[0002] Wide-range hypersonic air-breathing vehicles require inlets capable of operating under a wide range of conditions. However, inlets operating with fixed geometry cannot achieve stable air intake across this wide range. For example, when a wide-range hypersonic inlet operates at Mach 2-10, it may fail to start at lower Mach numbers, such as Mach 2-3, when the design operating point is high. In such cases, variable geometry adjustment mechanisms must be introduced. Furthermore, when the vehicle operates over a wide speed range, the ramjet engine may require a mode transition from subsonic to scramjet mode. In subsonic mode, the expansion section after the inlet throat often requires continuous compression of the subsonic airflow following the tail shock wave. In scramjet mode, the section after the inlet throat must be a constant-area section or a small-expansion-angle profile, known as the isolation section.

[0003] The variable geometry method for solving intake start-up problems generally involves increasing the intake throat area. However, for intakes operating at hypersonic speeds, the section of the intake throat that is behind the throat is called the isolation section. This section is typically a constant-area profile or is required to have a small expansion angle. In this case, without corresponding adjustments to the combustion chamber, it is impossible to achieve a significant expansion of the throat. Combustion chambers used for hypersonic flow have high airflow velocities and temperatures, and are subject to severe structural and thermal challenges. Mechanical adjustments to these chambers present engineering difficulties and high costs, making them impractical in engineering.

[0004] Therefore, a highly feasible variable geometry method is needed to avoid excessive mechanical adjustment, solve the intake duct starting problem and ensure the intake duct operates stably and normally over a wide speed range, while also achieving matching with different working modes of the combustion chamber and improving intake duct performance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the problem of the initiation of wide-speed-range inlet with equal area or small expansion angle isolation section at the hypersonic design point in the low Mach number operating range and the matching problem with different modes of ramjet engine combustion chamber. The present invention provides a single-dual flow channel switching type two-dimensional hypersonic variable geometry inlet and its switching method.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] The single / dual flow switching two-dimensional hypersonic variable geometry inlet includes an external pressure section, an internal pressure section, a splitter plate, and an expander section.

[0008] The manifold is disposed between the lip and the lower profile of the expansion section, parallel to the lower end face of the lip, and has the same length as the expansion section, dividing the expansion section into two flow channels. The manifold and the lip of the expansion section form a flow channel with equal cross-sectional areas, and the manifold and the lower profile of the expansion section form a flow channel with an outlet cross-sectional area larger than the inlet cross-sectional area.

[0009] The lower profile of the inner pressure section is rotatably connected to the lower profile of the outer pressure section via a rotating shaft at one end; the rotating shaft and the outer pressure section profile are coplanar and perpendicular to the airflow direction.

[0010] The rotating shaft is equipped with a locking device, which is used to lock the lower profile of the inner pressure section and the profile of the outer pressure section when the lower profile of the inner pressure section and the lower profile of the expansion section or the diverter plate are smoothly connected, so that they cannot rotate relative to each other.

[0011] As a further optimization of the single / dual flow channel switching binary hypersonic variable geometry inlet of the present invention, the external pressure section adopts a curved compression profile.

[0012] This invention also discloses a switching method for the single / dual-channel switching two-dimensional hypersonic variable geometry inlet, characterized by comprising the following steps:

[0013] If the Mach number of the incoming flow in the single-dual flow switching type two-dimensional hypersonic variable geometry inlet is in the range of [2, 4], the lower profile of the inner pressure section is controlled to rotate relative to the profile of the outer pressure section around the axis of rotation. When the lower profile of the inner pressure section and the lower profile of the expansion section are smoothly connected downstream, the lower profile of the inner pressure section and the profile of the outer pressure section are locked so that they cannot rotate relative to each other.

[0014] If the incoming Mach number of the single / dual flow switching type two-dimensional hypersonic variable geometry inlet is in the range of [5, 10], the lower profile of the inner pressure section is controlled to rotate relative to the profile of the outer pressure section around the axis of rotation. When the lower profile of the inner pressure section is smoothly connected to the splitter plate downstream, the lower profile of the inner pressure section and the profile of the outer pressure section are locked so that they cannot rotate relative to each other.

[0015] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0016] 1. This invention solves the starting problem of an intake at low Mach numbers when the design point is high by constructing a single / dual-flow-channel switching variable geometry intake, greatly widening the stable operating speed range of the intake. Compared with a fixed geometry prototype intake, it has better flow capture within the required operating speed range. Compared with other variable geometry solutions, it avoids the need for mechanical adjustment of the combustion chamber, and has the advantages of simple structure and high engineering feasibility.

[0017] 2. This invention achieves matching with different modes of the ramjet engine by switching between single and dual flow channels. In the low incoming Mach number operating range, the ramjet engine operates in subsonic combustion mode, and the inlet is switched to dual flow channel mode, at which time the section after the throat is generally an expansion section; in the high incoming Mach number operating range, the ramjet engine operates in scramjet mode, and the inlet is a single flow channel with an equal cross-sectional area, at which time the section after the throat is generally an equal area section;

[0018] 3. This invention, by setting up a flow divider, allows the airflow to flow into the combustion chamber in two streams. Under the forward transmission of the intake back pressure, the expanded flow divider always has a lower airflow velocity, providing a concentrated low-speed airflow within a limited space, which is potentially beneficial for ignition and complete combustion of fuel in the combustion chamber. Furthermore, the design parameters of the flow divider can be flexibly adjusted to provide airflow that meets performance requirements for different combustion chambers. Attached Figure Description

[0019] Figure 1 It is a two-dimensional cross-sectional schematic diagram of a fixed geometry air intake;

[0020] Figure 2 It is a contour plot of Mach number when the incoming Mach number of the intake duct is Ma=2 for a given geometry.

[0021] Figure 3 It is a contour plot of Mach number when the incoming Mach number of the intake duct is Ma=3 for a given geometry.

[0022] Figure 4 It is a contour plot of Mach number when the incoming Mach number of the intake duct is Ma=4 for a given geometry.

[0023] Figure 5 It is a contour plot of Mach number when the incoming Mach number of the intake duct is Ma=8 for a given geometry.

[0024] Figure 6 It is a contour plot of Mach number when the incoming Mach number of the intake duct is Ma=10 for a given geometry;

[0025] Figure 7 This is a two-dimensional cross-sectional schematic diagram of the present invention;

[0026] Figure 8 This is a contour map of the Mach number when the Mach number Ma=2 in the flow according to the present invention;

[0027] Figure 9 This is a contour map of the Mach number when the Mach number Ma=3 in the flow according to the present invention;

[0028] Figure 10 This is a contour map of the Mach number when the Mach number Ma=4 in the flow according to the present invention;

[0029] Figure 11 This is a schematic diagram comparing the flow coefficient of the present invention with the Mach number of the incoming flow in a fixed geometry air intake.

[0030] In the figure, 1-the profile of the external pressure section, 2-the lower profile of the internal pressure section in the dual-channel mode, 3-the lower profile of the expansion section, 4-the lip, 5-the manifold, 6-c, 7-the lower profile of the internal pressure section in the single-channel mode, 8-the throat in the single-channel mode, 9-the flow channel between the manifold and the lip of the expansion section, 10-the flow channel between the manifold and the lower profile of the expansion section, 11-the rotating shaft. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings:

[0032] This invention can be implemented in many different forms and should not be considered limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully express the scope of the invention to those skilled in the art. In the drawings, components are enlarged for clarity.

[0033] like Figure 7 As shown, the present invention discloses a single / dual flow channel switching type two-dimensional hypersonic variable geometry inlet, which includes an external pressure section, an internal pressure section, a splitter plate and an expansion section;

[0034] The manifold is disposed between the lip and the lower profile of the expansion section, parallel to the lower end face of the lip, and has the same length as the expansion section, dividing the expansion section into two flow channels. The manifold and the lip of the expansion section form a flow channel with equal cross-sectional areas, and the manifold and the lower profile of the expansion section form a flow channel with an outlet cross-sectional area larger than the inlet cross-sectional area.

[0035] The lower profile of the inner pressure section is rotatably connected to the lower profile of the outer pressure section via a rotating shaft at one end; the rotating shaft and the outer pressure section profile are coplanar and perpendicular to the airflow direction.

[0036] The rotating shaft is equipped with a locking device, which is used to lock the lower profile of the inner pressure section and the profile of the outer pressure section when the lower profile of the inner pressure section and the lower profile of the expansion section or the diverter plate are smoothly connected, so that they cannot rotate relative to each other.

[0037] This invention also discloses a switching method for the single / dual-channel switching two-dimensional hypersonic variable geometry inlet, characterized by comprising the following steps:

[0038] If the Mach number of the incoming flow in the single-dual flow switching type two-dimensional hypersonic variable geometry inlet is in the range of [2, 4], the lower profile of the inner pressure section is controlled to rotate relative to the profile of the outer pressure section around the axis of rotation. When the lower profile of the inner pressure section and the lower profile of the expansion section are smoothly connected downstream, the lower profile of the inner pressure section and the profile of the outer pressure section are locked so that they cannot rotate relative to each other.

[0039] If the incoming Mach number of the single / dual flow switching type two-dimensional hypersonic variable geometry inlet is in the range of [5, 10], the lower profile of the inner pressure section is controlled to rotate relative to the profile of the outer pressure section around the axis of rotation. When the lower profile of the inner pressure section is smoothly connected to the splitter plate downstream, the lower profile of the inner pressure section and the profile of the outer pressure section are locked so that they cannot rotate relative to each other.

[0040] The external pressure section preferentially adopts a curved compression profile, which gradually bends outward along the flow direction from the initial compression angle at its leading edge to form a curved configuration. Under supersonic inflow conditions, it will generate a curved compression shock wave, which, in conjunction with the inlet lip, has a high flow capture capability over a wide range of Mach number variations.

[0041] The internal pressure section can switch between single and dual flow modes by rotating its lower profile, and can also adjust the flow area of ​​the throat of the internal pressure section to ensure the flow capacity of the intake at lower Mach numbers; the rotation adjustment achieves compatibility between high Mach number compression and low Mach number start-up, ensuring stable operation of the intake across a wide speed range.

[0042] The expansion section is connected to the downstream sudden expansion combustion chamber. When the high Mach number ramjet engine is operating in scramjet mode, the lower profile of the internal pressure section closes the flow channel between the splitter plate and the lower profile of the expansion section by rotation. At this time, the intake is in single-channel mode with a high internal contraction ratio, which matches the scramjet operating mode of the downstream combustion chamber.

[0043] When a low Mach number ramjet engine operates in sub-gas mode, the lower profile of the internal pressure section opens the flow channel between the splitter and the lower profile of the expansion section by rotation, increasing the throat. At this time, the intake duct has a dual-flow channel mode with a low internal contraction ratio, which matches the sub-gas operating mode of the downstream combustion chamber.

[0044] This invention abandons the traditional internal flow intake layout with a single-channel intake and proposes a variable geometry adjustment method that switches between single and dual-channel intakes. Existing technologies, when dealing with intakes with isolating sections of equal area or small expansion angles, cannot effectively control the throat height or flow area without requiring corresponding mechanical adjustments to the combustion chamber. This invention achieves switching between single and dual-channel operating modes by rotating and adjusting the profile of the inner compression section. This allows the intake to have throat characteristics and an expansion / equal-area isolating section after the throat that adapt to the combustion chamber's operating modes in different Mach number ranges, and solves the problem of not starting under low incoming Mach number conditions.

[0045] like Figure 1 As shown, a two-dimensional curved surface compression inlet with a fixed geometry is given. The inlet operates in the range of Ma=2-10 and the flight altitude is between 10.93-31.79km. The incoming flow Mach number at the design point is selected as Ma=8 and the flight altitude is 28.79km. The isolation section after the throat of the inlet is a section of equal area.

[0046] Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 Mach number contour plots obtained from numerical simulations of a two-dimensional constant geometry inlet under incoming Mach numbers of Ma=2, 3, 4, 8, and 10 are presented. At an incoming Mach number of Ma=10, the curved shock wave enters the lip, indicating the inlet is operating beyond its rated capacity, yet it still allows normal air intake. At an incoming Mach number of Ma=8, the external compression curved shock wave formed by the hypersonic flow compression surface enters at the leading edge of the lip. At Ma=2 and Ma=3, the constant geometry inlet remains stationary; in these conditions, its flow capture capability drops sharply, failing to provide sufficient airflow for the normal operation of the aircraft.

[0047] When the intake is in dual-flow mode, the airflow enters the combustion chamber through two separate flow channels. When the intake switches to single-flow mode, the airflow enters the combustion chamber through the flow channel between the splitter and the diffuser lip. The throat of the dual-flow mode and the throat of the single-flow mode are as follows: Figure 7 As shown.

[0048] A specific example of variable geometry implementation is as follows: In the low Mach number range (Ma=2-4), the intake is in dual-flow mode, with a throat diameter of 40.5991 mm. The airflow is split by the splitter and flows into the two separate flow channels before entering the combustion chamber. As the incoming Mach number further increases to the high Mach number range (Ma=5-10), the lower profile of the inner compression section is rotated counterclockwise around the axis, putting the intake in single-flow mode. In this single-flow mode, the throat diameter is 29 mm. The airflow enters the combustion chamber only through the flow channel between the splitter and the diffuser lip.

[0049] Figure 8 , Figure 9 , Figure 10 The Mach number contour maps obtained through numerical simulation are shown for the intake duct switching to dual-flow mode in the low Mach number operating range (Ma=2-4) at Ma=2, Ma=3, and Ma=4, respectively. As can be seen from the figure, after switching to dual-flow mode, the throat flow area of ​​the intake duct expands, allowing airflow to flow smoothly into the intake duct at Ma=2-3, thus avoiding blockage of the intake duct's flow channels.

[0050] Figure 11 The graph shows the flow coefficient variation curves of a fixed geometry inlet and a single / dual-flow-channel switching variable geometry inlet under different incoming Mach numbers. The horizontal axis represents the incoming Mach number, and the vertical axis represents the inlet flow capture coefficient. This demonstrates that the single / dual-flow-channel switching variable geometry method solves the initiation problem of a fixed geometry inlet at Mach 2 and Mach 3.

[0051] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0052] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A single / dual-channel switching two-dimensional hypersonic variable geometry inlet, comprising an external pressure section, an internal pressure section, and a diffuser section, characterized in that, It also includes a splitter plate; The manifold is disposed between the lip and the lower profile of the expansion section, parallel to the lower end face of the lip, and has the same length as the expansion section, dividing the expansion section into two flow channels. The manifold and the lip of the expansion section form a flow channel with equal cross-sectional areas, and the manifold and the lower profile of the expansion section form a flow channel with an outlet cross-sectional area larger than the inlet cross-sectional area. The lower profile of the inner pressure section is rotatably connected to the lower profile of the outer pressure section via a rotating shaft, allowing the lower profile of the inner pressure section to rotate freely relative to the outer pressure section profile around the rotating shaft; the rotating shaft and the outer pressure section profile are coplanar and perpendicular to the airflow direction. The rotating shaft is equipped with a locking device, which is used to lock the lower profile of the inner pressure section and the profile of the outer pressure section when the lower profile of the inner pressure section and the lower profile of the expansion section or the diverter plate are smoothly connected, so that they cannot rotate relative to each other.

2. The single / dual-channel switching binary hypersonic variable geometry inlet according to claim 1, characterized in that, The external pressure section adopts a curved compression profile.

3. The switching method for a single / dual-channel switching binary hypersonic variable geometry inlet as described in claim 1, characterized in that, Includes the following steps: If the Mach number of the incoming flow in the single-dual flow switching type two-dimensional hypersonic variable geometry inlet is in the range of [2, 4], the lower profile of the inner pressure section is controlled to rotate relative to the profile of the outer pressure section around the axis of rotation. When the lower profile of the inner pressure section and the lower profile of the expansion section are smoothly connected downstream, the lower profile of the inner pressure section and the profile of the outer pressure section are locked so that they cannot rotate relative to each other. If the incoming Mach number of the single / dual flow switching type two-dimensional hypersonic variable geometry inlet is in the range of [5, 10], the lower profile of the inner pressure section is controlled to rotate relative to the profile of the outer pressure section around the axis of rotation. When the lower profile of the inner pressure section is smoothly connected to the splitter plate downstream, the lower profile of the inner pressure section and the profile of the outer pressure section are locked so that they cannot rotate relative to each other.

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