A waverider precursor hypersonic inlet with dual cantilever pre-injection

Abstract

The present invention discloses a waverider forebody hypersonic inlet with double cantilever pre-injection, comprising an inlet inner wall, a lip cover located on the inlet inner wall, a compression surface extending forward from the inlet inner wall, and a waverider lower surface directly connected to the compression surface; the inlet inner wall and the lip cover together form an inlet inner channel; a straight section extending rearward from the inner channel; a swept side panel arranged on one side of the inlet inner channel and the straight section; and a waverider upper surface for integrating the inlet with the aircraft; a cantilever structure is provided on the last-stage compression surface of the forebody and the inner wall of the lip cover of the waverider forebody inlet, through which fuel is injected, and while ensuring the inlet flow coefficient and the total pressure recovery coefficient, the longer forebody and the inner channel of the hypersonic inlet are utilized to achieve early and sufficient mixing of fuel and incoming air, thereby providing a combustible mixture conducive to combustion for the combustion chamber connected to the rear of the inlet.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft air inlets, and in particular to a waverider precursor hypersonic air inlet with double cantilever pre-injection. Background Art

[0002] The development of hypersonic vehicles since the 1960s has fully demonstrated that airframe / engine integrated design is key to hypersonic aircraft design. Efficient forebody / inlet integrated design is a research focus for this type of design. The waverider body relies on the contact of the leading edge shock wave to efficiently capture the incoming flow, reducing the overflow of the airflow from the lower surface to the upper surface, thereby improving the aerodynamic performance of the aircraft. It also pre-compresses the incoming flow, increasing the inlet flow coefficient and total pressure recovery coefficient, and improving the lift-to-drag ratio of the aircraft, gradually becoming the ideal forebody configuration for hypersonic aircraft.

[0003] For air-breathing ramjets, the fuel's residence time in the combustion chamber is extremely short, on the order of milliseconds. To ensure fuel ignition and stable combustion, the ideal state for the fuel and incoming air is a molecular-level mixing at a chemically appropriate ratio. Cantilevered injectors utilize a long inlet duct for pre-injection of fuel, allowing the fuel and air to be mixed before entering the combustion chamber, ensuring stable and complete combustion of the fuel / air mixture within the combustion chamber.

[0004] The application of cantilevered injectors in the waverider forebody inlet not only meets the requirements for airframe / inlet integration, but also enables pre-mixing of fuel and air in the inlet, ensuring ideal ramjet detonation and settling. Therefore, designing a waverider forebody inlet with dual cantilevered pre-injectors is key to achieving integrated inlet mixing for hypersonic vehicles. Summary of the Invention

[0005] Purpose of the invention: The present invention provides a waverider precursor hypersonic inlet with dual cantilever pre-injection, the purpose of which is to achieve aircraft / inlet integration and provide a uniformly mixed combustible mixture for the scramjcter at the inlet outlet.

[0006] Technical solution: The present invention proposes a waverider front hypersonic inlet with dual cantilever pre-injection, comprising an inlet inner wall, a lip cover located on the inlet inner wall, the inlet inner wall and the lip cover together forming an inlet inner channel, a straight section extending rearward from the inner channel, a waverider front, and a swept side plate arranged on one side of the inlet inner channel and the straight section; the waverider front comprises a compression surface extending forward from the inner channel and a waverider lower surface directly connected to the front end of the compression surface; the compression surface is provided with a plurality of lower cantilever pre-injection structures arranged side by side, the compression surface A first high-pressure fuel chamber is provided inside that is connected to the lower cantilever pre-injection structure; a plurality of upper cantilever pre-injection structures are arranged side by side on the inner wall of the lip cover, and a second high-pressure gas chamber is provided inside the lip cover that is connected to the upper cantilever pre-injection structure; and the lower cantilever pre-injection structure corresponds one to one with the upper cantilever pre-injection structure; the axis of the lower cantilever pre-injection structure is at a specific angle to the compression surface of the intake duct, and the axis of the upper cantilever pre-injection structure is at a specific angle to the straight section of the intake duct, and both the upper cantilever pre-injection structure and the lower cantilever pre-injection structure extend into the inner channel of the intake duct.

[0007] Preferably, it also has an upper surface of the waverider that realizes the integrated design of the air inlet and the aircraft; the lower surface of the waverider is connected to the upper surface of the waverider, the lower surface of the waverider is the pre-compression surface of the air inlet, and the upper surface of the waverider is the upper surface of the aircraft.

[0008] Preferably, the lower cantilever injection structure includes a cantilever outer wall, a gas channel connected to the first high-pressure gas chamber, and an injection port; the upper cantilever pre-injection structure includes a cantilever outer wall, a gas channel connected to the second high-pressure gas chamber, and an injection port.

[0009] Preferably, the cross-sectional shape of the upper cantilever pre-injection structure and the lower cantilever pre-injection structure is circular.

[0010] Preferably, the upper cantilever pre-injection structure and the lower cantilever pre-injection structure are arranged side by side on the compression surface and the inner wall surface of the lip mask at a center distance of 8 times the cantilever outer diameter.

[0011] Preferably, a specific distance is maintained between the center point of the end face where the lower cantilever injection port is located and the compression surface; a specific distance is maintained between the center point of the end face where the upper cantilever injection port is located and straight sections such as the air inlet duct.

[0012] Preferably, the distance between the center point of the end face where the lower cantilever injection port is located and the compression surface is 20 mm; the distance between the center point of the end face where the upper cantilever injection port is located and the straight section such as the air inlet duct is 10 mm.

[0013] Preferably, a specific flow distance is maintained between the center point of the end face where the lower cantilever injection port is located and the leading edge of the air inlet lip cover; a specific flow distance is maintained between the center point of the end face where the upper cantilever injection port is located and the leading edge of the air inlet lip cover.

[0014] Preferably, the flow distance between the center point of the end face where the lower cantilever injection port is located and the leading edge of the air inlet lip cover is 30 mm; the flow distance between the center point of the end face where the upper cantilever injection port is located and the leading edge of the air inlet lip cover is 190 mm.

[0015] Preferably, the axis of the lower cantilever pre-injection structure is at an angle of 10° to the last-stage compression surface of the air inlet duct; and the axis of the upper cantilever pre-injection structure is at an angle of 3° to the straight section of the air inlet duct.

[0016] Beneficial Effects: This invention directly connects the inlet to the waverider body, creating a waverider forebody inlet. This design satisfies the integrated design requirements of the aircraft and the inlet, achieving pre-compression of the incoming airflow while improving its capture efficiency. Furthermore, cantilevered pre-injection structures are provided on the compression surface of the inlet and the inner surface of the lip shield for fuel injection. The long forebody and inner flow channel of the inlet enable pre-mixing of the fuel and incoming air, providing a uniformly mixed oil-air mixture for the hypersonic engine combustion chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is a schematic cross-sectional view of a waverider precursor hypersonic inlet with a double-cantilever pre-injection structure according to the present invention;

[0018] Figure 2 This is a schematic diagram of the cantilever position and structure of the waverider precursor hypersonic inlet with a double-cantilever pre-injection structure of the present invention;

[0019] Figure 3 1. It is an overall schematic diagram of the waverider precursor hypersonic inlet with a double-cantilever pre-injection structure of the present invention;

[0020] Figure 4 It is a partial enlarged view of the position of the upper and lower cantilever pre-injection structure in the present invention;

[0021] Figure 5 Experiment 1 is a Mach number contour diagram of the original inlet forebody along the streamwise cross section when the waverider forebody hypersonic inlet with a double cantilever pre-injection structure of the present invention is not provided with a cantilever structure;

[0022] Figure 6 Experiment 1 is a numerical schlieren diagram of the original hypersonic inlet along the spanwise cross section when the waverider precursor hypersonic inlet with a double cantilever pre-injection structure of the present invention is not provided with a cantilever structure;

[0023] Figure 7Experiment 2 is a numerical schlieren diagram of the inlet along the spanwise cross section when the waverider hypersonic inlet with a dual-cantilever pre-injection structure of the present invention is equipped with a dual-cantilever structure but without injection;

[0024] Figure 8 Experiment 3 is a numerical schlieren diagram of the inlet duct along the spanwise cross section when the double cantilever structure of the double cantilever pre-injection structure of the precursor of the present invention is injected;

[0025] Figure 9 is a graph showing the change in the outlet total pressure recovery coefficient along the inlet height for the three experimental inlets mentioned above;

[0026] Figure 10 This is the ethylene fuel distribution map taken along the flow direction in Experiment 3;

[0027] Figure 11 This is the mass fraction curve of ethylene fuel along the inlet height at the throat position in Experiment 3;

[0028] Figure 12 is the static temperature distribution curve along the throat height at the throat position in Experiment 3;

[0029] Figure 13 It is an overall three-dimensional schematic diagram of the waverider precursor hypersonic inlet with a double-cantilever pre-injection structure of the present invention.

[0030] Among them, 1. Inner wall of the air inlet; 2. Lip cover; 3. Compression surface; 4. Lower surface of the waverider; 5. Inner channel of the air inlet; 6. Straight section of the air inlet; 7. Swept side plate; 8. Upper surface of the waverider; 9. Pre-injection structure of the lower cantilever; 10. First high-pressure gas chamber; 11. Pre-injection structure of the upper cantilever; 12. Second high-pressure gas chamber; 91. Outer wall of the lower cantilever; 92. Gas channel of the lower cantilever; 93. Injection port of the lower cantilever; 111. Outer wall of the upper cantilever; 112. Gas channel of the upper cantilever; 113. Injection port of the upper cantilever. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.

[0032] like Figure 1The waverider precursor hypersonic inlet with dual cantilever pre-injection shown includes an inlet inner wall 1, a lip cover 2, a compression surface 3 extending forward from the inner wall 1, a waverider lower surface 4 directly connected to the compression surface, an inlet inner channel 5 surrounded by the inlet inner wall 1 and the lip cover 2, a straight section 6 extending rearward from the inlet inner channel 5, a swept side panel 7 arranged on one side of the inlet inner channel 5 and the straight section 6, and an upper surface 8 of the waverider serving as the upper surface of the aircraft; the lower cantilever pre-injection structure 9 arranged on the compression surface 3, a first high-pressure gas chamber 10 disposed in the compression surface 3, an upper cantilever pre-injection structure 11 arranged on the inner wall of the lip cover 2, and a second high-pressure gas chamber 12 disposed in the lip cover 2.

[0033] The lower surface of the waverider is directly connected to the compression surface of the inlet, ensuring a rectangular inlet inlet profile. The lower surface of the waverider is used to pre-compress the incoming airflow, ensuring efficient airflow capture. The upper surface of the waverider also serves as the upper surface of the vehicle, achieving an integrated vehicle / inlet design and improving the vehicle's aerodynamic performance.

[0034] The upper and lower cantilever pre-injection structures are respectively arranged on the inner wall of the lip cover 2 and the compression surface 3 and are in a certain proportion to the length of the intake duct. The purpose is to achieve sufficient mixing of fuel and air by utilizing the long flow length of the intake duct without affecting the intake duct capture flow and the intake duct front body wave system structure. Figure 2 As shown, the cantilever pre-injection structure mainly includes cantilever outer walls 91 and 111, a gas channel 92 and an injection port 93 connected to the first high-pressure gas chamber 10, and a gas channel 112 and an injection port 113 connected to the second high-pressure gas chamber 12.

[0035] The design method of the waverider front body air inlet with the double cantilever pre-injection structure is further explained. Take the combination of the cone and the wedge surface as the reference flow field, take the waverider rear edge profile as the straight line, and use the streamline tracing method to trace the streamline as the lower surface 4 of the waverider; at the same time, take the free streamline backward through the leading edge profile of the lower surface 4, and take the free streamline as the upper surface 8 of the waverider. The two-stage compression surface 3 of the front body of the air inlet is directly connected to the lower surface of the waverider, and is designed according to the intersection of the oblique shock wave generated by the lower surface of the waverider and the compression surface at the leading edge of the air inlet lip cover 2. At the same time, the air inlet width is set according to the flow rate required by the engine. In order to ensure the capture efficiency of the air inlet and take into account the problem of air inlet starting, swept side panels 7 are set on the sides of the channel 5 and the straight section 6 in the air inlet, as shown in FIG. Figure 3 shown.

[0036] To minimize the impact of the cantilever pre-injection structure on the compression surface 3 and the shock wave system on the waverider's lower surface 4, the lower cantilever pre-injection structure 9 is positioned on the inlet compression surface 3, while the upper cantilever pre-injection structure 11 is located on the inner wall of the lip shield 2, virtually eliminating any impact on the compression surface 3 and the shock wave system on the waverider's lower surface 4. To minimize the impact of the cantilever pre-injection structure on the inlet total pressure recovery coefficient, the cantilever cross-section is designed to be circular, with an outer diameter of 4 mm and a center-to-center distance of 32 mm. The lower cantilever forms a specific angle with the inlet compression surface 3, and the upper cantilever forms a specific angle with the straight section. To ensure that the fuel injected by the cantilever pre-injection structure is fully mixed with the captured inlet flow and is not pre-ignited by the high-temperature gas near the wall, the center-to-center heights of the cantilever pre-injection structure's injection ports 93 and 113 are set to specific values ​​from the wall surface on which they are located, and the flow direction distances of the center-to-center distances of the injection ports 93 and 113 from the leading edge of the lip shield 2 are set to specific values.

[0037] Based on the above design criteria, a waverider forebody hypersonic inlet with a dual-cantilever pre-injection structure was designed. A verification experiment was then conducted, with ethylene selected as the injection fuel. The feasibility of the present invention was demonstrated by comparing the flow fields of an inlet without a cantilever pre-injection structure, an inlet with a dual-cantilever structure but without injection, and an inlet with a dual-cantilever pre-injection structure and injection, and evaluating the distribution of the pre-injected fuel within the inlet. The experiment employed a three-wave system (shock waves generated on the waverider's lower surface and two-stage compression on the inlet forebody) designed for Ma10 operation. The shock wave angle generated by the waverider's lower surface (4) was 10.6°, and the corresponding wedge angles of the two-stage compression surfaces of the inlet were 3° and 3.4°, respectively. At this point, the shock waves emitted by each compression surface converged precisely at the leading edge of the inlet lip (2). Cantilever pre-injection structures are installed on the inlet duct compression surface and the inner wall of the lip shield. The cantilever outer diameter is 4mm, and the injection port diameter is 3mm, resulting in a center-to-center distance of 32mm between the cantilevers. The position and dimensions of the cantilever pre-injection structures are determined according to the following conditions: the cantilevers are arranged side by side, with four cantilever structures placed on one side. The angle between the lower cantilever pre-injection structure 9 and the inlet duct compression surface 3 is 10°, the center height of the injection port 93 is 20mm from the inlet duct compression surface, and the flow distance from the leading edge of the inlet lip shield is 30mm. The angle between the upper cantilever pre-injection structure 11 and the upper wall of the inlet straight section 6 is 3°, the center height of the injection port 113 is 10mm from the upper wall of the inlet straight section 6, and the flow distance from the leading edge of the inlet lip shield is 190mm.

[0038] Figures 5 to 8 The wave structure changes of the inlet flow field after setting up the cantilever pre-injection structure and further implementing the pre-injection are given. Figure 5It can be seen that the wave system structure of the designed waverider forebody can effectively capture the incoming flow and improve the aerodynamic performance of the aircraft. In both the non-injection state and the injection state, the lower cantilever pre-injection structure 9 will induce a new shock wave in the inlet channel to further compress the incoming flow; at the same time, the lip shock wave is affected by the induced shock wave generated by the lower cantilever pre-injection structure 9 and deflected toward the inner wall of the lip mask, intersecting with the induced shock wave generated by the upper cantilever pre-injection structure 11 to form a stronger shock wave, but it does not affect the wave system of the inlet forebody and its ability to capture the incoming flow. After the injection is implemented, the cantilever induced shock wave is deflected upward under the influence of the injection, and its impact point on the lip shock wave moves forward. From the given schlieren diagram in the spanwise direction of the inlet, it can be seen that the flow field structure generated by each cantilever in the inlet is basically the same, and the shock wave intersection point near the side panel (the larger the z value, the closer to the side panel) moves slightly toward the inner channel.

[0039] Table 1 compares the inlet outlet performance of the three experiments described above. It shows that the designed waverider forebody inlet is able to fully compress the incoming flow while achieving a high total pressure recovery coefficient and incoming flow capture efficiency. The cantilever pre-injection structure and fuel pre-injection further compress the inlet outlet flow, reducing the Mach number and total pressure recovery coefficient. However, since the inlet forebody shock wave system has little effect, the inlet flow coefficient remains essentially unchanged. When pre-injection is implemented using the scheme described in the present invention, the average total pressure recovery coefficient at the inlet outlet remains around 0.2.

[0040] from Figure 9 It can be seen that the effects of the cantilever pre-injection structure and its use for fuel pre-injection on the total pressure recovery coefficient of the intake duct are concentrated in the main flow area near the lower wall (10mm to 30mm from the wall). The addition of the cantilever pre-injection structure reduces the boundary layer thickness on the lower wall of the intake duct. In the middle of the intake duct, where the cantilever injection is most strongly affected, the total pressure recovery coefficient reaches a maximum of 0.2. On the symmetrical surface of the intake duct, where the cantilever injection is less affected, the total pressure recovery coefficient reaches a maximum of 0.5.

[0041] Table 1 Comparison of air intake performance

[0042]

[0043] Figure 10 The distribution of injected ethylene fuel within the inlet duct's straight sections is shown. As can be seen from the figure, the upper cantilever jet is concentrated at the throat due to its smaller mixing distance, vertically contacting the lower cantilever jet, while some spanwise distance exists between the cantilever jets. As the jets develop along the flow, they gradually merge vertically and spanwise, forming a hilly shape that is evenly mixed with the captured flow at the inlet duct exit. Figure 11 and Figure 12 The ethylene fuel mass fraction and static temperature distribution along the symmetry line (sym) and centerline (z = 80 mm) of the inlet outlet cross section are shown. Ethylene concentration varies across the span, with a higher concentration near the center. The ethylene mass fraction is lower near the upper wall, where temperatures are higher, and higher near the lower wall, where temperatures are higher. Therefore, thermal protection of the lower wall is necessary in practical applications.

[0044] Table 2 shows the mixing efficiency of the ethylene fuel and the main flow along the flow direction within the straight section of the inlet duct. L is the length of the straight section, and the efficiency is calculated according to the Rogers mixing efficiency. As can be seen from Table 2, the mixing efficiency reaches 0.79 at the inlet duct outlet, indicating that the ethylene fuel and the incoming air are mixed relatively evenly.

[0045] In summary, it can be seen that the use of the waverider front hypersonic inlet with a double cantilever pre-injection structure of the present invention (such as Figure 13 ) enables efficient capture of incoming air, ensuring aerodynamic performance in the intake duct, while also ensuring efficient mixing between the pre-injected fuel and the captured incoming air. The intake duct with a dual-cantilever pre-injection structure provides a highly evenly mixed, high-total-pressure gas mixture for the subsequent scramjet combustor.

[0046] Table 2 Mixing efficiency

[0047]

Claims

1. A waverider precursor hypersonic inlet with dual cantilever pre-injection, characterized in that: The invention comprises an air inlet duct inner wall surface (1), a lip cover (2) located on the air inlet duct inner wall surface (1), the air inlet duct inner wall surface (1) and the lip cover (2) together enclosing an air inlet duct inner channel (5), and an equal straight section (6) extending backward from the inner channel (5), a waverider front body, and a swept side plate (7) arranged on one side of the air inlet duct inner channel (5) and the equal straight section (6); the waverider front body comprises a compression surface (3) extending forward from the inner channel (5) and a waverider body lower surface (4) directly connected to the front end of the compression surface (3); the compression surface (3) is provided with a plurality of lower cantilever pre-injection structures (9) arranged side by side, and the compression surface (3) is provided with a plurality of lower cantilever pre-injection structures (9) connected to the lower cantilever pre-injection structures (9) inside. The invention relates to a first high-pressure gas chamber (10) connected to the intake duct; the inner wall surface of the lip cover (2) is provided with a plurality of upper cantilever pre-injection structures (11) arranged side by side, and the interior of the lip cover (2) is provided with a second high-pressure gas chamber (12) connected to the upper cantilever pre-injection structure (11); and the lower cantilever pre-injection structure (9) corresponds to the upper cantilever pre-injection structure (11) one above and one below; the axis of the lower cantilever pre-injection structure (9) forms a specific angle with the intake duct compression surface (3), the axis of the upper cantilever pre-injection structure (11) forms a specific angle with the intake duct straight section (6), and both the upper cantilever pre-injection structure (11) and the lower cantilever pre-injection structure (9) extend toward the intake duct inner channel (5).

2. The waverider precursor hypersonic inlet with dual cantilever pre-injection according to claim 1, characterized in that: The invention also has a waverider upper surface (8) for realizing an integrated design of an air inlet and an aircraft; a waverider lower surface (4) is connected to the waverider upper surface (8); the waverider lower surface (4) is a pre-compression surface of the air inlet, and the waverider upper surface (8) is an upper surface of the aircraft.

3. The waverider precursor hypersonic inlet with dual cantilever pre-injection according to claim 1, characterized in that: The lower cantilever pre-injection structure (9) comprises a cantilever outer wall surface (91), a gas channel (92) connected to the first high-pressure gas chamber (10), and a lower cantilever injection port (93); the upper cantilever pre-injection structure (11) comprises a cantilever outer wall surface (111), a gas channel (112) connected to the second high-pressure gas chamber (12), and an upper cantilever injection port (113).

4. The waverider precursor hypersonic inlet with dual cantilever pre-injection according to claim 1, characterized in that: The cross-sectional shapes of the upper cantilever pre-injection structure (11) and the lower cantilever pre-injection structure (9) are circular.

5. The waverider precursor hypersonic inlet with dual cantilever pre-injection according to claim 4, characterized in that: The upper cantilever pre-injection structure (11) and the lower cantilever pre-injection structure (9) are arranged side by side on the compression surface (3) and the inner wall surface of the lip cover (2) at a center distance of 8 times the cantilever outer diameter.

6. The waverider precursor hypersonic inlet with dual cantilever pre-injection according to claim 3, characterized in that: A specific distance is maintained between the center point of the end face where the lower cantilever injection port (93) is located and the compression surface; a specific distance is maintained between the center point of the end face where the upper cantilever injection port (113) is located and the straight section such as the air inlet.

7. The waverider precursor hypersonic inlet with dual cantilever pre-injection according to claim 6, characterized in that: The distance between the center point of the end face where the lower cantilever injection port (93) is located and the compression surface is 20 mm; the distance between the center point of the end face where the upper cantilever injection port (113) is located and the straight section of the air inlet is 10 mm.

8. The waverider precursor hypersonic inlet with dual cantilever pre-injection according to claim 7, characterized in that: A specific flow distance is maintained between the center point of the end face where the lower cantilever injection port (93) is located and the front edge of the air inlet lip cover (2); and a specific flow distance is maintained between the center point of the end face where the upper cantilever injection port (113) is located and the front edge of the air inlet lip cover (2).

9. The waverider precursor hypersonic inlet with dual cantilever pre-injection according to claim 8, characterized in that: The flow distance between the center point of the end face where the lower cantilever injection port (93) is located and the front edge of the air inlet lip cover is 30 mm; the flow distance between the center point of the end face where the upper cantilever injection port (113) is located and the front edge of the air inlet lip cover is 190 mm.

10. The waverider precursor hypersonic inlet with dual cantilever pre-injection according to claim 1, characterized in that: The axis of the lower cantilever pre-injection structure (9) is at an angle of 10° to the last-stage compression surface (3) of the air inlet duct; and the axis of the upper cantilever pre-injection structure (11) is at an angle of 3° to the straight section (6) of the air inlet duct.

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