Fuel injection and reinforced mixing device of oblique detonation engine

Abstract

The invention discloses an oblique detonation engine fuel injection and reinforced mixing device which comprises a fuel injection support plate arranged in a combustion chamber, a cylindrical reinforced mixing plate horizontally erected and fixed in the combustion chamber, and a plurality of fuel injection holes formed in the tail end of the fuel injection support plate in the width direction of the fuel injection support plate. The circumferential side wall of the cylindrical reinforced mixing plate is opposite to the tail end of the fuel injection support plate, and the cylindrical reinforced mixing plate and the fuel injection support plate meet the following conditions at the same time: Hgt; d; llt; 2H; wherein D is the diameter of the cylindrical reinforced mixing plate, H is the height of the tail end of the fuel injection support plate, and L is the horizontal linear distance from the center of the cylindrical reinforced mixing plate to the tail end of the fuel injection support plate. According to the invention, through the arrangement of the cylindrical reinforced mixing plate, a new vortex structure can be induced to be formed during fuel injection for reinforced mixing, and the cylindrical reinforced mixing plate can divide the fuel into an upper layer and a lower layer, so that the fuel can be respectively mixed, and the fuel mixing efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, specifically to a fuel injection and enhanced mixing device for a slant detonation engine. Background Technology

[0002] The speed of the oblique detonation engine exceeds Mach 7. After the fuel is injected from the fuel injection hole, it only stays in the combustion chamber for a few milliseconds. It is very difficult to achieve uniform fuel mixing in such a short time. Uneven fuel mixing has a huge impact on the detonation performance and stability of the oblique detonation engine.

[0003] Currently, oblique detonation engines widely use fuel injection support plates as the main fuel supply and flame stabilization solution. The fuel injection support plate is used for injection by a single support plate or a combination of multiple support plates. Conventional fuel injection support plates have only one main recirculation zone. Although this recirculation zone helps to anchor the flame, its size is limited and the vortex intensity decreases rapidly with downstream distance. As a result, its entrainment and mixing effect on fuel and air is mainly concentrated in the near-field region. Furthermore, the fuel injected from the fuel injection port of the fuel injection support plate is often concentrated in the center of the fuel injection support plate, which is not conducive to fuel diffusion and mixing. Summary of the Invention

[0004] The purpose of this invention is to provide a fuel injection and enhanced mixing device for a tilt detonation engine, so as to solve the problem of low fuel mixing efficiency in existing tilt detonation engines.

[0005] The technical solution of this invention is: A fuel injection and enhanced mixing device for a tilt-knock engine includes a fuel injection support plate disposed in a combustion chamber. The tail end of the fuel injection support plate has multiple fuel injection holes along its width direction. It also includes a cylindrical enhanced mixing plate, horizontally mounted and fixed within the combustion chamber, with its circumferential sidewall directly opposite the tail end of the fuel injection support plate. Both the cylindrical enhanced mixing plate and the fuel injection support plate simultaneously satisfy the following conditions: H>D; L<2H; Wherein, D is the diameter of the cylindrical reinforced blending plate, H is the height of the tail end of the fuel injection support plate, and L is the horizontal straight-line distance between the center of the cylindrical reinforced blending plate and the tail end of the fuel injection support plate.

[0006] Preferably, as a further improvement of the present invention, the ratio of H to D is in the range of 1:(0.41~0.99), and the ratio of H to L is in the range of 1:(0.5~1.99).

[0007] Preferably, as a further improvement of the present invention, the ratio of H to D is 1:0.9, and the ratio of H to L is 1:1.4.

[0008] Preferably, as a further improvement of the present invention, the cylindrical reinforced blending plate is provided with a plurality of annular grooves in the circumferential direction, and the plurality of annular grooves are evenly distributed along the axial direction of the cylindrical reinforced blending plate. The plurality of annular grooves give the cylindrical reinforced blending plate a plurality of alternating protruding sections and recessed sections, wherein the diameter of the protruding section is D.

[0009] Preferably, as a further improvement of the present invention, the circumferential sidewalls of the protruding section and the circumferential sidewalls of the recessed section are both straight surfaces.

[0010] Preferably, as a further improvement of the present invention, the circumferential sidewall of the protruding segment is an outwardly convex arc-shaped surface, and the circumferential sidewall of the concave segment is an inwardly concave arc-shaped surface.

[0011] Preferably, as a further improvement of the present invention, the axial length of the protruding segment is equal to the axial length of the recessed segment.

[0012] Preferably, as a further improvement of the present invention, the cylindrical reinforced blending plate is made of a high-temperature resistant alloy or a high-temperature resistant ceramic matrix composite material.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. By setting a cylindrical reinforcing mixing plate behind the fuel injection support plate, a new vortex structure can be induced during fuel injection. The vortex structure is used to enhance mixing. In addition, the cylindrical reinforcing mixing plate can divide the fuel into upper and lower layers, so that they can be mixed separately, instead of the traditional method where the fuel is concentrated in the middle of the rear of the support plate. This improves the fuel mixing efficiency and thus improves the performance of the oblique detonation engine.

[0014] 2. Cylindrical reinforced blending plates can lift the fuel, increasing its penetration depth. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of a detonation engine fuel injection and enhanced mixing device according to the present invention.

[0016] Figure 2 This is a schematic diagram showing the horizontal distance between the fuel injection support plate and the cylindrical reinforcing mixing plate in a fuel injection and enhanced mixing device for a detonation engine according to the present invention.

[0017] Figure 3 This is a three-dimensional schematic diagram of an optimized structure of the cylindrical reinforcing blending plate in a detonation engine fuel injection and reinforcing blending device according to the present invention.

[0018] Figure 4 For the present invention Figure 3 Front view diagram.

[0019] Figure 5 This is a three-dimensional schematic diagram of another optimized structure of the cylindrical reinforcing blending plate in the fuel injection and reinforcing blending device for a detonation engine according to the present invention.

[0020] Figure 6 For the present invention Figure 5 Front view diagram.

[0021] Figure 7 This is a comparative experimental data graph showing the fuel mass fraction distribution in two cases: one without the cylindrical reinforcing blending plate and the other with the cylindrical reinforcing blending plate.

[0022] Figure 8 This is a comparative experimental data graph showing the distribution of the reflux zone in two cases: one without the cylindrical reinforcing blending plate and the other with the cylindrical reinforcing blending plate. Detailed Implementation

[0023] The following is combined Figures 1-8 The specific embodiments of the present invention will be described in detail below. In the description of the invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0024] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0025] Example 1 like Figures 1-7 As shown, this embodiment of the invention provides a fuel injection and enhanced mixing device for a detonation engine, including a fuel injection support plate 2 disposed in a combustion chamber 1. In specific implementation, the shape of the fuel injection support plate 2 can be selected as an isosceles triangle, and the tip of the fuel injection support plate 2 is positioned directly opposite the inlet 11 of the combustion chamber 1. The bottom edge of the fuel injection support plate 2 serves as the tail end of the fuel injection support plate 2, and a plurality of fuel injection holes 3 are provided along the width direction of the fuel injection support plate 2.

[0026] To facilitate the diffusion and mixing of fuel, a cylindrical enhanced mixing plate 4 is added behind the tail end of the fuel injection support plate 2. The cylindrical enhanced mixing plate 4 is horizontally installed and fixed in the combustion chamber 1. Both ends of the cylindrical enhanced mixing plate 4 are fixed to the inner walls on both sides of the combustion chamber 1, and the circumferential side wall of the cylindrical enhanced mixing plate 4 is arranged opposite to the tail end of the fuel injection support plate 2.

[0027] In this embodiment, the supersonic oncoming flow enters the combustion chamber from the combustion chamber inlet 11. The oncoming flow is the air compressed by the intake duct. This air flows out from the combustion chamber outlet 12 after being mixed with fuel and enters the detonation section to complete the oblique detonation wave initiation. During mixing, the fuel is ejected from the fuel injection holes 3 behind the tail end of the fuel injection support plate 2 and mixes with the oncoming air. When the air flow passes through the cylindrical enhanced mixing plate 4, boundary layer separation will occur behind it, thus forming a vortex structure. The vortex structure can be used for enhanced mixing, and the cylindrical enhanced mixing plate 4 can divide the fuel into upper and lower layers, so that mixing can be carried out separately, instead of concentrating the fuel in the middle behind the fuel injection support plate 2 as in the traditional single fuel injection support plate 2, thereby improving the fuel mixing efficiency and the performance of the oblique detonation engine. In addition, the cylindrical enhanced mixing plate 4 can lift the fuel, increasing its penetration depth.

[0028] It should be noted that the cylindrical enhanced mixing plate 4 of the present invention and the fuel injection support plate 2 simultaneously satisfy the following conditions: H > D; L < 2H; Where, D is the diameter of the cylindrical enhanced mixing plate 4, H is the height of the tail end of the fuel injection support plate 2, and L is the horizontal linear distance between the center of the cylindrical enhanced mixing plate 4 and the tail end of the fuel injection support plate 2.

[0029] If H < D, the cylindrical enhanced mixing plate 4 cannot be blocked and hidden by the fuel injection support plate 2, and the high-speed air flow directly acts on the cylindrical enhanced mixing plate 4, which will induce the formation of a bow shock wave, increasing the flow resistance and total pressure loss.

[0030] Since the low-speed recirculation zone behind the fuel injection support plate 2 will gradually recover to be consistent with the mainstream zone as the distance L increases, it is necessary to make the cylindrical enhanced mixing plate 4 within the distance limit range of L < 2H to ensure that the cylindrical enhanced mixing plate 4 is always hidden in the low-speed recirculation zone behind the fuel injection support plate 2.

[0031] Furthermore, the ratio range of H to D is 1:(0.41 - 0.99). If it is lower than this ratio, the diameter of the cylindrical enhanced mixing plate 4 will be too small, approaching the diameter of the fuel injection hole 3. The diameter of the cylindrical enhanced mixing plate 4 is relatively too small, and the vortex intensity generated by it is insufficient, and the disturbance range is limited, making it difficult to effectively divide and lift the fuel cloud, and the enhanced mixing effect will be greatly reduced.

[0032] The ratio of H to L is in the range of 1: (0.5~1.99). If it is lower than this ratio, the cylindrical reinforcing mixing plate 4 will be too close to the fuel injection hole 3, which will interfere with the initial development and penetration of the fuel jet, destroy the mixing process, and cause local overheating and ablation of the cylindrical reinforcing mixing plate 4.

[0033] In practical implementation, the preferred ratio of H to D is 1:0.9, and the preferred ratio of H to L is 1:1.4.

[0034] Example 2 This embodiment improves upon Embodiment 1 by modifying the structure of the cylindrical reinforced blending plate 4, making its axial profile no longer smooth. Specifically, as follows... Figure 3 and Figure 4 As shown, multiple annular grooves are provided in the circumference of the cylindrical reinforced blending plate 4, and the multiple annular grooves are evenly distributed along the axial direction of the cylindrical reinforced blending plate 4. The opening of multiple annular grooves causes the circumferential sidewall of the cylindrical reinforced blending plate 4 to present alternating protruding sections 41 and concave sections 42 along its axial direction, thereby forming a cylindrical structure with variable cross-section characteristics. The diameter of the protruding section 41 is D, and the axial length of the protruding section 41 is equal to the axial length of the concave section 42.

[0035] By alternately setting the raised section 41 and the recessed section 42 as described above, refer to Figure 4 As shown, a flow-oriented vortex structure 5 can be induced at the included angle of the end face of the protruding section 41, and the flow-oriented vortex structure 5 can be used to further enhance mixing.

[0036] Furthermore, such as Figure 3 and Figure 4 As shown, as an optimized scheme of the cylindrical reinforced blending plate 4, the circumferential sidewalls of the protruding section 41 and the circumferential sidewalls of the recessed section 42 are both straight, thereby transforming the cylindrical reinforced blending plate 4 into a stepped cylindrical structure with a Z-shaped outer contour. The flow vortex structure 5 induced by the straight surface has higher strength.

[0037] Furthermore, such as Figure 5 and Figure 6 As another optimization scheme for the cylindrical reinforced blending plate 4, the circumferential sidewall of the protruding section 41 is an outwardly protruding arc-shaped surface, and the circumferential sidewall of the recessed section 42 is an inwardly recessed arc-shaped surface. This transforms the cylindrical reinforced blending plate 4 into a wavy cylinder with an outer contour. In terms of structural stability, especially in terms of resistance to supersonic airflow erosion, the wavy cylinder is better. Compared with the stepped cylinder structure, the arc-shaped surface design of the wavy cylinder is more suitable for high total temperature incoming flow environments. The end face of the alternating stepped cylinder is relatively sharp and easily ablated.

[0038] In another embodiment of the present invention, the cylindrical reinforced blending plate 4 is made of a high-temperature resistant alloy or a high-temperature resistant ceramic matrix composite material, which can adapt to high-temperature environments and avoid being ablated.

[0039] The following uses experimental data to verify the effectiveness of the embodiments of the present invention. The fuel injection support plate 2 is set to an isosceles triangle shape, the height H of the tail end of the fuel injection support plate 2 is 7mm, the diameter D of the cylindrical reinforcing mixing plate 4 is 6.3mm, and the horizontal straight-line distance L from the center of the cylindrical reinforcing mixing plate 4 to the tail end of the fuel injection support plate 2 is 9.8mm. The data obtained from the simulation experiment within this parameter range is shown in the following figure. Figure 7 and Figure 8 As shown.

[0040] Reference Figure 7 As shown, Figure 7 (a) is a schematic diagram of the fuel mass fraction distribution when fuel injection support plate 2 injects fuel alone without cylindrical reinforcing mixing plate 4. The fuel is concentrated at the center of fuel injection support plate 2. Figure 7 (b) is a schematic diagram of the fuel mass fraction distribution when fuel is injected through the fuel injection support plate 2 with the cylindrical reinforcing mixing plate 4. By comparing the two, it can be seen that the addition of the cylindrical reinforcing mixing plate 4 makes the fuel penetration depth greater. Moreover, the cylindrical reinforcing mixing plate 4 divides the fuel into upper and lower parts, which can be mixed with the air on both sides of the support plate respectively, further enhancing the mixing.

[0041] Reference Figure 8 As shown, Figure 8 (a) is a schematic diagram of the recirculation zone distribution when the fuel injection support plate 2 injects fuel alone without the cylindrical reinforcing mixing plate 4. Without the cylindrical reinforcing mixing plate 4, there are only four vortex structures in the main vortex zone behind the fuel injection support plate 2. Figure 8 (b) is a schematic diagram of the recirculation zone distribution of fuel injected by the fuel injection support plate 2 when the cylindrical reinforcing mixing plate 4 is included. By comparing the two, it can be seen that after adding the cylindrical reinforcing mixing plate 4, a secondary recirculation zone is formed behind the cylindrical reinforcing mixing plate 4. Furthermore, the vortex structure of the main recirculation zone behind the fuel injection support plate 2 is larger, which is more conducive to mixing, while the secondary recirculation zone further enhances the mixing.

[0042] The above-disclosed embodiments are merely preferred embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A fuel injection and enhanced mixing device for a detonation engine, comprising a fuel injection support plate (2) disposed in a combustion chamber (1), wherein the tail end of the fuel injection support plate (2) is provided with a plurality of fuel injection holes (3) along its width direction, characterized in that, Also includes: A cylindrical reinforcing mixing plate (4) is horizontally mounted and fixed inside the combustion chamber (1), and the circumferential sidewall of the cylindrical reinforcing mixing plate (4) is directly opposite the tail end of the fuel injection support plate (2). The cylindrical reinforcing mixing plate (4) and the fuel injection support plate (2) simultaneously satisfy the following conditions: H>D; L<2H; Wherein, D is the diameter of the cylindrical reinforced mixing plate (4), H is the height of the tail end of the fuel injection support plate (2), and L is the horizontal straight-line distance between the center of the cylindrical reinforced mixing plate (4) and the tail end of the fuel injection support plate (2).

2. The oblique detonation engine fuel injection and enhanced mixing device according to claim 1, characterized in that, The ratio of H to D ranges from 1:(0.41~0.99), and the ratio of H to L ranges from 1:(0.5~1.99).

3. The oblique detonation engine fuel injection and enhanced mixing device according to claim 1, characterized in that, The ratio of H to D is 1:0.9, and the ratio of H to L is 1:1.

4.

4. The oblique detonation engine fuel injection and enhanced mixing device according to claim 1, characterized in that, The cylindrical reinforced blending plate (4) has multiple annular grooves in its circumference, and the multiple annular grooves are evenly distributed along the axial direction of the cylindrical reinforced blending plate (4). The multiple annular grooves give the cylindrical reinforced blending plate (4) multiple alternating protrusions (41) and recesses (42). The diameter of the protrusions (41) is D.

5. The oblique detonation engine fuel injection and enhanced mixing device according to claim 4, characterized in that, The circumferential sidewalls of the protruding section (41) and the circumferential sidewalls of the recessed section (42) are both straight surfaces.

6. The oblique detonation engine fuel injection and enhanced mixing device according to claim 4, characterized in that, The circumferential sidewall of the protruding section (41) is an outwardly protruding arc-shaped surface, and the circumferential sidewall of the recessed section (42) is an inwardly recessed arc-shaped surface.

7. The oblique detonation engine fuel injection and enhanced mixing device according to claim 4, characterized in that, The axial length of the protruding section (41) is equal to the axial length of the recessed section (42).

8. The inclined detonation engine fuel injection and enhanced mixing device according to any one of claims 1 to 7, wherein the cylindrical enhanced mixing plate (4) is made of high-temperature resistant alloy or high-temperature resistant ceramic matrix composite material.

Images