An injection configuration for a scramjet fuel injection module

Abstract

The present invention discloses an injection configuration for a fuel injection module of a scramjet engine, comprising a fuel injection assembly, wherein the fuel injection assembly is provided with a row of fuel injection holes, the direction of the center line of the fuel injection holes is perpendicular to the flow direction of the airflow in the combustion chamber, and the aperture of the fuel injection holes gradually decreases from the center of the fuel injection assembly to both sides; beneficial effect: the present invention makes the jet penetration depth of each fuel injection hole consistent by changing the aperture of the fuel injection holes, the incoming flow in the central area of ​​the combustion chamber can be fully utilized, the fuel is evenly distributed in the combustion chamber, the mixing effect of the fuel and the high-speed incoming flow is enhanced, and the components are more uniform when entering the downstream concave cavity of the combustion chamber for ignition and combustion, thereby improving the combustion efficiency.

Description

Technical Field

[0001] The present invention relates to a fuel injection module, and in particular provides an injection configuration for a fuel injection module of a scramjet engine, belonging to the technical field of efficient combustion of scramjet engines. Background Art

[0002] Aircraft speeds have reached the hypersonic stage. Scramjets, with their excellent performance at high Mach numbers, have become the preferred propulsion system for aircraft operating at these speeds. Liquid hydrocarbon fuels (primarily aviation kerosene) are expected to be the fuel of choice for future scramjets operating at these high Mach numbers due to their safety and ease of storage.

[0003] The Mach number of the airflow at the inlet of the scramjet engine combustion chamber is greater than 1, the airflow velocity in the combustion chamber is very high, and the combustion chamber length is limited. The fuel residence time in the combustion chamber is very short, only on the order of milliseconds. Liquid hydrocarbon fuel must undergo atomization, evaporation, mixing and other processes before combustion, and the ignition delay time is relatively long. Therefore, achieving efficient atomization and sufficient mixing is a necessary condition to ensure efficient ignition and stable combustion of the fuel. The good injection characteristics and atomization quality of liquid hydrocarbon fuel directly affect the combustion efficiency of the scramjet engine.

[0004] To increase jet penetration and improve fuel mixing characteristics, researchers have investigated mixing enhancement technologies such as support plates, physical ramps, and aerodynamic ramps. While these methods can significantly enhance jet atomization and mixing, they do so at the expense of flow field stability, total pressure loss, and thermal protection. Therefore, a wall-mounted injection scheme is needed that can significantly enhance jet atomization and mixing while minimizing changes to the flow field structure to achieve higher total pressure recovery. In practice, this approach utilizes a combination of wall-mounted fuel nozzles to achieve coupled enhancement of jet atomization between nozzles through the use of combined injection. However, when combined injection is used, the airflow velocity near the walls is relatively low due to the influence of the boundary layer on both sides of the combustion chamber. This results in weak acceleration and shear along the flow direction, resulting in relatively high jet penetration depth. However, the airflow velocity in the center of the combustion chamber is relatively high, resulting in relatively low penetration depth. This results in inconsistent jet penetration depth across the nozzles, insufficient utilization of the incoming flow in the center of the combustion chamber, and uneven fuel distribution within the combustion chamber. Summary of the Invention

[0005] Purpose of the Invention: To address the deficiencies in the prior art, the present invention provides an injection configuration for a scramjet engine fuel injection module to address the problems of inconsistent penetration depth of the jets from each hole due to the wall boundary layer, insufficient utilization of the incoming flow in the center of the combustion chamber, and low mixing of the fuel and incoming flow in existing scramjet engines using combined nozzles.

[0006] Technical solution: An injection configuration for a scramjet engine fuel injection module, comprising a fuel injection assembly, wherein the fuel injection assembly is provided with a row of fuel injection holes, wherein the direction of the connecting line of the centers of the fuel injection holes is perpendicular to the direction of the airflow in the combustion chamber; the aperture of the fuel injection holes gradually decreases from the center of the fuel injection assembly toward both sides.

[0007] The present invention changes the penetration depth of the jet from each fuel injection hole by changing the fuel injection hole diameter. When the fuel injection pressure drop is constant, changing the fuel injection hole diameter actually changes the flow rate of the fuel injection hole jet. The jet from a large-aperture fuel injection hole has a large flow rate, a large initial momentum, and a strong inertial effect. The aerodynamic acceleration of the large-aperture fuel injection hole jet along the flow direction is less than that of the jet from a smaller-aperture fuel injection hole. The velocity reduction of the large-aperture fuel injection hole jet along the initial injection direction is less than that of the jet from a smaller-aperture fuel injection hole. Therefore, the penetration depth of the large-aperture fuel injection hole jet is greater than that of the smaller-aperture fuel injection hole jet. This ensures that the jet penetration depth of each fuel injection hole remains consistent, fully utilizing the incoming flow from the center area of ​​the combustion chamber, evenly distributing the fuel within the combustion chamber, and improving combustion efficiency.

[0008] Preferably, the cross-section of the fuel injection hole outlet is circular.

[0009] Preferably, the circular aperture of the fuel injection hole is 2-3 mm.

[0010] Preferably, the center distance between every two adjacent fuel injection holes is 2-3 times the maximum hole diameter of the fuel injection holes.

[0011] Preferably, the change in the diameter of the fuel injection hole is the difference between the maximum diameter of the fuel injection hole and the minimum diameter of the fuel injection hole divided by the number of fuel injection holes on a single side of the fuel injection assembly.

[0012] Preferably, in order to enhance the mixing effect of the fuel and the high-speed incoming flow, the fuel injection assembly is provided with a mixing cavity on one side of the fuel injection hole, and the mixing cavity includes a cavity trailing edge and a cavity leading edge, and the cavity trailing edge and the cavity leading edge form a structure that is recessed to the wall surface of the fuel injection assembly, and the cavity leading edge is vertically connected to the wall surface of the fuel injection assembly.

[0013] Preferably, the front edge of the cavity is a semicircular arc surface.

[0014] Preferably, the aspect ratio of the mixed flow cavity is 6-8.

[0015] The present invention increases the width of the wave system at the trailing edge of the mixing cavity through the design of the mixing cavity. This increases the pressure at the trailing edge of the cavity. The interaction of the shock wave with the boundary layer and shear layer promotes the diffusion of vortices, further enhancing the mixing performance of the mixing cavity and effectively reducing the flow resistance of the high-speed incoming flow within the combustion chamber. This enhances the mixing effect of the fuel and the high-speed incoming flow, resulting in a more uniform composition when the fuel enters the downstream cavity of the combustion chamber and ignites and burns, thereby improving combustion efficiency.

[0016] Preferably, in order to ensure the processing accuracy and smoothness of the fuel injection hole, the fuel injection hole is processed by laser micro drilling.

[0017] Beneficial Effects: The present invention changes the penetration depth of the jets from each fuel injection hole by changing the aperture of the fuel injection hole, so that the penetration depth of the jets from each fuel injection hole remains consistent. The incoming flow from the center area of ​​the combustion chamber can be fully utilized, and the fuel is evenly distributed in the combustion chamber, thereby improving combustion efficiency. At the same time, the provision of a mixing cavity increases the pressure at the rear edge of the cavity. The interaction between the shock wave, the boundary layer, and the shear layer promotes the diffusion of vortices, further enhancing the mixing performance of the mixing cavity and effectively reducing the flow resistance of the high-speed incoming flow in the combustion chamber. This enhances the mixing effect of the fuel and the high-speed incoming flow, making the components more uniform when entering the downstream cavity of the combustion chamber for ignition and combustion, thereby improving combustion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0019] Figure 1 It is a structural diagram of the injection configuration of the present invention.

[0020] Figure 2 It is a top view of the injection configuration of the present invention.

[0021] Figure 3 This is a cross-sectional structural diagram of the fuel injection hole AA of the injection configuration of the present invention.

[0022] Figure 4 This is a cross-sectional structural diagram of the injection configuration mixed flow cavity BB of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0025] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0026] like Figure 1-3 As shown, an injection configuration for a scramjet engine fuel injection module includes a fuel injection assembly 1, wherein the fuel injection assembly 1 is provided with a row of fuel injection holes 2, wherein the center connecting line of the fuel injection holes 2 is perpendicular to the flow direction of the airflow in the combustion chamber; the aperture of the fuel injection holes 2 gradually decreases from the center of the fuel injection assembly 1 to both sides.

[0027] The present invention changes the penetration depth of the jet from each fuel injection hole 2 by changing the diameter of the fuel injection hole 2. When the fuel injection pressure drop is constant, changing the diameter of the fuel injection hole 2 actually changes the flow rate of the jet from the fuel injection hole 2. The jet from a large-aperture fuel injection hole 2 has a large flow rate, a large initial momentum, and a strong inertial effect. The aerodynamic acceleration of the jet from the large-aperture fuel injection hole 2 along the flow direction is less than that of the jet from the smaller-aperture fuel injection hole 2. The velocity reduction of the jet from the large-aperture fuel injection hole 2 along the initial jet direction is less than that of the jet from the smaller-aperture fuel injection hole 2. Therefore, the penetration depth of the jet from the large-aperture fuel injection hole 2 is greater than that of the jet from the smaller-aperture fuel injection hole 2. This ensures that the penetration depth of the jet from each fuel injection hole 2 remains consistent, fully utilizing the incoming flow from the central area of ​​the combustion chamber, evenly distributing the fuel within the combustion chamber, and improving combustion efficiency.

[0028] The cross section of the discharge port of the fuel injection hole 2 is circular.

[0029] The circular aperture of the fuel injection hole 2 is 2-3 mm.

[0030] The center distance between every two adjacent fuel injection holes 2 is 2-3 times the maximum hole diameter of the fuel injection hole 2.

[0031] The variation in the diameter of the fuel injection hole 2 is the difference between the diameter of the largest fuel injection hole 2 and the diameter of the smallest fuel injection hole 2 divided by the number of the fuel injection holes 2 on a single side of the fuel injection assembly.

[0032] In order to ensure the processing accuracy and smoothness of the fuel injection hole 2, the fuel injection hole 2 is processed by laser micro-drilling.

[0033] like Figure 4 As shown, in order to enhance the mixing effect of the fuel and the high-speed incoming flow, the fuel injection assembly 1 is provided with a mixing cavity 3 on one side of the fuel injection hole 2, and the mixing cavity 3 includes a cavity trailing edge 31 and a cavity leading edge 32. The cavity trailing edge 31 and the cavity leading edge 32 form a structure that is recessed to the wall of the fuel injection assembly 1, and the cavity leading edge 32 is vertically connected to the wall of the fuel injection assembly 1.

[0034] The front edge 32 of the concave cavity is a semicircular arc surface.

[0035] The length-to-depth ratio of the mixed flow cavity 3 is 6-8.

[0036] The present invention increases the width of the wave system at the trailing edge 31 of the mixing cavity 3 through its design. This increases the pressure at the cavity's trailing edge 31. The interaction of the shock wave with the boundary layer and shear layer promotes the diffusion of vortices, further enhancing the mixing performance of the mixing cavity 3 and effectively reducing the flow resistance of the high-speed incoming flow within the combustion chamber. This enhances the mixing of the fuel and the high-speed incoming flow, resulting in a more uniform composition upon ignition and combustion in the downstream cavity of the combustion chamber, thereby improving combustion efficiency.

[0037] Example 1

[0038] like Figure 1-4 The figure shows an injection configuration for a scramjet engine fuel injection module, comprising a fuel injection assembly 1 having nine fuel injection holes 2 arranged in a single row and evenly spaced apart. The fuel injection holes 2 have a circular cross-section at their outlets. To ensure machining accuracy and smoothness, the fuel injection holes 2 are machined using laser micro-drilling. The centerline of the fuel injection holes 2 is perpendicular to the flow direction within the combustion chamber.

[0039] The fuel injection holes 2 gradually decrease in size from the center of the fuel injection assembly 1 toward both sides, with a maximum aperture of 3 mm and a minimum aperture of 2 mm. The change in the aperture of the fuel injection holes 2 is the difference between the aperture of the maximum fuel injection hole 2 and the aperture of the minimum fuel injection hole 2 divided by the number of fuel injection holes 2 on a single side of the fuel injection assembly 1; the center-to-center distance between each two adjacent fuel injection holes 2 is twice the maximum aperture of the fuel injection holes 2.

[0040] Fuel is injected into the combustion chamber via nine fuel injection holes 2 on the fuel injection assembly 1. The combined injection pattern of the fuel injection holes 2 facilitates fuel diffusion across the width and height of the combustion chamber, promoting fuel-gas mixing. Compared to intrusive injection methods such as struts, wall injection eliminates thermal protection issues and effectively reduces pressure loss within the combustion chamber.

[0041] The tapered design of the fuel injection hole 2, which gradually decreases from the center of the fuel injection assembly 1 to both sides, effectively solves the problem of inconsistent penetration depth of the jet of the combined fuel injection hole caused by the wall boundary layer in the combustion chamber and the total pressure loss caused by the large penetration depth of the single hole jet in the combined fuel injection hole, and makes full use of the high-speed flow in the central area of ​​the combustion chamber to promote the uniform distribution of fuel in the combustion chamber.

[0042] In order to enhance the mixing effect of the fuel and the high-speed incoming flow, the fuel injection assembly 1 is provided with a mixing cavity 3 on one side of the fuel injection hole 2, and the ratio of the length L to the depth H of the mixing cavity 3 is 6; the mixing cavity 3 includes a cavity trailing edge 31 and a cavity leading edge 32, and the cavity trailing edge 31 and the cavity leading edge 32 form a structure that is recessed against the wall of the fuel injection assembly 1, and the cavity leading edge 32 is vertically connected to the wall of the fuel injection assembly 1, and the cavity leading edge 32 is a semicircular surface.

[0043] The present invention increases the width of the wave system at the trailing edge 31 of the mixing cavity 3 through its design. This increases the pressure at the cavity's trailing edge 31. The interaction of the shock wave with the boundary layer and shear layer promotes the diffusion of vortices, further enhancing the mixing performance of the mixing cavity 3 and effectively reducing the flow resistance of the high-speed incoming flow within the combustion chamber. This enhances the mixing of the fuel and the high-speed incoming flow, resulting in a more uniform composition upon ignition and combustion in the downstream cavity of the combustion chamber, thereby improving combustion efficiency.

[0044] Example 2

[0045] like Figure 1-4 The figure shows an injection configuration for a scramjet engine fuel injection module, comprising a fuel injection assembly 1 having nine fuel injection holes 2 arranged in a single row and evenly spaced apart. The fuel injection holes 2 have a circular cross-section at their outlets. To ensure machining accuracy and smoothness, the fuel injection holes 2 are machined using laser micro-drilling. The centerline of the fuel injection holes 2 is perpendicular to the flow direction within the combustion chamber.

[0046] The fuel injection holes 2 gradually decrease in diameter from the center of the fuel injection assembly 1 toward both sides, with a maximum diameter of 3 mm and a minimum diameter of 2 mm. The change in diameter of the fuel injection holes 2 is the difference between the diameter of the maximum fuel injection hole 2 and the diameter of the minimum fuel injection hole 2 divided by the number of fuel injection holes 2 on a single side of the fuel injection assembly 1; the center-to-center distance between each two adjacent fuel injection holes 2 is three times the maximum diameter of the fuel injection holes 2.

[0047] Fuel is injected into the combustion chamber via nine fuel injection holes 2 on the fuel injection assembly 1. The combined injection pattern of the fuel injection holes 2 facilitates fuel diffusion across the width and height of the combustion chamber, promoting fuel-gas mixing. Compared to intrusive injection methods such as struts, wall injection eliminates thermal protection issues and effectively reduces pressure loss within the combustion chamber.

[0048] The tapered design of the fuel injection hole 2, which gradually decreases from the center of the fuel injection assembly 1 to both sides, effectively solves the problem of inconsistent penetration depth of the jet of the combined fuel injection hole caused by the wall boundary layer in the combustion chamber and the total pressure loss caused by the large penetration depth of the single hole jet in the combined fuel injection hole, and makes full use of the high-speed flow in the central area of ​​the combustion chamber to promote the uniform distribution of fuel in the combustion chamber.

[0049] In order to enhance the mixing effect of the fuel and the high-speed incoming flow, the fuel injection assembly 1 is provided with a mixing cavity 3 on one side of the fuel injection hole 2, and the ratio of the length L to the depth H of the mixing cavity 3 is 8; the mixing cavity 3 includes a cavity trailing edge 31 and a cavity leading edge 32, and the cavity trailing edge 31 and the cavity leading edge 32 form a structure that is recessed against the wall of the fuel injection assembly 1, and the cavity leading edge 32 is vertically connected to the wall of the fuel injection assembly 1, and the cavity leading edge 32 is a semicircular surface.

[0050] The present invention increases the width of the wave system at the trailing edge 31 of the mixing cavity 3 through its design. This increases the pressure at the cavity's trailing edge 31. The interaction of the shock wave with the boundary layer and shear layer promotes the diffusion of vortices, further enhancing the mixing performance of the mixing cavity 3 and effectively reducing the flow resistance of the high-speed incoming flow within the combustion chamber. This enhances the mixing of the fuel and the high-speed incoming flow, resulting in a more uniform composition upon ignition and combustion in the downstream cavity of the combustion chamber, thereby improving combustion efficiency.

[0051] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0052] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An injection configuration for a scramjet engine fuel injection module, comprising a fuel injection assembly (1), wherein the fuel injection assembly (1) is provided with a row of fuel injection holes (2), wherein the center line of the fuel injection holes (2) is perpendicular to the direction of airflow in the combustion chamber; and characterized in that: The diameter of the fuel injection hole (2) gradually decreases from the center of the fuel injection assembly (1) toward both sides; the fuel injection assembly (1) is provided with a mixed flow cavity (3) on one side of the fuel injection hole (2); the mixed flow cavity (3) includes a cavity trailing edge (31) and a cavity leading edge (32); the cavity trailing edge (31) and the cavity leading edge (32) form a structure that is recessed with respect to the wall surface of the fuel injection assembly (1); and the cavity leading edge (32) is vertically connected to the wall surface of the fuel injection assembly (1).

2. The injection configuration for a scramjet fuel injection module according to claim 1, characterized in that: The cross section of the discharge port of the fuel injection hole (2) is circular.

3. The injection configuration for a scramjet fuel injection module according to claim 2, characterized in that: The circular diameter of the fuel injection hole (2) is 2-3 mm.

4. The injection configuration for a scramjet fuel injection module according to claim 2 or 3, characterized in that: The center distance between every two adjacent fuel injection holes (2) is 2-3 times the maximum hole diameter of the fuel injection hole (2).

5. The injection configuration for a scramjet fuel injection module according to claim 2 or 3, characterized in that: The change in the diameter of the fuel injection hole (2) is the difference between the diameter of the maximum fuel injection hole (2) and the diameter of the minimum fuel injection hole (2) divided by the number of the fuel injection holes (2) on a single side of the fuel injection assembly (1).

6. The injection configuration for a scramjet fuel injection module according to claim 1, characterized in that: The front edge (32) of the concave cavity is a semicircular arc surface.

7. The injection configuration for a scramjet fuel injection module according to claim 1, characterized in that: The length-to-depth ratio of the mixed flow cavity (3) is 6-8.

8. The injection configuration for a scramjet fuel injection module according to claim 1, characterized in that: The fuel injection hole (2) is processed by laser micro-drilling.

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