A fuel inlet structure for an annular collector chamber

Abstract

The application belongs to the technical field of air-breathing ramjet, and particularly relates to a fuel inlet structure for a ring-shaped liquid collecting cavity, which comprises a ring-shaped liquid collecting cavity, a fuel input head and a jetting hole. The fuel input head is in an elbow structure, the outlet of the fuel input head is communicated with the ring-shaped liquid collecting cavity, and the inner cavity of the fuel input head is in an expanding trend from the inlet to the outlet. By changing the structure of the fuel input head, the tangential velocity of the fuel in the ring-shaped liquid collecting cavity is reduced, the flow path of the fuel is shortened, the flow resistance is reduced, the pressure potential energy lost in the tangential motion of the jetting hole in the jetting process is reduced, the pressure loss of the fuel along the path in the liquid collecting cavity is reduced, the electric energy consumed by the fuel supply system is saved, and the ultimate design goal of reducing the weight of the engine is achieved.

Description

Technical Field

[0001] This invention belongs to the field of air-breathing ramjet engine technology, specifically relating to a fuel inlet structure for an annular liquid collection chamber. Background Technology

[0002] Air-breathing ramjet engines possess advantages such as simple structure and high specific impulse, enabling them to provide power for hypersonic vehicles. The total temperature of supersonic incoming airflow is extremely high, especially under high Mach conditions, where the wall stagnation temperature can reach 3000K, far exceeding the temperature resistance limits of existing high-temperature alloy materials. Driven by the need to meet long-endurance power requirements, adopting an active cooling scheme based on liquid fuel is currently one of the most promising technological approaches.

[0003] The basic principle of an actively cooled air-breathing ramjet engine is to use liquid fuel as the cooling medium. Its physical and chemical heat sinks absorb heat from the combustion chamber, keeping the wall temperature within a safe range. The cracking process produces smaller fuel molecules, effectively reducing ignition delay time and increasing the chemical reaction rate. Simultaneously, the recovered heat is released back into the combustion chamber to contribute to power. After absorbing heat, the liquid fuel undergoes boiling, vaporization, and cracking processes within the cooling channel, existing in multiple phases including liquid, gas, and supercritical states, resulting in drastic changes in its physical properties. Although the density decreases, the temperature of the supercritical fluid increases significantly after heat absorption, and the molecular weight of the cracking products increases, thus increasing the absolute pressure within the pipe at the same flow rate. Designing a reciprocating flow path is a technique to extend the cooling distance and improve the heat exchange capacity of the cooling channel, but this inevitably increases flow resistance along the path. Whether it is increased local pressure or increased pipeline flow resistance, it will increase the load on the fuel supply system, leading to a reduction in range under the condition of a certain total weight constraint. This contradicts the design goal of long-endurance power for traction. Therefore, reducing flow losses in the cooling channels is crucial in the system design phase.

[0004] Currently, the commonly used fuel inlet cooling solutions are as follows: Figure 1 As shown, the fuel enters the annular collecting chamber tangentially. This method avoids energy loss due to flow impact to some extent, but it also has significant drawbacks. Specifically, the fuel enters the annular collecting chamber tangentially, and the flow path is approximately the circumference of the entire annular structure. Furthermore, under the same flow rate conditions, the fluid velocity along the tangential direction within a fixed geometric cross-section is greater. Assuming minimal changes in fuel properties, the flow resistance can be estimated using the formula... ,in Indicates mass flow rate, For flow velocity, This represents the flow path. Considering the high flow velocity and long flow path of this tangential entry scheme, the flow resistance generated during fuel flow is relatively large. In addition, the excessive tangential velocity will result in a large tangential velocity of the jet injected into the combustion chamber. This velocity component will cause significant flow losses, reduce penetration depth, easily lead to near-wall combustion, and consequently have an adverse effect on thermal protection. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a fuel inlet structure for an annular liquid collecting cavity that simultaneously reduces the tangential velocity and flow resistance of fuel in the annular liquid collecting cavity.

[0006] The present invention includes an annular liquid collection chamber, a fuel inlet head, and an injection hole. The fuel inlet head has an elbow structure, and its outlet is connected to the annular liquid collection chamber. The inner cavity of the fuel inlet head expands from the inlet to the outlet.

[0007] Furthermore, the cross-section of the fuel input head is an ellipse that gradually lengthens from the inlet to the outlet.

[0008] Furthermore, the inlet cross-section of the fuel input head is circular, and the cross-section of the fuel input head from the inlet to the outlet is an ellipse that gradually increases in length from a circle to the horizontal axis.

[0009] Furthermore, the difference between the inlet diameter of the fuel input head and the cavity diameter of the annular liquid collection chamber is between 0 and 3 mm.

[0010] Furthermore, the inner cavity of the fuel input head has a left-right symmetrical structure.

[0011] Furthermore, the outlet end of the fuel input head is tangent to both sides of the annular liquid collection chamber.

[0012] Furthermore, the outlet cross-section of the fuel inlet head is perpendicular to the annular surface of the annular liquid collection chamber.

[0013] Furthermore, the inlet axis of the fuel input head is parallel to the axis of the annular liquid collection chamber.

[0014] Furthermore, multiple injection holes are provided on the inner wall of the annular liquid collection cavity, and the multiple injection holes are arranged in a ring array along the axis of the annular liquid collection cavity.

[0015] Furthermore, one of the injection holes is positioned directly opposite the center of the outlet of the fuel input head.

[0016] The beneficial effects of this invention are that by changing the structure of the fuel input head, it reduces both the tangential velocity of the fuel in the annular liquid collection chamber and the flow path of the fuel, thereby reducing flow resistance, reducing the pressure potential energy lost by tangential motion during injection through the injection hole, and ultimately reducing the pressure loss of the fuel along the liquid collection chamber, thereby saving the electrical energy consumed by the fuel supply system and achieving the ultimate design goal of reducing engine weight. Attached Figure Description

[0017] Appendix Figure 1 This is a structural diagram of an existing technical solution;

[0018] Appendix Figure 2 A velocity vector diagram of the existing technical solution;

[0019] Appendix Figure 3 Pressure distribution cloud map of existing technical solutions;

[0020] Appendix Figure 4 This is a schematic diagram of the structure of the present invention;

[0021] Appendix Figure 5 This is a front view of the present invention;

[0022] Appendix Figure 6 for Figure 5 Sectional view along line AA;

[0023] Appendix Figure 7 This is a schematic diagram of the structure of the present invention after the injection hole is hidden;

[0024] Appendix Figure 8 This is a top view of the invention after the injection hole is hidden;

[0025] Appendix Figure 9 for Figure 8 Sectional view along the BB direction;

[0026] Appendix Figure 10 This is a front view of the invention after the injection hole is hidden;

[0027] Appendix Figure 11 for Figure 10 C-axis sectional view;

[0028] Appendix Figure 12 for Figure 10 Sectional view along the DD direction;

[0029] Appendix Figure 13 for Figure 10 EE-directed sectional view;

[0030] Appendix Figure 14 This is the velocity vector diagram of the present invention;

[0031] Appendix Figure 15This is a pressure distribution cloud map for the present invention.

[0032] In the diagram, 1-annular liquid collection chamber; 2-fuel input head; 21-inlet; 22-outlet; 23-rounded corner; 3-injection hole. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0035] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0036] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0038] As attached Figure 1-15As shown, the present invention includes an annular liquid collection chamber 1, a fuel inlet head 2, and an injection port 3. The fuel inlet head 2 has an elbow structure, that is, the inlet direction 21 and the outlet direction 22 are at a certain angle. This is mainly to adapt to conventional fuel entry schemes without requiring redesign of the engine structure. Secondly, the angle between the inlet direction 21 and the outlet direction 22 facilitates the diffusion transition of fuel through flow distribution as it passes from the small cross-sectional area of ​​the inlet 21 through the gradually expanding cross-sectional area of ​​the intermediate section to the outlet 22. The outlet 22 of the fuel inlet head 2 and the annular liquid collection chamber 3 are connected. The liquid chamber 1 is connected and used to allow fuel entering the fuel input head 2 to enter the annular liquid collection chamber 1. The inner cavity of the fuel input head 2 expands from the inlet 21 to the outlet 22, so that the cross-sectional area of ​​the inner cavity of the fuel input head 2 gradually increases. At the same time, fuel can enter the annular liquid collection chamber 1 from both sides of the outlet 22. The inlet 21 and the outlet 22 represent the two ends of the fuel input head 2, respectively. The inlet 21 represents the upstream entry end of the fuel input head 2, and the outlet 22 represents the downstream outflow end at the connection with the annular liquid collection chamber 1.

[0039] Specifically, according to the flow formula, the mass flow rate within fuel input head 2 :

[0040] ;

[0041] in and These represent fluid density and fluid velocity, respectively. This indicates the cross-sectional area. The cross-sectional areas of the inlet 21 and outlet 22 of the fuel input head 2 are respectively... and Assuming the fluid density remains almost constant, the flow velocity decreases. :

[0042] ;

[0043] Therefore, by designing the inner cavity of the fuel inlet head 2 to expand from the inlet 21 to the outlet 22, the flow velocity of the fuel in the annular collection chamber 1 can be effectively reduced. With a constant flow rate, the flow resistance is positively correlated with the velocity, thus reducing the absolute value of the flow resistance. Furthermore, the expanding design of the fuel inlet head 2 simultaneously diverts the upstream fuel to both sides of the annular collection chamber 1, changing the flow from unidirectional to bidirectional. This doubles the instantaneous flow area. At this point, with the total flow rate remaining constant, the average flow rate on both sides of the annular collection chamber 1 decreases, significantly reducing the tangential velocity and minimizing the pressure potential energy loss due to tangential motion during injection from the injection hole 3. , specifically:

[0044] ;

[0045] in and These are the total pressure and static pressure at injection port 3, respectively. and These represent the radial and tangential velocities at position 3 of the flow nozzle, respectively. Reducing the tangential velocity can significantly reduce the pressure potential energy loss caused by tangential motion.

[0046] In addition, the upstream fuel is diverted to both sides of the annular liquid collecting cavity 1, which halves the flow path of the fuel, that is, the flow path is only half the circumference. No backflow will occur in the annular liquid collecting cavity 1, further reducing the flow resistance.

[0047] This invention, by simply changing the structure of the fuel input head 2, can effectively reduce the flow velocity and flow resistance of the annular liquid collection chamber 1, and also reduce the flow loss caused by collision with the wall of the annular liquid collection chamber 1, thereby significantly reducing the pressure loss caused by the injection process. In the field of engines, reducing the pressure loss of fuel along the liquid collection chamber can save the electrical energy consumed by the fuel supply system and achieve the ultimate design goal of reducing engine weight.

[0048] like Figures 10-13 As shown, the cross-section of the fuel input head 2 is an ellipse that continuously increases in length from the inlet 21 to the outlet 22. This ensures that while the cross-section of the fuel input head 2 is continuously expanded, the thickness of the minor axis on the cross-section is not affected, thus ensuring that the overall height of the fuel input head 2 is basically close to the height of the annular liquid collection chamber 1.

[0049] The inlet 21 of the fuel input head 2 has a circular cross-section, and the cross-section of the portion of the fuel input head 2 from the inlet 21 to the outlet 22 is an ellipse that gradually increases in length from a circle to the horizontal axis. In this embodiment, the inlet 21 of the fuel input head 2 is set to be circular to facilitate adaptation to the conventional upstream pipeline of the engine.

[0050] The difference between the diameter of the inlet 21 of the fuel input head 2 and the diameter of the annular liquid collection chamber 1 is between 0 and 3 mm, which can reduce the local pressure loss caused by the fluid generating eddies due to sudden expansion or contraction.

[0051] The inner cavity of the fuel inlet head 2 has a symmetrical structure, which ensures that the fluid flow is consistent when fuel flows in from both sides of the annular liquid collection chamber 1, thus ensuring the uniformity of fuel flow.

[0052] like Figure 7 , 12 and Figure 13As shown, the outlet 22 of the fuel inlet head 2 has a rounded corner 23 with the annular liquid collection chamber 1, so that the two sides of the outlet 22 of the fuel inlet head 2 are tangent to the two sides of the annular liquid collection chamber 1. This is beneficial to guide the fuel to move in two directions and reduce the flow loss caused by backflow or impact.

[0053] The cross-section of the outlet 22 of the fuel inlet head 2 is perpendicular to the annular surface of the annular liquid collection chamber 1. That is, the flow direction of the fuel from the outlet 22 is perpendicular to the inner wall of the annular liquid collection chamber 1. The fuel is evenly distributed to both sides of the annular liquid collection chamber 1, and there will be no component of the movement direction inclined to the annular surface, which further reduces the flow loss of fuel.

[0054] The axis of the inlet 21 of the fuel input head 2 is parallel to the axis of the annular liquid collection chamber 1. That is, the fuel input head 2 in this invention is preferably a 90° elbow structure. The direction of fuel flow from the inlet 21 is perpendicular to the direction of fuel flow from the outlet 22, which is suitable for conventional engine fuel entry schemes.

[0055] Multiple injection holes 3 are provided on the inner wall of the annular liquid collection cavity 1. These injection holes 3 are arranged in a circular array along the axis of the annular liquid collection cavity 1 to ensure the uniformity of the injection holes 3. In this embodiment, for example... Figure 6 As shown, one of the injection holes 3 is positioned directly opposite the center of the outlet 22 of the fuel inlet head 2, ensuring that fuel flowing to this location can directly enter the injection hole 3 without colliding perpendicularly with the annular liquid collection chamber 1, thus reducing pressure loss. Figure 6 The middle arrow indicates the direction of fuel flow.

[0056] The simulation was conducted with the fuel flow rate at inlet 21 being 0.280 kg / s, the temperature at inlet 21 being 807.55 K, and the static pressure at injection hole 3 being 0.8 MPa.

[0057] Figure 2 The velocity vector diagram under the existing technical solution shows that the velocity amplitude in the annular liquid collecting chamber 1 is on the order of 40-100 m / s. The tangential velocity in the annular liquid collecting chamber 1 is very high, which increases the frictional resistance within the chamber. At the same time, it causes a large tangential velocity component to be generated during fuel injection, meaning that the fuel enters the combustion chamber not perpendicular to the wall, which easily leads to near-wall combustion and increases the difficulty of thermal protection.

[0058] Figure 14 The velocity vector diagram of this invention shows that the velocity amplitude within the annular liquid collecting chamber 1 is on the order of 2-50 m / s. The tangential velocity within the annular liquid collecting chamber 1 is very small, which helps to reduce the pressure loss of fuel flow within the chamber.

[0059] Under the existing technical solution and the solution of this invention, the pressure of the injection hole 3 and the flow rate of the inlet 21 are kept the same. The performance of the optimized configuration compared with the original solution is analyzed.

[0060] Figure 3 This is a pressure distribution cloud map of the fluid domain in the original scheme model. The local static pressure is the lowest in the region where the fluid enters tangentially, and the static pressure gradually increases during the axial movement. The mass-weighted average pressure at inlet 21 is 1.4901 MPa.

[0061] Figure 15 The pressure distribution cloud map of the fluid domain of the design model for this scheme is shown. The fluid enters the liquid collection chamber in two directions. At the position of the injection hole 3 directly opposite the outlet 22, the maximum pressure distribution is 1.321 MPa. The pressure distribution in the entire liquid collection chamber is relatively uniform, with an average value of 1.28 MPa. The mass-weighted average pressure at the boundary of inlet 21 is 1.2726 MPa.

[0062] The pressure at injection orifice 3 is the same at 0.8 MPa in both schemes, and the flow resistance under both schemes can be calculated. By optimizing the fuel input head 2 scheme, the flow resistance in the liquid collection chamber is reduced by approximately 31.52% compared to the original baseline scheme.

[0063] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A fuel inlet structure for an annular liquid collecting cavity, characterized in that, It includes an annular liquid collection chamber (1), a fuel input head (2) and an injection hole (3). The fuel input head (2) is a bent structure. The outlet (22) of the fuel input head (2) is connected to the annular liquid collection chamber (1), and the inner cavity of the fuel input head (2) expands from the inlet (21) to the outlet (22). The inlet (21) of the fuel input head (2) has a circular cross-section, and the cross-section of the fuel input head (2) from the inlet (21) to the outlet (22) is an ellipse that gradually increases in length from a circle to the horizontal axis. Thus, while continuously expanding the cross-section of the fuel input head, the thickness of the short axis on the cross-section will not be affected, ensuring that the overall height of the fuel input head is basically close to the height of the annular liquid collection chamber. The difference between the diameter of the inlet (21) of the fuel input head (2) and the diameter of the annular liquid collection chamber (1) is between 0 and 3 mm; The inner cavity of the fuel input head (2) is a left-right symmetrical structure. The outlet of the fuel input head and the annular liquid collection cavity are provided with rounded corners, so that the two sides of the outlet end of the fuel input head are tangent to the two sides of the annular liquid collection cavity, which is conducive to guiding the fuel to move in two directions and reducing the flow loss caused by backflow or impact. Multiple injection holes (3) are provided on the inner wall of the annular liquid collection chamber (1). The multiple injection holes (3) are arranged in annular array along the axis of the annular liquid collection chamber (1). One of the injection holes (3) is set directly opposite the center of the outlet (22) of the fuel input head (2), ensuring that the fuel flowing to this position can directly enter the injection hole without vertically colliding with the annular liquid collection chamber, thereby reducing pressure loss.

2. The fuel inlet structure for an annular liquid collecting chamber as described in claim 1, characterized in that, The cross-section of the outlet (22) of the fuel input head (2) is perpendicular to the annular surface of the annular liquid collection chamber (1).

3. The fuel inlet structure for an annular liquid collecting chamber as described in claim 1, characterized in that, The axis of the inlet (21) of the fuel input head (2) is parallel to the axis of the annular liquid collection chamber (1).

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