A flame stabilizer with fuel-directed impact cooling

Abstract

This invention discloses a flame stabilizer with directional fuel impact cooling, comprising a flame stabilizer body, which includes a fuel supply chamber and a jet cooling chamber. The fuel supply chamber and the jet cooling chamber are separated by an open wall surface, which is provided with a plurality of jet impact cooling holes. The jet impact cooling holes connect the corresponding fuel supply chamber and the jet cooling chamber. Fuel in the fuel supply chamber is directed towards the jet cooling chamber through the jet impact cooling holes. The fuel supply chamber is connected to a fuel supply pipe for supplying fuel to the fuel supply chamber. The jet cooling chamber is provided with a plurality of fuel injection holes for spraying fuel out of the jet cooling chamber. The fuel injection holes are located on the side wall surface of the flame stabilizer body. This design eliminates the need for additional cooling air, using only the existing fuel as the cooling medium. It achieves wall cooling while simultaneously increasing fuel temperature, promoting evaporation and mixing, thereby improving combustion efficiency.

Description

Technical Field

[0001] This invention relates to afterburners for turbofan engines, combustion chambers for subsonic ramjet engines, multi-mode combustion chambers for turbofan / ramjet combined cycle engines, and combustion chambers for hypersonic engines. Specifically, it relates to a flame stabilizer with fuel-directed impact cooling. Background Technology

[0002] With the development of aero-engine technology and the increasing demands for engine performance, the flight envelope of aero-engines is constantly expanding, and the inlet temperature of the engine combustion chamber is constantly rising, facing more severe thermal load problems and putting forward higher and more urgent demands for thermal protection. At present, the most commonly used cooling methods for scramjet engines are regenerative cooling technology and air film cooling technology based on the principle of pipe convection heat transfer.

[0003] Air film cooling involves introducing air from the outer bypass duct into areas requiring thermal protection through air film cooling holes. The airflow forms an air film on the surface of the cooling hole walls, providing thermal protection. However, the direct entry of cooling air from the cooling holes into the combustion zone can affect combustion, disrupting the original combustion organization and affecting the location of combustion, thus weakening the radial stabilizer's effectiveness. The introduction of airflow alters the gas flow near the cooling holes. For example, with a radial stabilizer, since combustion primarily occurs in the recirculation zone behind the stabilizer, the stabilizer's trailing edge is the primary area requiring cooling. The introduction of airflow increases the air volume at the stabilizer's trailing edge, causing cold air to mix with the flame, lowering the flame temperature. Furthermore, the airflow pushes the flame downstream of the combustion chamber, reducing the stabilizer's flame stabilization and flame connection capabilities, thus affecting combustion efficiency. Summary of the Invention

[0004] Purpose of the invention: To address the above-mentioned shortcomings, the present invention provides a flame stabilizer with directional fuel impact cooling that is unaffected by the cooling medium, providing thermal protection.

[0005] Technical Solution: To solve the above problems, the present invention employs a flame stabilizer with directional fuel impact cooling, comprising a flame stabilizer body, which includes a fuel supply chamber and a jet cooling chamber. The fuel supply chamber and the jet cooling chamber are separated by an open wall surface, which is provided with a plurality of jet impact cooling holes. The jet impact cooling holes are connected to the corresponding fuel supply chamber and jet cooling chamber. Fuel in the fuel supply chamber is directed to the jet cooling chamber through the jet impact cooling holes. The fuel supply chamber is connected to a fuel supply pipe, which is used to supply fuel to the fuel supply chamber. The jet cooling chamber is provided with a plurality of fuel injection holes, which are used to spray fuel from the jet cooling chamber. The fuel injection holes are located on the side wall surface of the flame stabilizer body.

[0006] Furthermore, several fuel supply partition plates are fixedly connected to the perforated wall surface along the flow direction of the fuel supplied by the fuel supply pipe. The plane of the fuel supply partition plates is perpendicular to the fuel flow direction. The fuel supply partition plates divide the perforated wall surface, fuel supply chamber, and jet cooling chamber into several perforated wall surface units, fuel supply chamber units, and cooling chamber units, respectively. Each perforated wall surface unit is provided with several jet impact cooling holes for connecting the fuel supply chamber unit and the cooling chamber unit. Each fuel supply chamber unit is connected to a fuel supply pipe, and each cooling chamber unit is provided with a fuel injection hole. The fuel supply pipe outlet of each fuel supply chamber unit is located at the center of the fuel supply partition plate at the upper end of the fuel supply chamber unit.

[0007] Furthermore, the rear wall surface of the jet cooling chamber, parallel to the opening wall, is provided with several raised transverse guide ribs. The extension direction of the transverse guide ribs is perpendicular to the flow direction of the fuel supplied by the fuel supply pipe, and the transverse guide ribs are located between two jet impact cooling holes to restrict the flow direction of the fuel ejected from the jet impact cooling holes. The cross-section of the transverse guide ribs is semi-circular.

[0008] Furthermore, the opening wall surface is provided with several rows of jet impact cooling hole groups. Each row of jet impact cooling hole groups includes several jet impact cooling holes. The jet impact cooling holes in each row of jet impact cooling hole groups are symmetrically distributed with the centerline of the flame stabilizer body as the axis of symmetry. The extension direction of the side wall surface of the jet impact cooling holes forms an acute angle with the plane containing the radial centerline of the flame stabilizer body, forming a situation where the fuel impacts each other at a distance. The fuel impact cooling points on the rear wall surface of the flame stabilizer body corresponding to the jet impact cooling holes in each row of jet impact cooling hole groups are evenly distributed.

[0009] Furthermore, the flame stabilizer body includes interconnected V-shaped sections and straight sections, with the oil supply chamber and jet cooling chamber both located on the straight section. The oil injection holes are located on both sides of the straight section of the flame stabilizer body.

[0010] The present invention also employs a combustion chamber, including the flame stabilizer described above.

[0011] Beneficial Effects: Compared with existing technologies, the significant advantage of this invention is that it does not require the introduction of additional cooling gas; it only needs to use the existing fuel as the cooling medium. This achieves wall cooling while simultaneously increasing fuel temperature, promoting evaporation and mixing, thereby improving combustion efficiency. Forced convection heat transfer via lateral jets enhances heat exchange. Since the cooling medium does not directly intervene in the combustion zone, it does not affect the combustion behavior itself. Furthermore, using the fuel itself as the cooling medium improves cooling efficiency through impact cooling and also heats the fuel to a certain extent through heat exchange, further facilitating kerosene evaporation. Better kerosene evaporation improves combustion efficiency. Attached Figure Description

[0012] Figure 1This is a schematic diagram of the overall structure of the flame stabilizer of the present invention.

[0013] Figure 2 This is a schematic diagram showing the direction of the jet impact cooling hole in this invention.

[0014] Figure 3 This is a schematic diagram of the arrangement of the jet impact cooling holes in this invention.

[0015] Figure 4 This is a schematic diagram of the oil supply pipe layout in this invention.

[0016] Figure 5 This is a schematic diagram of the arrangement of the jet impact cooling holes and the transverse guide ribs in this invention.

[0017] Figure 6 This is a schematic diagram of the overall structure of the transverse guide rib in this invention.

[0018] Figure 7 This is a schematic diagram illustrating the working principle of the thermal protection structure of the flame stabilizer in this invention. Detailed Implementation

[0019] like Figure 1 As shown, this embodiment of a fuel-directed impact cooling flame stabilizer includes a flame stabilizer body 1. Based on the original radial flame stabilizer, a fuel supply chamber 2 and a jet cooling chamber 3 are added. The flame stabilizer body 1 includes interconnected V-shaped sections and straight sections. Both the fuel supply chamber 2 and the jet cooling chamber 3 are located in the straight section. The fuel supply chamber 2 and the jet cooling chamber 3 are separated by an open wall surface 5. Several fuel supply partition plates 6 are fixedly connected to the open wall surface 5 along the flow direction of the fuel supplied by the fuel supply pipe 4. The fuel supply partition plates 6 are used for partitioning within the fuel supply chamber 2 and the jet cooling chamber 3 to reduce the impact of increased fuel temperature caused by heat accumulation due to increased distance along the flow direction during fuel flow, thus reducing the cooling effect. The plane of the fuel supply partition plate 6 is perpendicular to the fuel flow direction. The fuel supply partition plate 6 divides the perforated wall surface 5, the fuel supply chamber 2, and the jet cooling chamber 3 into several perforated wall surface units, fuel supply chamber units, and cooling chamber units, respectively. Each perforated wall surface unit is provided with several jet impact cooling holes 9 for connecting the fuel supply chamber unit and the cooling chamber unit. Fuel in the fuel supply chamber unit is jetted towards the cooling chamber unit through the jet impact cooling holes. Each fuel supply chamber unit is connected to a fuel supply pipe 4, which is used to supply fuel to the fuel supply chamber unit. In this embodiment, five partitioned fuel supply pipes 4 are used to supply fuel to the fuel supply area respectively. Each cooling chamber unit is provided with a fuel injection hole 8, which is used to spray fuel from the jet cooling chamber 3. The fuel injection holes 8 are located on both sides of the straight section of the flame stabilizer body 1. A transverse guide rib 7 is provided on the jet impact cooling area of ​​the rear wall of the radial flame stabilizer 1 to further restrict the fuel flow direction.

[0020] like Figure 2 As shown, the perforated wall unit of the perforated wall surface 5 is provided with several rows of jet impact cooling hole groups. Each row of jet impact cooling hole groups includes several jet impact cooling holes 9. The jet impact cooling holes 9 in each row of jet impact cooling hole groups are symmetrically distributed with the center line of the flame stabilizer body 1 as the axis of symmetry. The side wall extension direction of the jet impact cooling holes 9 forms an acute angle with the plane where the radial center line of the flame stabilizer body 1 is located. They spray oil to the side and rear respectively, forming a mutual impact of fuel, adding a jet velocity to the fuel jet along the rear wall of the stabilizer in a transverse outward direction, so as to make the fuel flow direction more uniform.

[0021] like Figure 3 As shown, each row of jet impact cooling holes includes multiple jet impact cooling holes 9 to enhance the jet impact cooling effect. The hole spacing, number of holes, size of the jet cooling chamber 3, and other factors are related to actual engineering needs, stabilizer size, type of cooling medium, and flow rate. Taking kerosene as an example, at a gas temperature of 900K and a kerosene equivalence ratio of 0.6, the diameter of the jet impact holes 9 should not exceed 1.5mm, the hole spacing should preferably not exceed 15mm, and the jet impact cooling distance of the jet cooling chamber 3 should not exceed 3mm. To ensure the jet cooling effect, the jet impact cooling points on the rear wall of the stabilizer should be evenly distributed. Therefore, the two middle rows of jet impact cooling holes 9 will be closer together, while the outermost row will be farther from the side wall of the stabilizer.

[0022] like Figure 4 As shown, since all fuel flows into the radial flame stabilizer body 1 from the same direction, the arrangement of the fuel supply pipes 4 in the fuel supply chamber 2 below the fuel supply pipe 4 is affected by the arrangement of the fuel supply pipes in the previous fuel supply chamber. In order to reduce the influence of the fuel supply position on the fuel distribution in the fuel supply chamber unit, the fuel supply position of the fuel supply pipes 4 in all fuel supply chamber units is located at the center of the upper fuel supply partition plate 6 of the fuel supply chamber unit.

[0023] like Figure 5 and Figure 6As shown, in each cooling chamber unit of the jet cooling chamber 3, several protruding transverse guide ribs 7 are provided on the rear wall surface parallel to the opening wall surface 5. The extension direction of the transverse guide ribs 7 is perpendicular to the flow direction of the fuel supplied by the fuel supply pipe 4, and the transverse guide ribs 7 are located between two jet impact cooling holes 9 to limit the flow direction of the fuel ejected from the jet impact cooling holes 9. The number of rows of jet impact holes 9 in each cooling chamber unit is the same as the number of radial flame stabilizer rear wall surface areas separated by the transverse guide ribs 7, that is, each row of jet impact holes 9 corresponds one-to-one with the cooling area divided by the transverse guide ribs 7, so as to reduce the interference between the two rows of impact jets and facilitate the uniform flow of fuel to the side of the stabilizer. In order to increase the jet depth of fuel injection into the combustion gas, the number of injection holes 8 should not be too many. The shape of the transverse guide ribs 7 is a semi-circular rib, that is, the cross-section of the transverse guide ribs 7 is semi-circular, which reduces the fuel flow resistance between the two rows of jet impact cooling areas, facilitates fuel exchange near the injection holes, and allows it to be smoothly ejected from the injection holes.

[0024] The thermal protection process of the aforementioned flame stabilizer is as follows:

[0025] Fuel flows evenly from five zoned fuel supply pipes 4 into each fuel supply chamber unit, and is then sprayed into the cooling chamber unit of the jet cooling chamber 3 through the side-rear injection cooling holes 9 on the perforated wall 5. Finally, it is sprayed onto the corresponding radial flame stabilizer rear wall surface divided by transverse guide ribs. Through jet impact cooling, the cooling effect is enhanced. The direction of the jet impact cooling holes 9 and the design of the transverse guide ribs 7 achieve a certain degree of flow rectification, allowing the jet-cooled fuel to flow more smoothly and evenly to the vicinity of the injection hole 8 and be sprayed out from the injection hole 8. After the fuel is injected into the combustion chamber, it is mixed and evaporated by the fuel gas and then burned behind the stabilizer.

[0026] The thermal protection principle of the above-mentioned flame stabilizer is as follows:

[0027] like Figure 7 As shown, depending on the wall temperature caused by the external combustion temperature of the flame stabilizer and the fuel equivalence ratio, the jet impact cooling may exhibit the following three scenarios as the heat exchange increases and the fuel flow rate decreases:

[0028] When the heat exchange wall temperature is low or the fuel flow rate is high, the wall superheat is low, the fuel temperature rises but has not yet reached the fuel boiling point. At this time, the fuel does not undergo phase change, but only undergoes a heating process. At this time, the wall temperature is reduced mainly through convection heat transfer, while the fuel temperature rises, which is conducive to the subsequent evaporation and mixing in the combustion chamber.

[0029] When the heat exchange wall temperature rises or the fuel flow rate decreases, the wall superheat increases to a certain value, and the fuel temperature rises to the fuel boiling point. At this point, a local phase change occurs in the fuel, and a small number of fuel bubbles are generated, grow, and eventually leave the heating surface. The bubbles and their interactions significantly promote the convective heat transfer process. During this stage, the heat flux density increases significantly with the increase of wall superheat, resulting in high heat transfer efficiency. This phase change phenomenon is nucleation boiling. Because the phase change absorbs a large amount of latent heat, which is much higher than the convective heat transfer, the wall temperature drops faster, resulting in better cooling. At this time, the fuel injected into the combustion chamber from the injection point is in a gas-liquid mixed state, with the liquid phase still accounting for the majority. However, the presence of gaseous fuel can act as evaporation nuclei, accelerating fuel evaporation and mixing.

[0030] When the heat exchange wall temperature is higher or the fuel flow rate is lower, the wall superheat continues to increase. Based on the principles described above, a large number of bubbles will be generated on the heat exchange wall surface. These bubbles aggregate and connect to form a vapor film on the wall. The formation of this vapor film hinders the smooth escape of the bubbles, thus impeding the heat exchange process. As the superheat on the heat exchange surface further increases, the vapor film gradually stabilizes, and the generated bubbles detach systematically. At this point, the heat flux density increases again with the increase in wall superheat. The injected fuel then contains a higher vapor content, which is more conducive to mixing and combustion.

[0031] In this embodiment, aviation kerosene is used as the cooling medium. Since aviation kerosene is itself a combustion fuel, there is a certain correlation between the flow rate of aviation kerosene and the flow rate of the combustion chamber inlet gas. Therefore, the flow rate of the cooling medium can be changed according to the gas inlet conditions to achieve adaptive regulation. This invention provides a stabilizer thermal protection method for radial flame stabilizers that protects against liquid fuel jet impact and improves combustion efficiency, but is not limited to the jet impact direction and the use of aviation kerosene zoned supply as the cooling medium proposed in this invention.

Claims

1. A flame stabilizer with fuel-directed impact cooling, comprising a flame stabilizer body (1), characterized in that, The flame stabilizer body (1) includes a fuel supply chamber (2) and a jet cooling chamber (3). The fuel supply chamber (2) and the jet cooling chamber (3) are separated by an open wall (5). The open wall (5) is provided with a plurality of jet impact cooling holes (9). The jet impact cooling holes (9) are connected to the corresponding fuel supply chamber (2) and jet cooling chamber (3). The fuel in the fuel supply chamber (2) is propelled to the jet cooling chamber (3) through the jet impact cooling holes (9). The fuel supply chamber (2) is connected to a fuel supply pipe (4). The fuel supply pipe (4) is used to supply fuel to the fuel supply chamber (2). The jet cooling chamber (3) is provided with a plurality of fuel injection holes (8). The fuel injection holes are used to spray out the fuel in the jet cooling chamber (3). The fuel injection holes (8) are located on the side wall of the flame stabilizer body (1). The perforated wall surface (5) is fixedly connected to several fuel supply partition plates (6) along the flow direction of the fuel supplied by the fuel supply pipe (4). The plane of the fuel supply partition plate (6) is perpendicular to the fuel flow direction. The fuel supply partition plate (6) divides the perforated wall surface (5), the fuel supply chamber (2), and the jet cooling chamber (3) into several perforated wall surface units, fuel supply chamber units, and cooling chamber units, respectively. Each perforated wall surface unit is provided with several jet impact cooling holes (9) for connecting the fuel supply chamber unit and the cooling chamber unit. Each fuel supply chamber unit is connected to a fuel supply pipe (4), and each cooling chamber unit is provided with a fuel injection hole (8). The jet cooling chamber (3) has several raised transverse guide ribs (7) on the rear wall surface parallel to the opening wall surface (5). The extension direction of the transverse guide ribs (7) is perpendicular to the flow direction of the fuel supplied by the fuel supply pipe (4), and the transverse guide ribs (7) are located between two jet impact cooling holes (9) to restrict the flow direction of the fuel ejected from the jet impact cooling holes (9).

2. The flame stabilizer according to claim 1, characterized in that, The oil supply pipe outlet of each oil supply chamber unit is located at the center of the oil supply partition plate (6) at the upper end of the oil supply chamber unit.

3. The flame stabilizer according to claim 1, characterized in that, The cross-section of the transverse guide rib (7) is semi-circular.

4. The flame stabilizer according to claim 1, characterized in that, The opening wall (5) is provided with several rows of jet impact cooling hole groups. Each row of jet impact cooling hole groups includes several jet impact cooling holes (9). The jet impact cooling holes (9) in each row of jet impact cooling hole groups are symmetrically distributed with the center line of the flame stabilizer body (1) as the axis of symmetry. The side wall extension direction of the jet impact cooling holes (9) forms an acute angle with the plane where the radial center line of the flame stabilizer body (1) is located, so that the fuel impacts each other away from each other.

5. The flame stabilizer according to claim 4, characterized in that, The fuel impact cooling points on the rear wall of the flame stabilizer body (1) corresponding to the jet impact cooling holes (9) in each row of jet impact cooling hole groups are evenly distributed.

6. The flame stabilizer according to claim 1, characterized in that, The flame stabilizer body (1) includes interconnected V-shaped sections and straight sections, and the oil supply chamber (2) and jet cooling chamber (3) are both located in the straight section.

7. The flame stabilizer according to claim 6, characterized in that, The oil injection holes (8) are located on both sides of the straight section of the flame stabilizer body (1).

8. A combustion chamber, characterized in that, Including the flame stabilizer as described in any one of claims 1-7.

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