Novel fuel regenerative cooling structure for combined nozzle

Abstract

The application discloses a novel fuel regenerative cooling structure of a combined nozzle, which comprises a curved section and straight pipe sections; one side of the straight pipe sections is configured as an inlet far from one end of the curved section, and the other side of the straight pipe sections is configured as an outlet far from the other end of the curved section; an upper pipe heating channel and a lower pipe heating channel are formed in the cooling structure; and a communication hole for connecting the upper pipe heating channel and the lower pipe heating channel is arranged at the curved section. The cooling structure is provided with the communication hole for connecting the upper and lower pipe heating channels, and the improved U-shaped structure of the liquid collecting cavity, which effectively alleviates the uneven flow distribution phenomenon of the curved parallel channels of the nozzle wall surface, reduces the local high temperature of the nozzle wall surface, effectively reduces the average temperature of the nozzle wall surface, avoids the nozzle damage caused by the local over-temperature, and meanwhile, the fuel temperature entering the combustion chamber is increased, the small molecular substances generated by the fuel cracking are easy to be atomized, and the combustion efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of turbine-based combined cycle engine technology, and in particular to a novel fuel regeneration cooling structure with a combined nozzle. Background Technology

[0002] Turbine-based combined cycle (TBCC) engines can achieve flight across a wide speed range from subsonic to hypersonic (Ma>6) and a large airspace range from 0 to 30 km, while also being highly efficient and economical, possessing broad application prospects and military and civilian value. During hypersonic flight, the high-temperature, high-pressure gas generated by the TBCC expands and accelerates within the combined nozzle, generating thrust. During hypersonic flight, the nozzle faces severe thermal pressure—the exhaust gas temperature from the combustion chamber can reach over 2800 K, while the stagnation temperature of the incoming air is very high; at a cruise Mach 6, the total temperature of the incoming air exceeds 1600 K, making it unsuitable for direct cooling of the nozzle walls.

[0003] To improve the thermal environment of TBCC (Thickened-Tube-Combined-Road) nozzles, a fuel-based active regenerative cooling technology is proposed to address nozzle thermal protection issues. However, the convergent-divergent structure of the nozzle inevitably results in curved sections in the cooling channels. The flow and heat transfer characteristics of fuel in these curved sections differ from those of typical straight parallel cooling channels. Uneven heat load within the nozzle also leads to flow distribution problems in the regenerative cooling channels. Furthermore, a flow dead zone exists at the trailing edge of the nozzle exit divergence section, resulting in poor heat transfer. These issues can easily cause localized overheating of the nozzle, potentially even leading to engine damage. Existing literature contains limited research on fuel regenerative cooling for nozzles, and there is insufficient research on the optimized design of parallel curved cooling channels.

[0004] Based on the above-mentioned technical problems, those skilled in the art urgently need to develop a new fuel regeneration cooling structure with a combined nozzle. Summary of the Invention

[0005] The purpose of this invention is to provide a novel fuel regeneration cooling structure for a combined nozzle that effectively alleviates the uneven flow distribution caused by nozzle wall bending and connecting pipes, reduces local high temperature on the nozzle wall, and effectively lowers the average temperature of the nozzle wall to avoid nozzle damage due to local overheating.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The present invention discloses a novel fuel regeneration cooling structure for a combined nozzle, the structure comprising:

[0008] The curved section; and

[0009] The straight pipe sections formed at both ends of the curved section are configured such that the end of one side of the straight pipe section away from the curved section is configured as an inlet, and the end of the other side of the straight pipe section away from the curved section is configured as an outlet.

[0010] The cooling structure has an upper pipe heating channel and a lower pipe heating channel inside, both of which extend along the extension direction of the structure;

[0011] A connecting hole is provided at the curved section to connect the upper heating pipe channel and the lower heating pipe channel.

[0012] Furthermore, the ratio of the opening width of the connecting hole to the radius of curvature of the curved section is not less than 0.1.

[0013] Furthermore, both the inlet and the outlet have liquid collection chambers that communicate with the upper pipeline heating channel and the lower pipeline heating channel;

[0014] The liquid collection chamber has a U-shaped structure.

[0015] In the above technical solution, the novel fuel regeneration cooling structure of the combined nozzle provided by the present invention has the following beneficial effects:

[0016] The cooling structure of this invention features a connecting hole that links the upper and lower heating channels and an improved U-shaped liquid collection chamber. This effectively alleviates the uneven flow distribution caused by the curved parallel channels on the nozzle wall, reduces local high temperatures on the nozzle wall, and effectively lowers the average temperature of the nozzle wall, preventing local overheating that could damage the nozzle. At the same time, the increased temperature of the fuel entering the combustion chamber makes it easier for the small molecules produced by fuel cracking to atomize, thus improving combustion efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0018] Figure 1 This is a schematic diagram of the novel fuel regeneration and cooling structure with a combined nozzle provided in an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of fluid temperature distribution and flow field when the width of the connecting hole in the novel fuel regeneration cooling structure of the combined nozzle provided in this embodiment of the invention is 2 mm;

[0020] Figure 3A schematic diagram of fluid temperature distribution and flow field when the width of the connecting hole in the novel fuel regeneration cooling structure of the combined nozzle provided in this embodiment of the invention is 3 mm.

[0021] Figure 4 A schematic diagram of fluid temperature distribution and flow field when the width of the connecting hole in the novel fuel regeneration cooling structure of the combined nozzle provided in an embodiment of the present invention is 4 mm;

[0022] Figure 5 A schematic diagram of fluid temperature distribution and flow field when the radius of curvature of the novel fuel regeneration cooling structure with combined nozzle provided in an embodiment of the present invention is 20 mm.

[0023] Figure 6 A schematic diagram of fluid temperature distribution and flow field when the radius of curvature of the novel fuel regeneration cooling structure with combined nozzle provided in an embodiment of the present invention is 30 mm.

[0024] Figure 7 A schematic diagram of fluid temperature distribution and flow field when the radius of curvature of the novel fuel regeneration cooling structure with combined nozzle provided in an embodiment of the present invention is 40 mm.

[0025] Figure 8 A schematic diagram of the liquid collection chamber of the novel fuel regeneration and cooling structure of the combined nozzle provided in an embodiment of the present invention;

[0026] Figure 9 This is a cloud map showing the temperature distribution at the coupling surface of the initial cooling channel in the prior art.

[0027] Figure 10 Temperature distribution cloud of the coupling surface of the cooling channel after structural optimization of the novel fuel regeneration cooling structure of the combined nozzle provided in the embodiments of the present invention. Figure 1 ;

[0028] Figure 11 Temperature distribution cloud of the coupling surface of the cooling channel after structural optimization of the novel fuel regeneration cooling structure of the combined nozzle provided in the embodiments of the present invention. Figure 2 .

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Bend section; 2. Straight pipe section;

[0031] 101. Import; 102. Export; 103. Liquid collection chamber;

[0032] 201. Upper pipe heating channel; 202. Lower pipe heating channel; 203. Connecting hole. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] See Figures 1 to 11 As shown;

[0035] This embodiment presents a novel combined nozzle fuel regeneration cooling structure, which includes:

[0036] Bending segment 1; and

[0037] Straight pipe sections 2 formed at both ends of the curved section 1, one end of the straight pipe section 2 away from the curved section 1 is configured as an inlet 101, and the other end of the straight pipe section 2 away from the curved section 1 is configured as an outlet 102.

[0038] The cooling structure has an upper pipe heating channel 201 and a lower pipe heating channel 202 inside, and both the upper pipe heating channel 201 and the lower pipe heating channel 202 extend along the extension direction of the structure.

[0039] A connecting hole is provided at the bend section 1 to connect the upper pipe heating channel 201 and the lower pipe heating channel 202.

[0040] In this embodiment, a 1 / 4 section of parallel curved cooling channel is selected, and straight pipe sections 2 with a diameter more than twice the length are selected before and after for rectification. The cooling channels are arranged vertically, and the upper pipe heating channel 201 and the lower pipe heating channel 202 are connected through a connecting hole 203 opened at the curved section 1.

[0041] First, the cross-sectional dimensions of the upper pipeline heating channel 201 and the lower pipeline heating channel 202 in this embodiment are 3mm*2mm. Therefore, based on the principle of equal difference, the connecting holes 203 with widths of 2mm, 3mm and 4mm are selected to carry out the heat exchange pyrolysis calculation of RP-3 under the same working conditions.

[0042] The temperature distribution and flow field structure of the fluid near the connecting structure can be seen from the figure when using connecting holes 203 of different widths. When the width of the connecting hole 203 is 2 mm, a single vortex is formed over a large area of ​​fluid within the connecting hole 203, creating a "flow dead zone" and generating a local high-temperature zone. However, when the width of the connecting hole 203 is 3 mm and 4 mm, the fluids from both sides of the upper and lower pipes fill the connecting hole 203 together, forming a symmetrical double vortex. Furthermore, the fluid temperature near the lower wall of the upper pipe is lower, effectively cooling the high-temperature fluid on the upper wall of the lower pipe. The heat transfer effect within the connecting hole 203 is enhanced, and the local high-temperature zone is eliminated. In addition, as the width of the connecting hole 203 increases, the double vortex within the hole fully develops, the mixing effect gradually strengthens, and the fluid temperature distribution tends to be more uniform.

[0043] Width of connecting hole (mm) Flow difference without connecting orifices (g / s) Flow rate difference (g / s) after connecting orifices Ratio of flow differences 2 0.168 -0.022 -13.10％ 3 0.168 0.012 7.14％ 4 0.168 0.088 52.38％

[0044] Table 1 shows comparative data for different widths of connecting holes;

[0045] Considering the wide speed range of the TBCC engine, based on the similarity criterion, the selected curvature radii are 20mm, 30mm and 40mm, respectively, to ensure that the heating power is the same under each curvature radius.

[0046] The figure shows the fluid temperature distribution and flow field structure near the connecting structure when using different radii of curvature. It can be seen that when the radius of curvature is 40 mm, the flow field near the hole exhibits similar characteristics to that when using a 2 mm connecting hole, forming a "flow dead zone" and generating a local high-temperature region. However, when the radii of curvature are 20 mm and 30 mm, a symmetrical double-vortex structure forms within the hole, enhancing the heat transfer effect within the connecting hole 203 and eliminating the local high-temperature region. From the flow structure perspective, the larger the radius of curvature, the similarity to that when using a smaller connecting hole structure is also observed.

[0047] Radius of curvature (mm) Flow difference without connecting orifices (g / s) Flow rate difference (g / s) after connecting orifices Ratio of flow differences 20 0.152 0.058 38.16％ 30 0.168 0.012 7.14％ 40 0.180 -0.128 -71.11％

[0048] Table 2 shows comparative data for different radii of curvature;

[0049] Preferably, in this embodiment, the ratio of the opening width of the connecting hole 203 to the radius of curvature of the curved section 1 is not less than 0.1.

[0050] The above research shows a clear negative correlation between the radius of curvature and the width of the connecting hole 203. When the radius of curvature is large, the width of the connecting hole 203 needs to be adjusted accordingly to avoid the formation of local high-temperature zones and achieve the desired cooling effect. The research also found that to prevent the formation of high-temperature zones within the connecting hole and to ensure the formation of a stable double-streamline vortex structure within the connecting hole 203, the width of the connecting hole 203 / radius of curvature must be ≥0.1 under the corresponding operating conditions.

[0051] Preferably, in this embodiment, both the inlet 101 and the outlet 102 are provided with a liquid collection chamber 103 that communicates with the upper pipeline heating channel 201 and the lower pipeline heating channel 202;

[0052] The liquid collection chamber 103 has a U-shaped structure.

[0053] In this embodiment, the inlet and outlet liquid collection chamber 103 is modified into a U-shaped structure and lengthened to increase the distance between the two oil supply inlet pipes, so that the coolant flows through the vicinity of the upper wall first and then flows into the cooling channel; a connecting hole is added to the curved section 1 to optimize the flow distribution and heat exchange effect; at the same time, a turbulence column is added to the local high temperature area to enhance heat exchange.

[0054] Figures 9 to 11 This is a temperature distribution cloud map of the coupling surface of the initial and optimized cooling channel in this invention. Under the initial cooling channel, obvious high-temperature zones appear at the channel inlet section, the outlet edge, and between the two oil supply ports. Figure 9In the area marked by the dashed box, the local maximum temperature was close to 1100K, indicating that the cooling effect was not ideal. After optimization, the high-temperature zone on the wall of the cooling channel outlet section and the "sharp corner" area at the trailing edge was significantly eliminated, with the maximum temperature around 1000K, and the cross-sectional temperature decreased significantly.

[0055] from Figures 10 to 11 As can be seen, under the initial cooling channel, a "flow dead zone" is formed in the high-temperature area corresponding to the nozzle exit edge. The fluid in the "sharp corner" area of ​​the trailing edge forms a vortex structure, resulting in poor cooling. Furthermore, in the area near the cooling channel exit, because the coolant supply line is perpendicular to the cooling plate cross-section, the fluid experiences a significant velocity deflection, forming a centripetal vortex. This results in lower fluid velocity and poor heat exchange in this area. Under the optimized cooling channel, the "flow dead zone" in the "sharp corner" area near the cooling channel inlet disappears, and the high-temperature area is eliminated.

[0056] In the above technical solution, the novel fuel regeneration cooling structure of the combined nozzle provided by the present invention has the following beneficial effects:

[0057] The cooling structure of this invention features a connecting hole 203 that connects the upper and lower heating channels, and an improved U-shaped liquid collection chamber 103. This effectively alleviates the uneven flow distribution caused by the curved parallel channels of the nozzle wall, reduces local high temperatures on the nozzle wall, effectively lowers the average temperature of the nozzle wall, and avoids nozzle damage caused by local overheating. At the same time, the fuel temperature entering the combustion chamber increases, and the small molecules produced by fuel cracking are easily atomized, thus improving combustion efficiency.

[0058] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A combined nozzle fuel regeneration cooling structure, characterized in that, The structure includes: The curved segment (1); and Straight pipe sections (2) formed at both ends of the curved section (1) are configured as an inlet (101) at one end of the straight pipe section (2) away from the curved section (1) and as an outlet (102) at the other end of the straight pipe section (2) away from the curved section (1). The cooling structure has an upper pipe heating channel (201) and a lower pipe heating channel (202) inside, and both the upper pipe heating channel (201) and the lower pipe heating channel (202) extend along the extension direction of the structure. A connecting hole (203) is provided at the curved section (1) to connect the upper pipeline heating channel (201) and the lower pipeline heating channel (202). Both the inlet (101) and the outlet (102) have a liquid collection chamber (103) that communicates with the upper pipeline heating channel (201) and the lower pipeline heating channel (202). The liquid collection chamber (103) has a U-shaped structure; The ratio of the opening width of the connecting hole (203) to the radius of curvature of the curved section (1) is not less than 0.1.

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