A microribbed jet impingement cooling channel for hot-end components of aircraft

Abstract

This invention relates to a microribbed jet impact cooling channel for hot-end components of aircraft. It is an integral structure comprising 1 to 100 sub-channels arranged side-by-side, with adjacent sub-channels sharing sidewalls. Each sub-channel includes a main channel, microribs, and jet holes. Fuel enters the main channel from one end and through the jet holes, exiting from the other end. The main channel has a rectangular cross-section. Microribs are arranged at the bottom of the main channel, forming an array of microribs. Jet holes are arranged at the top of the main channel, with uniform or non-uniform distribution. The sidewalls of the main channel are smooth planes. This invention, with its arrayed microribs and jet holes, couples the effects of the microribs and the jet impact, effectively reducing the wall temperature of the scramjet engine combustion chamber without adding extra mass, effectively suppressing the temperature rise of high-heat components in the aircraft, thereby achieving higher Mach numbers.

Description

Technical Field

[0001] This invention relates to the field of high-temperature thermal protection technology, and in particular to a micro-ribbed jet impact cooling channel for hot-end components of aircraft. Background Technology

[0002] Hypersonic vehicles generally refer to aircraft with speeds exceeding Mach 5, operating at altitudes within the atmosphere and in near-space (20km–100km). Examples include hypersonic cruise missiles and hypersonic aircraft capable of interplanetary-to-space travel. With technological advancements, hypersonic flight technology is experiencing rapid development. Besides its significant national defense and military importance, hypersonic vehicles also hold immense scientific value for future space exploration and interstellar missions. As the primary power source for hypersonic vehicles, scramjet engines have garnered significant attention in the aerospace field.

[0003] Scramjet engines face extremely harsh thermal environments during operation, making efficient engine thermal protection systems a key factor restricting their development. Currently, engine thermal protection technologies are mainly divided into passive and active types. Passive thermal protection uses new high-temperature resistant and ablation-resistant materials to achieve heat insulation and cooling effects. While structurally simple, it alters the aerodynamic shape and increases the aircraft's structural volume. At Mach 8, the total temperature of the combustion chamber can reach 4000K, while the highest known heat-resistant C / C composite material can only withstand temperatures up to 2200K. Therefore, relying solely on existing heat-resistant materials is insufficient to meet the operational requirements of scramjet engines. Active thermal protection technology has thus come into focus. It mainly includes regenerative cooling, film cooling, evaporative cooling, and radiative cooling, offering strong cooling capabilities but with complex systems. Film cooling refers to spraying cooling airflow onto the surface of the parts requiring cooling to form a film, preventing direct contact between the high-temperature combustion gases and the combustion chamber, thereby achieving a cooling and heat insulation effect. However, the high Mach numbers of hypersonic vehicles mean intense aerodynamic heating, and the incoming air temperature is already high enough to fail to achieve ideal cooling. Therefore, film cooling cannot be used as the primary method. Sweating cooling refers to the seepage of coolant through porous cooling surfaces and its mixing with the high-temperature mainstream, thereby altering the flow and heat transfer characteristics of the boundary layer to achieve a cooling effect. It can be divided into single-phase sweating cooling and phase-change sweating cooling. Sweating cooling has high cooling efficiency and minimal impact on the mainstream, but the strong pressure gradient on the combustion chamber wall leads to uneven coolant distribution during sweating cooling, resulting in insufficient cooling in certain areas, and the manufacturing process is complex. Therefore, zonal control and combined cooling methods can be used to improve the efficiency of sweating cooling, such as combining it with film cooling.

[0004] Unlike other engines that can be cooled by introducing external air, fuel is the only available cooling source for scramjet engines. Therefore, regenerative cooling using fuel as a coolant is the optimal cooling method for scramjet engines. Regenerative cooling refers to reducing the wall temperature through convective heat transfer of fuel in the cooling channels of the combustion chamber walls. Simultaneously, the fuel undergoes endothermic decomposition to generate small-molecule products, which are more conducive to combustion, shortening the fuel ignition delay time. Furthermore, the chemical changes during the decomposition process result in higher heat absorption capacity, which can be used not only for thermal protection of the engine combustion chamber but also for cooling the external casing. In flight tests of the US Hyper-X program, the X-43A aircraft flew for less than 10 seconds using a passive thermal protection system, while the X-51A operated at Mach 4.8 for 140 seconds using a regenerative cooling system. This demonstrates that regenerative cooling technology for scramjet engines has significant advantages over other thermal protection technologies.

[0005] Scramjet engines typically use either hydrogen or hydrocarbon fuels. Hydrogen-fueled scramjet engines have a high specific impulse, but hydrogen fuel is difficult to store and has a relatively low volumetric energy density. Hydrocarbon fuels, on the other hand, have attracted widespread attention due to their higher energy density, ease of storage, and easier achievement of thrust-drag balance in the engine. For regenerative cooling of hydrocarbon fuels, the fuel is usually in a supercritical state within the cooling channel. Under supercritical pressure, the properties of hydrocarbon fuels undergo drastic nonlinear changes near the quasi-critical temperature. Furthermore, as the temperature increases further, the fuel undergoes thermal decomposition, further altering its thermal properties and affecting the flow and heat transfer characteristics of the fluid within the cooling channel, leading to heat transfer deterioration. Therefore, methods such as improving the fuel's own heat sink and optimizing the regenerative cooling channel structure can be used to further improve the system's cooling capacity. Traditional single-layer cooling channels are no longer sufficient to meet the increasingly high Mach number cooling requirements of aircraft high-temperature components.

[0006] Strengthening the regenerative cooling channels of scramjet engines can be achieved by adding nanoparticles to hydrocarbon fuels to improve the material's chemical heat sink, or by modifying the structure of the regenerative cooling channels or adding turbulence-enhancing elements such as fins, concave spheres, and convex spheres within the channels. However, a single method of enhancing heat transfer is often insufficient to meet the system's ever-increasing cooling demands. Therefore, it is necessary to explore more forms of composite cooling methods to adapt to the complex thermal environment of the scramjet engine's combustion chamber walls. Summary of the Invention

[0007] To overcome the low cooling efficiency of cooling channels for hot-end components of aircraft, this invention provides a micro-ribbed jet impact cooling channel for hot-end components of aircraft.

[0008] The technical solution adopted by this invention to solve its technical problem is as follows:

[0009] A microribbed jet impact cooling channel for hot-end components of aircraft is an integral structure comprising 1 to 100 sub-channels arranged in parallel, with adjacent sub-channels sharing the same sidewalls.

[0010] The sub-channel includes a main channel, microribs, and jet orifices. Fuel enters the main channel from one end and the jet orifice, and exits from the other end. The main channel has a rectangular cross-section, with microribs at the bottom and jet orifices at the top. The side walls of the main channel are smooth planes.

[0011] The microribs are cubes, located at the bottom of the main channel, and are evenly distributed to form an array of microribs.

[0012] The jet holes are through holes, located on the vertical plane of the center line of the main channel, and are evenly distributed.

[0013] The microribs in the aforementioned microrib jet impact cooling channel can also be prisms, cylinders, or elliptical cylinders.

[0014] In the aforementioned micro-ribbed jet impact cooling channel, the through holes of the jet holes can be circular, elliptical, triangular, or square.

[0015] In the aforementioned micro-ribbed jet impact cooling channel, the jet holes can also be arranged in two rows, evenly distributed.

[0016] In the aforementioned micro-ribbed jet impact cooling channel, the jet holes can also be arranged in two rows, evenly and alternately distributed.

[0017] In the aforementioned micro-ribbed jet impact cooling channel, the jet holes can also be in multiple rows and unevenly distributed.

[0018] In the aforementioned micro-ribbed jet impact cooling channel, the jet holes can also be conical, contracting along the fuel flow direction.

[0019] In the aforementioned micro-ribbed jet impact cooling channel, the jet holes can also be conical-straight, first contracting and then straightening along the fuel flow direction.

[0020] The beneficial effects of this invention are:

[0021] A microribbed jet impact cooling channel for hot-end components of aircraft is disclosed. Through the rational arrangement of microribs and jet impact in the cooling channel, the impact jet directly enhances the heat transfer in areas prone to heat transfer deterioration, based on the enhanced heat transfer capacity of the system by the microribs. This improves the heat transfer performance of the jet impact area and the upstream and downstream areas of the mainstream. The effects of the microribs and jet impact are coupled, effectively reducing the wall temperature of the scramjet engine combustion chamber or effectively suppressing the temperature rise of high-heat components of the aircraft without adding extra mass burden, thereby achieving the goal of higher Mach number flight. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a schematic diagram illustrating the cooling cycle principle of the combustion chamber wall of a hypersonic vehicle.

[0024] Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0025] Figure 3 This is a schematic diagram of the distribution of array microribs in the main channel according to Embodiment 1 of the present invention;

[0026] Figure 4 This is a top view of Embodiment 1 of the present invention;

[0027] Figure 5 A schematic diagram illustrating the cooling cycle principle of a micro-ribbed jet impact cooling system for the combustion chamber wall of an aircraft with five sub-channels;

[0028] Figure 6 This is a schematic diagram showing two rows of uniformly distributed jet orifices along the flow direction of the main channel.

[0029] Figure 7 This is a schematic diagram showing the uneven distribution of jet orifices along the flow direction of the main channel;

[0030] Figure 8 This is a schematic diagram showing the staggered distribution of jet orifices along the flow direction of the main channel;

[0031] Figure 9 A cross-sectional view along the centerline of a tapered jet orifice that contracts along the direction of fuel flow.

[0032] Figure 10 This is a cross-sectional view along the centerline of a conical jet orifice that first contracts and then straightens along the direction of fuel flow.

[0033] In the diagram: 1. Main channel; 2. Microrib; 3. Jet orifice; 4. Fuel tank; 5. Fuel pump; 6. Control device; 7. Combustion chamber. Detailed Implementation

[0034] Example 1

[0035] A microribbed jet impact cooling channel for hot-end components of aircraft is an integral structure comprising one sub-channel.

[0036] The sub-channel includes the main channel 1, micro-ribs 2, and jet holes 3.

[0037] The main channel has a rectangular cross-section. Microribs 2 are provided at the bottom of the main channel 1, jet holes 3 are provided at the top of the main channel, and the two side walls of the main channel are smooth planes.

[0038] Fuel enters the main channel from one end and through the jet orifice, and exits from the other end.

[0039] like Figure 3 As shown, microrib 2 is a cube, and there are 14 microribs 2. These 14 microribs 2 form an array of microribs, which are evenly distributed in two columns along the center line of the main channel 1. Each column has 7 microribs 2. The closest distance of a microrib 2 to the fuel inlet end of the main channel 1 is equal to the closest distance of a microrib 2 to the fuel outlet end of the main channel 1, and the spacing between the microribs 2 in each column is equal. The distance between the two columns of microribs 2 is equal to the distance of each column from the side wall of the main channel 1.

[0040] like Figure 4 As shown, the jet orifice 3 is a through hole, and the through hole is a circular hole. Fuel enters the main channel 1 through the jet orifice 3. The jet orifice 3 is located on the vertical plane of the center line of the main channel 1. There are 6 jet orifices 3, which are evenly distributed. The spacing between the jet orifices 3 is equal to the closest distance of the jet orifice 3 from the fuel inlet end of the main channel 1, and the closest distance of the jet orifice 3 from the fuel inlet end of the main channel 1 is equal to the closest distance of the jet orifice 3 from the fuel outlet end of the main channel 1.

[0041] Example 2

[0042] The micro-ribbed jet impact cooling channel can also include two sub-channels, which are arranged side by side and share adjacent sidewalls.

[0043] It can even include n sub-channels, for example, n = 5, 50, or 100. The n sub-channels are arranged side by side, and the side walls of adjacent sub-channels are shared.

[0044] Example 3

[0045] The microrib 2 can also be a triangular prism, a quadrangular prism, a cylinder, or an elliptical cylinder.

[0046] Example 4

[0047] The jet hole 3 can also be an elliptical through hole, a triangular through hole, or a square through hole.

[0048] Example 5

[0049] The jet orifice 3 can also be in two rows, and the arrangement can also be as follows: Figure 6 As shown, there are 12 jet holes, evenly distributed in two rows along the center line of the main channel. Each row contains 6 jet holes and the spacing between the jet holes is equal, and equal to the distance between the first jet hole and the main channel inlet and the last jet hole and the main channel outlet along the fuel flow direction of the main channel.

[0050] Or as Figure 7The diagram shows a non-uniform distribution along the centerline of main channel 1, with a total of 9 jet holes. The first jet hole along the fuel flow direction of the main channel is located at the centerline of the channel. The number of jet holes increases to 2 and is symmetrically and evenly distributed on both sides of the centerline of the main channel. Then, the number of jet holes decreases to 1, and so on. The interval between each group of jet holes is equal to the distance from the first jet hole to the inlet of the main channel and the distance from the last group of jet holes to the outlet of the main channel.

[0051] Or as Figure 8 The staggered distribution shown has a total of 6 jet holes, which are distributed sequentially on both sides of the center line of the main channel. The first jet hole along the fuel flow direction of the main channel is located on the right side of the center line of the main channel, the second jet hole is located on the left side of the center line of the main channel, the third jet hole is located on the right side of the center line of the main channel and is in the same column as the first jet hole, and so on. The distance between each jet hole along the fuel flow direction is equal and equal to the distance between the first jet hole and the main channel inlet and the distance between the last jet hole and the main channel outlet.

[0052] Example 6

[0053] The jet orifice 3 can also be a tapered shape that contracts along the fuel flow direction, such as... Figure 9 As shown; or a conical shape that first contracts and then straightens along the fuel flow direction, such as... Figure 10 As shown.

[0054] The working process of the micro-ribbed jet impact cooling channel of this invention is as follows:

[0055] Fuel in fuel tank 4 is pumped by fuel pump 5 to control device 6. A small portion of the hydrocarbon fuel enters main channel 1 through jet orifice 3, while the majority enters main channel 1 through its inlet. The combined effect of arrayed microribs 2 and jet orifice 3 enhances the heat exchange performance of main channel 1 to the bottom surface. Low-temperature fuel loses heat through convective heat exchange with the bottom wall of the channel, and undergoes a cracking reaction after absorbing heat. Finally, high-temperature fuel flows out from the outlet of main channel 3, and its flow rate is controlled by control device 6 before reaching combustion chamber 7 for mixing and combustion, thereby driving the engine to generate thrust.

Claims

1. A microribbed jet impact cooling channel for hot-end components of an aircraft, characterized in that, The overall structure includes 1 to 100 sub-channels, which are arranged side by side and share the side walls of adjacent sub-channels; The sub-channel includes a main channel (1), microribs (2), and jet holes (3); fuel enters the main channel (1) from one end of the main channel (1) and the jet holes (3), and is discharged from the other end of the main channel (1); the main channel (1) has a rectangular cross-section, the microribs (2) are provided at the bottom of the main channel (1), the jet holes (3) are provided at the top of the main channel (1), and the two side walls of the main channel (1) are smooth planes; The microribs (2) are cubes located at the bottom of the main channel (1), and are evenly distributed to form an array of microribs; The jet holes (3) are through holes, located on the vertical plane of the center line of the main channel (1), and are evenly distributed.

2. The micro-ribbed jet impact cooling channel for hot-end components of aircraft according to claim 1, characterized in that, The microrib (2) is a prism, a cylinder, or an elliptical cylinder.

3. The micro-ribbed jet impact cooling channel for hot-end components of an aircraft according to claim 1, characterized in that, The through hole of the jet hole (3) is circular, elliptical, triangular, or square.

4. The micro-ribbed jet impact cooling channel for hot-end components of an aircraft according to claim 1, characterized in that, The jet holes (3) are arranged in two rows and are evenly distributed.

5. The micro-ribbed jet impact cooling channel for hot-end components of an aircraft according to claim 1, characterized in that, The jet holes (3) are arranged in two rows, evenly staggered.

6. The microribbed jet impact cooling channel for hot-end components of an aircraft according to claim 1, characterized in that, The jet holes (3) are arranged in multiple rows and are unevenly distributed.

7. The micro-ribbed jet impact cooling channel for hot-end components of an aircraft according to claim 1, characterized in that, The jet orifice (3) is a cone shape that contracts along the fuel flow direction.

8. The micro-ribbed jet impact cooling channel for hot-end components of an aircraft according to claim 1, characterized in that, The jet orifice (3) is a conical shape that first contracts and then straightens along the fuel flow direction.

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