High-heat-mass-ratio cooling flow distribution and resistance reduction structure and method based on boundary layer disturbance

Abstract

The invention relates to a high-heat-mass-ratio cooling flow distribution resistance reduction structure and method based on boundary layer disturbance, and belongs to the technical field of aerospace propulsion active thermal protection. The problem that a traditional flow distribution method of a regenerative cooling parallel channel is too high in flow resistance is solved. Comprising a flow distribution structure, a plurality of channels are arranged in the flow distribution structure, and disturbance structures are arranged in the channels. Through the disturbance structures arranged on the channels, the flow deviation between the channels connected in parallel can be remarkably reduced, and the hidden danger of high-temperature damage is completely eradicated. Compared with a traditional flow distribution method such as a throttling hole and a flow guide plate, the flow resistance loss brought by the flow distribution method is greatly reduced.

Description

Technical Field

[0001] The present invention relates to a flow distribution structure and method, and belongs to the technical field of aerospace propulsion active thermal protection. Background Art

[0002] Regenerative cooling technology is the core active thermal protection method for aerospace propulsion systems and hypersonic propulsion systems. In order to cool the high-temperature surfaces of the engine combustion chamber, the cryogenic propellant in the engine tank acts as a cooling medium. It first flows through the parallel cooling channels on the combustion chamber wall, absorbs heat from the high-temperature combustion gas side, and thus cools the engine combustion chamber wall, and then enters the combustion chamber for combustion. Regenerative cooling channels are usually millimeter-level parallel micro-channels with rectangular, circular, elliptical and other cross-sections. The reasonable distribution of coolant in the parallel channels is a prerequisite for achieving the cooling goal. However, the regenerative cooling system is usually composed of dozens or even hundreds of tiny parallel channels. The difficulty of achieving reasonable distribution is remembered. In fact, the flow distribution in the parallel regenerative cooling channels is subject to many factors.

[0003] First, the coolant in the regenerative cooling channel operates under supercritical pressure conditions. As the temperature continues to rise, the fluid passes through the subcritical temperature zone, transcritical temperature zone, supercritical temperature zone, and thermal cracking temperature zone in sequence, with significant temperature zone characteristics. The thermal properties, flow state, heat transfer and resistance characteristics of the fluid in the flow direction have significant differences. Therefore, the flow distribution of the coolant in the parallel channel is easily affected.

[0004] Secondly, the regenerative cooling channels are heated unilaterally by the high-temperature combustion gases from the combustion chamber, subjecting them to extremely high thermal loads. For air-breathing propulsion systems, the heat-to-mass ratio of the coolant increases exponentially with flight speed, further exacerbating the coolant's thermal load. Thermal stratification within the cooling channels is extremely severe, with the temperature difference between the central flow and the near-wall fluid exceeding 500K. Under strong thermal stratification, the thermophysical properties, flow state, heat transfer, and resistance characteristics of the fluids within the cross-section of the high-heat-to-mass ratio cooling channels vary significantly, exacerbating flow distribution differences between parallel channels and worsening flow distribution effectiveness. In engine systems, the design freedom and space for pipeline flow paths are extremely limited. If the flow distribution is uneven or some channels have no flow, the channels will suffer serious consequences, including heat damage, at temperatures of 2300°C-2500°C.

[0005] Existing control methods for flow distribution within the regenerative cooling parallel channels primarily include local baffles and cold-end throttling. Local baffles primarily involve installing baffles in the diversion chamber to guide the fluid into the parallel channels. This method has limited control effectiveness and poor adaptability to operating conditions. Cold-end throttling, on the other hand, involves installing throttling orifices or reducing the flow area in the low-temperature section of the cooling channel, thereby increasing the flow resistance in the low-temperature section to reduce the interference from the high-temperature section, thereby achieving flow distribution control. However, this method significantly increases the flow resistance in the cooling channel, adversely affecting the engine supply system.

[0006] Therefore, it is urgent to propose a high heat and mass ratio cooling flow distribution and drag reduction structure and method based on boundary layer disturbance to solve the above technical problems. Summary of the Invention

[0007] To address the high flow resistance problem of conventional flow distribution methods for regenerative cooling parallel channels, a high heat-to-mass ratio cooling flow distribution and drag reduction structure and method based on boundary layer disturbance is provided. The following provides a brief overview of the present invention to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important aspects of the present invention, nor is it intended to limit the scope of the present invention.

[0008] The technical solution of the present invention: The invention discloses a high heat-mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance, comprising a flow distribution structure, a plurality of channels in the flow distribution structure and disturbance structures in the channels.

[0009] Preferably, the channel cross-section is square, rectangular, circular or elliptical, and several channels arranged in parallel are evenly arranged.

[0010] Preferably, the disturbance structure in the channel is any one or more of transverse ribs, hexahedral pin ribs, cylindrical pin ribs, and micro-turbation generators.

[0011] Preferably, the cross ribs are square rod structures perpendicular to the working medium flow direction. The cross ribs are arranged in a linear array at a distance p along the flow direction. The height of the cross ribs is h, the width is e, and the height is h Channel height H Ratio h / H 10%~20%, flow pitch p and width e Ratio p r / e 5~15.

[0012] Preferably, the height of the hexahedral needle ribs and the cylindrical needle ribs is h, the width (diameter) is e, the needle ribs in odd and even rows are arranged in a 2x, y linear array, the gaps between the hexahedral needle ribs in odd rows and the adjacent hexahedral needle ribs in even rows are arranged correspondingly, and the height is h Channel height H Ratio h / H 10%~20%, flow pitch x , spanwise pitch y and width e Ratio x / e、y / e 5~15.

[0013] Preferably, the micro-turbine generator is a cone, and the micro-turbine generators in adjacent rows are arranged in a mirror image to form an angle β. Several micro-turbine generators adopt an Lx, Ly linear array with a side length of h Channel height H Ratio h / H 10%~20%, angle β is 30 。 ~60 。 , flow pitch L x , spanwise pitch L y With side length h The ratio is 5~15.

[0014] Preferably, the high heat and mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance is applied to the wall surface of the combustion chamber of the engine.

[0015] Preferably, it further comprises a fuel tank, a fuel pump and a valve, wherein the fuel tank is filled with fuel, the fuel tank, the fuel pump, the valve, the channel of the flow distribution structure and the combustion chamber are connected in sequence, and the fuel pump is a liquid pump.

[0016] Preferably, the disturbance structure is arranged on the inner wall of the channel on the side close to the combustion chamber.

[0017] The method for reducing drag by distributing a high thermal mass ratio cooling flow based on boundary layer disturbance adopts the high thermal mass ratio cooling flow distribution structure based on boundary layer disturbance, comprising the following steps: Use the engine fuel as the working fluid, turn on the fuel pump, and adjust the working fluid flow rate by adjusting the valve; When the working fluid enters the channel, the throttling effect is achieved through the disturbance structure, so that the working fluid is evenly distributed to each parallel channel. The airflow direction changes at the disturbance structure, and the fluid in the channel is mixed, which improves the heat exchange efficiency and reduces the resistance loss. The heated working fluid enters the combustion chamber.

[0018] The present invention has the following beneficial effects: The present invention can significantly reduce the flow deviation between parallel channels through the disturbance structure arranged in the channels, and eliminate the hidden danger of high-temperature damage.

[0019] Compared with traditional flow distribution methods such as throttle holes, guide plates, etc., the present invention greatly reduces the flow resistance loss and increases the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional diagram of the flow distribution structure; Figure 2 This is the main view schematic diagram of the traffic distribution structure; Figure 3 This is a schematic diagram of the arrangement of transverse ribs in the channel; Figure 4 Schematic diagram of transverse rib structural parameters; Figure 5 This is a schematic diagram of the arrangement of hexahedral pin fins in the channel; Figure 6 Schematic diagram of the hexahedral pin-fin structure parameters; Figure 7 This is a schematic diagram of the arrangement of cylindrical pin fins in the channel; Figure 8 Schematic diagram of cylindrical pin-fin structure parameters; Figure 9 This is a schematic diagram of the arrangement of the micro-turbulation generator in the channel; Figure 10 Schematic diagram of the structural parameters of the micro-turbine generator; Figure 11 Schematic diagram of the principle of high heat and mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance; Figure 12 This is a three-dimensional schematic diagram of the flow distribution structure.

[0021] In the figure, 1-fuel, 2-fuel tank, 3-fuel pump, 4-valve, 5-flow distribution structure, 5-1-channel. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0023] Specific implementation method 1: Combination Figure 1-12The present embodiment is described. The high heat-to-mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance in the present embodiment includes a flow distribution structure 5. The flow distribution structure 5 is a plate-shaped structure that can be bent as needed. The plate-shaped structure has a plurality of channels 5-1 therein, and the channels 5-1 have disturbance structures therein. The cross section of the channel 5-1 is square, rectangular, circular or elliptical, and several channels 5-1 arranged in parallel are evenly arranged; The disturbance structure in channel 5-1 is any one or more of transverse ribs, hexahedral pin ribs, cylindrical pin ribs, and micro-turbulation generators. The disturbance structure is used to disturb the boundary layer. Compared with traditional flow distribution methods such as throttle holes and guide plates, the flow resistance loss caused by it is greatly reduced. The arrangement of the boundary layer disturbance structure in the parallel channel and its structural parameters should provide a significant disturbance effect on the basis of limited resistance loss. The boundary layer disturbance structure mainly includes transverse ribs, pin ribs, micro-turbulation generators, etc., and ultimately achieves the regulation of flow distribution in the regenerative cooling parallel channel with low resistance loss. like Figure 4 The cross ribs are square rod structures perpendicular to the flow direction of the working medium. The cross ribs are arranged in a linear array at a distance p along the flow direction. The height of the cross ribs is h, the width is e, and the height is h Height with channel 5-1 H Ratio h / H 10%~20%, flow pitch p and width e Ratio p r / e 5~15; like Figure 6 、 Figure 8 The height of the hexahedral pin ribs and cylindrical pin ribs is h, and the width (diameter) is e. The pin ribs in odd and even rows are arranged in a linear array with a distance of 2x, y. The gaps between the hexahedral pin ribs in odd rows and the adjacent hexahedral pin ribs in even rows are arranged correspondingly, so that the pin ribs are evenly arranged. If the boundary layer disturbance structure uses pin ribs, their height is h Channel height H Ratio h / H 10%~20%, flow pitch x , spanwise pitch y and width e Ratio x / e、y / e 5~15; like Figure 10The micro-turbine generator is a cone, preferably a linearly evenly arranged quadrangular pyramid, the square face of the quadrangular pyramid is set facing the working medium flow direction, the micro-turbine generator height is h, the quadrangular pyramid has an angle with the working medium flow direction, that is, it is arranged obliquely, and the micro-turbine generators in adjacent rows (working medium flow direction) are arranged in a mirror image to form an angle β. Several micro-turbine generators are arranged in a linear array with a distance Lx, Ly. If the boundary layer disturbance structure adopts a micro-turbine generator, its side length is h Channel height H Ratio h / H 10%~20%, angle β is 30 。 ~ 60 。 , flow pitch L x , spanwise pitch L y With side length h The ratio is 5~15; The high heat and mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance is applied to the wall of the combustion chamber 6 of the engine or as its wall; that is, the parallel channels are arranged on the outside of the wall of the scramjet engine combustion chamber, and the boundary layer disturbance structure is arranged inside; The fuel tank 2, fuel pump 3 and valve 4 are further included. The fuel tank 2 is filled with working medium fuel 1. The fuel tank 2, fuel pump 3, valve 4, channel 5-1 of flow distribution structure 5 and combustion chamber 6 are connected in sequence. The fuel pump 3 is a liquid pump. The disturbance structures arranged in a linear array form a group of disturbance structures. Multiple groups of disturbance structures are arranged in the channel 5-1. The disturbance structures are arranged on the inner wall of the channel 5-1 close to the combustion chamber 6. When the fluid (working medium) in the cooling channel 5-1 is in the transcritical temperature zone (i.e. 0.8 T pc < T b <1.2 T pc hour, T pc is the pseudo-critical temperature of the fuel at a given pressure; T b is the average temperature of the fuel in the channel and the thermal cracking temperature zone T w > T crack hour, T crack is the initial cracking temperature of the fuel, T wWhen the temperature of the channel wall is 0.0443°, the boundary layer disturbance structure is evenly arranged in the heating section of the cooling channel; the present invention not only increases the airflow disturbance on the heating surface and improves the heat exchange efficiency, but also further improves the heat exchange efficiency by increasing the heat exchange area. At the same time, it also reduces the problem of excessive resistance of the traditional throttle ring, thereby achieving the purpose of reducing resistance.

[0024] Specific implementation method 2: Combination Figure 1-11 Describe this embodiment. The high heat and mass ratio cooling flow distribution and drag reduction method based on boundary layer disturbance in this embodiment adopts the high heat and mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance. The regenerative cooling system includes a fuel tank 2, a fuel pump 3, a valve 4, a disturbance structure 5 with a boundary layer and a combustion chamber 6, and parallel channels of the structure.

[0025] The fuel 1 is stored in a fuel tank 2 and enters a flow distribution structure 5 with a boundary layer disturbance structure through a fuel pump 3. The total flow rate is controlled by a first valve 4. The boundary layer disturbance structure is located in a parallel channel 5-1. Under the action of the boundary layer disturbance structure, the boundary layer development in the channel is continuously disrupted, the flow resistance difference between the parallel channels is reduced, the flow non-uniformity coefficient of the parallel channels is reduced, and the resistance loss is small, so that the combustion chamber 6 is cooled more evenly. After completing the regenerative cooling process, the heated fuel is sprayed into the combustion chamber 6 for combustion. The method comprises the following steps: Using the engine's fuel 1 as the working medium not only reduces the volume of the structure, but also preheats the fuel 1 while cooling it, thereby improving the engine's energy utilization rate, saving energy and protecting the environment. Turn on the fuel pump 3 and adjust the working medium flow rate by adjusting the valve 4. The working medium enters the channel 5-1 and realizes the throttling effect through the disturbance structure, so that the working medium is evenly distributed to each parallel channel 5-1, and the airflow direction changes at the disturbance structure, so that the fluid in the channel 5-1 is mixed, the heat exchange efficiency is improved and the resistance loss is reduced; the fuel enters the parallel channel with the boundary layer disturbance structure, provides cooling for the engine combustion chamber, and absorbs heat and heats up during the flow process. In the channel with higher temperature, the boundary layer disturbance structure promotes the mixing of the fluid in the channel by changing the velocity gradient, thereby reducing the thermal stratification effect; in the channel with lower temperature, the boundary layer disturbance structure acts as a throttling element. The invention uses a boundary layer disturbance structure such as a transverse rib, a needle rib, and a micro-turbulation generator to break the boundary layer development in the channel, reduce the flow resistance difference between the parallel channels, and reduce the flow non-uniformity coefficient of the parallel channels. The parallel channel with the disturbance structure only adds a boundary layer disturbance structure inside the smooth channel. The process is simple, the effect on the overall spatial size change is small, and compared with the smooth channel, it does not increase excessive resistance loss. Its resistance is much smaller than that of the traditional throttle ring. The heated working fluid enters the combustion chamber 6, improving energy utilization; the regenerative cooling working fluid uses the engine's own fuel. After the fuel cools the combustion chamber wall in the parallel channel, it is sprayed into the combustion chamber in the form of a high-temperature supercritical fluid for combustion. The high heat and mass ratio parallel cooling channel flow distribution and resistance reduction structure and method based on boundary layer disturbance can significantly reduce the flow deviation between channels.

[0026] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutations and combinations. Therefore, the present invention will no longer describe the technical solutions after permutations and combinations one by one, but it should be understood that the technical solutions after permutations and combinations have been disclosed by the present invention.

[0027] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A high heat-mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance, characterized by: The invention comprises a flow distribution structure (5), wherein the flow distribution structure (5) has a plurality of channels (5-1), and the channels (5-1) have a disturbance structure.

2. The high thermal mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance according to claim 1 is characterized in that: The cross section of the channel (5-1) is square, rectangular, circular or elliptical, and the multiple channels (5-1) arranged in parallel are evenly arranged.

3. The high thermal mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance according to claim 2 is characterized in that: The disturbance structure in the channel (5-1) is any one or more of a transverse rib, a hexahedral pin rib, a cylindrical pin rib, and a micro-turbation generator.

4. The high thermal mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance according to claim 3 is characterized in that The cross ribs are square rod structures perpendicular to the flow direction of the working medium. The cross ribs are arranged in a linear array at a distance p along the flow direction. The height of the cross ribs is h, the width is e, and the height is h Height to channel (5-1) H Ratio h / H 10%~20%, flow pitch p and width e Ratio p r / e 5~15.

5. The high thermal mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance according to claim 3 is characterized in that: The height of the hexahedral pin ribs and cylindrical pin ribs is h, and the width is e. The pin ribs in odd and even rows are arranged in a 2x,y linear array. The gaps between the hexahedral pin ribs in odd rows and the adjacent hexahedral pin ribs in even rows are set correspondingly. h Channel height H Ratio h / H 10%~20%, flow pitch x , spanwise pitch y and width e Ratio x / e、y / e 5~15.

6. The high thermal mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance according to claim 4 or 5, characterized in that: The micro-turbine generator is a cone. The micro-turbine generators in adjacent rows are arranged in a mirror image to form an angle β. Several micro-turbine generators adopt Lx, Ly linear arrays with side lengths h Channel height H Ratio h / H 10%~20%, angle β is 30 。 ~ 60 。 , flow pitch L x , spanwise pitch L y With side length h The ratio is 5~15.

7. The high thermal mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance according to any one of claims 4 to 6, characterized in that: A high heat-mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance is applied to the wall surface of the combustion chamber (6) of the engine.

8. The high thermal mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance according to claim 7 is characterized in that: The invention also includes a fuel tank (2), a fuel pump (3) and a valve (4). The fuel tank (2) contains fuel (1). The fuel tank (2), the fuel pump (3), the valve (4), the channel (5-1) of the flow distribution structure (5) and the combustion chamber (6) are connected in sequence. The fuel pump (3) is a liquid pump.

9. The high thermal mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance according to claim 7, characterized in that: The disturbance structure is arranged on the inner wall of the channel (5-1) on a side close to the combustion chamber (6).

10. A high heat-to-mass ratio cooling flow distribution and drag reduction method based on boundary layer disturbance, characterized by: The high heat and mass ratio cooling flow distribution and drag reduction structure based on boundary layer disturbance according to any one of claims 1 to 9 comprises the following steps: Using the engine fuel (1) as the working medium, turning on the fuel pump (3), and adjusting the flow rate of the working medium by adjusting the valve (4); When the working medium enters the channel (5-1), the throttling effect is achieved through the disturbance structure, so that the working medium is evenly distributed to each parallel channel (5-1), and the airflow direction changes at the disturbance structure, so that the fluid in the channel (5-1) is mixed, thereby improving the heat exchange efficiency and reducing the resistance loss; The heated working medium enters the combustion chamber (6).

Images