Circumferential variable-diameter fuel element, engine and nuclear heat rocket

Abstract

The invention belongs to the field of reactor cores in nuclear heat rocket engines, particularly relates to a circumferential variable-diameter fuel element, an engine and a nuclear heat rocket, and aims to solve the problem of uneven temperature distribution in the fuel element. The circumferential variable-diameter fuel element comprises a nuclear base body of a hexagonal prism structure, a plurality of working medium channels are arranged and distributed in the nuclear base body in the circumferential direction; three areas R1, R2 and R3 are arranged on the nuclear base body in the radial direction, the diameters of the working medium channels in the ranges of the three areas R1, R2 and R3 are d1, d2 and d3 correspondingly, the diameters of the working medium channels are increased in a gradient mode according to the formula that d1 < d2 < d3, through the radial gradient diameter of the working medium channels, temperature distribution is optimized, the method is suitable for a nuclear thermal rocket engine, and heat source balance is achieved by dividing a fuel section and a cavity heat exchange section in the axial direction. The problem of uneven temperature distribution in the fuel element is solved.

Description

Technical Field

[0001] The invention belongs to the field of cores in nuclear thermal rocket engines, and in particular relates to a circumferentially variable diameter fuel element, an engine and a nuclear thermal rocket. Background Art

[0002] Traditional space propulsion systems can hardly guarantee the launch of deep space exploration missions with large scale, long mission cycle and high cost, and can hardly meet the requirements of high-complexity missions represented by manned Mars exploration in the future.

[0003] Nuclear thermal rocket engine systems have unique advantages in the field of space propulsion performance. They can use the propellant with the smallest molecular mass (hydrogen) and produce extremely high propellant temperature (about 3000K), thereby providing relatively large thrust (hundreds of kN) and high specific impulse (greater than 900s) operation.

[0004] The core is the energy source of the nuclear thermal propulsion system, with the characteristics of high density and high energy; the fuel element is the core component in the core, and the content of fissile nuclides determines the power of the element. The uniform distribution of the temperature of the working fluid and solid area in the fuel element has an important influence on its structure. Uneven temperature distribution will lead to the appearance of thermal stress in the structure, which will seriously damage the fuel element structure and even affect the overall performance of the core. Summary of the invention

[0005] In order to solve the problem of uneven temperature distribution in the fuel element in the prior art, on the one hand, the present invention provides a circumferentially variable diameter fuel element, comprising: The nucleus matrix has a hexagonal prism structure; A plurality of working fluid channels are provided and distributed circumferentially in the core matrix; The core matrix is ​​provided with three regions R1, R2 and R3 from inside to outside in the radial direction. The diameters of the working fluid channel in the three regions R1, R2 and R3 are d1, d2 and d3 respectively. The diameter of the working fluid channel increases in a gradient of d1<d2<d3.

[0006] According to some embodiments of the present application, a circumferentially variable diameter fuel element, d1, d2, d3, meets the following conditions: d2=ad1, d3=ad2, Among them, a is the preset coefficient, and its value range is 1.1~1.5.

[0007] According to a circumferentially variable diameter fuel element provided in some embodiments of the present application, the axial direction of the working fluid channel is parallel to the axial direction of the core matrix.

[0008] According to a circumferentially variable diameter fuel element provided in some embodiments of the present application, the working fluid channel in the R1 region is coaxially arranged with the core matrix.

[0009] According to a circumferentially variable diameter fuel element provided in some embodiments of the present application, the three regions R1, R2, and R3 are all arranged concentrically with the core matrix.

[0010] According to some embodiments of the present application, a circumferentially variable diameter fuel element is provided, wherein the fuel element is axially provided with a first fuel segment, a second fuel segment and a cavity heat exchange segment, wherein the cavity heat exchange segment is arranged between the first fuel segment and the second fuel segment and is connected to the first fuel segment and the second fuel segment.

[0011] According to a circumferentially variable diameter fuel element provided in some embodiments of the present application, the heat source intensity of the second fuel segment is greater than that of the first fuel segment.

[0012] According to some embodiments of the present application, a circumferentially variable diameter fuel element is provided, in which the value of a is 1.3.

[0013] On the other hand, some embodiments of the present application also provide an engine, comprising the circumferentially variable diameter fuel element.

[0014] On the other hand, some embodiments of the present application also provide a nuclear thermal rocket, including the above-mentioned engine.

[0015] Beneficial effects of the present invention: The radial diameter of the working fluid channel changes, and the diameter gradient increases, which can balance the local heat exchange efficiency, reduce the temperature difference, and coordinate the temperature unevenness caused by the working fluid flow channel under the three conditions of equal diameter, uneven heat source distribution, and uniform inlet. The axial segmented structure alleviates the axial temperature uneven distribution phenomenon and solves the problem of uneven temperature distribution in the fuel element. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 is a schematic diagram of the core matrix area distribution of some embodiments of the present application; Figure 2 is a schematic diagram of the distribution of working fluid channels in some embodiments of the present application; Figure 3 is a schematic diagram of an axial cross-section of a fuel element in some embodiments of the present application; Figure 4 is a schematic diagram of the end face of a cavity heat exchange section in some embodiments of the present application; Figure 5 It is a stereoscopic diagram of the cavity heat exchange section of some embodiments of the present application.

[0017] In the figure: 1. first fuel section; 2. cavity heat exchange section; 3. second fuel section; 4. core matrix; 5. working fluid channel; 6. outer wall of fuel element; 7. wall of working fluid channel. DETAILED DESCRIPTION

[0018] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0019] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0020] like Figure 1-5 As shown, the present invention provides a circumferentially variable diameter fuel element, comprising: The core matrix 4 has a hexagonal prism structure; A plurality of working medium channels 5 are provided and distributed in the core matrix 4 from the inside to the outside along the circumferential direction; The core matrix 4 is provided with three regions R1, R2, and R3 in the radial direction. The diameters of the working fluid channel 5 in the three regions R1, R2, and R3 are d1, d2, and d3 respectively. The diameter of the working fluid channel 5 increases in a gradient of d1<d2<d3 and satisfies the relationship: d2=ad1, d3=ad2, Among them, a is the preset coefficient, and its value range is 1.1~1.5.

[0021] In specific implementation, for the same volume heat source, under the condition of uniform inlet, the temperature distribution between the various regions in the radial cross section of the traditional fuel element fluctuates greatly. In order to coordinate the temperature unevenness of the working fluid flow channel under the three conditions of equal diameter, uneven heat source distribution and uniform inlet, under the condition that the center of the heat source distribution of the fuel element is high and the periphery is low, the flow rate in area 1 should be increased to take away more heat, thereby reducing the temperature of this area and making the flow rate of area 2 uniform; and the flow rate in area 3 should be reduced. Based on this design principle, a design idea of ​​a variable diameter concentrated fuel element is proposed. On the premise of ensuring the spacing of the working fluid channel, the diameter of the working fluid channel is gradually increased in the order of area R1, area R2, and area R3, wherein the diameter of the working fluid channel 5 within the range of R1 is d1, the diameter within the range of R2 is d2, and the diameter within the range of R3 is d3, and a is the growth multiple of the coolant channel diameters d1, d2, and d3 within the regions R1, R2, and R3. The value range of a is between 1.1-1.5. In some embodiments, the value of a can be 1.3, such as Figure 1 As shown, the outer wall surface 6 of the fuel element is a plane, and the wall surface 7 of the working medium channel is a curved surface.

[0022] In some embodiments, the axial direction of the working fluid channel 5 is parallel to the axial direction of the core matrix 4 , the working fluid channel 5 in the R1 region is coaxially arranged with the core matrix 4 , and the three regions R1 , R2 , and R3 are all concentrically arranged with the core matrix 4 .

[0023] In some embodiments, the fuel element is axially provided with a first fuel segment 1, a second fuel segment 3 and a cavity heat exchange segment 2. The cavity heat exchange segment 2 is provided between the first fuel segment 1 and the second fuel segment 3 and is connected with the first fuel segment 1 and the second fuel segment 3. A plurality of trapezoidal baffle structures are provided in the cavity heat exchange segment 2, which can form a certain shielding for the working fluid channel 5 located in the region R2 and the region R3, and is used to limit the flow rate of the region R2 and the region R3. The heat source intensity of the second fuel segment 3 is greater than that of the first fuel segment 1.

[0024] In specific implementation, the excessive length of the fuel element will also lead to uneven temperature distribution, the temperature difference between region R2 and region R3 will increase, temperature fluctuations will occur between the working fluid channels 5 in region R3, and the overall temperature will be limited. To improve this phenomenon, the traditional fuel element is divided and volume heat sources are set one by one, such as Figure 2 As shown, the heat source at the first fuel segment 1 is higher than that at the second fuel segment 3, so as to ensure that the working fluid outlet temperature reaches the design reference value. This method can effectively adjust the flow rate in the working fluid channel 5, control the heat exchange effect, and make the temperature distribution uniform.

[0025] In some embodiments, an engine is also provided, in which the above-mentioned fuel element is applied.

[0026] In some embodiments, a nuclear thermal rocket is also provided, in which a nuclear thermal rocket engine having the above-mentioned fuel element is applied.

[0027] In the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0028] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article, or apparatus / device.

[0030] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A circumferentially variable diameter fuel element, characterized in that: include: The nucleus matrix has a hexagonal prism structure; A plurality of working fluid channels are provided and distributed circumferentially in the core matrix; The core matrix is ​​provided with three regions R1, R2 and R3 from inside to outside in the radial direction. The diameters of the working fluid channel in the three regions R1, R2 and R3 are d1, d2 and d3 respectively. The diameter of the working fluid channel increases in a gradient of d1<d2<d3.

2. A circumferentially variable diameter fuel element according to claim 1, characterized in that: d1, d2, d3 meet the following conditions: d2=ad1, d3=ad2, Among them, a is the preset coefficient, and its value range is 1.1~1.

5.

3. A circumferentially variable diameter fuel element according to claim 1, characterized in that: The axial direction of the working fluid channel is parallel to the axial direction of the core matrix.

4. A circumferentially variable diameter fuel element according to claim 1, characterized in that: The working fluid channel in the R1 region is coaxially arranged with the core matrix.

5. A circumferentially variable diameter fuel element according to claim 1, characterized in that: The three regions R1, R2 and R3 are all arranged concentrically with the core matrix.

6. A circumferentially variable diameter fuel element according to claim 1, characterized in that: The fuel element is axially provided with a first fuel section, a second fuel section and a cavity heat exchange section, wherein the cavity heat exchange section is arranged between the first fuel section and the second fuel section and is communicated with the first fuel section and the second fuel section.

7. A circumferentially variable diameter fuel element according to claim 6, characterized in that: The heat source intensity of the second fuel segment is greater than that of the first fuel segment.

8. A circumferentially variable diameter fuel element according to claim 2, characterized in that: The value of a is 1.

3.

9. An engine, characterized in that: A circumferentially variable diameter fuel element comprising any one of claims 1 to 8.

10. A nuclear thermal rocket, characterized in that: An engine comprising the engine described in claim 9.

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