Quantitative judgment method for size of pressure relief hole of multilayer closed cavity of spacecraft

Abstract

The invention relates to a method for quantitatively judging the size of a pressure relief hole of a multi-layer closed cavity of a spacecraft. The method comprises the following steps: S1, estimating the volume V in the multi-layer closed cavity; s2, estimating the area S of the multi-layer pressure relief hole; s3, the proportion # imgabs0 # is calculated; S4, if tau is smaller than 0.01 + / -40%, the risk of multi-layer fracture caused by cavity pressure relief meets the requirement; and if the tau is greater than or equal to 0.01 + / -40%, increasing the size of the reserved pressure relief hole, and repeating the steps S2-S4 until the tau is less than 0.01 + / -40%. By using the method provided by the invention, the multilayer on-orbit fracture risk caused by too small pressure relief holes and the influence on the multilayer heat insulation effect caused by too large pressure relief holes are avoided, and the reliability of multilayer coating on the surface of the spacecraft is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of overall design of spacecraft, and relates to a method for quantitatively determining the size of pressure relief holes in multi-layer closed cavities of a spacecraft. Background Art

[0002] Multilayer insulation materials have outstanding insulation performance in a vacuum environment. Since its appearance in the 1950s, it has been widely used in passive thermal control of spacecraft surfaces, mainly to reduce heat loss in spacecraft and isolate heating from other heat sources in the external environment. When wrapping the surface of a spacecraft, in order to ensure the excellent insulation performance of multilayer insulation materials, it is generally necessary to implement good overlap or stitching technology at the junction of the multilayer screens to form a closed system between the screens. Since the spacecraft is in a vacuum environment when it is in orbit, in order to allow the air inside the multilayer to be discharged smoothly, many small pressure relief holes are opened in the outermost layer of the multilayer. However, when the spacecraft's multiple layers completely seal the interior of the spacecraft, a closed cavity will be formed inside the spacecraft, and the small pressure relief holes in the outermost layer of the multiple layers can only discharge the air inside the multiple layers themselves. Therefore, for the spacecraft cavity that is sealed by multiple layers, a larger pressure relief hole needs to be reserved at the closed mouth to discharge the air in the cavity. The previous experience design only qualitatively gives "if a closed cavity is formed when the spacecraft is wrapped in multiple layers, a pressure relief hole needs to be reserved at the sealed mouth of the multiple layers", but how big the hole should be is often based on the experience of each designer. If the designer is not experienced enough, then the multiple layers of the spacecraft surface may be broken in orbit. For example, a satellite has multiple layers broken after being launched into orbit because the reserved pressure relief holes in the cabin closed by multiple layers are too small. The on-orbit rupture of multiple layers of spacecraft not only reduces the thermal control performance of the spacecraft, thereby affecting other functions of the spacecraft, but also for optical spacecraft, the broken debris of multiple layers may enter the optical system, causing the optical system to be contaminated. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a method for quantitatively determining the size of multi-layer closed cavity pressure relief holes in spacecraft, so as to avoid the risk of multi-layer on-orbit rupture caused by too small pressure relief holes and the risk of multi-layer thermal insulation effect affected by too large pressure relief holes.

[0004] The solution to the technical problem of the present invention is: a method for quantitatively determining the size of a multi-layer closed cavity pressure relief hole in a spacecraft, comprising:

[0005] S1, estimate the volume V of the multi-layer closed cavity;

[0006] S2, estimate the area S of the multi-layer pressure relief holes;

[0007] S3,

[0008] S4. If τ<0.01±40%, the risk of multi-layer rupture caused by cavity pressure relief meets the requirement; if τ≥0.01±40%, increase the size of the reserved pressure relief hole, and repeat S2 to S4 until τ<0.01±40%.

[0009] Furthermore, the estimated volume V of the multi-layer closed cavity is estimated using 3D CAD software or measured using a tape measure, with the estimation error being no greater than 20%, in units of m. 3 .

[0010] Furthermore, the estimation of the area S of the multi-layer pressure relief holes is performed using 3D CAD software for the reserved pressure relief holes with fixed shapes, or actual measurement using a tape measure, with the estimation error required to be no greater than 20%, in units of m 2 ;

[0011] For the reserved pressure relief holes of non-fixed shapes, the estimation method is:

[0012]

[0013] Furthermore, the safety factor is less than or equal to 1; when the gap is loose, the safety factor is 1, and when the gap is tight, the safety factor is 0.8.

[0014] A spacecraft multi-layer closed cavity pressure relief hole size quantitative determination system, including a multi-layer closed cavity volume estimation module, a multi-layer pressure relief hole area estimation module, a ratio calculation module and a pressure relief hole size determination module;

[0015] A multi-layer closed cavity volume estimation module, used to estimate the volume V of the multi-layer closed cavity;

[0016] A multi-layer pressure relief hole area estimation module is used to estimate the area S of the multi-layer pressure relief holes;

[0017] Ratio calculation module, used to calculate the ratio

[0018] The pressure relief hole size determination module is used to perform the following judgments: if τ<0.01±40%, the risk of multi-layer rupture caused by cavity pressure relief meets the requirements; if τ≥0.01±40%, the size of the reserved pressure relief hole is increased until τ is met. < 0.01±40%.

[0019] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for quantitatively determining the size of multi-layer closed cavity pressure relief holes in a spacecraft.

[0020] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for quantitatively determining the size of multi-layer closed cavity pressure relief holes of a spacecraft are implemented.

[0021] A computer program product includes a computer program, which, when executed by a processor, implements the steps of the method for quantitatively determining the size of multi-layer closed cavity pressure relief holes in a spacecraft.

[0022] The beneficial effects of the present invention compared with the prior art are:

[0023] (1) Before the present invention was proposed, there was no literature on the quantitative determination method of the size of multi-layer closed cavity pressure relief holes on the surface of aerospace, and the size of the pressure relief holes was only reserved as large as possible based on experience. The present invention provides a quantitative determination method for the size of multi-layer closed cavity pressure relief holes on the surface of a spacecraft, which not only reduces the risk of multiple layers being ruptured due to pressure relief on orbit, but also can effectively avoid the pressure relief holes being opened too large to affect the thermal insulation effect of the multiple layers;

[0024] (2) The method for quantitatively determining the size of multi-layer closed cavity pressure relief holes on the surface of a spacecraft provided by the present invention avoids the pressure relief holes being opened too small, which increases the risk of multi-layer rupture on orbit, thereby improving the reliability of the multi-layer coating on the surface of the spacecraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the relationship between the multi-layer closed cavity, pressure relief holes and carrier fairing on the surface of the spacecraft;

[0026] Figure 2 This is a typical curve of the pressure inside the fairing changing with time during the launch of a carrier rocket;

[0027] Figure 3 When S / V = 0.0001 (1 / m), ΔP changes with t. max ≈17000Pa;

[0028] Figure 4 When S / V = 0.001 (1 / m), ΔP changes with t. max ≈380Pa;

[0029] Figure 5 When S / V = 0.0063 (1 / m), ΔP changes with t. max ≈10Pa;

[0030] Figure 6 When S / V = 0.01 (1 / m), ΔP changes with t. max ≈4Pa;

[0031] Figure 7 This is a flow chart of the method for quantitatively determining the size of multi-layer closed cavity pressure relief holes on the surface of a spacecraft. DETAILED DESCRIPTION

[0032] The spacecraft is first installed in the fairing of the launch vehicle, and then launched into deep space with the launch vehicle. When the launch vehicle reaches the outer atmosphere, the fairing is opened and discarded. Figure 1 As shown in the figure, let the volume of the multi-layer closed cavity on the surface of the spacecraft be V(m 3 ), gas pressure P S (Pa), temperature is T (K), density is ρ (kg / m 3 ), the molar mass of the gas is M (kg / mol). The area of ​​the pressure relief hole in the closed cavity is S (m 2 ), the pressure of the space outside the multiple layers of the spacecraft surface (i.e., inside the fairing) is P L .

[0033] For the gas in the multi-layer closed cavity on the surface of the spacecraft, according to the ideal gas state equation:

[0034]

[0035] Where R = 8.31441 J / (mol·K) is the ideal gas constant. Before the satellite is launched, the fairing temperature is controlled by air conditioning at room temperature T = 293 K. The molar mass of air is M = 29×10 -3 kg / mol, then:

[0036]

[0037] When there is a pressure difference between the inside and outside of a multi-layer closed cavity of a spacecraft, the gas will be discharged from the cavity to the outside. When the launch vehicle fairing is opened, the gas in the cavity is basically completely discharged. Assuming the gas discharge rate is v (m / s), according to the Bernoulli equation:

[0038]

[0039] Then the mass of the gas in the cavity will be lost, that is, the increased mass of the gas in the cavity is:

[0040]

[0041] Since the time from launch to fairing separation of a launch vehicle is generally about 100 seconds, the temperature of the gas in the multi-layer closed cavity of the spacecraft can be approximately unchanged before the fairing separation. Differentiating both sides of formula (1) yields:

[0042]

[0043] Substituting formula (3) and formula (4) into formula (5) yields:

[0044]

[0045] Move dt to the left and rearrange it to get:

[0046]

[0047] P S (0) = P L (0)

[0048] The measured pressure variation over time in the fairing of a typical launch vehicle from takeoff to fairing separation is as follows Figure 2 shown.

[0049] Equation (7) is a nonlinear differential equation and is difficult to solve analytically. However, according to P L The measured time-varying curve of Figure 2 ), and then numerically calculate equation (7) to calculate the pressure difference between the inside and outside of the closed cavity under different S / V. S (t)-P L The curve of (t) changing with time is as follows:

[0050] When S / V=0.0001(1 / m), the curve of AP changing with t is as follows: Figure 3 As shown, ΔP max ≈17000Pa;

[0051] When S / V = 0.001 (1 / m), the curve of AP changing with t is as follows: Figure 4 As shown, ΔP max ≈380Pa;

[0052] When S / V=0.0063(1 / m), the curve of ΔP changing with t is as follows: Figure 5 As shown, ΔP max ≈10Pa;

[0053] When S / V = 0.01 (1 / m), the curve of AP changing with t is as follows: Figure 6 As shown, ΔP max ≈4Pa;

[0054] The multi-layer spacecraft is usually fixed with thermal control pins, and the pressure difference it can withstand is relatively small. Practice shows that the maximum pressure difference that the multi-layer spacecraft surface can withstand is about 100Pa. Therefore, to ensure safety, the maximum value of AP ΔP max <<100Pa. In experience, ΔP is generally taken max<10Pa, which can ensure that multiple layers of the spacecraft will not fall off due to pressure relief during the orbital stage. According to the results of numerical calculations, theoretically, as long as S / V>0.0063(1 / m), multiple layers can be avoided from falling off. However, considering that the estimation of cavity volume and pressure relief hole area in actual engineering applications is inevitably subject to certain errors, we further select ΔP when S / V<0.01 max <4Pa multilayer can avoid the risk of shedding, where the estimation error of S / V is allowed to be

[0055] In summary, the quantitative determination method of the size of multi-layer closed cavity pressure relief holes on the surface of spacecraft is as follows: Figure 7 As shown, the following steps are included:

[0056] S1. Estimate the volume V m of the multi-layer closed cavity 3 ;

[0057] S2. Estimate the area of ​​multi-layer pressure relief holes S m 2 ;

[0058] S3. Calculate the ratio

[0059] S4. If τ<0.01 (estimated value) ±40% (allowable estimated error), the risk of multi-layer rupture caused by cavity pressure relief meets the requirements; if τ≥0.01 (estimated value) ±40% (allowable estimated error), increase the size of the reserved pressure relief hole, and repeat S2 to S4 until τ<0.01 (estimated value) ±40% (allowable estimated error).

[0060] The present invention will be further described below in conjunction with the embodiments.

[0061] Example 1

[0062] 1. Estimate the volume V of multi-layer closed cavity

[0063] Use 3D CAD software such as ProE, UG, SolidWorks for estimation, or use a tape measure for actual measurement. The estimation error is required to be no more than 20%. Unit: m 3 .

[0064] 2. Estimate the area S of the multi-layer reserved pressure relief holes

[0065] For reserved pressure relief holes with fixed shapes, such as round holes, square holes and holes on other structures of spacecraft structures, use 3D CAD software such as ProE, UG, SolidWorks for estimation, or use a tape measure for actual measurement. The estimation error is required to be no more than 20%. The unit is m. 2 .

[0066] For reserved pressure relief holes of non-fixed shapes, such as gaps reserved at multi-layer overlaps, the estimation method is:

[0067]

[0068] Among them: safety factor ≤ 1; when the gap is loose, the recommended safety factor is 1, and when the gap is tight, the recommended safety factor is 0.8.

[0069] 3. Calculate the ratio:

[0070]

[0071] 4. If τ<0.01, there is no risk of multiple layers on track being ruptured due to exhaust. If τ≥0.01, the size of the reserved pressure relief holes is increased until τ<0.01 is met.

[0072] In this embodiment, the cabin where a satellite hyperspectral camera is located is sealed by multiple layers around it. According to the ProE 3D model, it can be estimated that the volume of the sealed cabin is about 1m 3 , then according to the determination method provided by the present invention, multiple layers need to reserve at least 0.01m 2 That is, the pressure relief hole. Since the reserved pressure relief hole is a non-fixed shape pressure relief hole, it can be calculated under the condition that the safety factor is 1 that the side length of the gap is at least 180mm. After the above-mentioned treatment measures, the satellite was successfully launched into orbit in December 2020. The multiple layers are in good condition and no multi-layer rupture occurs, which proves the effectiveness of the present invention.

[0073] The present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and when the computer instructions are executed on a computer, the computer executes Figure 7 The method described.

[0074] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) that contain computer-usable program code.

[0075] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0076] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0077] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0078] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

[0079] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for quantitatively determining the size of pressure relief holes in multi-layer closed cavities of spacecraft, characterized in that: include: S1, estimate the volume V of the multi-layer closed cavity; S2, estimate the area S of the multi-layer pressure relief holes; S3. Calculate the ratio S4. If τ<0.01±40%, the risk of multi-layer rupture caused by cavity pressure relief meets the requirement; if τ≥0.01±40%, increase the size of the reserved pressure relief hole, and repeat S2 to S4 until τ<0.01±40%.

2. The method for quantitatively determining the size of pressure relief holes in multi-layer closed cavities of spacecraft according to claim 1, characterized in that: The estimated volume V of the multi-layer closed cavity is estimated using 3D CAD software or measured with a tape measure, with the estimation error being no greater than 20%. The unit is m 3 .

3. The method for quantitatively determining the size of pressure relief holes in multi-layer closed cavities of spacecraft according to claim 1, characterized in that: The estimation of the area S of the multi-layer pressure relief holes is carried out using 3D CAD software for the reserved pressure relief holes with fixed shapes, or actual measurement using a tape measure, with the estimation error required to be no greater than 20%. The unit is m 2 ; For the reserved pressure relief holes of non-fixed shapes, the estimation method is:

4. The method for quantitatively determining the size of pressure relief holes in multi-layer closed cavities of spacecraft according to claim 3, characterized in that: The safety factor is less than or equal to 1; when the gap is loose, the safety factor is 1, and when the gap is tight, the safety factor is 0.

8.

5. A quantitative determination system for the size of pressure relief holes in multi-layer closed cavities of spacecraft, characterized in that: It includes a multi-layer closed cavity volume estimation module, a multi-layer pressure relief hole area estimation module, a ratio calculation module and a pressure relief hole size determination module; A multi-layer closed cavity volume estimation module, used to estimate the volume V of the multi-layer closed cavity; A multi-layer pressure relief hole area estimation module is used to estimate the area S of the multi-layer pressure relief holes; Ratio calculation module, used to calculate the ratio The pressure relief hole size determination module is used to perform the following determination: if τ<0.01±40%, the risk of multi-layer rupture caused by cavity pressure relief meets the requirement; if τ≥0.01±40%, the size of the reserved pressure relief hole is increased until τ<0.01±40% is met.

6. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 4 are implemented.

8. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method described in any one of claims 1 to 4 are implemented.

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