Solid rocket grain deformation monitoring system and method based on optical frequency domain reflection

Abstract

The present invention relates to a solid motor charge deformation monitoring system and method based on optical frequency domain reflection. The system comprises: an optical fiber sensor arranged on a solid motor charge, the optical fiber sensor surface is rough, and is spirally arranged along the side wall of the inner hole of the charge and the interface between the solid motor lining and the charge. The monitoring system provided by the present invention can provide a deformation measurement range far greater than the elongation of the optical fiber sensor itself, thereby well meeting the solid charge deformation measurement requirements, and has dense measurement points and high spatial resolution, and can fully reflect the three-dimensional deformation and random cracks of the charge.

Description

Technical Field

[0001] The invention relates to the technical field of material performance monitoring, and in particular to a solid motor charge deformation monitoring system and method based on optical frequency domain reflection. Background Art

[0002] With the development of modern science and technology and material technology, solid engines have been widely used. With the advantages of simple structure, long storage time, rapid start-up and high thrust, solid engines have become an important power source in the aerospace field such as artificial satellite deployment and sonde launch, and play a vital role in meteorological detection, earthquake remote sensing, mineral exploration, environmental monitoring, scientific research, etc.

[0003] The solid charge is the core component of the solid motor. It is mainly made of particle-filled composite materials that are cast and solidified. It accounts for more than 90% of the total mass of the solid motor and largely determines the safety and storage life of the solid motor.

[0004] However, the materials that make up the solid grain are chemically unstable. During the long-term storage of solid motors, the solid grain will creep, crack, and other damages under the action of gravity. If the solid grain whose structural integrity has been damaged is not discovered and continues to be used, it may cause the engine to fail to operate or even explode, endangering the safety of the platform and personnel; on the contrary, if the engine is retired prematurely before reaching its storage life, it will not only waste resources and cause economic losses, but also pollute the environment.

[0005] Existing nondestructive testing and electrical sensing technologies have their own shortcomings in terms of reliability, durability, compatibility and safety, and are difficult to meet the long-term monitoring needs of a large number of solid motor grain deformation. Although optical fiber sensors have advantages such as small diameter, electrical insulation, stable chemical properties, anti-electromagnetic interference, and large transmission capacity, the fiber grating technology currently used in the field of solid motor monitoring has problems such as complex grating and packaging processes, fragile and easy-to-break optical fibers, low survival rate, and low resolution that cannot achieve true distributed measurement. In particular, the elastic modulus of optical fibers and solid grains is very different, making it difficult to use for large deformation measurement of solid grains. Summary of the invention

[0006] Based on this, it is necessary to provide a solid motor grain deformation monitoring system and method based on optical frequency domain reflection, which can enable the optical fiber and the solid grain to maintain effective grip and bonding and can deform cooperatively, in order to address the above technical problems.

[0007] A solid motor grain deformation monitoring system based on optical frequency domain reflection comprises: an optical fiber sensor arranged on the solid motor grain, wherein the optical fiber sensor has a rough surface and is spirally arranged along the side wall of the grain inner hole and the interface between the solid motor lining and the grain.

[0008] A method for monitoring deformation of solid motor grain based on optical frequency domain reflection, the method comprising:

[0009] Step 201, determining the spiral layout parameters of the optical fiber sensor;

[0010] Step 202, laying a lining layer on the solid motor casing, and then pre-marking a layout position on the lining layer based on the spiral layout parameters;

[0011] Step 203, introducing the optical fiber sensor from the nozzle plugging cap of the solid rocket engine, and laying the optical fiber sensor in a spiral shape according to the pre-marked laying position on the lining layer determined in step 202, and then pouring the charge;

[0012] Step 204, after the drug column is initially solidified, pre-marking the layout position on the side wall of the inner hole of the drug column based on the spiral layout parameters;

[0013] Step 205 , according to the pre-marked placement positions on the side walls of the inner hole of the drug column determined in step 204 , the optical fiber sensors are placed in a spiral shape.

[0014] Compared with the prior art, the solid motor charge deformation monitoring system and method based on optical frequency domain reflection provided by the present invention has the following effects:

[0015] 1. The fiber optic sensor is arranged in a spiral shape, which can provide a deformation measurement range far greater than the elongation of the fiber optic sensor itself, thus meeting the deformation measurement requirements of solid drug column.

[0016] 2. The fiber optic sensors are arranged along the side walls of the inner hole of the grain and the interface between the solid engine lining and the grain. This two-layer arrangement makes the fiber optic sensor measurement points dense and the spatial resolution high, which can fully reflect the three-dimensional deformation and random cracks of the grain.

[0017] 3. The rough surface of the fiber optic sensor can maintain a better grip and adhesion with the drug column to achieve more accurate measurement.

[0018] 4. The system has a simple structure and is corrosion-resistant and electrically insulating. It has little impact on the structural integrity of the charge column during deployment, is easy to deploy, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0020] Figure 1 Schematic diagram of the structure of a solid motor charge deformation monitoring system based on optical frequency domain reflection in one embodiment;

[0021] Figure 2 FIG. 1 is a cross-sectional schematic diagram of the layout of an optical fiber sensor in an embodiment.

[0022] Reference numerals:

[0023] Solid engine 1, grain 11, optical fiber sensor 12, capillary steel tube 13, tail end reflection eliminator 14, optical fiber connector 15, optical frequency domain reflectometer 16, data processing module 17, control line 18, protective layer 19, ferrule 20.

[0024] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0027] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] The following will describe the implementation of the present invention in detail with reference to the accompanying drawings in the embodiment diagram of the present invention.

[0030] Example 1

[0031] like Figure 1 and Figure 2 As shown, a solid motor charge deformation monitoring system based on optical frequency domain reflection is provided, comprising: an optical fiber sensor 12 arranged on the charge of a solid motor 1, the optical fiber sensor 12 having a rough surface, and being spirally arranged along the side wall of the inner hole of the charge 11 and the interface between the solid motor lining and the charge.

[0032] It can be understood that, since the elastic modulus of the optical fiber sensor 12 and the cured drug column 11 are very different, in this embodiment, the optical fiber sensor 12 is spirally arranged on the side wall of the inner hole of the drug column 11 and the interface between the solid engine lining and the drug column. At the same time, the rough surface of the optical fiber sensor 12 can effectively increase the friction resistance with the drug column 11, so that the optical fiber sensor 12 and the drug column 11 maintain effective grip and bonding, so that the optical fiber sensor 12 and the drug column 11 can be deformed in coordination to meet the large deformation measurement requirements of the drug column 11. Through such a layout combination, the present invention can monitor the health status of the drug column 11 in large quantities, for a long time, in real time, and comprehensively.

[0033] In one embodiment, the number of the optical fiber sensors 12 is one or two.

[0034] When there is only one optical fiber sensor 12 , it is firstly arranged in a spiral shape along the interface between the lining of the solid engine 1 and the grain 11 , then goes around from the end of the grain to the inner hole of the grain 11 , and is arranged in a spiral shape along the side wall of the inner hole of the grain 11 .

[0035] When there are two optical fiber sensors 12 , one is arranged in a spiral shape along the side wall of the inner hole of the grain 11 , and the other is arranged in a spiral shape along the interface between the lining of the solid engine 1 and the grain 11 .

[0036] Specifically, when the side wall of the inner hole of the grain 11, the interface between the lining of the solid engine 1 and the grain 11 are continuously laid out with an optical fiber sensor 12, the optical fiber sensor 12 is introduced from the nozzle plugging cover of the solid engine 1, and is spirally laid on the surface of the lining of the solid engine 1, and is reserved at the end of the solid engine 1. After the grain 11 is poured and initially solidified, the reserved optical fiber sensor 12 is spirally laid along the side wall of the inner hole of the grain 11, and its tail end is placed in the inner hole of the solid engine 1. It can be understood that the overall performance of the grain 11 is monitored by an optical fiber sensor 12, and the data collected by it has temporal and spatial consistency, which is convenient for data synchronization and analysis, and only one optical fiber sensor 12 and one monitoring unit are needed, which reduces equipment cost and installation cost and simplifies data processing.

[0037] When there are two optical fiber sensors 12, first introduce one optical fiber sensor 12 from the nozzle plugging cap of the solid engine 1, arrange it spirally along the surface of the lining of the solid engine 1, and place its tail end at the end of the solid engine 1, and then pour the medicine column 11. After the medicine column 11 is poured and initially solidified, another optical fiber sensor 12 is introduced from the nozzle plugging cap of the solid engine 1, and is spirally arranged along the side wall of the inner hole of the medicine column 11, and its tail end is placed in the inner hole of the solid engine 1. It can be understood that the use of two optical fiber sensors 12 to independently monitor the inner wall and outer wall of the medicine column 11 can obtain more detailed and accurate local information, improve monitoring accuracy and reliability, and can also accurately analyze the deformation and cracks of the medicine column 11, which is conducive to optimizing the manufacturing process of the medicine column 11; in addition, when one optical fiber sensor 12 fails, the other can still continue to work, which increases the reliability of the system. In addition, according to different monitoring requirements, optical fiber sensors 12 of different types and specifications can be used to improve resolution and sensitivity.

[0038] In one embodiment, it also includes: a capillary steel tube 13; the tail end of the optical fiber sensor 12 penetrates into the capillary steel tube 13 and moves freely in the capillary steel tube 13 but does not slide out; or a temperature compensation optical fiber is arranged, and the temperature compensation optical fiber is arranged parallel to the optical fiber sensor 12 on the solid engine 1.

[0039] Specifically, the number of capillary steel tubes 13 matches the number of optical fiber sensors 12, and is located near the tail end of the optical fiber sensor 12. When one optical fiber sensor 12 is used, the capillary steel tube 13 is arranged in the inner hole of the medicine column 11. When two optical fiber sensors 12 are used, one capillary steel tube 13 is arranged at the end of the solid engine 1, and the other capillary steel tube 13 is arranged in the inner hole of the medicine column 11. When the optical fiber sensor 12 is arranged and fixed in a spiral shape, its tail end penetrates into the inner hole of the capillary steel tube 13, and moves freely in the inner hole of the capillary steel tube 13 but does not slide out, so that the optical fiber sensor 12 in the capillary steel tube is only affected by temperature, and is not affected by the deformation of the medicine column 11, so as to play a role of temperature compensation. The capillary steel tube 13 is fixed by gluing.

[0040] In addition, in order to reduce the impact of the capillary steel tube on the structural integrity, a temperature compensation optical fiber can also be set. The temperature compensation optical fiber is not shown in the figure. The temperature compensation optical fiber is made of the same material as the optical fiber sensor 12 and is arranged parallel to the optical fiber sensor 12 on the solid engine 1.

[0041] It is worth noting that the capillary steel tube 13 and the temperature compensation optical fiber can be used either alone or simultaneously depending on the situation.

[0042] In one embodiment, it further includes: a tail end reflection eliminator 14; the tail end reflection eliminator 14 is connected to the tail end of the optical fiber sensor 12 and is placed at the end or inner hole of the solid engine 1.

[0043] It can be understood that the tail end reflection eliminator 14 is a section of optical fiber that has been specially treated to increase optical loss. It is connected to the tail end of the optical fiber sensor 12, and the number used is adapted to the number of optical fiber sensors 12. The tail end reflection eliminator 14 is connected to the tail end of the optical fiber sensor 12, and passes through the capillary steel tube 13 together with the tail end of the optical fiber sensor 12, and then is placed in the inner hole of the solid engine 1 to eliminate the high reflection at the tail end of the optical fiber sensor 12, reduce interference, and improve the stability of the measurement. It can be connected to the tail end of the optical fiber sensor 12 by fusion splicing, or it can be integrally formed with the optical fiber sensor 12, or a section of the tail end of the optical fiber sensor 12 can be specially treated to serve as the tail end reflection eliminator 14. Special treatment of optical fiber to increase optical loss is a prior art and will not be elaborated here.

[0044] It is worth noting that when the connection is made by fusion splicing, the tail end of the optical fiber sensor 12 can be connected first, and then passed through the capillary steel tube 13 together with the tail end of the optical fiber sensor 12; or the tail end of the optical fiber sensor 12 can be passed through the capillary steel tube 13 and then connected to the tail end reflection eliminator 14.

[0045] In one embodiment, a monitoring unit is further included; the optical fiber sensor 12 is connected to the monitoring unit via an optical fiber connector 15 .

[0046] In one embodiment, the monitoring unit includes an optical frequency domain reflectometer 16 and a data processing module 17; the optical frequency domain reflectometer 16 is connected to the optical fiber sensor 12 and the data processing module 17 respectively.

[0047] In one embodiment, the optical fiber connector 15 has a protective layer; and the optical frequency domain reflectometer 17 has a shielding layer 19 .

[0048] Specifically, the optical fiber connector 15 has a thicker protective layer, and is equipped with connecting plugs at both ends, which are used to connect the optical fiber sensor 12 and the optical frequency domain reflectometer 16 respectively.

[0049] The optical frequency domain reflectometer 16 integrates a linear frequency sweeping light source, a Michelson interferometer, a photodetector, a spectrometer, etc., and uses the frequency sweeping light source coherent detection technology to measure the distributed fiber Rayleigh scattering spectrum frequency shift signal to monitor the fiber Rayleigh scattering spectrum frequency shift change caused by the deformation of the drug column 11. It is worth noting that the fiber Rayleigh scattering spectrum frequency shift technology is a conventional method and will not be described in detail here.

[0050] The optical frequency domain reflectometer 16 is detachably fixed to the outer shell surface of the solid engine 1 by means of a hoop 20, and can be disassembled before launch to achieve reuse, thereby improving the economy of the value monitoring equipment. Furthermore, the outer layer of the optical frequency domain reflectometer 16 is wrapped with a protective layer 19, and the protective layer 19 is made of a multi-layer protective material that is resistant to high and low temperatures, corrosion, impact, and water. The protective layer 19 provides long-term protection for the optical frequency domain reflectometer 16 to prevent the optical frequency domain reflectometer 16 from being damaged by collisions and to extend its service life. It is worth noting that the optical frequency domain reflectometer 16 preferably adopts a miniature optical frequency domain reflectometer.

[0051] The data processing module 17 is connected to the optical frequency domain reflectometer 16 via a control line 18, and can convert the real-time strain data monitored by the optical frequency domain reflectometer 16 into a real-time strain three-dimensional cloud map, thereby identifying and locating cracks and monitoring their development according to the abnormal strain data. Data processing and analysis by the data processing module 17 is a conventional technical means, which will not be described in detail here.

[0052] In one embodiment, the optical fiber sensor 12 is a quartz optical fiber encapsulated by an organic polymer material, and the surface of the organic polymer material is roughened; or the optical fiber sensor is a quartz optical fiber encapsulated by a tightly wrapped thermoplastic polyester elastomer material, and the surface of the thermoplastic polyester elastomer material is roughened.

[0053] Among them, the quartz optical fiber encapsulated by organic polymer materials is a single-mode or multi-mode quartz optical fiber encapsulated by organic polymer materials that is resistant to high and low temperatures, highly resistant to creep, has a low thermal expansion coefficient, and is corrosion-resistant; the quartz optical fiber encapsulated by thermoplastic polyester elastomer materials is a single-mode or multi-mode quartz optical fiber encapsulated by thermoplastic polyester elastomer materials.

[0054] It can be understood that the single-mode or multi-mode quartz optical fiber encapsulated by organic polymer materials that are resistant to high and low temperatures, highly resistant to creep, have a low thermal expansion coefficient, and are resistant to corrosion is used as the optical fiber sensor 12, which has excellent thermal stability, electrical insulation, mechanical strength, weather resistance, and good bonding performance with other materials. Specifically, the organic polymer material can be polyimide, polyetheretherketone, polyphenylene sulfide, polyaryletherketone, liquid crystal polymer and other materials, preferably polyimide. After the single-mode quartz optical fiber is encapsulated with an organic polymer material, a roughening activation process is used to roughen the surface of the organic polymer coating to increase the surface friction resistance, thereby improving the grip and bonding effect. It is worth noting that the diameter of the optical fiber sensor 12 made after encapsulation with an organic polymer material needs to consider the impact on the structural integrity of the solid engine bonding interface as much as possible while ensuring the survival rate of the optical fiber, and the preferred diameter is 160μm.

[0055] Or, in order to improve the survival rate of the optical fiber, a single-mode or multi-mode quartz optical fiber encapsulated by a tightly wrapped thermoplastic polyester elastomer material can be used as the optical fiber sensor 12. The polyester elastomer has good weather resistance, high resilience and excellent mechanical properties. After the single-mode quartz optical fiber is encapsulated with a high-wrapping material, a high-frequency vibration process is used to roughen the surface of the high-wrapping material to increase the surface friction resistance and improve the grip and bonding effect. It is worth noting that the optical fiber sensor 12 made by encapsulating a tightly wrapped thermoplastic polyester elastomer material needs to consider minimizing the impact on the structural integrity of the solid engine bonding interface while ensuring the survival rate of the optical fiber. The preferred diameter is 1.5 mm.

[0056] Example 2

[0057] In this embodiment, a method for monitoring deformation of a solid motor charge based on optical frequency domain reflection is provided, comprising the following steps:

[0058] Step 201 , determining the spiral layout parameters of the optical fiber sensor 12 .

[0059] Step 202: Lay a lining on the casing of the solid engine 1, and then pre-mark the layout position on the lining based on the spiral layout parameters.

[0060] In step 203 , the optical fiber sensor 12 is introduced from the nozzle plugging cover of the solid engine 1 , and the optical fiber sensor 12 is spirally arranged according to the pre-marked arrangement position on the lining determined in step 202 , and then the charge 11 is poured.

[0061] It can be understood that the fiber optic sensor 12 located in the interface between the lining of the solid engine 1 and the charge 11 is laid out after the lining is paved and before the charge 11 is poured. The laying position is pre-marked on the lining by laying out lines to determine the spiral direction of the fiber optic sensor 12, and then the fiber optic sensor 12 is fixed along the spiral direction by point bonding with an adhesive having a faster curing speed, and then the charge 11 is poured.

[0062] Step 204 : After the drug column 11 is initially solidified, the placement position is pre-marked on the wall of the drug column 11 based on the spiral placement parameters.

[0063] Step 205 , according to the pre-marked placement position of the inner hole side wall of the drug column 11 determined in step 204 , the optical fiber sensor 12 is placed in a spiral shape.

[0064] It can be understood that the fiber optic sensor 12 located on the side wall of the inner hole of the drug column 11 is laid out after the drug column 11 is initially solidified after being poured. The laying position is pre-marked on the side wall of the inner hole of the drug column 11 by laying out the line to determine the spiral direction of the fiber optic sensor 12, and then the fiber optic sensor 12 is pasted in parallel with a fixed spacing on both sides of the spiral direction using tape, and then the fiber optic sensor 12 is fixed by brushing the adhesive material by gluing. After the brushing is completed, the tape is torn off. The tape is preferably a polyimide tape; the adhesive material is an adhesive such as solid propellant glue or silicone rubber, and the brushing method is to brush the area between the two tapes at a fixed thickness.

[0065] Alternatively, a shallow groove may be carved along the spiral direction on the inner hole side wall surface of the drug column 11 , the optical fiber sensor 12 may be placed in the groove, the groove may be filled with solid propellant glue or adhesive such as silicone rubber, and then continued to solidify together with the drug column 11 .

[0066] In one embodiment, the solid motor charge deformation monitoring method based on optical frequency domain reflection further includes:

[0067] Step 301 : constructing a spatial position relationship model between the optical fiber sensor 12 and the drug column 11 according to the layout parameters of the optical fiber sensor 12 .

[0068] Specifically, the layout parameters of the optical fiber sensor 12 include pitch, helix angle, and the like.

[0069] According to these layout parameters and the length of the optical fiber sensor 12 from the nozzle plugging point of the solid engine 1 to the introduction starting point, a spatial position relationship model of the optical fiber sensor 12 and the charge 11 is constructed.

[0070] After the solid engine 1 is manufactured, the monitoring unit is started based on the spatial position relationship model, and the position of the introduction point of the optical fiber sensor 12 at the nozzle plugging cover of the solid engine 1 is calibrated with liquid nitrogen cryogenically, and the initial value of the length / strain data of the optical fiber sensor 12 collected by the optical frequency domain reflectometer 16 is recorded as the reference value of the state of the solid engine 1.

[0071] Step 302, based on the spatial position relationship model, after the pouring of the grain is completed, the monitoring unit is started to monitor the solid engine 11 during non-production period to obtain real-time strain data of the grain 11, and the health status of the grain 11 is evaluated according to the real-time strain data to obtain the status evaluation result.

[0072] The non-production period includes the vulcanization cooling, transportation, storage, and duty periods. By starting the monitoring unit during the non-production period, the real-time strain data of the grain 11 is obtained, and the engine status is evaluated in real time based on the strain data such as the deformation and cracks of the grain 11, and the damaged engine is cleaned out in time.

[0073] Step 303, before use, determine whether the charge 11 is qualified based on the status evaluation result of step 302. If so, turn off the monitoring unit to end the monitoring, then cut off the optical fiber sensor 12 from the nozzle plug of the solid engine 1, remove the optical fiber sensor 12, optical fiber connector 15 and monitoring unit outside the solid engine 1, and then prepare for use.

[0074] It should be understood that, although the various steps in the present embodiment are written in order, these steps are not necessarily executed in order according to the indicated order. Unless there is a clear explanation in this article, the execution of these steps does not have strict order restrictions, and these steps can be executed in other orders. Moreover, in the present embodiment, at least a part of the steps may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily carried out in order, but can be executed in turn or alternately with at least a part of other steps or sub-steps or stages of other steps.

[0075] It can be seen that the solid motor charge deformation monitoring system and method based on optical frequency domain reflection provided by the present invention can accurately obtain the real-time strain distribution cloud map of the charge 11 of the solid motor 1, clearly reflect the deformation of the motor charge 11; can identify and locate the cracks in the charge 11 and monitor their development in real time. The monitoring unit and monitoring method have little effect on the structural integrity of the solid motor charge, and have dense distributed measurement points, high spatial resolution, high measurement accuracy, simple structure, easy layout, corrosion resistance, and electrical insulation. It can monitor the deformation and cracks of the charge 11 in the solid motor 1 in real time for a long time, reduce safety risks, and ensure the safety and reliability of the solid motor 1.

[0076] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A solid motor grain deformation monitoring system based on optical frequency domain reflection, characterized in that: include: The optical fiber sensor is arranged on the solid motor grain, the surface of the optical fiber sensor is rough, and the optical fiber sensor is arranged in a spiral shape along the side wall of the inner hole of the grain and the interface between the solid motor lining and the grain; the frequency shift signal of the distributed optical fiber Rayleigh scattering spectrum is measured by using the swept light source coherent detection technology to monitor the change of the optical fiber Rayleigh scattering spectrum frequency shift caused by the deformation of the grain; During deployment, the optical fiber sensor is deployed according to the spiral deployment parameters so as to be compatible and synergistically deformed with the solid motor charge; The number of the optical fiber sensors is one or two; When there is one optical fiber sensor, it is firstly arranged in a spiral shape along the interface between the solid engine lining and the grain, then wound from the end of the grain to the inner hole of the grain, and arranged in a spiral shape along the side wall of the inner hole of the grain; When there are two optical fiber sensors, one is arranged in a spiral shape along the side wall of the inner hole of the grain, and the other is arranged in a spiral shape along the interface between the solid engine lining and the grain; The optical fiber sensor is a quartz optical fiber encapsulated by an organic polymer material, and the surface of the organic polymer material is roughened; Or the optical fiber sensor is a quartz optical fiber encapsulated by a tightly wrapped thermoplastic polyester elastomer material, and the surface of the thermoplastic polyester elastomer material is roughened; It also includes: a capillary steel tube; the tail end of the optical fiber sensor penetrates into the capillary steel tube and moves freely in the capillary steel tube but does not slide out; and a temperature compensation optical fiber is arranged, and the temperature compensation optical fiber is arranged parallel to the optical fiber sensor; Tail end reflection eliminator; the tail end reflection eliminator is connected to the tail end of the optical fiber sensor and is placed in the solid engine end or the inner hole of the machine.

2. The solid motor grain deformation monitoring system based on optical frequency domain reflection according to claim 1 is characterized in that: Also includes a monitoring unit; The optical fiber sensor is connected to the monitoring unit via an optical fiber connector.

3. The solid motor grain deformation monitoring system based on optical frequency domain reflection according to claim 2 is characterized in that: The monitoring unit includes an optical frequency domain reflectometer and a data processing module; The optical frequency domain reflectometer is connected to the optical fiber sensor and the data processing module respectively.

4. The solid motor grain deformation monitoring system based on optical frequency domain reflection according to claim 3 is characterized in that: The optical fiber connector has a protective layer; the optical frequency domain reflectometer has a shielding layer.

5. A method for monitoring deformation of solid motor grain based on optical frequency domain reflection, characterized in that: The method comprises: Step 201, determining the spiral layout parameters of the optical fiber sensor; Step 202, laying a lining layer on the solid motor casing, and then pre-marking a layout position on the lining layer based on the spiral layout parameters; Step 203, introducing the optical fiber sensor from the nozzle plugging cap of the solid rocket engine, and laying the optical fiber sensor in a spiral shape according to the pre-marked laying position on the lining layer determined in step 202, and then pouring the charge; Step 204, after the drug column is initially solidified, pre-marking the layout position on the side wall of the inner hole of the drug column based on the spiral layout parameters; Step 205, laying out the optical fiber sensor in a spiral shape according to the pre-marked laying positions on the side walls of the inner hole of the drug column determined in step 204; Also includes: Step 301, constructing a spatial position relationship model between the optical fiber sensor and the drug column according to the layout parameters of the optical fiber sensor; Step 302, based on the spatial position relationship model, after the grain pouring is completed, the monitoring unit is started to monitor during the non-production period of the solid engine to obtain the real-time strain data of the grain, and the health status of the grain is evaluated according to the real-time strain data to obtain the status evaluation result; Step 303, before use, determine whether the propellant is qualified based on the status evaluation result of step 302. If so, turn off the monitoring unit to end the monitoring, then cut off the optical fiber sensor from the engine nozzle plug, and remove the optical fiber sensor, optical fiber connector and monitoring unit outside the solid engine.

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