Fluid transient temperature sensor based on FP principle

Abstract

The invention relates to a fluid transient temperature sensor based on the FP principle, and belongs to the field of optical temperature sensing. One axial end of the 99 corundum ceramic tube is lapped on the 316 stainless steel metal seat, and the optical fiber collimator is coaxially arranged in an inner cavity of the end of the 99 corundum ceramic tube; the 99 corundum adapter is in butt joint with the other axial end of the 99 corundum ceramic tube; the transparent reflector plate is vertically arranged in an inner cavity of the 99 corundum adapter, and the transparent reflector plate is axially perpendicular to the 99 corundum ceramic tube; the fluid holes are evenly formed in the outer wall of the 99 corundum adapter in the circumferential direction, and the positions of the fluid holes correspond to the positions of the transparent reflection pieces. One end, extending out of the 99 corundum ceramic tube, of the optical fiber collimator is connected with the circulator through a cable; the circulator is respectively connected with the broadband light source and the demodulation terminal through optical fibers; the temperature resistance degree and the temperature measurement upper limit of the whole structure are improved, the service life is long, and the problem of service life attenuation does not exist under the conditions that external damage is avoided and the temperature sensing element is kept clean.

Description

Technical Field

[0001] The invention belongs to the field of optical temperature sensing and relates to a fluid transient temperature sensor based on the FP principle. Background Art

[0002] Temperature is an important physical parameter. Temperature measurement is widely used in the status assessment of many devices such as vehicles, aircraft, and pipelines, and is of great significance to device design and operation monitoring. In some special scenarios, such as the temperature field in the fluid flow path of an aircraft engine, it may be a non-uniform temperature field. The temperatures at different measurement points may be inconsistent, and the temperature changes rapidly. If the fluid temperature at a certain point can be quickly measured, it will be of great significance to the confirmation of the working status and health monitoring of the engine.

[0003] In special application conditions, such as in the combustion chamber pipes of aviation and aerospace engines, the fluid temperature can often reach thousands of degrees Celsius. Therefore, how to measure the fluid temperature at a specific point in the ultra-high temperature range has become an urgent engineering solution. At the same time, the airflow velocity in this area may reach up to 1 to 2 Mach, and the response speed of the temperature sensor will directly affect the ability to monitor the health of the flow channel.

[0004] At present, under special working conditions, fluid temperature measurement is usually carried out using special thermocouples. Thermocouple temperature measurement is an electrical temperature measurement and is easily interfered in a strong electromagnetic environment. The optical anti-electromagnetic interference property is incomparable to electrical temperature measurement. In addition, thermocouples are usually corroded by high temperature environments, resulting in heat loss and need to be replaced regularly. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a fluid transient temperature sensor based on the FP principle, which improves the temperature resistance and upper limit of the temperature measurement of the overall structure, has a long service life, and does not have the problem of life attenuation when it is not damaged by the outside world and the temperature sensing element is kept clean.

[0006] The solution of the present invention is:

[0007] A fluid transient temperature sensor based on the FP principle, comprising a transparent reflector, a 99 corundum adapter, a 99 corundum ceramic tube, a 316 stainless steel metal seat, an optical fiber collimator, a circulator, a wide spectrum light source, and a demodulation terminal;

[0008] Among them, the 316 stainless steel metal seat is placed horizontally; the 99 corundum ceramic tube is placed horizontally in the axial direction, and one axial end of the 99 corundum ceramic tube is overlapped on the 316 stainless steel metal seat, and the optical fiber collimator is coaxially arranged in the inner cavity of the 99 corundum ceramic tube at this end; the 99 corundum adapter is connected to the other axial end of the 99 corundum ceramic tube; the transparent reflector is vertically arranged in the inner cavity of the 99 corundum adapter, and the transparent reflector is perpendicular to the axial direction of the 99 corundum ceramic tube; fluid holes are evenly arranged on the outer wall of the 99 corundum adapter along the circumferential direction, and the positions of the fluid holes correspond to the positions of the transparent reflector; one end of the optical fiber collimator extending out of the 99 corundum ceramic tube is connected to the circulator through a cable; the circulator is connected to the wide-spectrum light source and the demodulation terminal through optical fibers respectively.

[0009] In the above-mentioned fluid transient temperature sensor based on the FP principle, the working process of the fluid transient temperature sensor is:

[0010] The wide-spectrum light source sends a divergent light signal to the circulator; the circulator switches the transmission direction of the divergent light signal to transmit it to the collimator; the collimator converts the divergent light signal into a collimated light signal, and sends the collimated light signal to the transparent reflector along the axial direction of the 99 corundum ceramic tube;

[0011] The external fluid to be measured enters the inner cavity of the 99 corundum adapter through the fluid hole, contacts the transparent reflector, and transmits the temperature to the transparent reflector; the transparent reflector deforms after being heated; the transparent reflector receives the collimated light signal from the collimator and reflects it; the collimator receives the reflected light and transmits the reflected light to the circulator; the circulator switches the transmission direction of the reflected light to transmit it to the demodulation terminal; the demodulation terminal demodulates the temperature of the external fluid to be measured.

[0012] In the above-mentioned fluid transient temperature sensor based on the FP principle, the transparent reflector is a temperature sensing element; the transparent reflector is made of a transparent material such as quartz, single crystal silicon carbide or single crystal aluminum oxide.

[0013] In the above-mentioned fluid transient temperature sensor based on the FP principle, FP cavities are provided on the top surface and the bottom surface of the transparent reflector, that is, both reflect the transmitted collimated light signal; after the transparent reflector is deformed by heat, there is an optical path difference between the reflected light on the top surface and the reflected light on the bottom surface.

[0014] In the above-mentioned fluid transient temperature sensor based on the FP principle, the collimator transmits the reflected light from the top surface and the reflected light from the bottom surface of the transparent reflector to the demodulation terminal through a circulator; the demodulation terminal obtains the thermal deformation of the transparent reflector according to the optical path difference of the two reflected lights, and obtains the temperature of the external fluid to be measured according to the known curve of the deformation of the transparent reflector and the temperature.

[0015] In the above-mentioned fluid transient temperature sensor based on the FP principle, the transparent reflective sheet is bonded to the inner cavity glue spot position of the 99 corundum adapter by spot coating; the glue is ceramic glue; after bonding, it is cured at room temperature for 24 hours, and then placed on a heating platform, cured at 70°C for 2 hours, and cured at 200°C for 4 hours.

[0016] In the above-mentioned fluid transient temperature sensor based on the FP principle, the end of the 99 corundum adapter without the axial fluid hole is bonded to the corresponding axial end of the 99 corundum ceramic tube by using ceramic glue; after bonding, the 99 corundum adapter and the 99 corundum ceramic tube remain coaxial, and after curing at room temperature for 24 hours, they are placed on a heating platform, cured at 70°C for 2 hours, and cured at 200°C for 4 hours.

[0017] In the above-mentioned fluid transient temperature sensor based on the FP principle, the 99 corundum ceramic tube and the 316 stainless steel metal seat are bonded by ceramic glue using a ring coating method; during bonding, the 99 corundum ceramic tube is made perpendicular to the 316 stainless steel metal seat by a tooling; and the tube is cured at room temperature for 24 hours, at 70°C for 2 hours, and at 200°C for 4 hours.

[0018] In the above-mentioned fluid transient temperature sensor based on the FP principle, the collimator adjusts the angle of the collimator through an external three-dimensional displacement platform so that the collimator receives the reflected light after being reflected by the transparent reflector; the collimator is bonded to the 99 corundum ceramic tube by AB epoxy glue and cured at room temperature for 24 hours.

[0019] In the above-mentioned fluid transient temperature sensor based on the FP principle, the optical fiber collimator is connected to the circulator by using an optical fiber coupler or optical fiber fusion splicing.

[0020] The beneficial effects of the present invention compared with the prior art are:

[0021] (1) The present invention uses a transparent reflector as a temperature sensing element. The transparent reflector can be made very thin, small in size, fast in heat conduction, and small in heat capacity. In addition, the connection with the adapter is dotted to reduce the contact surface between the two, thereby reducing the heat exchange rate, and realizing a transient response to temperature changes.

[0022] (2) The present invention uses a high temperature resistant ceramic tube as a supporting structure, the length of which can be changed to achieve accurate measurement of measuring points at different positions;

[0023] (3) The present invention uses a collimator as the sending and receiving end of the optical signal to prevent the optical fiber from directly entering the temperature field, thereby improving the overall temperature resistance and the upper limit of temperature measurement;

[0024] (4) The temperature measurement principle of the present invention is the FP principle, which has high temperature measurement accuracy and has the advantages of anti-electromagnetic interference and no life attenuation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the fluid transient temperature sensor of the present invention;

[0026] Figure 2 This is a schematic diagram of the 99 corundum adapter of the present invention;

[0027] Figure 3 It is a schematic diagram of the interference spectrum of the present invention;

[0028] Figure 4 It is a schematic diagram of the distribution of the interference pattern energy spectrum along with the EFPI cavity length of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the embodiments.

[0030] The present invention provides a fluid transient temperature sensor based on the FP principle, which improves the temperature resistance and upper temperature measurement limit of the overall structure, has a long service life, and does not have the problem of life attenuation when it is not damaged by the outside world and the temperature sensing element is kept clean.

[0031] Fluid transient temperature sensor based on FP principle, such as Figure 1 As shown, it includes a transparent reflector 2, a 99 corundum adapter 3, a 99 corundum ceramic tube 4, a 316 stainless steel metal seat 5, an optical fiber collimator 6, a circulator 7, a wide spectrum light source 8, and a demodulation terminal 9;

[0032] Among them, the 316 stainless steel metal seat 5 is placed horizontally; the 99 corundum ceramic tube 4 is placed horizontally in the axial direction, and one axial end of the 99 corundum ceramic tube 4 is overlapped on the 316 stainless steel metal seat 5, and the optical fiber collimator 6 is coaxially arranged in the inner cavity of the end of the 99 corundum ceramic tube 4; the 99 corundum adapter 3 is connected to the other axial end of the 99 corundum ceramic tube 4; the transparent reflector 2 is vertically arranged in the inner cavity of the 99 corundum adapter 3, and the transparent reflector 2 is axially perpendicular to the 99 corundum ceramic tube 4; the fluid holes 1 are evenly arranged on the outer wall of the 99 corundum adapter 3 along the circumferential direction, and the position of the fluid hole 1 corresponds to the position of the transparent reflector 2; one end of the optical fiber collimator 6 extending out of the 99 corundum ceramic tube 4 is connected to the circulator 7 through a cable; the circulator 7 is connected to the wide-spectrum light source 8 and the demodulation terminal 9 respectively through optical fibers.

[0033] The working process of the fluid transient temperature sensor is:

[0034] The wide-spectrum light source 8 sends a divergent light signal to the circulator 7; the circulator 7 switches the transmission direction of the divergent light signal to transmit it to the collimator 6; the collimator 6 converts the divergent light signal into a collimated light signal, and sends the collimated light signal to the transparent reflector 2 along the axial direction of the 99 corundum ceramic tube 4.

[0035] The external fluid to be measured enters the inner cavity of the 99 corundum adapter 3 through the fluid hole 1, contacts the transparent reflector 2, and transmits the temperature to the transparent reflector 2; the transparent reflector 2 is deformed after being heated; the transparent reflector 2 receives the collimated light signal transmitted by the collimator 6 and reflects it; the collimator 6 receives the reflected light and transmits the reflected light to the circulator 7; the circulator 7 switches the transmission direction of the reflected light to transmit it to the demodulation terminal 9; the demodulation terminal 9 demodulates the temperature of the external fluid to be measured.

[0036] The transparent reflector 2 is a temperature sensing element; the transparent reflector 2 is made of a transparent material such as quartz, single crystal silicon carbide or single crystal aluminum oxide. FP cavities are set on the top and bottom surfaces of the transparent reflector 2, that is, both reflect the collimated light signal transmitted; after the transparent reflector 2 is deformed by heat, there is an optical path difference between the reflected light on the top surface and the reflected light on the bottom surface.

[0037] The collimator 6 transmits the reflected light from the top surface and the reflected light from the bottom surface of the transparent reflector 2 to the demodulation terminal 9 through the circulator 7; the demodulation terminal 9 obtains the thermal deformation of the transparent reflector 2 according to the optical path difference of the two reflected lights, and obtains the temperature of the external fluid to be measured according to the known curve of the deformation of the transparent reflector 2 and the temperature.

[0038] like Figure 2 As shown, the transparent reflective sheet 2 is bonded to the inner cavity glue spot position of the 99 corundum adapter 3 by a dot coating method; the glue is ceramic glue; after bonding, it is cured at room temperature for 24 hours, and then placed on a heating platform, cured at 70°C for 2 hours, and cured at 200°C for 4 hours.

[0039] One end of the 99 corundum adapter 3 without the axial fluid hole 1 is bonded to the corresponding axial end of the 99 corundum ceramic tube 4 with ceramic glue; after bonding, the 99 corundum adapter 3 and the 99 corundum ceramic tube 4 remain coaxial, and after curing at room temperature for 24 hours, they are placed on a heating platform, cured at 70°C for 2 hours, and cured at 200°C for 4 hours.

[0040] The 99 corundum ceramic tube 4 and the 316 stainless steel metal seat 5 are bonded by ceramic glue using a ring coating method; during bonding, the 99 corundum ceramic tube 4 is made perpendicular to the 316 stainless steel metal seat 5 by a tooling; the materials are cured at room temperature for 24 hours, at 70°C for 2 hours, and at 200°C for 4 hours.

[0041] The collimator 6 adjusts the angle of the collimator 6 through the external three-dimensional displacement platform so that the collimator 6 receives the reflected light after being reflected by the transparent reflector 2; the collimator 6 is bonded to the 99 corundum ceramic tube 4 by AB epoxy glue and cured at room temperature for 24 hours. The optical fiber collimator 6 is connected to the circulator 7 by an optical fiber coupler or optical fiber fusion splicing.

[0042] The working principle of each component of the present invention is:

[0043] Fluid hole 1: This structure ensures that the fluid to be measured can directly contact the transparent reflective sheet, providing a faster and more accurate source of temperature values.

[0044] Transparent reflector 2: As a temperature sensing element, the upper and lower surfaces of the reflector 2 form a FP cavity, and the material may be (including but not limited to): quartz, single crystal silicon carbide, single crystal aluminum oxide and other transparent materials.

[0045] Adapter 3: As a protective and supporting structure for the transparent reflector, it can provide protection for the transparent reflector to prevent damage caused by collision between the transparent reflector and the foreign matter in the fluid, and connect the transparent reflector to the ceramic tube. The typical structure is as follows: Figure 2 shown.

[0046] Ceramic tube 4: As the overall supporting structure of the temperature sensing part, the length of the ceramic tube can be determined according to different temperature measurement positions, so that the temperature sensing part is directly at the temperature point to be measured, achieving more accurate temperature measurement.

[0047] Metal seat 5: As the supporting and fixing structure of the sensor as a whole, the metal material can achieve a better heat dissipation function for the ceramic tube after being heated.

[0048] Collimator 6: This sensor is an active temperature measurement device. The collimator can convert the divergent light transmitted in the optical fiber into a collimated light beam, and transmit and receive optical signals.

[0049] Circulator 7: controls the transmission direction of optical signals in optical fibers.

[0050] Light source module 8: emits light signals.

[0051] Demodulation module 9: performs signal processing according to the return light signal.

[0052] The schematic diagram of the adapter structure 3 is as follows Figure 2 The dispensing position in the figure is a step structure, and the transparent reflector is placed there after dispensing. The adapter structure can protect the transparent reflector from being damaged by foreign objects in the fluid. At the same time, the position of the transparent reflector can change with the change of the support rod, and the temperature measurement at any point in the flow field can be realized; the aperture size of the fluid hole can be changed according to the size of foreign objects that may exist in the flow field, so as to protect the transparent reflector. Compared with the adapter without holes, the design of the fluid hole allows the fluid to directly contact the transparent reflector, making the temperature measurement more accurate and faster, thereby improving the response speed.

[0053] The transparent reflective sheet 2 is used as a temperature sensing element. To achieve the purpose of transient temperature measurement, the thickness of the sheet should be reduced as much as possible to reduce the heat capacity, thereby increasing the response speed.

[0054] The collimator 6 is used as a transmitting and receiving device for optical signals. The collimator can output collimated light beams and receive signals reflected from the upper and lower surfaces of the transparent reflector 2. Since it is collimated light, the length change of the ceramic tube 4 has no effect on the measurement of the signal, so that it can produce a length change, thereby realizing temperature measurement at any point in the full flow field range.

[0055] The selection of the light source should take into account the passband of the collimator 6 and the identification band of the demodulation module 9. The demodulation module 9 obtains the interference spectrum period information by Fourier transforming the reflected light signal spectrum, and then obtains the EFPI cavity length, and obtains the temperature value to be measured by matching the known calibration curve.

[0056] Selection and connection of transparent reflector and adapter: The material selection of the two should be based on the adaptability to the temperature range to be measured and the compatibility with the fluid. The connection method usually adopts the gluing method. In order to reduce the contact area between the transparent reflector and the adapter, thereby reducing the heat exchange rate between the two and improving the response speed of the sensor, the gluing method adopts the spot coating method for bonding. The choice of glue can be selected according to the material of the transparent reflector and the temperature range of temperature measurement.

[0057] The connection between the adapter and the ceramic tube is usually made of gluing. Since both are made of ceramic, ceramic glue can usually be used for bonding.

[0058] The connection between the ceramic tube and the metal seat is usually made by gluing. The choice of glue can be selected according to the temperature range of the temperature measurement. The more typical ones are ceramic glue or epoxy glue.

[0059] The connection between the optical fiber collimator and the metal seat is usually made by gluing, and the typical glue used can be epoxy glue.

[0060] Example

[0061] The installation process of the fluid transient temperature sensor is as follows:

[0062] Step 1: The transparent reflector 2 uses a quartz sheet with a thickness of 50um and a diameter of 5mm as a temperature sensing element, and uses a high-viscosity ceramic glue to bond it to the glue point of the adapter by dotting. During bonding, the transparent reflector 2 is kept at a vertical angle to the fluid hole 1 through the tooling. After curing at room temperature for 24 hours, it is placed on a heating platform and cured at 70℃ for 2 hours and 200℃ for 4 hours.

[0063] Step 2: The end of the adapter without the fluid hole is ring-coated and bonded to one end of the 99 corundum ceramic tube 4 using ceramic glue. During bonding, the 99 corundum adapter 3 and the 99 corundum ceramic tube 4 are kept parallel through tooling. After curing at room temperature for 24 hours, place it on a heating platform, cure at 70°C for 2 hours, and cure at 200°C for 4 hours.

[0064] Step 3: The 99 corundum ceramic tube 4 and the 316 stainless steel metal seat 5 are bonded by ring coating using ceramic glue. During bonding, the 99 corundum ceramic tube 4 is made perpendicular to the 316 stainless steel metal seat 5 through tooling. The tube is cured at room temperature for 24 hours, at 70°C for 2 hours, and at 200°C for 4 hours.

[0065] Step 4: The collimator 6 adjusts the angle of the collimator 6 through the external three-dimensional displacement platform so that the collimator 6 receives the reflected light after being reflected by the transparent reflector 2; the collimator 6 is bonded to the 99 corundum ceramic tube 4 by AB epoxy glue and cured at room temperature for 24 hours.

[0066] Step 5: The optical fiber collimator 6 is connected to the MOI via an optical fiber connector.

[0067] Step 6: The sensor is connected to the fixed position through a 316 stainless steel metal seat. The temperature sensing element penetrates into the point to be measured and the measurement can begin.

[0068] The demodulation method used in the demodulation device is double-beam interference demodulation. The typical reflection spectrum of the EFPI sensor obtained by the demodulation terminal is as follows, and its schematic diagram is as follows Figure 3 As shown:

[0069] I(v)=A+Bcos(4πdv) (1

[0070] in:

[0071] v=1 / λ (2

[0072] A and B are constant terms, λ is the wavelength, and d is the cavity length of the FP cavity. After filtering out the DC amount, (1) can be written as:

[0073] I(v)=∫P(f)exp(i2πfv)df (3

[0074] P is the frequency spectrum distribution corresponding to the interference spectrum, f is the frequency, and the Fourier transform is performed to obtain the distribution of spectral energy with the EFPI cavity length. The schematic diagram is shown in Figure 4 As shown, by reading the horizontal coordinate of the peak value, the cavity length value can be obtained, and by matching with the known calibration curve, the temperature value of the fluid to be measured can be obtained.

[0075] The present invention adopts a transparent reflector as a temperature sensing element. The material and thickness of the reflector are variable. Different materials can be suitable for different temperature measurement requirements. Thinner thickness corresponds to smaller heat capacity. In addition, a special dispensing method reduces the heat exchange rate and achieves a faster response speed.

[0076] The present invention has a novel structure, uses a high-temperature resistant ceramic tube as a supporting structure, and the length can be changed to achieve accurate measurement of different measuring points; a collimator is used as the sending and receiving end of the optical signal, which can prevent the optical fiber from directly entering the temperature field and being directly sensed, thereby improving the overall temperature resistance and the upper limit of temperature measurement, and on the other hand, the divergent light is converted into collimated light by using the collimator, which provides the possibility for the length change of the ceramic tube; a tubular structure is adopted, and the diameter can be controlled to be less than φ6mm, which can cause as little damage as possible to the flow field to be measured; optical principle measurement is adopted, and it can be used in a strong electromagnetic interference environment; it has a long service life, and theoretically, there is no problem of life attenuation when it is not damaged by the outside world and the temperature sensing element is kept clean.

[0077] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A fluid transient temperature sensor based on the FP principle, characterized in that: It includes a transparent reflector (2), a 99 corundum adapter (3), a 99 corundum ceramic tube (4), a 316 stainless steel metal seat (5), an optical fiber collimator (6), a circulator (7), a wide-spectrum light source (8), and a demodulation terminal (9); The 316 stainless steel metal seat (5) is placed horizontally; the 99 corundum ceramic tube (4) is placed horizontally in the axial direction, and one axial end of the 99 corundum ceramic tube (4) is overlapped on the 316 stainless steel metal seat (5); the optical fiber collimator (6) is coaxially arranged in the inner cavity of the end of the 99 corundum ceramic tube (4); the 99 corundum adapter (3) is butt-jointed with the other axial end of the 99 corundum ceramic tube (4); the transparent reflector (2) is vertically arranged in the inner cavity of the 99 corundum adapter (3), and the transparent reflector (2) is axially perpendicular to the 99 corundum ceramic tube (4); fluid holes (1) are evenly arranged on the outer wall of the 99 corundum adapter (3) along the circumferential direction, and the position of the fluid holes (1) corresponds to the position of the transparent reflector (2); one end of the optical fiber collimator (6) extending out of the 99 corundum ceramic tube (4) is connected to the circulator (7) through a cable; the circulator (7) is connected to the wide-spectrum light source (8) and the demodulation terminal (9) respectively through optical fibers.

2. The fluid transient temperature sensor based on the FP principle according to claim 1, characterized in that: The working process of the fluid transient temperature sensor is: The wide-spectrum light source (8) emits a divergent light signal to the circulator (7); the circulator (7) switches the transmission direction of the divergent light signal to transmit it to the collimator (6); the collimator (6) converts the divergent light signal into a collimated light signal, and transmits the collimated light signal to the transparent reflector (2) along the axial direction of the 99 corundum ceramic tube (4); The external fluid to be measured enters the inner cavity of the 99 corundum adapter (3) through the fluid hole (1), contacts the transparent reflector (2), and transmits the temperature to the transparent reflector (2); the transparent reflector (2) deforms after being heated; the transparent reflector (2) receives the collimated light signal transmitted by the collimator (6) and reflects it; the collimator (6) receives the reflected light and transmits the reflected light to the circulator (7); the circulator (7) switches the transmission direction of the reflected light to transmit it to the demodulation terminal (9); the demodulation terminal (9) demodulates the temperature of the external fluid to be measured.

3. The fluid transient temperature sensor based on the FP principle according to claim 2, characterized in that: The transparent reflector (2) is a temperature sensing element; the transparent reflector (2) is made of a transparent material such as quartz, single crystal silicon carbide or single crystal aluminum oxide.

4. The fluid transient temperature sensor based on the FP principle according to claim 2, characterized in that: The top surface and the bottom surface of the transparent reflective sheet (2) are both provided with FP cavities, that is, both reflect the transmitted collimated light signal; after the transparent reflective sheet (2) is deformed by heat, there is an optical path difference between the reflected light on the top surface and the reflected light on the bottom surface.

5. The fluid transient temperature sensor based on the FP principle according to claim 4, characterized in that: The collimator (6) transmits the reflected light from the top surface and the reflected light from the bottom surface of the transparent reflective sheet (2) to the demodulation terminal (9) through the circulator (7); the demodulation terminal (9) obtains the thermal deformation of the transparent reflective sheet (2) based on the optical path difference of the two reflected lights, and obtains the temperature of the external fluid to be measured based on a known curve of the deformation of the transparent reflective sheet (2) and temperature.

6. The fluid transient temperature sensor based on the FP principle according to claim 1, characterized in that: The transparent reflective sheet (2) is bonded to the inner cavity glue point position of the 99 corundum adapter (3) by a dot coating method; the glue is ceramic glue; after bonding, it is cured at room temperature for 24 hours, and then placed on a heating platform, cured at 70°C for 2 hours, and cured at 200°C for 4 hours.

7. The fluid transient temperature sensor based on the FP principle according to claim 1, characterized in that: The end of the 99 corundum adapter (3) without the axial fluid hole (1) is bonded to the corresponding axial end of the 99 corundum ceramic tube (4) by using ceramic glue; after bonding, the 99 corundum adapter (3) and the 99 corundum ceramic tube (4) remain coaxial, and after curing at room temperature for 24 hours, they are placed on a heating platform and cured at 70°C for 2 hours and 200°C for 4 hours.

8. The fluid transient temperature sensor based on the FP principle according to claim 1, characterized in that: The 99 corundum ceramic tube (4) and the 316 stainless steel metal seat (5) are bonded together by ceramic glue by ring coating; during bonding, the 99 corundum ceramic tube (4) is made perpendicular to the 316 stainless steel metal seat (5) by tooling; and the tube is cured at room temperature for 24 hours, at 70° C. for 2 hours, and at 200° C. for 4 hours.

9. The fluid transient temperature sensor based on the FP principle according to claim 1, characterized in that: The collimator (6) adjusts the angle of the collimator (6) through an external three-dimensional displacement platform so that the collimator (6) receives the reflected light after being reflected by the transparent reflective sheet (2); the collimator (6) is bonded to the 99 corundum ceramic tube (4) through AB epoxy glue and cured at room temperature for 24 hours.

10. The fluid transient temperature sensor based on the FP principle according to claim 9, characterized in that: The optical fiber collimator (6) is connected to the circulator (7) by using an optical fiber coupler or optical fiber fusion splicing.

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