CN109489855B - Sapphire temperature sensor, manufacturing method thereof and temperature measuring system - Google Patents

Sapphire temperature sensor, manufacturing method thereof and temperature measuring system Download PDF

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Publication number
CN109489855B
CN109489855B CN201811384335.2A CN201811384335A CN109489855B CN 109489855 B CN109489855 B CN 109489855B CN 201811384335 A CN201811384335 A CN 201811384335A CN 109489855 B CN109489855 B CN 109489855B
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optical fiber
sapphire
temperature
sapphire optical
temperature sensor
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CN109489855A (en
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于靖波
肖维忠
康国剑
王宏伟
马元宏
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China Academy of Aerospace Aerodynamics CAAA
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China Academy of Aerospace Aerodynamics CAAA
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01KMEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/32Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres

Abstract

A sapphire temperature sensor, a manufacturing method thereof and a temperature measuring system are disclosed. The sapphire temperature sensor includes: the device comprises a thermal protection device, a sapphire optical fiber probe and an optical fiber coupler; one end of the sapphire optical fiber probe is a sensing head, and the other end of the sapphire optical fiber probe is connected with the optical fiber coupler; the thermal protection device is enclosed outside the sapphire optical fiber; the sensing head is arranged at one end of the thermal protection device, and the other end of the protection device is connected with the optical fiber coupler; the sensor head is formed by coating a blackbody cavity on the outer surface of one end of the sapphire optical fiber, and the blackbody cavity is formed by heating various temperature sensing material particles to a molten state through a plasma arc and uniformly spraying the temperature sensing material particles on the outer surface of one end of the sapphire optical fiber. The sapphire optical fiber temperature sensor manufactured by using the plasma spraying method has the advantages of wide temperature measuring range, high thermal response speed, high precision, long service life, low cost and intrinsic insulation, has more outstanding advantages than the traditional thermometer, and has strong corrosion resistance and electromagnetic interference resistance.

Description

Sapphire temperature sensor, manufacturing method thereof and temperature measuring system
Technical Field
The invention relates to the field of transient high-temperature measurement, in particular to a sapphire temperature sensor, a manufacturing method thereof and a temperature measurement system.
Background
The accurate measurement of temperature and heat flow is one of the key problems in the development of the combustion field, has important significance and application value for developing and designing aviation turbine engines, scramjet engines, high-temperature wind tunnel tests and the like, and the transient high-temperature measurement work of gas under the complex working conditions has the common characteristics of high temperature, quick change, high-pressure or high-speed flow, more disposable processes, severe measurement conditions and incapability of meeting the test requirements of a traditional thermocouple.
The combustion temperature measuring method can be classified into a contact temperature measuring method and a non-contact temperature measuring method according to the measurement principle. The temperature sensing element of the contact type temperature measurement method is directly arranged in a measured temperature field and is not influenced by the thermophysical parameters of a measured medium, and the commonly used contact type temperature measurement methods comprise a thermocouple temperature measurement method, a plasma temperature measurement method and the like, so that the contact type temperature measurement method has the advantages of convenience in use, high measurement precision and the like. However, in recent years, the application of the thermocouple is limited by factors such as slow response speed, low upper limit temperature, short service life and the like. The non-contact temperature measurement method has the advantages of high response speed, no upper limit of temperature measurement, no influence on the temperature field of the measured object and the like, and is the key point of the current domestic and foreign research. According to different measurement methods, non-contact temperature measurement methods can be divided into four major categories, namely optical imaging methods, laser spectroscopy methods, spectral radiation methods and microwave methods. In common non-contact temperature measurement methods, an optical imaging method and a coherent anti-stokes Raman scattering method are easily interfered, and the accuracy of a measurement result cannot be ensured; the laser-induced fluorescence method has a quenching effect in a high-pressure oxygen environment and has weaknesses in the aspects of measurement and spatial resolution capability of unsteady flame; the emission absorption spectrum method has huge structure, high cost and complex technology; the atomic emission multi-spectral line method can not directly measure the emission spectrum of the measured object, but needs to introduce other element atoms as temperature scale atoms, thus increasing the test difficulty and interfering the original temperature field; the biggest obstacle of the radiation method is influenced by the emissivity of the measured object, the emissivity is difficult to correct, and the true temperature of the measured object cannot be obtained; the colorimetric method solves the problem of the influence of emissivity to a certain extent, but has higher requirements on the wavelength of a measured spectrum, and cannot obtain the true temperature of a measured object; the multispectral radiation method solves the problem of measuring the true temperature, but provides higher requirements for an assumed equation of emissivity, and whether the accuracy of the equation greatly affects the measurement result.
A Sapphire Optical Fiber High-temperature Sensor (Crystal Sapphire High-temperature Optical Fiber Sensor) is a High-temperature field transient measurement method combining blackbody radiation temperature measurement and Optical Fiber sensing technology, wherein one end of a Sapphire Optical Fiber is plated with a sensitive material film to form a blackbody cavity, and the radiant energy generated by the heat balance of the blackbody cavity is measured through the Planck blackbody radiation law to obtain the temperature of a measured object. Compared with the traditional measurement methods such as a thermocouple, the sapphire optical fiber high-temperature sensing technology combines the characteristics of high sensitivity, electromagnetic interference resistance and the like of the optical fiber sensing technology, has the advantages of small volume and high spatial resolution, has quick response, high upper limit of temperature measurement, low cost, long service life and the like, and is an effective way for measuring high temperature and heat flow in severe environments such as an aerospace engine combustion field and the like. Specific study content and methods references: shenyong, temperature measurement from room temperature to 1800 ℃ in the whole process, 2000,20(1): 83-87.
Sapphire (alpha-Al 2O3) is an excellent near-infrared high-temperature-resistant optical material, the single crystal melting point of the sapphire reaches 2318K, the sapphire is corrosion-resistant, the physical and chemical properties are stable, the mechanical strength is good, and the sapphire has good light transmission in a wave band of 0.3-4.0 um. The manufacturing method of the black body cavity type sapphire optical fiber temperature sensor can have the following 3 modes: one is a temperature sensing medium ceramic thin layer with high temperature sintering and high emissivity to form a micro optical fiber temperature sensing cavity, and the temperature sensing medium has to meet a series of harsh requirements of high temperature resistance, good stability, firm combination with a sapphire single crystal optical fiber substrate and the like; the other is sputtering a noble metal or ceramic temperature sensing medium film to form a temperature sensing blackbody cavity with tiny volume, but the shape control of the blackbody cavity cannot be ensured, and the stability is poor; thirdly, a ceramic blackbody cavity is manufactured by a plasma spraying method. The plasma spraying technology is a reflection of applying the plasma technology to the field of spraying, and the main technical principle is that fine particles of various materials are heated to a molten or semi-molten state by utilizing heat generated by a plasma arc, and the particles move to the surface of a pre-treated substrate at a high speed, so that a firm coating with good characteristics is formed on the surface of the substrate.
Disclosure of Invention
The invention aims to provide a sapphire temperature sensor, a manufacturing method thereof and a temperature measuring system, which solve the defects of the existing transient high-temperature field testing technology and realize high-temperature transient measurement of an aerospace engine in complex environments such as high-temperature gas and the like.
The invention provides a sapphire optical fiber temperature sensor for achieving the aim, which comprises a thermal protection device, a sapphire optical fiber probe and an optical fiber coupler;
one end of the sapphire optical fiber probe is a sensing head, and the other end of the sapphire optical fiber probe is connected with the optical fiber coupler;
the thermal protection device is enclosed outside the sapphire optical fiber;
the sensing head is arranged at one end of the thermal protection device, and the other end of the protection device is connected with the optical fiber coupler;
the sensing head is formed by coating a blackbody cavity on the outer surface of one end of the sapphire optical fiber, and the blackbody cavity is formed by heating various temperature sensing material particles to a molten state through plasma electric arcs and uniformly spraying the temperature sensing material particles on the outer surface of one end of the sapphire optical fiber.
Preferably, the protection device is a protection sleeve in a wedge shape, the sapphire optical fiber is installed at the axis inside the protection sleeve, the sensing head is located at the tip of the protection sleeve, and the sensing head is partially or completely exposed.
Preferably, the protective sleeve is made of tungsten alloy, a hollow cavity between the inner wall of the protective sleeve and the sapphire optical fiber is filled with heat insulation sealing materials, and the two ends of the protective sleeve are connected with the connection part of the sapphire optical fiber in a sealing mode through high-temperature glue.
Preferably, the sensor head further comprises a stagnation cover, wherein the stagnation cover is an extension of the tip of the protection sleeve, and the stagnation cover semi-surrounds the sensor head.
Preferably, the optical fiber coupler further comprises a flange sleeve, a protrusion is arranged on the non-tip edge of the protective sleeve, the flange sleeve is sleeved on the non-tip of the protective sleeve and matched with the protrusion, and the flange sleeve is fixedly connected with the optical fiber coupler through a bolt.
A manufacturing method of a sapphire optical fiber temperature sensor comprises the following steps:
grinding and polishing two end faces of the sapphire optical fiber, wherein one end of the sapphire optical fiber is ground along the circumferential direction;
heating the fine particle temperature sensing material to a molten state by adopting a plasma spraying mode, and spraying the particles in the molten state to the surface of one end of the sapphire optical fiber after circumferential polishing;
forming a firm high-temperature-resistant coating at one end of the sapphire optical fiber to finish the spraying of the sensing head;
and connecting the other end of the sapphire optical fiber with the transmission optical fiber through the optical fiber coupler and the universal interface.
Preferably, the method for manufacturing a sapphire optical fiber temperature sensor further comprises:
measuring the dynamic response time of the sensing head, and if the dynamic response time of the sensing head reaches an expected index, performing static calibration;
establishing an index table of temperature and voltage signals for the sapphire optical fiber temperature sensor;
and installing a thermal protection device for the sapphire optical fiber temperature sensor.
Preferably, the method for manufacturing a sapphire optical fiber temperature sensor further comprises: the method comprises the steps of carrying out static calibration on the sapphire optical fiber temperature sensor by adopting a high-temperature shock tube, and making a graduation table on the sapphire optical fiber temperature sensor by adopting a standard thermocouple and a thermocouple verification furnace.
A temperature measurement system, comprising: a sapphire optical fiber temperature sensor; and
one end of the transmission optical fiber is connected with the sapphire optical fiber temperature sensor through an optical fiber coupler and is used for transmitting optical signals collected by the sapphire optical fiber temperature sensor;
and the input end of the photoelectric conversion device is connected to the other end of the transmission optical fiber and is used for converting the optical signal into an amplified analog voltage signal.
Preferably, the temperature measurement system further comprises:
the input end of the dynamic data collector is connected with the output end of the photoelectric conversion device and is used for collecting the analog voltage signal and converting the analog voltage signal into a digital voltage signal;
and the data processing device is connected to the output end of the signal collector and used for converting a final high-frequency transient temperature measurement result according to the graduation table of the temperature and voltage signals.
The invention has the beneficial effects that: the sapphire optical fiber temperature sensor provided by the invention has the advantages of wide temperature measuring range, high thermal response speed, high precision, long service life, low cost and intrinsic insulation, has more outstanding advantages than the traditional thermometer, is strong in corrosion resistance and electromagnetic interference resistance, can be transmitted in a long distance, is high in sensitivity, and is suitable for temperature measurement in severe environments such as inflammable and explosive, severe vibration, strong magnetic field interference, high temperature and high pressure and the like. The sapphire optical fiber temperature sensor manufactured by the plasma spraying method has the advantages of controllable spraying parameters, batch spraying of sensing heads and good stability of the sensor. The temperature measuring system adopting the sapphire optical fiber temperature sensor is based on the blackbody radiation theory, the temperature of a measured object can be obtained by measuring the radiant energy generated by the heat balance of the blackbody cavity of the sapphire optical fiber sensor, the upper temperature measuring limit is up to 3000K, the upper temperature measuring limit is high, and the stability is good.
The apparatus of the present invention has other features and advantages which will be apparent from or are set forth in detail in the accompanying drawings and the following detailed description, which are incorporated herein, and which together serve to explain certain principles of the invention.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, wherein like reference numerals generally represent like parts in exemplary embodiments of the present invention.
Fig. 1 shows a schematic structural diagram of a sapphire optical fiber temperature sensor according to an embodiment of the invention.
FIG. 2 is a flow chart showing steps of a method for manufacturing a sapphire optical fiber temperature sensor according to the invention.
Fig. 3 shows a schematic diagram of a temperature measurement system employing a sapphire fiber temperature sensor in accordance with the present invention.
Fig. 4 shows a schematic diagram of the equipment and architecture of a plasma spraying laboratory for manufacturing a sapphire fiber temperature sensor of the present invention.
Description of reference numerals:
1. a sensor head; 2. a sapphire optical fiber; 3. protecting the sleeve; 4. a flange sleeve; 5. a fiber coupler; 6. a bolt; 7. a transmission optical fiber; 8. a stagnation cover; 9. a micro condenser; 10. a Si-based photodetector; 11. a power amplifier; 12. a dynamic data collector; 13. a computer; the blackbody cavity 14.
Detailed Description
The invention will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
A sapphire optical fiber temperature sensor according to the present invention comprises: the device comprises a thermal protection device, a sapphire optical fiber probe and an optical fiber coupler;
one end of the sapphire optical fiber probe is a sensing head, and the other end of the sapphire optical fiber probe is connected with the optical fiber coupler;
the thermal protection device is enclosed outside the sapphire optical fiber;
the sensing head is arranged at one end of the thermal protection device, and the other end of the protection device is connected with the optical fiber coupler;
the sensor head is formed by coating a blackbody cavity on the outer surface of one end of the sapphire optical fiber, and the blackbody cavity is formed by heating various temperature sensing material particles to a molten state through a plasma arc and uniformly spraying the temperature sensing material particles on the outer surface of one end of the sapphire optical fiber.
Specifically, sapphire optic fibre one end is as sensing head for the coating blackbody chamber that forms through the multiple temperature-sensing material granule of plasma spraying, and sapphire optic fibre has that temperature measurement range is wide, the thermal response is fast, the precision is high, longe-lived, advantage with low costs and insulating with essence, and plasma spraying can effectively control the appearance in blackbody chamber, is of value to the yields and the sensitivity that improve sensing head, and sapphire optic fibre outside has the heat protector of protection sapphire optic fibre, is of value to improving life.
In one example, the protection device is a wedge-shaped protection sleeve, the sapphire optical fiber is installed at the axle center inside the protection sleeve, the sensing head is located at the tip end of the protection sleeve, and the sensing head is partially or completely exposed.
Specifically, the sleeve with the wedge shape can realize the effects of small influence on a flow field, high pressure resistance and airflow impact resistance, and the sensing head is partially or completely exposed so that the sensing head is directly contacted with a heat source to ensure the accuracy of a sensor test result.
In one example, the protective sleeve is made of tungsten alloy, a hollow cavity between the inner wall of the protective sleeve and the sapphire optical fiber is filled with heat insulation sealing materials, and the joints of the two ends of the protective sleeve and the sapphire optical fiber are connected in a sealing mode through high-temperature glue.
Specifically, the tungsten-copper alloy has the characteristics of high melting point and high-temperature sweating, can be used at the temperature of up to 2000 ℃, the heat insulation sealing material is filled in the hollow cavity of the protective sleeve, and the two ends of the cavity are sealed by high-temperature glue, so that heat can be effectively insulated, and the sensor can be thermally protected.
In one example, a stagnation cover is also included, the stagnation cover being an extension of the protective sleeve tip, the stagnation cover semi-surrounding the sensor head.
Particularly, the stagnation cover adopts a half-shielding direct-blowing structure, so that high-temperature incoming flow can be effectively stagnated, the sensing head directly contacts the high-temperature incoming flow, and the quick response of the sensor is ensured
In one example, the optical fiber coupler further comprises a flange sleeve, the non-tip edge of the protective sleeve is provided with a protrusion, the flange sleeve is sleeved on the non-tip of the protective sleeve and matched with the protrusion, and the flange sleeve is fixedly connected with the optical fiber coupler through a bolt.
Specifically, the protective sleeve and the optical fiber coupler are fixedly connected through a flange.
A manufacturing method of a sapphire optical fiber temperature sensor comprises the following steps:
grinding and polishing two end faces of the sapphire optical fiber, wherein one end of the sapphire optical fiber is ground along the circumferential direction;
heating the fine particle temperature sensing material to a molten state by adopting a plasma spraying mode, and spraying the particles in the molten state to the surface of one end of the sapphire optical fiber after circumferential polishing;
forming a firm high-temperature-resistant coating at one end of the sapphire optical fiber to finish the spraying of the sensing head;
and connecting the other end of the sapphire optical fiber with the transmission optical fiber through the optical fiber coupler and the universal interface.
Specifically, the transmission performance is ensured by grinding and polishing two end faces of the sapphire optical fiber, and the shape of the blackbody cavity and good temperature sensing characteristic can be effectively controlled by adopting plasma spraying.
In one example, the method for manufacturing a sapphire optical fiber temperature sensor further comprises:
measuring the dynamic response time of the sensing head, and if the dynamic response time of the sensing head reaches an expected index, performing static calibration;
establishing an index table of temperature and voltage signals for the sapphire optical fiber temperature sensor;
and installing a thermal protection device for the sapphire optical fiber temperature sensor.
In one example, the method for manufacturing a sapphire optical fiber temperature sensor further comprises: the method comprises the steps of carrying out static calibration on the sapphire optical fiber temperature sensor by adopting a high-temperature shock tube, and making a graduation table on the sapphire optical fiber temperature sensor by adopting a standard thermocouple and a thermocouple verification furnace.
Specifically, after spraying, the dynamic response time static calibration is firstly carried out on the sapphire optical fiber temperature sensor through a high-temperature shock tube, and then a graduation table of the temperature and voltage signals of the sensor is formulated through a standard thermocouple and a thermocouple verification furnace.
A temperature measurement system, comprising: a sapphire optical fiber temperature sensor; and
one end of the transmission optical fiber is connected with the sapphire optical fiber temperature sensor through an optical fiber coupler and is used for transmitting optical signals collected by the temperature sensor;
and the input end of the photoelectric conversion device is connected to the other end of the transmission optical fiber and is used for converting the optical signal into an amplified analog voltage signal.
In one example, the temperature measurement system further comprises:
the input end of the dynamic data collector is connected with the output end of the photoelectric conversion device and used for collecting analog voltage signals and converting the analog voltage signals into digital voltage signals;
and the data processing device is connected to the output end of the signal collector and used for converting a final high-frequency transient temperature measurement result according to the graduation table of the temperature and voltage signals.
Specifically, the temperature detection system composed of the sapphire optical fiber temperature sensor, the photoelectric conversion device, the dynamic data acquisition device and the data processing device can realize the temperature measurement result of high-frequency transient state.
Example (b):
fig. 1 shows a schematic structural diagram of a sapphire optical fiber temperature sensor according to an embodiment of the invention.
As shown in fig. 1, the sapphire optical fiber temperature sensor of the present invention includes a thermal protection device, a sapphire optical fiber probe, and an optical fiber coupler 5; one end of the sapphire optical fiber 2 probe is a sensing head 1, and the other end is connected with an optical fiber coupler 5; the thermal protection device is enclosed outside the sapphire optical fiber 2; the sensing head 1 is arranged at one end of the thermal protection device, and the other end of the protection device is connected with the optical fiber coupler 5; the sensing head 1 is formed by coating a blackbody cavity 14 on the outer surface of one end of the sapphire optical fiber 2, and the blackbody cavity 14 is formed by heating various temperature sensing material particles to a molten state through a plasma arc and uniformly spraying the temperature sensing material particles on the outer surface of one end of the sapphire optical fiber 2. The protection device is a wedge-shaped protection sleeve 3, the sapphire optical fiber 2 is installed at the axis inside the protection sleeve 3, the sensing head 1 is located at the tip of the protection sleeve 3, and the sensing head 1 is partially or completely exposed. The protective sleeve 3 is made of tungsten alloy, a hollow cavity between the inner wall of the protective sleeve 3 and the sapphire optical fiber 2 is filled with heat insulation sealing materials, and the two ends of the protective sleeve 3 are connected with the connection part of the sapphire optical fiber 2 in a sealing mode through high-temperature glue. And the sensor also comprises a stagnation cover 8, wherein the stagnation cover 8 is an extension part of the tip of the protective sleeve 3, and the stagnation cover 8 semi-surrounds the sensor head 1. Still include flange cover 4, protective case 3's non-most advanced border is equipped with the arch, flange cover 4 cup joints in protective case 3's non-most advanced and with protruding cooperation, flange cover 4 passes through bolt 6 and 5 fixed connection of fiber coupler.
FIG. 2 is a flow chart showing steps of a method for manufacturing a sapphire optical fiber temperature sensor according to the invention. Fig. 4 shows a schematic diagram of the equipment and architecture of a plasma spraying laboratory for manufacturing a sapphire fiber temperature sensor of the present invention.
As shown in fig. 2, the method for manufacturing a sapphire optical fiber temperature sensor of the present invention includes the following steps:
(1) firstly, grinding and polishing two end faces of a sapphire optical fiber 2 to 0.1 mu m magnitude, wherein one end is used for manufacturing a sensing head 1, and the sensing head is ground along the circumferential direction and then is left for spraying; the other end is connected with a transmission optical fiber 7 through an optical fiber coupler 5 and a general interface and is used for transmitting received optical signals;
(2) taking the polished sapphire optical fiber 2 in the step (1), carrying out spraying operation in a plasma spraying test room, the plasma spraying laboratory which is built and shown in fig. 4 comprises a control console, a rotary worktable, a spray gun, a spraying mechanical arm, a powder feeder, a gas management center, a process control center, a plasma power supply cabinet, a filter, a water cooler, a heat exchanger, a power supply cabinet and other equipment, heats a fine particle temperature sensing material to a molten state by utilizing heat generated by plasma electric arc, and the particles are moved to the surface of the previously polished end of the sapphire optical fiber 2 at a high speed, thereby forming a firm coating with good characteristics, and finishing the spraying of the sensing head 1 by controlling parameters such as spraying slenderness ratio, spraying temperature, spraying speed and rotating speed, spraying distance and the like of the sensing head 1 to be matched with tool equipment for use; the sapphire optical fiber 2 is installed at the observation window position after the explosion by adopting a high-temperature shock tube with response time in microsecond order, and the dynamic response time of the sensor is determined by the temperature step change generated when the shock wave sweeps; if the response time of the sapphire optical fiber temperature sensor reaches an expected index, carrying out static calibration, and if the response time of the sapphire optical fiber temperature sensor does not reach the expected index, changing the spraying parameters and spraying again;
(3) and (3) according to the sapphire optical fiber 2 sensing head 1 sprayed in the step (2), carrying out static calibration by using thermocouple calibration equipment, aligning and bundling the tail ends of the high-temperature sensor and a standard thermocouple into a bundle by using a platinum rhodium wire in the static calibration of the optical fiber high-temperature sensor according to the Planck blackbody radiation law, and coaxially placing the bundle at the highest temperature of a thermocouple calibration furnace. The calibration furnace is heated point by point from low temperature to high temperature, when the temperature of the furnace is heated to a test point, the high-temperature sensor reaches a balance point, the thermocouple temperature and the output voltage of the sapphire optical fiber temperature sensor are recorded, the sapphire optical fiber temperature sensor is calibrated through the temperature of the test furnace and the detection temperature of the thermocouple in a certain temperature range, a fitting curve of the output voltage and the temperature is obtained, and the graduation table of the temperature sensor can be obtained by measuring the voltage for a certain calibrated temperature;
(4) after the step (3) is completed, according to the test characteristics of aerospace under severe environments such as high temperature, high speed and high impact, corresponding protective devices are required to be designed under a plurality of working conditions to improve the influence of high pressure resistance, high temperature resistance and impact resistance of the sapphire optical fiber 2, for example, a thermal protective device is designed as shown in fig. 1, tungsten alloy is selected as a barrier and a wedge protective sleeve 3 material, and the characteristics of high melting point and high temperature sweating of tungsten copper alloy are utilized, so that the sapphire optical fiber can be used at the temperature of up to 2000 ℃; the wedge shape is adopted to meet the requirements of small influence on a flow field, high pressure resistance and airflow impact resistance; the stagnation cover 8 adopts a semi-shielding direct-blowing structure, so that incoming flow can be effectively stagnated, and meanwhile, the sensing head 1 directly contacts high-temperature incoming flow, so that the quick response of the sensor is ensured; the cavity in the protective sleeve 3 is filled with heat insulation sealing materials, and the two ends of the cavity are sealed by high-temperature glue, so that heat insulation can be effectively realized, heat protection is realized on the sensor, and the manufacturing of the sapphire optical fiber temperature sensor is completed.
Fig. 3 shows a schematic diagram of a temperature measurement system employing a sapphire fiber temperature sensor in accordance with the present invention.
As shown in fig. 3, the temperature measurement system of the present invention includes a sapphire optical fiber temperature sensor, a transmission optical fiber 7, a photoelectric conversion device, a dynamic data acquisition device 12, and a data processing device, which are connected in sequence to complete the adjustment of the system optical path, the circuit construction, and the adjustment of the power amplifier. One end of the transmission optical fiber 7 is connected with the temperature sensor through an optical fiber coupler and is used for transmitting optical signals collected by the temperature sensor, and the transmission optical fiber 7 is a quartz optical fiber which is wrapped with an armor protective layer; the photoelectric conversion device comprises a micro collecting lens 9, a Si-based photoelectric detector 10 and a power amplifier 11 which are connected in sequence, optical signals are processed by the micro collecting lens 9, the Si-based photoelectric detector 10 and the power amplifier 11 in sequence, then converted into amplified analog voltage signals and transmitted to the input end of a dynamic data acquisition unit 12, the dynamic data acquisition unit 12 acquires the analog voltage signals and converts the analog voltage signals into digital voltage signals to be input to a data processing device, the data processing device is a computer 13, and the computer 13 converts the final temperature measurement result of the high-frequency transient state according to the indexing table of the temperature and the voltage signals.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims (7)

1. A sapphire optical fiber temperature sensor is applied to high-temperature transient measurement in a high-temperature gas environment of an aerospace engine and is characterized by comprising a thermal protection device, a sapphire optical fiber probe and an optical fiber coupler;
one end of the sapphire optical fiber probe is a sensing head, and the other end of the sapphire optical fiber probe is connected with the optical fiber coupler;
the thermal protection device is enclosed outside the sapphire optical fiber;
the sensing head is arranged at one end of the thermal protection device, and the other end of the protection device is connected with the optical fiber coupler;
the sensor head is formed by coating a blackbody cavity on the outer surface of one end of the sapphire optical fiber, and the blackbody cavity is formed by heating various temperature sensing material particles to a molten state through plasma electric arcs and uniformly spraying the temperature sensing material particles on the outer surface of one end of the sapphire optical fiber;
the protective device is a wedge-shaped protective sleeve, the sapphire optical fiber is arranged at the axis inside the protective sleeve, and the sensing head is positioned at the tip end of the protective sleeve;
the protective sleeve is made of tungsten alloy, a hollow cavity between the inner wall of the protective sleeve and the sapphire optical fiber is filled with heat insulation sealing materials, and the connection positions of the two ends of the protective sleeve and the sapphire optical fiber are in sealing connection through high-temperature glue;
the sensor also comprises a stagnation cover, wherein the stagnation cover is an extension part of one side of the tip end of the protection sleeve along the axial direction of the sensing head, the stagnation cover semi-surrounds the sensing head, and the end face of the other side of the tip end of the protection sleeve is a plane vertical to the axial direction of the sensing head.
2. The sapphire optical fiber temperature sensor of claim 1, further comprising a flange sleeve, wherein a protrusion is disposed on a non-tip edge of the protection sleeve, the flange sleeve is sleeved on the non-tip of the protection sleeve and is matched with the protrusion, and the flange sleeve is fixedly connected with the optical fiber coupler through a bolt.
3. A manufacturing method of a sapphire optical fiber temperature sensor is characterized by comprising the following steps:
grinding and polishing two end faces of the sapphire optical fiber, wherein one end of the sapphire optical fiber is ground along the circumferential direction;
heating the fine particle temperature sensing material to a molten state by adopting a plasma spraying mode, and spraying the particles in the molten state to the surface of one end of the sapphire optical fiber after circumferential polishing;
forming a firm high-temperature-resistant coating at one end of the sapphire optical fiber to finish the spraying of the sensing head;
connecting the other end of the sapphire optical fiber with a transmission optical fiber through an optical fiber coupler and a universal interface;
installing a thermal protection device for the sapphire optical fiber temperature sensor;
the protective device is a wedge-shaped protective sleeve, the sapphire optical fiber is arranged at the axis inside the protective sleeve, and the sensing head is positioned at the tip end of the protective sleeve;
the protective sleeve is made of tungsten alloy, a hollow cavity between the inner wall of the protective sleeve and the sapphire optical fiber is filled with heat insulation sealing materials, and the connection positions of the two ends of the protective sleeve and the sapphire optical fiber are in sealing connection through high-temperature glue;
the sensor also comprises a stagnation cover, wherein the stagnation cover is an extension part of one side of the tip end of the protection sleeve along the axial direction of the sensing head, the stagnation cover semi-surrounds the sensing head, and the end face of the other side of the tip end of the protection sleeve is a plane vertical to the axial direction of the sensing head.
4. The method of manufacturing a sapphire optical fiber temperature sensor as defined in claim 3, further comprising:
measuring the dynamic response time of the sensing head, and if the dynamic response time of the sensing head reaches an expected index, performing static calibration;
and establishing an index table of temperature and voltage signals for the sapphire optical fiber temperature sensor.
5. The method of manufacturing a sapphire optical fiber temperature sensor as defined in claim 4, further comprising: the method comprises the steps of carrying out static calibration on the sapphire optical fiber temperature sensor by adopting a high-temperature shock tube, and making a graduation table on the sapphire optical fiber temperature sensor by adopting a standard thermocouple and a thermocouple verification furnace.
6. A temperature measurement system, comprising: the sapphire optical fiber temperature sensor of any one of claims 1-2; and
one end of the transmission optical fiber is connected with the sapphire optical fiber temperature sensor through an optical fiber coupler and is used for transmitting optical signals collected by the sapphire optical fiber temperature sensor;
and the input end of the photoelectric conversion device is connected to the other end of the transmission optical fiber and is used for converting the optical signal into an amplified analog voltage signal.
7. The temperature measurement system of claim 6, further comprising:
the input end of the dynamic data collector is connected with the output end of the photoelectric conversion device and is used for collecting the analog voltage signal and converting the analog voltage signal into a digital voltage signal;
and the data processing device is connected to the output end of the dynamic data acquisition unit and used for converting a final high-frequency transient temperature measurement result according to the graduation table of the temperature and voltage signals.
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