A sapphire fiber-based ultrahigh-temperature phosphor temperature probe, a temperature measuring method thereof and application

Abstract

The application provides a sapphire optical fiber-based ultrahigh-temperature phosphor temperature measuring probe, a temperature measuring method and application thereof, and belongs to the technical field of phosphor temperature measurement. The temperature measuring probe comprises a sapphire optical fiber and a protective tooling, and the tooling comprises a conical head, a cylindrical tail and a gas inlet plug. The head is made of a high-temperature-resistant alloy and is sprayed with a thermal barrier coating, and six cooling channels are arranged in the head. High-speed airflow enters the probe through the gas inlet plug and cools the probe in the air. The sapphire optical fiber axially penetrates the tooling, is positioned and sealed through a flange, a positioning pin and a sealing plug, and the tail end of the sapphire optical fiber penetrates a central micropore of the head and extends out by 1-5 mm. In use, the probe head is 5-10 mm away from a surface to be measured coated with phosphor paint, and after being excited by laser, the signal is collected by the optical fiber and the temperature is calculated. The probe adopts double protection of external heat insulation and internal air cooling, the heat exchange airflow is discharged in an open loop and does not blow to the wall surface to be measured, the cold air can avoid interfering with the real wall temperature, and the probe has the advantages of high temperature measuring precision, ultrahigh-temperature resistance and the like.

Description

Technical Field

[0001] This invention belongs to the field of phosphorescent temperature measurement technology, specifically relating to an ultra-high temperature phosphorescent temperature measurement probe based on sapphire optical fiber, its temperature measurement method and application, and particularly to a non-contact temperature measurement probe that uses sapphire optical fiber as the phosphorescent signal transmission medium and has heat insulation, air cooling and sealing protection structure. Background Technology

[0002] Hot-end components such as turbine blades in aero-engines operate for extended periods in environments characterized by high temperatures, high flow rates, and strong vibrations. Their surface temperatures directly impact thermal protection design, cooling structure optimization, service life assessment, and operational safety. Therefore, accurately obtaining the true surface temperature without damaging the structure under test or the existing flow field is of significant engineering importance.

[0003] Existing wall temperature measurements can use contact sensors such as thermocouples. However, placing thermocouples on pre-formed blades usually requires slotting and embedding thermocouple wires, which can easily alter the blade's aerodynamic shape and local heat transfer state. The measurement results may also deviate from the true wall temperature due to the influence of material thermal conductivity. Although infrared radiation thermometry is a non-contact measurement, it is easily affected by background thermal radiation, emissivity changes, and spectral interference against high-temperature combustion gases or flames.

[0004] Phosphorescent thermometry uses an external laser to excite a phosphorescent coating applied to the surface to be measured, and obtains the wall temperature based on the calibration relationship between phosphorescent characteristic parameters and temperature. It has the advantages of being resistant to electromagnetic interference and non-contact measurement. However, in ultra-high temperature and high-speed gas environments, ordinary quartz optical fibers are prone to softening or melting; while sapphire optical fibers, which have higher temperature resistance, are brittle and have weak shear and vibration resistance. Their fixing, sealing, and connection parts are still prone to failure due to thermal shock or gas erosion.

[0005] Using cooling gas to protect the optical fiber and probe can reduce the structural temperature, but if the cooling gas flow is blown directly onto the wall surface to be measured, it will change the original temperature field of the measured area and introduce measurement errors. Therefore, a phosphorescent temperature probe is needed that can effectively insulate and cool the sapphire optical fiber and its mounting structure, while also controlling the exhaust direction to avoid disturbing the wall surface to be measured. Summary of the Invention

[0006] The purpose of this invention is to provide an ultra-high temperature phosphorescent temperature probe based on sapphire optical fiber, its temperature measurement method and application, in order to solve technical problems such as insufficient temperature resistance of ordinary optical fibers, easy damage of sapphire optical fibers in high-speed airflow and vibration environments, insufficient thermal protection of probe fixing and sealing devices, and interference of cooling airflow with the true temperature field of the wall surface to be measured.

[0007] To achieve the above objectives, this invention provides an ultra-high temperature phosphorescent temperature probe based on sapphire optical fiber, comprising a sapphire optical fiber and an external protective fixture. The protective fixture includes a probe head, a probe tail, an air inlet plug, and an optical fiber fixing plug. The probe head, probe tail, and air inlet plug are sequentially connected axially. The optical fiber fixing plug is threadedly connected to the probe tail. The sapphire optical fiber passes through the protective fixture axially. The front end of the sapphire optical fiber passes through the central channel of the probe head and extends out of the probe head. The rear end of the sapphire optical fiber constitutes an optical fiber output end. The optical fiber is used to collect the phosphorescent signal generated by the phosphorescent coating on the surface under test after being excited by an external laser; the probe head has a central channel that mates with the sapphire optical fiber, and the outer surface of the probe head is coated with a thermal barrier coating; the protective fixture has multiple cooling channels arranged around the sapphire optical fiber, the air inlet plug has an air inlet structure that communicates with the cooling channels, and the outer end of the air inlet structure is equipped with a pneumatic quick connector; the protective fixture also has multiple air outlets, each of which is connected to one of the cooling channels, and the exhaust direction of the air outlets avoids the surface under test.

[0008] As a preferred embodiment, the probe head is a composite rotating body formed by coaxially connecting a conical segment and a cylindrical segment. The conical segment gradually tapers towards the surface to be measured and smoothly transitions with the cylindrical segment. The generatrix of the conical segment is a straight line, an arc, or a continuous convergent curve.

[0009] As a preferred embodiment, a plurality of the cooling channels are arranged circumferentially around the central channel and extend along the axial direction of the protective fixture; the number of the cooling channels is three or more.

[0010] As a preferred embodiment, the air outlets are respectively located at the air outlet end of the corresponding cooling channel. The opening area and arrangement position of the air outlets are adapted to the cooling gas flow rate and predetermined exhaust direction of the corresponding cooling channel, and the exhaust direction of each air outlet avoids the surface to be tested.

[0011] As a preferred embodiment, the probe head and the probe tail are made of high-temperature resistant alloy material, the air inlet plug is made of metal material, and the thermal barrier coating is a ceramic thermal barrier coating.

[0012] As a preferred embodiment, a high-temperature resistant composite sealing gasket is provided at the connection between the probe head and the probe tail. The high-temperature resistant composite sealing gasket includes vermiculite-based sealing material and stainless steel reinforcing core material, and cooperates with the sealing groove at the connection to seal the connection gap. A rubber sealing ring is provided between the air inlet plug and the probe tail. An optical fiber fixing plug is provided in the central mounting hole of the air inlet plug, and the sapphire optical fiber is fixed to the optical fiber fixing plug. The protective fixture is also provided with a mounting flange for fixing the ultra-high temperature phosphorescent temperature measuring probe to the test device.

[0013] As a preferred embodiment, the front end of the sapphire optical fiber extends beyond the probe head by a first predetermined millimeter length.

[0014] As a preferred embodiment, the central channel is located on the axis of the tapered region of the probe head; in use, there is a second preset distance of millimeters between the probe head and the surface to be tested, and the front end of the sapphire optical fiber faces the phosphorescent coating of the surface to be tested.

[0015] Furthermore, this invention proposes an ultra-high temperature phosphorescence thermometry method based on sapphire optical fiber, employing the aforementioned ultra-high temperature phosphorescence thermometry probe based on sapphire optical fiber. This thermometry method includes the following steps:

[0016] A phosphorescent coating is applied to the surface to be tested, and a calibration relationship between the phosphorescent characteristic parameters of the phosphorescent coating and the temperature is established in advance. Connect the air intake plug to an external cooling air source to supply cooling gas to the cooling channel; Install the ultra-high temperature phosphorescent temperature probe, align the front end of the sapphire optical fiber with the phosphorescent coating, and ensure that the exhaust direction of the vent hole avoids the surface to be measured. The phosphorescent coating is excited by an external laser, and the phosphorescent signal generated by the sapphire optical fiber is collected and transmitted to a signal acquisition and processing device. The temperature of the surface to be tested is determined based on the phosphorescence characteristic parameters obtained by the signal acquisition and processing device and the calibration relationship.

[0017] As a preferred embodiment, the phosphorescence characteristic parameter is the phosphorescence lifetime.

[0018] As a preferred embodiment, cooling gas is continuously supplied to the cooling channel during the measurement process; after the measurement is completed, the excitation of the external laser is stopped and the ultra-high temperature phosphorescent thermometric probe is removed from the high temperature measurement area. The supply of cooling gas is stopped after the temperature of the ultra-high temperature phosphorescent thermometric probe decreases.

[0019] The ultra-high temperature phosphorescence thermometry method based on sapphire optical fiber disclosed above can be applied to the measurement of the temperature of hot-end components of aero-engines. It allows the probe to be brought very close to the target at extremely high temperatures without affecting the thermal environment of the target, obtaining a phosphorescence signal with a high signal-to-noise ratio; the closer the probe is, the stronger the signal.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects: First, the use of sapphire optical fiber to transmit phosphorescent signals improves the probe's tolerance to ultra-high temperature environments and reduces the direct effects of high-speed airflow and vibration on the brittle optical fiber through protective tooling.

[0021] Secondly, the thermal barrier coating on the outer surface of the probe head and the internal multi-channel air-cooling structure form a dual protection of heat insulation and cooling, which can simultaneously protect the probe structure, the fiber optic fixing part and the sealing connection part.

[0022] Third, after the cooling gas exchanges heat inside the protective fixture, it is discharged in an open loop, and the exhaust direction avoids the wall to be measured. This can reduce the disturbance of the temperature field of the area to be measured by the cooling airflow, which is conducive to improving the accuracy of the temperature measurement results.

[0023] Fourth, the probe adopts flange connection, high temperature resistant composite sealing gasket, rubber sealing ring, fiber optic fixing plug and pneumatic quick connector, which facilitates assembly, sealing, fiber optic fixing, air supply and maintenance, and has a compact structure.

[0024] Fifth, the phosphorescent coating on the surface under test is excited by an external laser, and the phosphorescent signal is collected non-contactly by a sapphire optical fiber. This eliminates the need to embed the sensor in the component under test, thus reducing the impact on the structure under test. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the working principle of the temperature measurement system in an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the overall structure of the ultra-high temperature phosphorescent thermometric probe in an embodiment of the present invention.

[0027] Figure 3 This is an axial cross-sectional view of the ultra-high temperature phosphorescent thermometric probe in an embodiment of the present invention.

[0028] Figure 4 yes Figure 3 Radial cross-sectional view of the cooling channel at point AA.

[0029] Figure 5 This is a schematic diagram showing the relative position of the probe and the surface to be tested, as well as the exhaust direction, in an embodiment of the present invention.

[0030] The meanings of the labels in the figures are as follows: 1-Sapphire fiber, 2-Probe head, 3-Probe tail, 4-Inlet plug, 5-Mounting flange, 6-Outlet hole, 7-Cooling channel, 8-Thermal barrier coating, 9-Rubber sealing ring, 10-Pneumatic quick connector, 11-High temperature resistant composite sealing gasket, 12-Phosphorescent coating on the surface to be tested, 13-Fiber output end, 14-Central channel, 15-Fiber fixing plug. Detailed Implementation

[0031] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid obscuring the invention. The term "comprising" as used herein indicates non-exclusive inclusion.

[0032] Example 1: This invention discloses an ultra-high temperature phosphorescent temperature probe based on sapphire optical fiber 1, including sapphire optical fiber 1 and its external protective fixture; the protective fixture includes a probe head 2, a probe tail 3, an air inlet plug 4, and an optical fiber fixing plug 15, wherein the probe head 2, probe tail 3, and air inlet plug 4 are connected sequentially along the axial direction, and the optical fiber fixing plug 15 is threadedly connected to the probe tail 3; the sapphire optical fiber 1 is arranged through the protective fixture along the axial direction, its front end passes through the central channel 14 of the probe head 2 and extends out of the probe head 2, and its rear end is connected to a signal acquisition device; the surface to be measured is provided with a phosphorescent coating that can be excited by an external laser, and the sapphire optical fiber 1 is used to acquire the phosphorescent signal generated by the phosphorescent coating.

[0033] The probe head 2 is a composite structure consisting of a conical section and a cylindrical section. The center of the probe head 2 is provided with a central channel 14 that cooperates with the sapphire optical fiber 1. The probe head 2 and the probe tail 3 are made of high-temperature resistant alloy material. The outer surface of the probe head 2 is provided with a thermal barrier coating 8 to reduce the heat transfer from the external high-temperature environment to the interior of the protective tooling.

[0034] Furthermore, the probe head 2 is a composite rotating body formed by coaxially connecting a conical segment and a cylindrical segment. The conical segment gradually contracts along the direction close to the surface to be measured and smoothly transitions with the cylindrical segment. The generatrix of the conical segment can be a straight line, a circular arc, or a continuous convergent curve.

[0035] Furthermore, the probe head 2 and probe tail 3 are made of high-temperature resistant alloy material, preferably MA956 high-temperature resistant alloy; the air inlet plug 4 is made of metal material, preferably stainless steel.

[0036] Furthermore, the thermal barrier coating 8 is a ceramic thermal barrier coating 8, preferably a yttrium oxide stabilized zirconia (YSZ) coating, wherein ZrO2 is the matrix and Y2O3 is the stabilizer; the thermal barrier coating 8 may also be a zirconia-based coating, an alumina-based coating, a rare earth zirconate-based coating, or other ceramic coating materials with high temperature resistance and low thermal conductivity.

[0037] The protective fixture has multiple cooling channels 7 arranged around the sapphire optical fiber 1 inside; the air inlet plug 4 has an air inlet structure that communicates with the cooling channels 7, and the outer end of the air inlet structure is provided with a pneumatic quick connector 10 so that external cooling gas enters the cooling channel 7 through the air inlet plug 4, cools the probe head 2 and the probe tail 3, and is discharged from the air outlet 6.

[0038] Furthermore, multiple cooling channels 7 are arranged circumferentially around the central channel 14 and extend along the axial direction of the protective fixture; the number of cooling channels 7 is three or more, preferably four to eight.

[0039] The protective fixture is equipped with multiple air outlets 6 that correspond one-to-one with the cooling channels 7. After the cooling gas completes heat exchange inside the protective fixture, it is discharged through the corresponding air outlets 6. The exhaust direction of the air outlets 6 avoids the wall surface to be measured, so that the cooling gas does not blow directly towards the area to be measured, thereby reducing the influence of the cooling airflow on the true temperature field of the wall surface to be measured.

[0040] The opening area and arrangement of the air outlet 6 are determined according to the cooling gas flow rate of the corresponding cooling channel 7 and the predetermined exhaust direction, and the exhaust direction of each air outlet 6 avoids the surface to be measured.

[0041] The probe tail 3 has flange structures at both ends and a cylindrical section in the middle. The end of the probe tail 3 that mates with the air inlet plug 4 extends axially from the flange end face to form a mating cylindrical section. The mating cylindrical section extends into the central hole of the air inlet plug 4, and the mating cylindrical section is provided with an internal thread that mates with the fiber optic fixing plug 15.

[0042] A high-temperature resistant composite sealing gasket 11 is provided at the connection between the probe head 2 and the probe tail 3, which cooperates with the sealing groove at the connection to seal the connection gap; a rubber sealing ring 9 is provided between the air inlet plug 4 and the probe tail 3 to reduce cooling gas leakage; the fiber optic fixing plug 15 is threadedly connected to the probe tail 3, and the sapphire fiber 1 is fixed to the fiber optic fixing plug 15; the air inlet plug 4 is also provided with a mounting flange 5, which is used to fix the ultra-high temperature phosphorescent temperature measuring probe to the test device or the mechanism to be installed.

[0043] Furthermore, the sapphire fiber 1 has a diameter of 400 micrometers and a total length of 180-250 millimeters; the front end of the sapphire fiber 1 extends 1-5 millimeters beyond the probe head.

[0044] Furthermore, the central channel 14 of the probe head 2 has a diameter of 0.5-0.6 mm, is located on the axis of the conical region of the probe head 2, and has a length of 5-10 mm.

[0045] Furthermore, during use, the probe head 2 is spaced 5-10 mm apart from the surface to be tested, the central channel 14 of the probe head 2 faces the phosphorescent coating 12 of the surface to be tested, and the exhaust direction of the vent 6 does not face the surface to be tested.

[0046] The above-mentioned ultra-high temperature phosphorescent temperature probe is used as follows: a phosphorescent coating is applied to the surface to be measured, and a calibration relationship between phosphorescent characteristic parameters (lifetime) and temperature is established in advance; the air inlet plug 4 is connected to an external cooling air source and air is supplied to the cooling channel 7; the probe is installed and the front end of the sapphire optical fiber 1 is aligned with the phosphorescent coating 12 of the surface to be measured; the phosphorescent coating is excited by an external laser, and the phosphorescent signal is collected by the sapphire optical fiber 1 and transmitted to the signal acquisition and processing device; the temperature of the surface to be measured is obtained according to the signal processing results and the calibration relationship.

[0047] Example 2: like Figure 1 As shown, this embodiment discloses a temperature measurement system, which includes an external laser, a phosphorescent coating 12 on the surface to be measured, an ultra-high temperature phosphorescent temperature probe, and a signal acquisition and processing device connected to an optical fiber output end 13. The external laser irradiates and excites the phosphorescent coating 12, and the sapphire optical fiber 1 collects the phosphorescent signal generated by the phosphorescent coating 12 and transmits the phosphorescent signal to the signal acquisition and processing device; the signal processing device obtains the temperature of the surface to be measured based on a pre-established calibration relationship between phosphorescent characteristic parameters and temperature.

[0048] like Figure 2 and Figure 3 As shown, the ultra-high temperature phosphorescent temperature probe includes a sapphire optical fiber 1 and its external protective fixture. The protective fixture consists of a probe head 2, a probe tail 3, an air inlet plug 4, and an optical fiber fixing plug 15 connected axially, and is fixed to the test device by a mounting flange 5. In this embodiment, the probe head 2 and probe tail 3 are made of MA956 high-temperature resistant alloy, and the air inlet plug 4 is made of stainless steel, to balance high-temperature resistance, structural strength, and connection processing performance.

[0049] The probe head 2 consists of a tapered front section and a cylindrical rear section. The tapered section reduces the size of the probe tip and provides support for the central channel 14. A thermal barrier coating 8 is applied to the outer surface of the probe head 2 to reduce the radiation and convective heat transfer from the high-temperature gas. The sapphire optical fiber 1 is positioned along the axial direction of the protective fixture and passes through the central channel 14. The diameter of the central channel 14 is 0.5-0.6 mm, and its length within the probe head 2 is 5-10 mm.

[0050] In this embodiment, the diameter of the sapphire optical fiber 1 is 400 micrometers, and its length can be determined according to specific working conditions; in this embodiment, it is 225 millimeters. The front end of the sapphire optical fiber 1 extends 1-5 millimeters beyond the probe head 2 to receive phosphorescent signals and maintain a certain structural strength. The rear end of the sapphire optical fiber 1 passes through the fiber fixing plug 15 and is fixed to the fiber fixing plug 15, forming the optical fiber output end 13. The fiber fixing plug 15 provides axial fixation and radial limitation for the rear end of the sapphire optical fiber 1. Adjustment shims can be added to this part to adjust the length of the fiber front end. The central channel 14 provides radial limitation and front-end protection for the sapphire optical fiber 1.

[0051] A high-temperature resistant composite sealing gasket 11 is provided at the connection between the probe head 2 and the probe tail 3. The high-temperature resistant composite sealing gasket 11 is inserted into a mating sealing groove to seal the connection gap. The high-temperature resistant composite sealing gasket 11 is composed of vermiculite-based sealing material and stainless steel reinforcing core material; in this embodiment, an annular gasket made of Thermiculite® 815 sealing material is used. A rubber sealing ring 9 is provided at the connection between the air inlet plug 4 and the probe tail 3 to maintain the seal between the air inlet structure and the cooling channel 7. All components are connected by flanges and fasteners for easy disassembly and inspection of the seals.

[0052] like Figure 3 and Figure 4 As shown, Figure 4 for Figure 3 A radial cross-sectional view at point AA. The protective fixture contains six cooling channels 7 and six vents 6. The six cooling channels 7 are formed within the solid area of ​​the probe tail 3 and are evenly spaced circumferentially around the central channel containing the sapphire fiber 1, extending along the axial direction of the protective fixture. The six vents 6 are connected to the six cooling channels 7 one-to-one. An air inlet plug 4 contains an air inlet structure communicating with the cooling channels 7, and a pneumatic quick-connect fitting 10 is provided at the outer end of the air inlet structure. External cooling gas enters each cooling channel 7 through the pneumatic quick-connect fitting 10 and the air inlet plug 4, cooling the air inlet plug 4, the probe tail 3, the probe head 2, and the mounting area of ​​the sapphire fiber 1.

[0053] Cooling gas flows along cooling channel 7 to probe head 2, carrying away heat transferred from the high-temperature environment to the protective fixture during its flow. It then exits through vents 6, which are connected to each cooling channel 7. The vents 6 are designed so that the exiting cooling airflow does not directly target the surface being measured, thus forming an open-loop cooling path with internal heat exchange and directional external discharge. The thermal barrier coating 8 reduces the heat load entering the protective fixture, and the cooling gas carries away the already transferred heat; together, they constitute the probe's composite thermal protection.

[0054] During installation, first insert the high-temperature resistant composite sealing gasket 11 into the sealing groove at the connection between the probe head 2 and the probe tail 3 and tighten the two parts; then install the rubber sealing ring 9 and the air inlet plug 4; fix the rear end of the sapphire optical fiber 1 to the optical fiber fixing plug 15, then insert the sapphire optical fiber 1 through the side of the air inlet plug 4, so that its front end passes through the central channel 14 of the probe tail 3 and the probe head 2 in sequence and extends out to a predetermined length, and install the optical fiber fixing plug 15 on the threaded hole of the probe tail 3; then fix the probe on the test device through the mounting flange 5; finally connect the pneumatic quick connector 10 to the external cooling air source.

[0055] In use, a phosphorescent coating 12 is applied to the surface to be tested, and the correlation between the phosphorescent characteristic parameters of the selected phosphorescent material and temperature is obtained through independent calibration. The probe head 2 is adjusted to maintain a distance of 5-10 mm from the surface to be tested, and the head of the sapphire fiber 1 is aligned with the phosphorescent coating 12. Simultaneously, it is ensured that the exhaust direction of the vent 6 avoids the surface to be tested.

[0056] Before starting the measurement, turn on the external cooling air source, allowing the cooling gas to evenly enter the six cooling channels 7 through the air inlet plug 4. Confirm that each cooling channel 7 is smoothly connected to its corresponding air outlet 6, and check for any obvious leaks at the connections. After the cooling air path is stable, place or maintain the probe at the high-temperature measurement position. During the measurement, continuously supply air to the cooling channels 7 to maintain thermal protection for the tooling and the area where the sapphire fiber 1 is installed.

[0057] After the phosphorescent coating 12 is irradiated by an external laser, the phosphorescence emitted by the coating 12 is received by the front end of the sapphire optical fiber 1 and transmitted along the sapphire optical fiber 1 to the optical fiber output end 13. After the signal acquisition device obtains the phosphorescence signal, the signal processing device extracts the temperature-related phosphorescence characteristic parameters and calculates the temperature of the surface to be measured by combining the calibration relationship. Since the front end of the sapphire optical fiber 1 maintains a distance from the surface to be measured, and the vent 6 does not face the surface to be measured, the measurement process does not require damage to the structure under test and can reduce the influence of the cooling airflow on the temperature field under test.

[0058] After the measurement is completed, first stop laser excitation and remove the probe from the high-temperature measurement area. After the probe temperature drops, stop the cooling gas. Then, disconnect the pneumatic quick connector 10, and remove the air inlet plug 4 as needed, check the rubber sealing ring 9 and the fiber optic fixing plug 15, and clean the front end of the sapphire fiber optic 1.

[0059] In other embodiments, the number, cross-sectional shape, and arrangement of the cooling channels 7 and the vents 6, the connection method of the mounting flange 5, the form of the conical generatrix of the probe head 2 (straight line, arc, etc.), and the structure of the fiber fixing plug 15 can be adjusted according to the installation space and heat load. The material and thickness of the thermal barrier coating 8 can also be selected according to the operating temperature. As long as an internal cooling path can be formed around the sapphire fiber 1, the vents 6 and the cooling channels 7 are kept in one-to-one correspondence and connected, and the exhaust direction of the cooling gas avoids the wall surface to be measured, the technical effects of the present invention can be achieved.

[0060] The specific dimensions and apertures of the probe head 2, probe tail 3, air inlet plug 4, mounting flange 5, cooling channel 7, and air outlet 6 are not particularly limited and can be determined based on the installation space of the test apparatus, the size of the sapphire fiber 1, the cooling gas flow rate, the allowable pressure drop, and the heat load borne by the probe. Provided that each cooling channel 7 is connected to the air inlet structure and the corresponding air outlet 6, effectively cools the probe structure and the mounting area of ​​the sapphire fiber 1, and that the exhaust direction of the cooling gas avoids the surface under test, the dimensions of each component can be adaptively adjusted.

[0061] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A high-temperature phosphorescent thermometric probe based on sapphire optical fiber, comprising sapphire optical fiber and its external protective fixture, characterized in that: The protective fixture includes a probe head, a probe tail, an air inlet plug, and an optical fiber fixing plug. The probe head, probe tail, and air inlet plug are connected sequentially along the axial direction. The optical fiber fixing plug is threaded to the probe tail. The sapphire optical fiber passes through the protective fixture along the axial direction. The front end of the sapphire optical fiber passes through the central channel of the probe head and extends out of the probe head. The rear end of the sapphire optical fiber forms an optical fiber output end. The sapphire optical fiber is used to collect the phosphorescence signal generated by the phosphorescent coating on the surface under test after external laser excitation. The probe head has a central channel that mates with the sapphire optical fiber. The outer surface of the probe head is coated with a thermal barrier coating. The protective fixture has multiple cooling channels arranged around the sapphire optical fiber. The air inlet plug has an air inlet structure that communicates with the cooling channels. The outer end of the air inlet structure is equipped with a pneumatic quick connector. The protective fixture also has multiple air outlets, each of which is connected to one of the cooling channels. The exhaust direction of the air outlets avoids the surface under test.

2. The ultra-high temperature phosphorescent thermometric probe based on sapphire optical fiber according to claim 1, characterized in that: The probe head is a composite rotating body formed by coaxially connecting a conical segment and a cylindrical segment. The conical segment gradually tapers along the direction close to the surface to be measured and smoothly transitions with the cylindrical segment. The generatrix of the conical segment is a straight line, an arc, or a continuous convergent curve.

3. The ultra-high temperature phosphorescent thermometric probe based on sapphire optical fiber according to claim 1, characterized in that: Multiple cooling channels are arranged circumferentially around the central channel and extend along the axial direction of the protective fixture; the number of cooling channels is three or more.

4. The ultra-high temperature phosphorescent thermometric probe based on sapphire optical fiber according to claim 1, characterized in that: The air outlets are respectively located at the air outlet end of the corresponding cooling channel. The opening area and arrangement position of the air outlets are adapted to the cooling gas flow rate and predetermined exhaust direction of the corresponding cooling channel, and the exhaust direction of each air outlet avoids the surface to be tested.

5. The ultra-high temperature phosphorescent thermometric probe based on sapphire optical fiber according to claim 1, characterized in that: The probe head and the probe tail are made of high-temperature resistant alloy material, the air inlet plug is made of metal material, and the thermal barrier coating is a ceramic thermal barrier coating.

6. The ultra-high temperature phosphorescent thermometric probe based on sapphire optical fiber according to claim 1, characterized in that: A high-temperature resistant composite sealing gasket is provided at the connection between the probe head and the probe tail. The high-temperature resistant composite sealing gasket includes vermiculite-based sealing material and stainless steel reinforcing core material, and cooperates with the sealing groove at the connection to seal the connection gap. A rubber sealing ring is provided between the air inlet plug and the probe tail. An optical fiber fixing plug is provided in the central mounting hole of the air inlet plug, and the sapphire optical fiber is fixed to the optical fiber fixing plug. The protective fixture is also provided with a mounting flange for fixing the ultra-high temperature phosphorescent temperature measuring probe to the test device.

7. The ultra-high temperature phosphorescent thermometric probe based on sapphire optical fiber according to claim 1, characterized in that: The tip of the sapphire optical fiber extends a first preset millimeter length beyond the probe head.

8. The ultra-high temperature phosphorescent thermometric probe based on sapphire optical fiber according to claim 1, characterized in that: The central channel is located on the axis of the tapered region of the probe head; in use, there is a second preset distance of millimeters between the probe head and the surface to be tested, and the front end of the sapphire optical fiber faces the phosphorescent coating of the surface to be tested.

9. A method for ultra-high temperature phosphorescence thermometry based on sapphire optical fiber, characterized in that, The ultra-high temperature phosphorescence thermometric probe based on sapphire optical fiber, as described in any one of claims 1 to 8, comprises the following steps: A phosphorescent coating is applied to the surface to be tested, and a calibration relationship between the phosphorescent characteristic parameters of the phosphorescent coating and the temperature is established in advance. Connect the air intake plug to an external cooling air source to supply cooling gas to the cooling channel; Install the ultra-high temperature phosphorescent temperature probe, align the front end of the sapphire optical fiber with the phosphorescent coating, and ensure that the exhaust direction of the vent hole avoids the surface to be measured. The phosphorescent coating is excited by an external laser, and the phosphorescent signal generated by the sapphire optical fiber is collected and transmitted to a signal acquisition and processing device. The temperature of the surface to be tested is determined based on the phosphorescence characteristic parameters obtained by the signal acquisition and processing device and the calibration relationship.

10. The temperature measurement method according to claim 9, characterized in that: The phosphorescence characteristic parameter is the phosphorescence lifetime.

11. The temperature measurement method according to claim 9, characterized in that: During the measurement process, cooling gas is continuously supplied to the cooling channel; after the measurement is completed, the excitation of the external laser is stopped and the ultra-high temperature phosphorescent thermometric probe is removed from the high temperature measurement area. After the temperature of the ultra-high temperature phosphorescent thermometric probe decreases, the supply of cooling gas is stopped.

12. The application of the ultra-high temperature phosphorescence thermometry method based on sapphire optical fiber as described in claim 9, characterized in that, Approaching the target and measuring its temperature without affecting the target's thermal environment specifically includes: Measure the temperature of hot-end components of an aircraft engine.

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