A thin-film heat flow sensor based on temperature measurement using a dual-color thermosensitive phosphorescent coating

Abstract

The present invention discloses a thin-film heat flux sensor based on temperature measurement using a two-color thermosensitive phosphorescent coating, which mainly solves technical problems such as low sensitivity and poor environmental adaptability of existing heat flux sensors. The heat flux sensor includes an excitation light source, a bundled optical fiber, a heat flux probe, a photoelectric detection unit, and a signal acquisition unit. The excitation light enters the heat flux probe through the bundled optical fiber, and after passing through a collecting lens and a coating substrate, it irradiates the two-color thermosensitive phosphorescent coating, thereby prompting the two-color thermosensitive phosphorescent coating to emit a phosphorescent signal; at the same time, the light-absorbing coating causes a temperature change due to the absorption of heat flux, and transmits this temperature to the two-color thermosensitive phosphorescent coating. The spectrum of the phosphorescent signal changes due to the change in the temperature of the two-color thermosensitive phosphorescent coating, and then the light signal returns to the photoelectric detection unit, which converts the light signal into an electrical signal, which is then collected by the signal acquisition unit, thereby achieving heat flux measurement.

Description

Technical Field

[0001] The invention relates to a radiation field heat flow transient measurement device, in particular to a thin film heat flow sensor based on temperature measurement of a dual-color thermosensitive phosphorescent coating. Background Art

[0002] Accurate measurement of internal heat flux distribution in internal combustion engines, aerospace engines, etc. is of great significance for evaluating the thermal efficiency of the engine and the thermal protection of the shell. Various thermal radiation sources also need to measure their heat flux distribution to evaluate their radiation effect on the effector. The heat flux distribution is generally measured by a heat flux sensor.

[0003] At present, most common heat flow sensors are thermal resistance heat flow sensors. However, this type of sensor is based on the principle of steady-state thermal conductivity and has problems such as long response time and large measurement error. It is not suitable for measuring unsteady heat flow fields. Based on this, thermal resistance thin film heat flow sensors have emerged. Its thermal resistance layer can be made very thin and the response time is greatly shortened. However, due to its weak electrical signal (typical heat flux density measurement sensitivity is 0.2μV / (W / m 2 )), a special charge amplifier is needed to enhance the electrical signal; at the same time, since it uses electrical signals to transmit heat flow information, it is also susceptible to electromagnetic interference, which leads to its low sensitivity and low measurement efficiency, and cannot meet the requirements of heat flow field measurement in complex and harsh environments. Summary of the Invention

[0004] In order to solve the technical problems of low sensitivity and poor environmental adaptability of existing heat flux sensors, the present invention provides a thin-film heat flux sensor based on temperature measurement of a two-color thermosensitive phosphorescent coating. Based on the temperature measurement of the two-color thermosensitive phosphorescent coating, the present invention combines optical fiber transmission signals to develop a compact thin-film heat flux sensor, thereby improving environmental adaptability and heat flux density measurement sensitivity.

[0005] To achieve the above objectives, the technical solutions of the present invention are:

[0006] A thin-film heat flux sensor based on dual-color thermosensitive phosphorescent coating temperature measurement, which is special in that it includes an excitation light source, a bundled optical fiber, a heat flux probe, a photoelectric detection unit and a signal acquisition unit;

[0007] The bundled optical fiber includes a plurality of splitting optical fibers, and each splitting optical fiber is independently arranged; one end of the bundled optical fiber is a plurality of single-core splitting ends, and the other end is a multi-core bundle end; one of the single-core splitting ends is connected to the excitation light source, and the other single-core splitting ends are connected to the input end of the photoelectric detection unit, and the signal acquisition unit is connected to the output end of the photoelectric detection unit;

[0008] The heat flux probe includes a probe housing, a collecting lens and a coating unit sequentially arranged in the probe housing along the optical path; the multi-core bundle end is located at the front end of the collecting lens and is fixed in the probe housing through an optical fiber fixing plate;

[0009] The coating unit includes a coating substrate, a two-color thermosensitive phosphorescent coating and a light-absorbing coating sequentially covering the outer surface of the coating substrate; the inner surface of the coating substrate is close to the rear end of the collecting lens and satisfies the object-image position relationship with the multi-core beam-bundling end; the light-absorbing coating is close to the external heat source and is used to absorb heat and transfer the heat to the two-color thermosensitive phosphorescent coating;

[0010] The photoelectric detection unit is used to convert the optical signal transmitted by the heat flux probe into an electrical signal;

[0011] The signal acquisition unit is used to acquire the electrical signal output by the photoelectric detection unit, and output the electrical signal in the form of data to an external storage device.

[0012] Furthermore, the material of the dual-color thermosensitive phosphorescent coating is a rare earth compound luminescent material having a double-peak or multi-peak structure in the luminescence spectrum. This material has high quantum efficiency, stronger luminescence, higher measurement sensitivity and wider measurement range.

[0013] Further, the photoelectric detection unit includes a first photoelectric detector and a second photoelectric detector;

[0014] The bunching optical fiber includes three splitting optical fibers, one end of the bunching optical fiber is three single-core splitting ends, and the other end is a three-core bunching end, one of the single-core splitting ends is connected to the excitation light source, and the other two single-core splitting ends are respectively connected to the input ends of the first photodetector and the second photodetector. The three-core bunching end is located at the front end of the collecting lens and is fixed in the probe housing through an optical fiber fixing plate; the output ends of the first photodetector and the second photodetector are both connected to the signal acquisition unit through optical fibers.

[0015] Furthermore, the input ends of the first photodetector and the second photodetector are respectively provided with a first filter and a second filter fixed by an adapter ring and an optical fiber fixing plate.

[0016] Furthermore, the first filter and the second filter are narrow band pass filters of different wavelength bands respectively.

[0017] Furthermore, the laser light source adopts a short-wave LED light source or a laser light source, which is used to stimulate the two-color thermosensitive phosphorescent coating to emit phosphorescent signals.

[0018] Furthermore, the probe housing is a cylindrical structure, and its material is hard aluminum or copper, which has good heat dissipation performance.

[0019] Furthermore, the coating substrate is quartz glass or sapphire, which is convenient for transmitting short-wave excitation light and signal light.

[0020] Furthermore, the light-absorbing coating is made of a high-temperature resistant coating containing graphite, which can adapt to the temperature of an external heat source and ensure stable operation of the sensor.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The thin-film heat flux sensor of the present invention comprises an excitation light source, a bundled optical fiber, a heat flux probe, a photoelectric detection unit, and a signal acquisition unit. The bundled optical fiber comprises a plurality of split optical fibers, each of which does not interfere with another. The heat flux probe comprises a probe housing, a collecting lens disposed within the probe housing, and a coating unit. The coating unit comprises a coating substrate, a two-color thermosensitive phosphorescent coating, and a light-absorbing coating sequentially covering the outer surface of the coating substrate. When the sensor is in operation, excitation light enters the heat flux probe through the bundled optical fiber, passes through the collecting lens and the coating substrate, and irradiates the two-color thermosensitive phosphorescent coating, thereby causing the two-color thermosensitive phosphorescent coating to emit a phosphorescent signal. Simultaneously, the light-absorbing coating absorbs the heat flux, causing the temperature to change, and transmits this temperature to the two-color thermosensitive phosphorescent coating. The spectrum of the phosphorescent signal changes due to the change in the temperature of the two-color thermosensitive phosphorescent coating. The signal then passes through the coating substrate, the collecting lens, and the bundled optical fiber to the photoelectric detection unit, where it converts the optical signal into an electrical signal, which is then collected by the signal acquisition unit, thereby achieving heat flux measurement. The thin film heat flow sensor of the present invention has high time resolution, which can reach millisecond level. The thermosensitive phosphorescent coating emits strong light, has high measurement sensitivity, and has a wide temperature resistance range, which can meet the requirements of heat flow field measurement in various complex environments.

[0023] 2. The dual-color thermosensitive phosphorescent coating of the present invention uses high-temperature resistant rare earth compounds, which have a wider temperature resistance and temperature measurement range, and a higher measurable heat flux range.

[0024] 3. The heat flux probe of the thin film heat flux sensor of the present invention uses light to transmit information in the measurement area and transmits it through optical fiber, so it has strong anti-electromagnetic interference capability.

[0025] 4. The thin film heat flow sensor of the present invention has a compact overall structure and can be used for heat flow measurement in a small space in a harsh environment.

[0026] 5. The thin film heat flow sensor of the present invention can be applied to the heat flow measurement of various thermal radiation sources such as wind tunnel flow field, engine internal flow field, space environment simulator, combustion field, etc. It is based on optical fiber transmission signal and has strong resistance to electromagnetic interference, and is especially suitable for strong electromagnetic interference environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1This is a schematic structural diagram of an embodiment of a thin-film heat flow sensor for temperature measurement based on a dual-color thermosensitive phosphorescent coating according to the present invention;

[0028] Figure 2 Schematic diagram of the bundled optical fiber structure in an embodiment of a thin-film heat flow sensor based on dual-color thermosensitive phosphorescent coating temperature measurement according to the present invention;

[0029] Figure 3 Schematic diagram of the heat flux probe structure in an embodiment of a thin-film heat flux sensor based on a dual-color thermosensitive phosphorescent coating for temperature measurement according to the present invention;

[0030] Figure 4 This is a schematic diagram of the flame heat flux density measurement optical path of an embodiment of a thin-film heat flux sensor based on dual-color thermosensitive phosphorescent coating temperature measurement according to the present invention;

[0031] Figure 5 This is a calibration curve diagram of the luminous intensity ratio of the two-color thermosensitive phosphorescent coating and the coating surface temperature of an embodiment of a thin-film heat flow sensor based on the two-color thermosensitive phosphorescent coating for temperature measurement of the present invention.

[0032] The reference numerals are as follows:

[0033] 1-excitation light source, 2-bundled optical fiber, 21-single-core beam splitting end, 22-multi-core beam bundling end, 3-heat flux probe, 31-probe housing, 32-collecting lens, 33-coating unit, 34-coating substrate, 35-dual-color thermosensitive phosphorescent coating, 36-light-absorbing coating, 4-photoelectric detection unit, 41-first photodetector, 42-second photodetector, 43-adapter ring, 44-first filter, 45-second filter, 5-signal acquisition unit. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0035] like Figure 1 As shown, the present invention provides a thin-film heat flux sensor based on dual-color thermosensitive phosphorescent coating temperature measurement, which includes an excitation light source 1, a bundled optical fiber 2, a heat flux probe 3, a photoelectric detection unit 4, and a signal acquisition unit 5. The excitation light source 1 is generally a short-wave LED light source or a laser light source.

[0036] Combine Figures 1 to 3 As shown, the bundled optical fiber 2 includes multiple splitting optical fibers, and each splitting optical fiber is independently arranged and does not interfere with each other; one end of the bundled optical fiber 2 is multiple single-core splitting ends 21, and the other end is a multi-core bundle end 22.

[0037] In this embodiment, the bundled optical fiber 2 includes three splitting optical fibers, wherein the single-core splitting end 21 of one of the splitting optical fibers is connected to the excitation light source 1, and the single-core splitting ends 21 of the remaining two splitting optical fibers are connected to the photoelectric detection unit 4. The photoelectric detection unit 4 includes two detectors, namely a first photodetector 41 and a second photodetector 42. The first photodetector 41 and the second photodetector 42 do not interfere with each other. The input ends of the first photodetector 41 and the second photodetector 42 are respectively provided with a first filter 44 and a second filter 45 fixed by an adapter ring 43 and a fiber fixing plate. The first filter 44 and the second filter 45 are respectively narrow bandpass filters of different wavelengths. The wavelength selection of the narrow bandpass filter is related to the selection of the dual-color thermosensitive phosphorescent coating material. Generally, the narrow bandpass filter should cover two luminescence peaks respectively, thereby ensuring that the intensity of each transmitted light is high and the sensitivity of the transmitted light intensity ratio to temperature is high. The single-core splitting ends 21 of the remaining two splitting optical fibers of the three splitting optical fibers pass through the first filter 44 and the second filter 45 respectively and are connected to the first photodetector 41 and the second photodetector 42 through the optical fiber fixing plate.

[0038] The multi-core bunching end 22 is connected to the heat flux probe 3, and the excitation light source 1 emits excitation light. The excitation light enters through the single-core splitting end 21 of one of the splitting optical fibers, and is emitted from the multi-core bunching end 22 into the heat flux probe 3, and irradiates the coating unit 33 to generate an optical signal. The optical signal is collected by the collecting lens 32 and then enters from the multi-core bunching end 22. One optical signal returns along the original path, and the other two optical signals enter the first photodetector 41 and the second photodetector 42 respectively through the corresponding splitting optical fibers. The first photodetector 41 and the second photodetector 42 convert the received optical signal into an electrical signal and output it to the signal acquisition unit 5 through the optical fiber. The signal acquisition unit 5 outputs the received electrical signal in the form of data to the external storage device, thereby completing the measurement of the thermal flow field temperature.

[0039] like Figure 3 As shown, the heat flux probe 3 includes a probe housing 31, a collection lens 32, and a coating unit 33, which are sequentially arranged within the probe housing 31 along the optical path. The probe housing 31 is cylindrical in structure, but can also be designed as a three-dimensional structure such as a cuboid or cube depending on the actual application. The probe housing 31 is made of metal, typically duralumin or copper, which has good heat dissipation properties.

[0040] The coating unit 33 includes a coating substrate 34, a two-color thermosensitive phosphorescent coating 35 and a light-absorbing coating 36 sequentially covering the outer side of the coating substrate 34. The multi-core bunching end 22 is located at the front end of the collecting lens 32 and is fixed in the probe housing 31 by an optical fiber fixing plate. The inner side of the coating substrate 34 is close to the rear end of the collecting lens 32 and satisfies the object-image position relationship with the multi-core bunching end 22. The distance between the two can be specifically designed according to the actual measurement requirements, thereby improving the measurement accuracy. The coating substrate 34 is generally made of quartz glass or sapphire, which is a material that facilitates the transmission of short-wave excitation light and signal light, thereby improving the measurement sensitivity.

[0041] The light-absorbing coating 36, located near the heat source of the external environment, primarily absorbs heat from the environment and transfers it to the dual-color thermosensitive phosphorescent coating 35. The light-absorbing coating 36 is typically made of a high-temperature, graphite-containing coating that absorbs heat quickly, conducts heat quickly, and responds quickly. This coating can also adapt to a variety of complex environmental temperatures. The dual-color thermosensitive phosphorescent coating 35 is made of a rare earth compound luminescent material with a bimodal or multimodal luminescence spectrum. This coating offers high quantum efficiency, high luminous intensity, enhanced measurement sensitivity, a wider temperature tolerance and measurement range, and a wider heat flux measurement range.

[0042] Combine Figure 1 and Figure 4 , taking a specific measurement process as an example, the working principle of the present invention is described in detail:

[0043] The heat flux probe 3 of the thin film heat flow sensor of the present invention is fixed at a distance of 0.5m from the heat source, and the height of the heat flux probe 3 is flush with the center of the heat source. The excitation light source 1 uses a 370nm continuous laser light source with a spectral width of 10nm and a typical power of 30mW.

[0044] The excitation light source 1 is input from the single-core splitter end 21 of a 3m-long bundled optical fiber 2. It is transmitted through the optical fiber and emitted from the multi-core bundled end 22. It then passes through the collecting lens 32 and the coating substrate 34 (typically 2mm thick and 12.7mm in diameter) in the heat flux probe 3 to illuminate a dual-color thermosensitive phosphorescent coating 35 (typically 100μm thick) composed of Mg4FGeO6:Mn. Under the stimulation of the excitation light source 1, the dual-color thermosensitive phosphorescent coating 35 emits a long-wavelength phosphorescent signal with two emission peaks (i.e., 636nm and 660nm). The intensity ratio of the two peaks of the phosphorescent signal changes due to the surface temperature change of the light-absorbing coating 36 caused by the heat flux. The changed phosphorescent signal then passes through the coating substrate 34 and the collecting lens 32 before being collected by the multi-core bundled end 22 of the bundled optical fiber 2. The collected phosphorescence signal is synchronously transmitted through three split optical fibers, one of which returns to the excitation light source 1; the remaining two paths pass through a first 636nm filter 44 and a second 660nm filter 45, respectively, before being irradiated onto a first photodetector 41 and a second photodetector 42 in the visible wavelength range. The first and second photodetectors 41, 42 convert the received optical signals into electrical signals (typically in the volt range), which are then collected by a signal acquisition unit 5 at a synchronous sampling frequency of 1kHz via a coaxial cable, thereby completing the acquisition of thermal flow field information.

[0045] The signal acquisition unit 5 outputs the collected electrical signal in the form of data to a recording storage device such as a computer through a USB transmission line, thereby completing the measurement of the heat flow of the ambient field. The user can compare the ratio of the light signal intensity of the two bands with the pre-calibrated temperature measurement curve (such as Figure 5 As shown in the figure), the temperature rise process of the environmental field heat flow over time can be obtained.

[0046] In this embodiment, the heat conduction equation uses Laplace transform to derive the approximate heat flux density based on the coating surface temperature changes at different times. The heat flux density calculation formula is:

[0047]

[0048] In the above formula, θ PS (t)=T(t,L)-T0, T(t,L) is t i The temperature of the coating surface at the moment, T0 is the initial temperature of the coating, t n is n moments, where n≥i, k p is the thermal conductivity of the two-color thermosensitive phosphorescent coating, ρ p is the density of the two-color thermosensitive phosphorescent coating, c pis the specific heat capacity of the two-color thermosensitive phosphorescent coating. When the thermal conductivity of the coating substrate and the thermosensitive phosphorescent coating material are similar, the heat flux density flowing through the coating surface at a certain moment (i.e., time n) is the sum of the ratio of the coating surface temperature difference in all unit sampling time intervals before this moment to the weight of the unit sampling time interval, multiplied by the coating physical property parameters.

[0049] In this embodiment, since the thermal conductivity of the coating substrate glass and the Mg4FGeO6:Mn thermosensitive phosphorescent coating material are similar, according to the above formula, t n The heat flux density flowing through the coating surface at time t i The thermal conductivity of the typical coating is 1.5Wm -1 K -1 , density 2520kgm -3 and specific heat capacity 750 Jkg -1 K -1 It can be seen from this that the response time of the thin film heat flow sensor of the present invention can reach the order of milliseconds to microseconds, and the response time is short.

[0050] Depend on Figure 5 It can be seen that the temperature measurement range of the thin film heat flux sensor is from room temperature to 850K, and the corresponding heat flux density measurement range is 0-0.4MW / m 2 , using sensitive phosphorescent coating materials with a wider temperature measurement range, a higher heat flux measurement range can be obtained), higher sensitivity (the electrical signal change range is 1V, and the heat flux measurement sensitivity is 2.5μV / (W / m 2 )), the measurable heat flux range is wider.

[0051] The thin-film heat flow sensor of the present invention is suitable for measuring heat flow in various thermal radiation sources, such as wind tunnel flow fields, engine flow fields, space environment simulators, and combustion fields. It features high measurement sensitivity and a short response time, making it suitable for non-steady-state heat flow fields. Furthermore, the sensor's optical fiber signal transmission and the use of an inorganic thermosensitive phosphorescent coating provide strong resistance to electromagnetic interference, making it suitable for use in environments with strong electromagnetic interference.

[0052] Although the embodiments of the present invention have been shown and described above, it will be apparent to those skilled in the art that any changes or modifications to the above embodiments shall fall within the scope of protection of the present invention as long as they are within the spirit of the present invention.

Claims

1. A thin-film heat flow sensor based on a two-color thermosensitive phosphorescent coating for temperature measurement, characterized by: The device comprises an excitation light source (1), a bundled optical fiber (2), a heat flux probe (3), a photoelectric detection unit (4), and a signal acquisition unit (5); the photoelectric detection unit (4) comprises a first photoelectric detector (41) and a second photoelectric detector (42); The bundled optical fiber (2) includes a plurality of splitting optical fibers, and each splitting optical fiber is independently arranged; one end of the bundled optical fiber (2) is a plurality of single-core splitting ends (21), and the other end is a multi-core bundled end (22); one of the single-core splitting ends (21) is connected to an excitation light source (1), and the remaining single-core splitting ends are respectively connected to the input ends of a first photodetector (41) and a second photodetector (42); and the signal acquisition unit (5) is respectively connected to the output ends of the first photodetector (41) and the second photodetector (42); The heat flux probe (3) comprises a probe housing (31), a collecting lens (32) and a coating unit (33) arranged in sequence along an optical path in the probe housing (31); the multi-core bundle end is located at the front end of the collecting lens (32) and is fixed in the probe housing (31) via an optical fiber fixing plate; The coating unit (33) includes a coating substrate (34), a two-color thermosensitive phosphorescent coating (35) and a light-absorbing coating (36) sequentially covering the outer surface of the coating substrate (34); the inner surface of the coating substrate (34) is close to the rear end of the collecting lens (32) and satisfies the object-image position relationship with the multi-core cluster end (22); the light-absorbing coating (36) is close to an external heat source and is used to absorb heat and transfer the heat to the two-color thermosensitive phosphorescent coating (35); The first photodetector (41) and the second photodetector (42) are used to convert the optical signal transmitted by the heat flux probe (3) into an electrical signal; The signal acquisition unit (5) is used to acquire the electrical signals output by the first photodetector (41) and the second photodetector (42), and output the electrical signals in the form of data to an external storage device.

2. The thin-film heat flow sensor based on dual-color thermosensitive phosphorescent coating temperature measurement according to claim 1, characterized in that: The material of the dual-color thermosensitive phosphorescent coating (35) is a rare earth compound luminescent material having a double-peak or multi-peak structure in its luminescence spectrum.

3. The thin-film heat flow sensor based on dual-color thermosensitive phosphorescent coating temperature measurement according to claim 2, characterized in that: The bundled optical fiber (2) includes three splitting optical fibers, one end of the bundled optical fiber (2) is three single-core splitting ends, and the other end is a three-core bundled end, one of the single-core splitting ends is connected to the excitation light source (1), and the other two single-core splitting ends are respectively connected to the input ends of the first photodetector (41) and the second photodetector (42), the three-core bundled end is located at the front end of the collecting lens (32) and is fixed in the probe housing (31) through an optical fiber fixing plate; the output ends of the first photodetector (41) and the second photodetector (42) are both connected to the signal acquisition unit (5) through optical fibers.

4. A thin-film heat flow sensor based on a dual-color thermosensitive phosphorescent coating for temperature measurement according to any one of claims 1 to 3, characterized in that: The input ends of the first photodetector (41) and the second photodetector (42) are respectively provided with a first filter (44) and a second filter (45) fixed by an adapter ring (43) and an optical fiber fixing disk.

5. The thin-film heat flow sensor based on dual-color thermosensitive phosphorescent coating temperature measurement according to claim 4, characterized in that: The first filter (44) and the second filter (45) are respectively narrow-band pass filters of different wavelength bands.

6. The thin-film heat flow sensor based on dual-color thermosensitive phosphorescent coating temperature measurement according to claim 5, characterized in that: The excitation light source (1) adopts a short-wave LED light source or a laser light source.

7. The thin-film heat flow sensor based on dual-color thermosensitive phosphorescent coating temperature measurement according to claim 6, characterized in that: The probe housing (31) is a cylindrical structure and is made of hard aluminum or copper.

8. The thin-film heat flow sensor based on dual-color thermosensitive phosphorescent coating temperature measurement according to claim 7, characterized in that: The coating substrate (34) is quartz glass or sapphire.

9. The thin-film heat flow sensor based on dual-color thermosensitive phosphorescent coating temperature measurement according to claim 8, characterized in that: The light-absorbing coating (36) is made of a high-temperature resistant coating containing graphite.

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