A method for correcting reflected radiation in radiation thermometry through a calibration experiment

Abstract

A method for correcting reflected radiation in radiation thermometry through a calibration experiment. A blackbody furnace is used to calibrate the radiation thermometry sensor to obtain the relationship between the system input radiance and the output. Then, in a temperature measurement environment with a high-temperature background, the reflected radiation is calibrated to establish the functional relationship between the reflected radiation and the system output. In subsequent temperature measurement experiments, the radiation energy received by the system is corrected according to the established functional relationship, and the true temperature of the object is calculated according to the radiation thermometry principle. The method of the present invention solves the problem that the reflected radiation under a high-temperature background affects the temperature measurement of the object, can effectively eliminate the temperature measurement error caused by the reflected radiation, and realizes high-precision temperature measurement.

Description

Technical Field

[0001] The present invention belongs to the technical field of radiation thermometry, and particularly relates to a method for correcting reflected radiation in radiation thermometry through a calibration experiment. By calibrating the reflected radiation through experiments and then correcting the radiation energy input to the radiation thermometry sensor, it is beneficial to improve the accuracy of radiation thermometry. Background Art

[0002] High-temperature measurement is of great significance in military, scientific research, and industrial production, and the requirements for its temperature measurement accuracy are also getting higher and higher. Among them, radiation thermometry has been widely used in high-temperature measurement due to its advantages of high measurement temperature, fast response speed, long service life, and no interference with the temperature field. However, when measuring the temperature of an object under a high-temperature background, the thermal radiation emitted by other objects will introduce reflected radiation after being reflected by the object to be measured, which will lead to temperature measurement errors. For example, in the temperature measurement of the turbine blades of an aeroengine, the radiation energy received by the sensor includes not only the thermal radiation of the blade to be measured but also the reflected radiation caused by adjacent blades and other hot-end components. And the accuracy of blade temperature measurement is of great significance for operation safety and improving the performance of the engine. Therefore, for the case of using the thermal radiation principle to measure temperature under a high-temperature background, it is crucial to correct the reflected radiation to improve the temperature measurement accuracy.

[0003] In the current research on reflected radiation, some scholars have proposed a method using a dual-detection pyrometer to calculate the measurement error of reflected radiation in an aeroengine by processing the responses of thermal radiation signals in two different wavelength bands. However, this method requires the background temperature to be constant over time and must be higher than the temperature of the measured surface, and it is only applicable to very few application scenarios. In addition, most research is to establish a mathematical model of the object to be measured and the high-temperature background surface, and then solve the view factor describing the radiation transfer relationship between the two surfaces to calculate the reflected radiation of the surface of the object to be measured. However, the mathematical modeling process of this method is relatively complex, and it is not applicable to some cases of non-regular surfaces, and the background temperature and emissivity must be determined first to correct the reflected radiation. Summary of the Invention

[0004] In order to solve the influence of reflected radiation on object temperature measurement under a high-temperature background, the present invention proposes a method for correcting reflected radiation in radiation thermometry through a calibration experiment. By calibrating the reflected radiation through experiments and then correcting the radiation energy input to the radiation thermometry sensor, it is beneficial to improve the accuracy of radiation thermometry.

[0005] The technical solution of the present invention is as follows:

[0006] A method for correcting reflected radiation in radiation thermometry through a calibration experiment, characterized by comprising the following steps:

[0007] Step 1, in the radiation temperature measurement experimental system, calibrate the response function relationship between the input radiance M and the output voltage value V of the radiation temperature measurement sensor by using a blackbody furnace, and determine the sensing system constant value K through M = KV;

[0008] Step 2, for the object to be measured in the high-temperature furnace, establish the following function relationship between the total radiance Mt of the object to be measured and the output voltage value Vt by using the radiation temperature measurement sensor:

[0009] Mt = KVt;

[0010] Step 3, measure the temperature To of the object to be measured by using a thermocouple, and calculate the radiant emittance Mo of the object to be measured from To according to Planck's formula;

[0011] Step 4, calculate the reflected radiation Mr = Mt - Mo of the object to be measured, and fit to obtain the function relationship M r between the reflected radiation M of the object to be measured and the voltage value V r = f(V);

[0012] Step 5, in radiation temperature measurement, calculate the reflected radiation according to the M r = f(V) function relationship, and subtract the reflected radiation M t from the total radiance M r received by the radiation temperature measurement sensor to achieve the correction of the radiation temperature measurement error.

[0013] The radiation temperature measurement sensor in Step 1 is an optical fiber temperature measurement sensor.

[0014] The radiation temperature measurement experimental system in Step 1 includes a data collector, the data collector is respectively connected to the upper computer and the output end of the radiation temperature measurement sensor, the input end of the radiation temperature measurement sensor can be selectively connected to the blackbody cavity of the blackbody furnace or the object to be measured in the high-temperature furnace, and the object to be measured is connected to the inspection instrument through a thermocouple.

[0015] The object to be measured in Step 2 is a ceramic blade.

[0016] Step 2 includes conducting a calibration experiment in the real high-temperature background environment where the object to be measured is located, and using the data collector to record the voltage value output by the radiation temperature measurement sensor.

[0017] Step 3 includes conducting a calibration experiment in the real high-temperature background environment where the object to be measured is located, using a thermocouple to measure the surface temperature of the object to be measured, and recording the temperature value displayed by the inspection instrument for the thermocouple output.

[0018] Step 5 includes, after correcting the total radiance, calculating according to the radiation temperature measurement formula to obtain the true temperature of the object to be measured.

[0019] The technical effects of the present invention are as follows: A method for correcting reflected radiation in radiation thermometry through a calibration experiment according to the present invention, compared with the prior art, has a simple and clear experimental process, simple and efficient calculation, does not require measuring the background temperature, can be applied to various temperature measurement scenarios, effectively eliminates the influence of reflected radiation, and greatly improves the temperature measurement accuracy.

[0020] A method for correcting reflected radiation in radiation thermometry through a calibration experiment according to the present invention first calibrates a radiation thermometry sensor using a blackbody furnace to obtain the relationship between the system input radiance and the output; then, in a temperature measurement environment with a high-temperature background, calibrates the reflected radiation to establish a functional relationship between the reflected radiation and the system output; in subsequent temperature measurement experiments, corrects the radiation energy received by the system according to the established functional relationship, and calculates the true temperature of the object according to the radiation thermometry principle. The method of the present invention solves the problem that the reflected radiation in a high-temperature background affects the temperature measurement of an object, can effectively eliminate the temperature measurement error caused by the reflected radiation, and realizes high-precision temperature measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of an experimental system used to implement a method for correcting reflected radiation in radiation thermometry through a calibration experiment according to the present invention.

[0022] Figure 2 is a schematic flow diagram of a method for correcting reflected radiation in radiation thermometry through a calibration experiment according to the present invention. Figure 2 Between the start and the end, it includes Step 1, blackbody furnace calibration experiment: obtaining the functional relationship between the radiance and the output voltage; Step 2, reflected radiation calibration experiment: calibrating the functional relationship between the reflected radiation and the output voltage; Step 3, radiation thermometry experiment: eliminating the reflected radiation and calculating the true temperature of the object.

[0023] The reference numerals are listed as follows: 1 - blackbody furnace; 2 - blackbody cavity; 3 - ceramic blade; 4 - thermocouple; 5 - inspection instrument; 6 - high-temperature furnace; 7 - fiber optic temperature sensor; 8 - data collector; 9 - host computer. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following will describe the present invention in conjunction with the drawings ( Figure 1 - Figure 2 ) and embodiments.

[0025] Figure 1 is a schematic structural diagram of an experimental system used to implement a method for correcting reflected radiation in radiation thermometry through a calibration experiment according to the present invention. Figure 2 is a schematic flow diagram of a method for correcting reflected radiation in radiation thermometry through a calibration experiment according to the present invention. Refer to Figures 1 to 2As shown in the figure, a method for correcting reflected radiation in radiation thermometry through a calibration experiment includes the following steps: Step 1, in a radiation thermometry experimental system, use a blackbody furnace to calibrate the response function relationship between the input radiance M and the output voltage value V of a radiation thermometry sensor, and determine the sensor system constant value K through M = KV; Step 2, establish the following functional relationship between the total radiance Mt of the object to be measured in a high-temperature furnace and the output voltage value Vt using the radiation thermometry sensor: Mt = KVt; Step 3, measure the temperature To of the object to be measured using a thermocouple, and calculate the radiant emittance Mo of the object to be measured from To according to Planck's formula; Step 4, calculate the reflected radiation Mr = Mt - Mo of the object to be measured, and fit to obtain the reflected radiation M r and the functional relationship M r = f(V) between the voltage value V; Step 5, in radiation thermometry, calculate the reflected radiation according to the M r = f(V) functional relationship, and subtract the reflected radiation M t from the total radiance M r received by the radiation thermometry sensor to achieve the correction of the radiation thermometry error.

[0026] The radiation thermometry sensor in Step 1 is an optical fiber thermometry sensor 7. The radiation thermometry experimental system in Step 1 includes a data collector 8, which is respectively connected to a host computer 9 and the output end of the radiation thermometry sensor. The input end of the radiation thermometry sensor can be selectively connected to the blackbody cavity 2 of the blackbody furnace 1 or the object to be measured in the high-temperature furnace 6. The object to be measured is connected to a patrol instrument 5 through a thermocouple 4 (the thermocouple can be a high-precision thermocouple such as a B-type thermocouple). The object to be measured in Step 2 is a ceramic blade 3. Step 2 includes conducting a calibration experiment in the real high-temperature background environment where the object to be measured is located, and using the data collector 8 to record the voltage value output by the radiation thermometry sensor. Step 3 includes conducting a calibration experiment in the real high-temperature background environment where the object to be measured is located, using the thermocouple 4 to measure the surface temperature of the object to be measured, and recording the temperature value displayed by the patrol instrument 5 for the output of the thermocouple 4. Step 5 includes, after correcting the total radiance, calculating according to the radiation thermometry formula to obtain the true temperature of the object to be measured.

[0027] In order to solve the influence of reflected radiation on object temperature measurement under a high-temperature background, the present invention proposes an error correction method that calibrates the reflected radiation through experiments, then corrects the radiation energy input to the radiation temperature sensor, and further improves the temperature measurement accuracy. The object of the present invention is achieved through the following technical solutions: A blackbody furnace is used to calibrate the sensor to obtain the relationship between the total radiance input to the system and the output voltage value; in a temperature measurement environment with a high-temperature background, the reflected radiation is calibrated to establish a functional relationship between the reflected radiation and the system output voltage value. Then, in the temperature measurement experiment, the radiation energy received by the system is corrected to eliminate the temperature measurement error caused by the reflected radiation and further improve the temperature measurement accuracy.

[0028] A method for correcting reflected radiation in radiation temperature measurement through calibration experiments. The experimental device used in this method includes a blackbody furnace (1), a thermocouple (2), a data logger (3), a radiation temperature sensor (4), a data collector (5), and a host computer (6). The response function relationship between the radiance input to the sensor (4) and the output voltage value is calibrated using the blackbody furnace (1); in a temperature measurement environment with a high-temperature background, the reflected radiation of the object to be measured is calibrated according to the temperature of the thermocouple (2) displayed by the data logger (3) and the response function of the sensor (4); in the subsequent temperature measurement experiment, the reflected radiation in the radiance input to the sensor (4) is subtracted, and the temperature measurement is realized using the radiation temperature formula.

[0029] This method calibrates the reflected radiation of the object to be measured under a high-temperature background through experiments and eliminates the influence of the reflected radiation in the temperature measurement experiment.

[0030] This method includes the following steps:

[0031] (1) In a temperature measurement environment with a high-temperature background, the thermal radiation emitted by the background is reflected by the surface of the object to be measured and becomes the reflected radiation M r , then the total radiance M t input to the sensor includes the radiant emittance M o of the object to be measured and the reflected radiation M r .

[0032] (2) Calibration of the sensor response function: When calibrating the radiation temperature sensor using the blackbody furnace, there is no reflected radiation. Then, according to Planck's formula, the total radiance M t input to the sensor can be calculated based on the temperature displayed by the blackbody furnace, and the relationship between M t and the output voltage value V is determined to obtain the function expression of M t - V.

[0033] (3) Reflective radiation calibration experiment: Conduct the calibration experiment in the real high-temperature background environment where the object to be measured is located. On the one hand, use a high-precision thermocouple to measure the surface temperature of the object to be measured and record the temperature value displayed by the inspection instrument for the thermocouple output. On the other hand, the data collector records the voltage value output by the radiation temperature measurement sensor.

[0034] (4) Calculate the reflective radiation: According to Planck's formula, calculate the radiant emittance M of the object to be measured from the temperature value output by the thermocouple o . Then, according to the response function M t -V of the sensor in step (2), calculate the total radiant emittance M received by the sensor at this time from the voltage value t . Calculate the reflective radiation M r using the following formula:

[0035] M r = M t - M o

[0036] (5) According to the experimental data in step (3) and the calculation results in step (4), fit to obtain the functional relationship M r = f(V) between the output voltage of the sensor and the reflective radiation.

[0037] (6) In the temperature measurement experiment of the object to be measured, calculate the reflective radiation according to the M r = f(V) functional relationship, and subtract the reflective radiation M t from the total radiant emittance M received by the sensor to correct the radiation temperature measurement error, and then measure the true temperature of the object according to the calculation of the temperature measurement formula. r

[0038] As Figure 1 shown, the experimental system applied in the method of the present invention includes: blackbody furnace 1, blackbody cavity 2, ceramic blade 3, B-type thermocouple 4, inspection instrument 5, high-temperature furnace 6, optical fiber temperature sensor 7, data collector 8 and host computer 9. Taking the temperature measurement experiment of the ceramic blade in the high-temperature furnace using a quartz optical fiber sensor as an example, the thermal radiation emitted by the furnace wall and the molybdenum disilicide rod as the heat source in the high-temperature furnace will introduce a reflective radiation temperature measurement error after being reflected by the ceramic blade. The surface of the blackbody cavity in the blackbody furnace is coated with a special material with an emissivity greater than 0.99, and its radiant emittance is used as the calibration value of the radiation energy. The numerical aperture of the quartz optical fiber is 0.22, the temperature measurement distance is 3 cm, and the target diameter is 6 mm.

[0039] A method for correcting reflective radiation through a calibration experiment, the specific steps are as follows:

[0040] (1) The thermal radiation emitted by the object is converted into a voltage signal by the optical fiber sensor, and the total radiant emittance M received by the sensor t ​has the following functional relationship with the output voltage value V:

[0041] M t = K·V

[0042] where K is a constant of the sensing system, including the transmittance of the optical lens, the spectral response function of the photoelectric converter, and the temperature measurement area.

[0043] (2) The K value of the system can be calibrated through a blackbody furnace temperature measurement experiment. Since the orifice of the blackbody furnace can be regarded as a blackbody radiation source, its radiant emittance M can be calculated according to Planck's formula. When using the fiber optic sensor to measure the blackbody cavity, there is no reflected radiation. Then, the radiant emittance M can be calculated from the temperature of the blackbody furnace according to Planck's formula, and at the same time, the data collector collects the output voltage V of the sensor. Then, the K value can be calculated at the upper computer end to obtain the functional relationship between the radiant emittance input to the sensor and the output voltage value.

[0044] (3) In a preferred embodiment of the present invention, the temperature measurement environment is to measure the temperature of ceramic blades in a high-temperature furnace. Thermocouples are arranged on the blades to measure the true temperature of the blades in real time. In the calibration experiment of reflected radiation, the temperature T output by the thermocouple is recorded by the inspection instrument o and the output voltage value V of the sensor also needs to be recorded by the data collector.

[0045] (4) According to Planck's formula, the radiant emittance M of the blade at this time is calculated from T o The total radiant emittance M received by the system can be calculated from the output voltage value V of the sensor and the calibrated K value of the system o . Then, the reflected radiation can be calculated by the following formula: t M

[0046] M r = M t - M o

[0047] (5) According to M r calculated in step (4) and the voltage value V output by the sensor in step (2), the functional relationship between the reflected radiation M r and the voltage value V can be fitted to obtain M r = f(V).

[0048] (6) In the temperature measurement experiment of ceramic blades in a high-temperature furnace, the total radiant emittance M received by the system is calculated from the voltage output by the sensor according to the K value t , and the reflected radiation at this time is calculated according to M r = f(V), and the radiant emittance M of the ceramic blade at this time oIt is equal to the difference between the two, and then the true temperature of the blade is solved according to the radiation temperature measurement formula, thus eliminating the influence of reflected radiation on temperature measurement.

[0049] The content not detailedly described in the specification of the present invention belongs to the prior art well-known to those skilled in the art. It is hereby specified that the above description helps those skilled in the art to understand the present invention, but does not limit the protection scope of the present invention. Any implementation that is an equivalent replacement, modification and improvement, and / or simplification of the above description without departing from the substantial content of the present invention falls within the protection scope of the present invention.

Claims

1. A method for correcting reflected radiation in radiation thermometry through calibration experiments, characterized in that It includes the following steps: Step 1: In the blackbody furnace calibration experiment, calibrate the response function relationship between the input radiance M and the output voltage value V of the radiation temperature sensor by using the blackbody furnace, and determine the sensing system constant value K through M = KV; Step 2: For the object to be measured in the high-temperature furnace, establish the following function relationship between the total radiance Mt of the object to be measured and the output voltage value V by using the radiation temperature sensor: Mt = KV; Step 3: In the reflected radiation calibration experiment, record the voltage value of the radiation temperature sensor, and calculate the total radiation amount Mt received by the radiation temperature sensor by using the formula Mt = KV; at the same time, measure the temperature To of the object to be measured by using a thermocouple, and calculate the radiant emittance Mo of the object to be measured according to Planck's formula from To; Step 4: Calculate the reflected radiation Mr at different temperatures according to the formula Mr = Mt - Mo, and further, the functional relationship M between the reflected radiation M of the object to be measured and the voltage value V can be obtained by fitting r to complete the calibration of the reflected radiation. r = f(V) Step 5: In the radiation temperature measurement experiment, calculate the total radiation amount Mt and the reflected radiation Mr respectively from Mt = KV and Mr = f(V) according to the voltage value V output by the radiation temperature sensor; then calculate the radiant emittance Mo of the turbine blade itself according to Mo = Mt - Mr to realize the correction of the reflected radiation.

2. The method for correcting reflected radiation in radiation thermometry through a calibration experiment according to claim 1, characterized in that The radiation temperature sensor in Step 1 is an optical fiber temperature sensor.

3. The method for correcting reflected radiation in radiation thermometry through a calibration experiment according to claim 1, characterized in that The radiation temperature measurement experimental system in Step 1 includes a data collector, the data collector is respectively connected to the upper computer and the output end of the radiation temperature sensor, the input end of the radiation temperature sensor is selectively connected to the blackbody cavity of the blackbody furnace and the object to be measured in the high-temperature furnace, and the object to be measured is connected to a patrol instrument through a thermocouple.

4. The method for correcting reflected radiation in radiation thermometry through a calibration experiment according to claim 1, characterized in that, The object to be measured in Step 2 is a ceramic blade.

5. The method for correcting reflected radiation in radiation thermometry through a calibration experiment according to claim 1, characterized in that, Step 3 includes performing a calibration experiment in the real high-temperature background environment where the object to be measured is located, and using the data collector to record the voltage value output by the radiation temperature sensor.

6. The method for correcting reflected radiation in radiation thermometry through a calibration experiment according to claim 1, characterized in that, Step 3 includes performing a calibration experiment in the real high-temperature background environment where the object to be measured is located, measuring the surface temperature of the object to be measured by using a thermocouple, and recording the temperature value displayed by the patrol instrument for the thermocouple output.

7. The method for correcting reflected radiation in radiation thermometry through a calibration experiment according to claim 1, characterized in that Step 5 includes calculating the true temperature of the object to be measured according to the radiation temperature measurement formula after correcting the total radiance.

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