A method for off-line measuring surface temperature of high-temperature components based on phosphor materials

Abstract

The application discloses a kind of high-temperature component surface temperature offline measurement method based on phosphor material, calibrates temperature indicating phosphor material, obtains the corresponding relationship f (t, tau) of temperature indicating phosphor material phosphorescence characteristic change rate and test temperature, test duration;Coating temperature indicating phosphor material on the object to be measured carries out actual service work or test, obtains the change curve of temperature and time in actual work or test process;The phosphorescence characteristic of temperature indicating phosphor material is measured, and compared with the phosphorescence characteristic before test, calculates its change rate;The equivalent temperature in the given test duration in test process is obtained from f (t, tau) obtained by calibration, and the highest temperature in test duration is obtained by correcting equivalent temperature.The method of the application does not need real-time measurement, can be used for moving parts and component measurement under working condition, and the obtained temperature result is more close to actual temperature under variable working condition test environment, and the measurement accuracy is improved.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature component temperature testing technology, specifically relating to an offline method for measuring the surface temperature of high-temperature components based on phosphorescent materials. Background Technology

[0002] In the aerospace field, spacecraft and their propulsion systems typically operate in extremely high-temperature environments. For example, near-space hypersonic vehicles flying within the atmosphere can reach surface temperatures exceeding 2000°C due to aerodynamic heating; therefore, both passive and active thermal protection measures are required to ensure structural safety. Similarly, for aerospace propulsion systems such as turbine gas engines and rocket engines, combustion chamber temperatures can typically reach 1700°C to 4000°C; stabilization and insulation measures are also necessary to ensure safe operation. Therefore, accurate measurement of component temperatures during design and testing is crucial for performance analysis and lifespan prediction. Current measurement technologies mainly include direct and indirect measurement techniques, with direct measurement techniques including:

[0003] Temperature can be directly measured by pre-embedding or using thin-film thermocouples on the surface to be measured. However, pre-embedding thermocouples requires slotting on the surface of the component and grinding after pre-embedding, which is complicated to install. The installation of thermocouples may affect the flow field and the data density is low.

[0004] Infrared thermal imagers are used to obtain temperature distribution by measuring the thermal radiation on the surface of high-temperature components. The measurement results are affected by the emissivity of the surface under test and the ambient radiation, resulting in large measurement uncertainty. It is difficult to measure moving parts and cannot be used for aircraft or propulsion systems in operation.

[0005] Irreversible temperature-indicating paint is sprayed onto the surface of high-temperature components. After the test, the color of the surface temperature-indicating paint is manually or automatically interpreted to obtain the contour lines or distribution of the highest temperature on the surface of the component under working conditions. However, the temperature-indicating paint is easy to peel off, has low accuracy, and is difficult to interpret.

[0006] The temperature of the surface of high-temperature components is measured using temperature-indicating crystal technology. This technology requires grooving and grinding on the surface of the component, which may affect the flow field. The installation and removal of temperature-indicating crystals are relatively complicated, and the number of measurement points is limited.

[0007] Phosphorescent temperature measurement technology is a semi-invasive two-dimensional wall temperature measurement technology with high measurement accuracy. However, existing phosphorescent temperature measurement technologies are all online measurements, which require the installation of optical observation windows on the test piece and the arrangement of camera light sources, optical paths, etc. For example, patent CN 114034405 A proposes a non-contact temperature measurement method, in which the proposed phosphorescent temperature measurement method is an online measurement. Such online measurements are all carried out in simulated test environments, and the measurement results cannot accurately reflect the actual working conditions. Moreover, it is difficult to achieve such online measurements for moving parts (such as high-speed rotating aero-engine blades) or parts under actual service conditions (such as in flight). Summary of the Invention

[0008] To achieve the above objectives, this invention provides an offline method for measuring the surface temperature of high-temperature components based on phosphorescent materials. This method solves the problems that existing phosphorescent temperature measurement technologies cannot measure components or moving parts under actual service conditions, and that the accuracy of the results is affected by measuring under constant temperature conditions.

[0009] To achieve the above objectives, the present invention employs the following technical solution:

[0010] An offline method for measuring the surface temperature of high-temperature components based on phosphorescent materials includes the following steps:

[0011] Step 1: Calibrate the thermo-phosphorescent material and obtain the relationship f(t,τ) between the rate of change of the phosphorescence properties of the thermo-phosphorescent material and the test temperature t and test duration τ.

[0012] The thermoluminescent phosphorescent material is a phosphorescent material with irreversible luminescence properties;

[0013] Step 2: Coat the object to be measured with the thermochromic phosphorescent material described in Step 1, and arrange temperature measurement points for actual service work or testing.

[0014] After the experiment, obtain the temperature versus time curves during actual operation or the experiment.

[0015] Step 3: Measure the phosphorescence properties of the thermochromic phosphorescent material on the test object after the test in Step 2, and compare it with the phosphorescence properties of the thermochromic phosphorescent material before the test to calculate the rate of change of its phosphorescence properties K; Based on the given test duration, the equivalent temperature t during the test can be obtained from K and f(t,τ) calibrated in Step 1.

[0016] K=f(t,τ) (1)

[0017] Step 4: Obtain the highest temperature t within the given test duration during the test using formula (4). max ,

[0018]

[0019] In the formula, τ A τ B These are any two time points during the test of the object to be measured.

[0020] Preferably, the calibration method in step 1 includes: coating a thermo-phosphorescent material onto a metal sheet to form a calibration sheet, and measuring the phosphorescence characteristics of the thermo-phosphorescent material before heating;

[0021] Then, thermocouples are installed on the calibration plate, and the calibration plate is heat-treated at different temperatures, with different heating times at each temperature.

[0022] After heating, the phosphorescence properties of the temperature-indicating phosphorescent material on the calibration sheet are measured and compared with the phosphorescence property data before heating to obtain the relationship f(t,τ) between the rate of change of phosphorescence properties and the heating temperature t and heating time τ.

[0023] Preferably, in step 2, when the temperature measurement point is on the moving part, a thermocouple probe is installed on a non-moving part where the airflow is on the same path as the moving part and the temperature is lower than that of the moving part, as the temperature measurement point.

[0024] Preferably, the thermoluminescent phosphorescent material is a mixture of rare earth elements and matrix material.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] (1) The present invention adopts an offline temperature measurement method. The luminescence characteristics of the phosphorescent material used are irreversible with temperature change. The test piece can be placed in the actual working service environment. After the heating cycle is completed, the test piece is removed and the characteristics of the phosphorescent material on the surface are measured. The measurement results are highly accurate. Moreover, the measurement process does not require real-time measurement and does not require grooving on the surface of the test part. The processing difficulty is low and it has almost no impact on the flow field. It can be used for measuring moving parts and parts in working condition.

[0027] (2) Based on the method of the present invention, the data density is high and the highest temperature distribution of the entire surface can be obtained.

[0028] (3) The method of the present invention corrects the measurement data, making the obtained temperature results more consistent with the actual temperature under the variable working condition test environment, thus improving the measurement accuracy.

[0029] (4) Based on the method of the present invention, a endoscopic endoscope can be used to measure components (such as turbine blades of aero-engines or throat sections of thrust chambers of rocket engines) in narrow spaces while ensuring structural integrity. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the temperature-indicating phosphorescent material calibration device described in the embodiments of the present invention.

[0031] Figure 2 This is a schematic diagram illustrating the relationship between the phosphorescence properties of the thermochromic phosphorescent material and the heating temperature and time, as described in the embodiments of the present invention.

[0032] Figure 3 This is a schematic diagram illustrating the change of turbine inlet temperature of an aircraft engine over time during a takeoff and landing process as described in an embodiment of the present invention.

[0033] Figure 4 This is a schematic diagram illustrating the principle of the temperature correction method under varying operating conditions as described in the embodiments of the present invention.

[0034] The meanings of the labels in the diagram are: 1-metal sheet, 2-thermocouple. Detailed Implementation

[0035] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0036] Example

[0037] This embodiment discloses an offline method for measuring the surface temperature of high-temperature components based on phosphorescent materials, which specifically includes the following steps:

[0038] Step 1: Calibrate the thermoluminescent phosphorescent material to obtain the relationship f(t,τ) between the rate of change of the phosphorescence properties of the thermoluminescent phosphorescent material and the test temperature t and test duration τ. Specifically:

[0039] A calibration sheet is formed by coating a thermoluminescent phosphor with a metal sheet 1. The thermoluminescent phosphor is a phosphorescent material with irreversible luminescence properties. In this embodiment, the thermoluminescent phosphor is a material composed of rare earth elements (such as Tb, Eu, Dy, Ce, etc.) and a matrix material (such as Y2SiO5, Y2O3, Al2O3).

[0040] First, the phosphorescence properties of the thermoluminescent phosphorescent material before heating are measured, such as light intensity, wavelength, and lifetime.

[0041] Then, grooves are cut into the metal sheet to install thermocouple 2, such as... Figure 1 The diagram shows a calibration plate, where metal plate 1 is a copper plate. It should be noted that the material of metal plate 1 is not limited to copper in this embodiment; the metal plate only needs to meet the test temperature.

[0042] The calibration sheet was heat-treated at different temperatures, such as 50°C intervals within the range of 600°C to 900°C, and different heating times were maintained at each temperature, such as 10 min, 20 min, and 30 min.

[0043] After heating, a modulated laser light source was used to excite the thermochromic phosphorescent material on the calibration sheet. The phosphorescence emitted after excitation was recorded using a spectrometer and compared with the phosphorescence characteristic data before heating. The relationship f(t,τ) between the rate of change of phosphorescence characteristics and the heating temperature t and heating time τ was obtained. Figure 2 As shown.

[0044] Step 2: Coat the object to be measured with the temperature-indicating phosphorescent material used for calibration, and arrange temperature measurement points for actual service work or testing; in this embodiment, the object to be measured is an engine blade.

[0045] As a preferred embodiment, when the temperature measurement point is on a moving part (such as an engine blade), it is not possible to directly place the thermocouple probe on the engine blade. Instead, the thermocouple probe can be placed at a location where measurement is easier to achieve. The selection criteria for this location are: the airflow is on the same path as the moving part, the temperature is lower than the moving part's temperature, and it is a non-moving part. Generally, airflow along the same path exhibits similar temperature change trends, which can reflect the temperature change trend of the surface of the component being measured. For example, for an aero-engine, placing a thermocouple probe at the exhaust nozzle, although the temperature at the exhaust nozzle differs from the temperature on the surface of the component being measured, their change trends are similar. Therefore, the temperature change trend at the exhaust nozzle can essentially reflect the temperature change at the blade.

[0046] After the experiment, obtain the temperature and time change curves during actual operation or experiment.

[0047] Step 3: Measure the phosphorescence properties of the thermochromic phosphorescent material on the test object (engine blade) after the test in Step 2, and compare it with the phosphorescence properties of the thermochromic phosphorescent material before the test, and calculate its rate of change K.

[0048] Based on the given test duration, the equivalent temperature t during the test can be obtained from K and f(t,τ) calibrated in step 1.

[0049] K=f(t,τ) (1)

[0050] Step 4: Since the calibration process is performed under stable and constant conditions, while this invention performs measurements under varying operating conditions, taking a turbine gas turbine aero-engine as an example, an aircraft goes through stages such as takeoff, climb, cruise, and landing during a single takeoff and landing. At different stages, the thrust required by the engine varies, leading to changes in the turbine inlet gas temperature. Therefore, the blade surface temperature changes over time, such as... Figure 3 As shown. Therefore, the equivalent temperature was corrected to improve its measurement accuracy.

[0051] For measurements under varying operating conditions, within a certain test duration (e.g.) Figure 4 From τ A To τ B The test duration can be divided into n intervals, each with a length of Δτ. When each interval is sufficiently small, the temperature variation is negligible; that is, the test temperature remains constant within this interval (t). i ).

[0052] Therefore, τ A To τ B The changes in phosphorescent material properties caused by the experimental process over a period of time can be expressed as follows:

[0053]

[0054] In the formula, i represents the corresponding time interval, and t i For the temperature within this time interval, equation (2) can be further expressed as:

[0055]

[0056] For a specific experimental process, the highest temperature t max Since is a constant, equation (3) can be written as:

[0057]

[0058] In the formula, τ A τ B For any two time points during the test of the object to be measured;

[0059] Therefore, the highest temperature t within the given test duration during the test can be obtained through equation (4). max .

Claims

1. An offline method for measuring the surface temperature of high-temperature components based on phosphorescent materials, characterized in that, Includes the following steps: Step 1: Calibrate the thermo-phosphorescent material and obtain the relationship f(t,τ) between the rate of change of the phosphorescence properties of the thermo-phosphorescent material and the test temperature t and test duration τ. The thermoluminescent phosphorescent material is a phosphorescent material with irreversible luminescence properties; Step 2: Coat the object to be measured with the thermochromic phosphorescent material described in Step 1, and arrange temperature measurement points for actual service work or testing. After the experiment, obtain the temperature versus time curves during actual operation or the experiment. Step 3: Measure the phosphorescence properties of the thermochromic phosphorescent material on the test object after the test in Step 2, and compare them with the phosphorescence properties of the thermochromic phosphorescent material before the test, and calculate its rate of change K; Based on the given test duration, the equivalent temperature t during the test can be obtained from K and f(t,τ) calibrated in Step 1. K=f(t,τ) (1) Step 4: Obtain the highest temperature t within the given test duration during the test using formula (4). max , In the formula, τ A τ B These are any two time points during the test of the object to be measured.

2. The offline method for measuring the surface temperature of high-temperature components based on phosphorescent materials as described in claim 1, characterized in that, The calibration method in step 1 includes: coating a thermo-phosphorescent material onto a metal sheet to form a calibration sheet, and measuring the phosphorescence characteristics of the thermo-phosphorescent material before heating; Then, thermocouples are installed on the calibration plate, and the calibration plate is heat-treated at different temperatures, with different heating times maintained at each temperature. After heating, the phosphorescence properties of the temperature-indicating phosphorescent material on the calibration sheet are measured and compared with the phosphorescence property data before heating to obtain the relationship f(t,τ) between the rate of change of phosphorescence properties and the heating temperature t and heating time τ.

3. The offline surface temperature measurement method for high-temperature components based on phosphorescent materials as described in claim 1, characterized in that, In step 2, when the temperature measurement point is on the moving part, a thermocouple probe is set on a non-moving part where the airflow is on the same path as the moving part and the temperature is lower than that of the moving part, as the temperature measurement point.

4. The offline method for measuring the surface temperature of high-temperature components based on phosphorescent materials as described in claim 1, characterized in that, The thermoluminescent phosphorescent material is a mixture of rare earth elements and matrix material.

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