A Thermocouple Error Correction Method for Small Temperature Rise Measurement of Aircraft Engines

Abstract

The present application provides a thermocouple error correction method for measuring small temperature rises in aircraft engines, which belongs to the field of aircraft engine technology. The method includes: performing a thermocouple static calibration test on a preset temperature range under the condition that the temperature rise range is no more than 60°C to obtain a thermoelectric characteristic database; placing the thermocouple probe in a standard normal temperature wind tunnel, performing a thermocouple static deviation calibration test at room temperature and a preset airflow velocity to obtain a static deviation database; placing the thermocouple probe in a standard hot wind tunnel, performing thermocouple temperature correction coefficient calibration tests under multiple different total temperature rise ranges and multiple different Mach number airflow conditions to obtain a temperature correction coefficient database; using the thermocouple probe for actual small temperature rise measurements, and correcting the temperature measured by the thermocouple based on the thermoelectric characteristic database, the static deviation database, and the temperature correction coefficient database. The present application scheme improves the temperature measurement accuracy and the accuracy of the temperature rise efficiency test.

Description

Technical Field

[0001] The present application relates to the technical field of aero-engines, and in particular to a method for correcting thermocouple errors in small temperature rise measurements of aero-engines. Background Art

[0002] As one of the three major components of an aircraft engine, the performance of the fan / compressor compression system directly determines the overall performance of the engine. Accurately understanding the characteristics of the compression system is crucial for designing high-performance aircraft engines. Efficiency is one of the most important performance indicators for the compression system, and every percentage point improvement represents a significant advancement. Accurately measuring compression system efficiency is a key technical support for the development of advanced aircraft engines. In compression component efficiency testing, accurate cross-sectional average temperature assessment is particularly critical, which necessitates high-precision steady-state temperature testing at the component inlet and outlet. Furthermore, with the rapid development of my country's aircraft engines, engines are required to operate stably at both design and off-design points throughout the entire flight envelope. Accurately measuring this data provides direct experimental data support for compression system design and a basis for iterative optimization, ensuring stable engine operation. However, currently, high-precision temperature measurement cannot meet the requirements for the development of high-performance aircraft engine compression systems, and relevant research is urgently needed.

[0003] For fans and compressors with fewer stages, the temperature rise ΔT* of their inlet and outlet sections is relatively low. In particular, when ΔT* is less than 50K, every 1K change will result in an efficiency change of more than 2%, which is a very large value for the compression system. In fan / compressor testing, if the temperature rise of the inlet and outlet sections cannot be measured with high precision, it will be impossible to correctly evaluate the temperature rise efficiency of the fan / compressor, verify the pros and cons of the design, and may even mislead the direction of design improvement. Therefore, during the compression system test process, accurately measuring ΔT*, especially ΔT* under small temperature rise conditions, is the key to accurately evaluating the basic characteristics of the compression system and providing real data support for fan / compressor design.

[0004] Currently, domestic research institutions primarily use thermocouple and RTD sensing elements to measure airflow temperatures at the inlet and outlet cross-sections of fans and compressors. Several domestic research institutions have also conducted research on direct temperature rise measurement using series-connected thermocouples, fluorescence temperature measurement, and fiber optic temperature measurement. However, these temperature measurement methods all suffer from issues such as insufficient accuracy, insufficient research into factors influencing errors, a lack of calibration capabilities, a lack of feasible specifications for the layout of cross-sectional temperature field measurement points, and in-depth research into data processing methods. These methods lag significantly behind advanced international standards and meet the requirements for model development.

[0005] In summary, high-precision small temperature rise testing technology, a basic testing technology that supports the development of high-performance fans / compressors, still has major deficiencies and urgently needs to be researched. Summary of the Invention

[0006] In view of this, an embodiment of the present application provides a thermocouple error correction method for small temperature rise measurement of aircraft engines, which performs high-precision correction on the main errors existing in thermocouple temperature measurement, and provides a new testing method with higher performance and better reliability for the field of high-precision temperature measurement of aircraft engines.

[0007] The present invention provides a method for correcting thermocouple errors in small temperature rise measurements of aircraft engines, the method comprising:

[0008] Under the condition that the temperature rise range is no more than 60°C, a static calibration test of the thermocouple is performed within the preset temperature range to obtain a thermoelectric characteristics database;

[0009] Place the thermocouple probe in a standard normal temperature wind tunnel and conduct a static deviation calibration test of the thermocouple at normal temperature and a preset airflow velocity to obtain a static deviation database.

[0010] The thermocouple probe is placed in a standard thermal wind tunnel. Temperature correction coefficient calibration tests are performed on the thermocouple under different total temperature rise ranges and different Mach number airflow conditions to obtain a temperature correction coefficient database.

[0011] Thermocouple probes are used in actual small temperature rise measurements, and the temperature measured by the thermocouple is corrected based on the thermoelectric characteristics database, static deviation database, and temperature correction coefficient database.

[0012] According to a specific implementation of the embodiment of the present application, the static calibration test of the thermocouple is performed within a preset temperature range to obtain a thermoelectric characteristics database, including:

[0013] Step 11: Place the thermocouple probe and the standard platinum resistor in the oil tank, connect the cold end of the thermocouple to the freezing point device and the acquisition system, turn on the oil tank heating power supply, set the oil tank temperature to 0°C within the range of 0-100°C until it stabilizes, and record the value of the standard platinum resistor at this time as the standard platinum resistor temperature T 铂 ;

[0014] Step 12: Immerse the thermocouple in the oil tank and obtain the thermocouple potential value U T , increase the current oil tank temperature setting value by 1℃, repeat steps 11 and 12, complete the calibration test of all temperature points in the range of 0-100℃, and obtain the temperature T of each standard platinum resistance 铂 And the potential value U of the thermocouple at this temperature T ;

[0015] Step 13: According to the temperature T of each standard platinum resistor 铂 And the potential value U of the thermocouple at this temperature T , corrected to each integer temperature T 标 The potential value under

[0016] Step 14: According to the potential value U at each integer temperature T标 , the thermoelectric characteristic conversion functions of each order polynomial from the first to the fifth order are fitted every 10℃, and the sum of the residuals of the polynomial under the current order in the current temperature range is calculated according to the thermoelectric characteristic conversion function. By comparing the sizes of the different sums of the residuals of each order polynomial from the first to the fifth order, the best order thermoelectric characteristic conversion function within the current 10℃ range is selected, and finally the thermoelectric characteristic database of the thermocouple is obtained.

[0017] According to a specific implementation of the embodiment of the present application, the correction is for each integer temperature T 标 The potential values ​​under

[0018] When the thermocouple is of the type with an international temperature scale, the international temperature scale is used to convert the standard platinum resistance temperature T 铂 The potential value U of the thermocouple under T Corrected to the potential value U at integer temperature T标 , U T标 The calculation formula is:

[0019] ,

[0020] in, is the integer temperature T 标 Seebeck coefficient of the lower thermocouple;

[0021] When the thermocouple is of other types, according to the current standard platinum resistance temperature T 铂 The Seebeck coefficients at the first two integer temperatures are iteratively updated based on the potential value at the previous standard platinum resistance temperature, and the potential value is corrected.

[0022] According to a specific implementation of the embodiment of the present application, the current standard platinum resistance temperature T 铂 The Seebeck coefficients at the first two integer temperatures are iteratively updated based on the potential value at the previous standard platinum resistance temperature, and the potential value is corrected, including:

[0023] The first step is to use the current standard platinum resistance temperature T 铂 The potential value U of the thermocouple under T , the previous standard platinum resistance temperature T 铂-1 The potential value U of the thermocouple under T-1 、The first two standard platinum resistance temperatures T 铂-2The potential value U of the thermocouple under T-2 , the previous integer temperature T 标-1 and the first two integer temperatures T 标-2 , calculate the potential value of the first corrected integer temperature and the potential values ​​of the first two integer temperatures of the first correction , the calculation formula is:

[0024]

[0025] ;

[0026] Step 2: Update the first two integer temperatures T 标-2 The Seebeck coefficient S under T标-2 , the update formula is:

[0027] ;

[0028] Step 3: Update the first two integer temperatures T 标-2 The potential values ​​of the first two integer temperatures under the second correction , the calculation formula is:

[0029] ;

[0030] Step 4: Repeat steps 2 to 3 until S T标-2 No longer changes, and the potential value of the last correction in the third step formula is used as T 标-2 The potential value U at integer temperature T标-2 .

[0031] According to a specific implementation of the embodiment of the present application, the calculation formula for the sum of the residuals is:

[0032] ,

[0033] Where v is the sum of the residuals, i is the i-th temperature within the current 10°C range, and f is the thermoelectric characteristic conversion function of a certain order polynomial.

[0034] According to a specific implementation of the embodiment of the present application, a thermocouple probe is placed in a standard normal temperature wind tunnel, and a static deviation calibration test of the thermocouple is performed at normal temperature and a preset airflow velocity to obtain a static deviation database, including:

[0035] Step 21: Place the thermocouple probe under the standard normal temperature wind tunnel, with the fairing facing the center of the incoming flow. Insert the cold end of the thermocouple and the standard platinum resistor into the ice-water mixture. The standard platinum resistor in the ice-water mixture will show the value T 冷铂 As the freezing point error μ;

[0036] Step 22: Compare the temperature measured by the thermocouple at room temperature with the temperature measured by the standard platinum resistance thermometer after correcting the freezing point error to obtain the static deviation λ of the thermocouple. The calculation formula is:

[0037] ,

[0038] Among them, T1 is the reading temperature value after the thermocouple corrects the freezing point error, F is the best order thermoelectric characteristic conversion function in the current temperature range, T 铂 is the standard platinum resistance temperature, U T is the standard platinum resistance temperature T 铂 The potential value of the thermocouple under the condition of , μ is the freezing point error.

[0039] According to a specific implementation of the embodiment of the present application, the step of performing a temperature correction coefficient calibration test on a thermocouple to obtain a temperature correction coefficient database includes:

[0040] Step 31: Calculate the temperature correction coefficient at different total airflow temperatures and Mach numbers. ;

[0041] Step 32: Based on the temperature correction coefficient The temperature correction coefficient database is constructed based on the correspondence between the Mach number and the total airflow temperature. The temperature correction coefficient database is stored in a two-dimensional array matrix. The rows and columns of the two-dimensional array matrix are divided according to the Mach number and the total airflow temperature. Each matrix unit stores the temperature correction coefficient under the Mach number and the total airflow temperature. , the piecewise linear fitting under the same Mach number is Function, the piecewise linear fitting under the same total temperature is Function, T * is the total temperature of the airflow, and Ma is the Mach number.

[0042] According to a specific implementation of the embodiment of the present application, the temperature correction coefficient The calculation formula is:

[0043] ,

[0044] Where T2 is the temperature value after correcting the freezing point error and static deviation, and k is the insulation coefficient.

[0045] According to a specific implementation of the embodiment of the present application, the correction of the temperature measured by the thermocouple based on the thermoelectric characteristics database, the static deviation database, and the temperature correction coefficient database includes:

[0046] Step 41: Arrange total pressure and static pressure measurement points at the test site and calculate the current Mach number Ma i ;

[0047] Step 42: Convert the voltage value of the thermocouple at each measuring point into the temperature value T of each measuring point according to the thermoelectric characteristic database. i ;

[0048] Step 43: The temperature value T of each measuring point i Perform freezing point error correction to obtain the reading temperature value T of the thermocouple at each measuring point after the freezing point error correction. 1i , T 1i =T i +μ;

[0049] Step 44: According to the static deviation database, the reading temperature value T after the freezing point error of the thermocouple at each measuring point is corrected 1i Perform static deviation correction to obtain the corrected freezing point error and the temperature value T after static deviation at each measuring point. 2i , T 2i =T 1i +λ;

[0050] Step 45: The temperature value T after correcting the freezing point error and static deviation of each measuring point 2i , using the temperature correction coefficient database Function interpolation calculation of the temperature value T at each Mach number 2i Corresponding temperature correction coefficient ξ T2i ;

[0051] Step 46: Piecewise linear fitting of the temperature values ​​T at each Mach number 2i Temperature correction coefficient ξ T2i , get the temperature value T 2i The temperature correction coefficient is a function of the Mach number: ξ T2i =ξ(Ma);

[0052] Step 47: Enter the current Mach number Ma i , according to ξ obtained in step 46 T2i =ξ(Ma) function interpolation calculation to obtain the temperature value T 2i and the current Mach number Ma i Temperature correction coefficient value ξ under T2i，Mai ;

[0053] Step 48: Based on the temperature value T 2i and the current Mach number Ma i Temperature correction coefficient value ξ under T2i，Mai , for temperature T 2i Perform speed error correction to obtain the dynamic temperature value T3 of the speed error correction;

[0054] Step 49: Take the dynamic temperature value T3 corrected by the speed error as input and re-execute steps 45 to 47 to obtain the temperature value T3 and the current Mach number Mai Temperature correction factor under , and according to the temperature correction coefficient Re-iterate to obtain the dynamic temperature value T4 of the secondary velocity error correction;

[0055] Step 410: If the absolute value of the difference between the dynamic temperature value T4 corrected by the secondary speed error and the dynamic temperature value T3 corrected by the speed error meets the temperature criterion, the dynamic temperature value T4 corrected by the secondary speed error is used as the final dynamic temperature value after error correction; if the absolute value of the difference between the dynamic temperature value T4 corrected by the secondary speed error and the dynamic temperature value T3 corrected by the speed error does not meet the temperature criterion, continue to iteratively obtain the temperature correction coefficient and the corrected temperature value in step 49 until the temperature criterion is met, and the final dynamic temperature value after error correction is obtained, and the final dynamic temperature value after error correction is used as the thermocouple temperature value T after data processing of each measuring point at the outlet. n ;

[0056] Step 411: Execute steps 42 to 44 on the original data of each measuring point at the inlet to obtain the thermocouple temperature value T of each measuring point at the inlet after data processing. 2进 , according to the thermocouple temperature value T of each measuring point at the outlet after data processing n And the thermocouple temperature value T of each measuring point at the inlet after data processing 2进 Obtain the temperature rise range ΔT of each measuring point. The calculation formula for the temperature rise range ΔT is:

[0057] ΔT=T n -T 2进 .

[0058] According to a specific implementation of the embodiment of the present application, the calculation formula of the dynamic temperature value T3 of the speed error correction is:

[0059] ,

[0060] The calculation formula of the dynamic temperature value T4 of the secondary speed error correction is:

[0061] ,

[0062] Among them, ξ T2i，Mai is the temperature value T 2i and the current Mach number Ma i The temperature correction coefficient value under is the temperature value T3 and the current Mach number Ma i The temperature correction coefficient under , k is the insulation coefficient.

[0063] Beneficial effects:

[0064] The thermocouple error correction method for small temperature rise measurement of an aircraft engine in the embodiment of the present application has the following beneficial effects:

[0065] 1. Separate static calibration greatly reduces the indexing error: The existing mainstream thermocouple temperature measurement data processing mainly calibrates several temperature points, and calibrates the indexing error through the national standard indexing table. Since the thermocouple material, thermocouple batch, probe structure, welding process, etc. will affect the indexing error of the thermocouple, this data processing method is still difficult to avoid the indexing error of the temperature segment between temperature points. The present invention statically calibrates the thermocouple separately and establishes a indexing table, constructs the optimal thermoelectric fitting function, and greatly reduces the indexing error; at the same time, it provides a standardized process for indexing calibration data processing. For thermocouple materials that do not have a national standard indexing table, the Seebeck coefficient can still be solved and the indexing calibration data processing can be performed;

[0066] 2. Considering thermal conductivity error, the temperature measurement accuracy is greatly improved: The existing commonly used thermocouple processing method only corrects the velocity error through the normal temperature reheating coefficient. At an airflow velocity of Mach number 0.4, the temperature measurement accuracy within the total temperature of 200°C is generally ±1.5°C to ±2.5°C. This level of temperature measurement accuracy is difficult to meet the requirements of fan / compressor temperature rise efficiency testing. The high-precision temperature measurement data processing method based on thermocouples described in the present invention considers the temperature correction coefficient, which is related not only to the Mach number but also to the total temperature. It also performs two-dimensional interpolation calculations to correct the velocity error and thermal conductivity error, which can improve the temperature measurement accuracy to within 0.2°C, greatly improving the accuracy of temperature rise efficiency testing.

[0067] 3. Easy to implement through programming and can be integrated into the test system: This method can import the database into the software program to realize batch correction and processing of data; further, it can embed the acquisition program and real-time display software to integrate the test system to realize real-time acquisition, real-time processing, and real-time waveform display, which is feasible from the perspective of engineering application. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0069] Figure 1 Schematic diagram of the composition of a thermocouple data processing system according to an embodiment of the present invention;

[0070] Figure 2 A thermocouple static deviation and temperature correction coefficient calibration test system according to an embodiment of the present invention;

[0071] Figure 3 2 is a schematic diagram of a temperature rise signal test and data correction according to an embodiment of the present invention.

[0072] In the figure: 1. Jet hot wind tunnel; 2. Jet hot wind tunnel measurement and control system; 3. High-precision thermocouple probe for outlet; 4. Ejector tube; 5. Signal conditioning and data acquisition system; 6. Host computer software; 7. Standard normal temperature wind tunnel; 8. High-precision thermocouple probe for inlet; 9. Standard normal temperature wind tunnel measurement and control system. DETAILED DESCRIPTION

[0073] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0074] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0075] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0076] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show components related to the present application and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0077] Additionally, in the following description, specific details are provided to provide a thorough understanding of the examples. However, one skilled in the art will appreciate that the aspects described can be practiced without these specific details.

[0078] This embodiment of the present application provides a method for correcting thermocouple errors in aircraft engine temperature rise measurements. Based on the measured voltage signals from the thermocouples, a database is established by calibrating the resulting data. This method performs thermoelectric conversion, corrects for major temperature measurement errors, and outputs a true airflow temperature waveform. This method can be implemented in software and downloaded to an embedded module for standalone operation, or it can be implemented by acquiring the raw thermocouple voltage signals through a digital voltage acquisition system, conditioning them through A / D conversion, and then outputting them to a host computer for programmable calculations. A detailed description is provided below with reference to the accompanying drawings.

[0079] In one embodiment, a method for correcting thermocouple errors in small temperature rise measurements of an aircraft engine is provided, the method comprising the following steps:

[0080] Step 1: Under the condition that the temperature rise range is not greater than 60°C, a static calibration test of the thermocouple is performed within a preset temperature range to obtain a thermoelectric characteristics database;

[0081] Step 2: Place the thermocouple probe in a standard normal temperature wind tunnel, perform a static deviation calibration test of the thermocouple at normal temperature and a preset airflow velocity to obtain a static deviation database;

[0082] Step 3: Place the thermocouple probe in a standard thermal wind tunnel and perform temperature correction coefficient calibration tests on the thermocouple under multiple different total temperature rise ranges and multiple different Mach number airflow conditions to obtain a temperature correction coefficient database;

[0083] Step 4: Use the thermocouple probe in actual small temperature rise measurement, and correct the temperature measured by the thermocouple based on the thermoelectric characteristics database, the static deviation database, and the temperature correction coefficient database.

[0084] In this embodiment, the error correction of thermocouples is targeted at measuring small engine temperature rises when the temperature rise range is no more than 60°C, where the preset temperature range is generally set to 0°C-100°C. In this embodiment, through separate static calibration and the establishment of a thermoelectric characteristics database, the indexing error is greatly reduced; through static deviation calibration tests, static deviation calibration is performed, and the thermocouple error is corrected using a temperature correction coefficient, further improving the accuracy of the temperature rise efficiency test. At the same time, the method of this embodiment can import the database into a software program to implement batch data correction processing. Furthermore, it can embed an acquisition program and real-time display software to integrate the test system, achieving real-time acquisition, real-time processing, and real-time waveform display, which is feasible from the perspective of engineering application.

[0085] Furthermore, the static calibration test of the thermocouple is performed within the preset temperature range to obtain a thermoelectric characteristics database, which specifically includes the following steps:

[0086] Step 11: Place the thermocouple probe and the standard platinum resistor in the oil tank, connect the cold end of the thermocouple to the freezing point device and the acquisition system, turn on the oil tank heating power supply, set the oil tank temperature to 0°C within the range of 0-100°C until it stabilizes, and record the value of the standard platinum resistor at this time as the standard platinum resistor temperature T 铂 ;

[0087] Step 12: Immerse the thermocouple in the oil tank and obtain the thermocouple potential value U T , increase the current oil tank temperature setting value by 1℃, repeat steps 11 and 12, complete the calibration test of all temperature points in the range of 0-100℃, and obtain the temperature T of each standard platinum resistance 铂 And the potential value U of the thermocouple at this temperature T ;

[0088] Step 13: Since the actual oil tank temperature cannot be raised to the standard set temperature accurately, the temperature of each standard platinum resistance is T 铂 And the potential value U of the thermocouple at this temperature T , corrected to each integer temperature T 标 The potential value under

[0089] Step 14: According to the potential value U at each integer temperature T标 , the thermoelectric characteristic conversion functions of each order polynomial from the first to the fifth order are fitted every 10℃, and the sum of the residuals of the polynomial under the current order in the current temperature range is calculated according to the thermoelectric characteristic conversion function. By comparing the sizes of the different sums of the residuals of each order polynomial from the first to the fifth order, the best order thermoelectric characteristic conversion function within the current 10℃ range is selected, and finally the thermoelectric characteristic database of the thermocouple is obtained.

[0090] In the specific implementation, the thermocouple is immersed in the oil tank to obtain the potential value U of the thermocouple. T , specifically including:

[0091] Immerse the test piece (thermocouple) to be calibrated in the oil tank. The depth of the liquid should not be less than 1 / 2 of the maximum depth of the oil. After the thermocouple reaches thermal equilibrium, record the potential value it outputs within 3 minutes and calculate the average value. The average value is used as the potential value U of the thermocouple. T .

[0092] Furthermore, for each standard platinum resistance temperature T 铂 And the potential value U of the thermocouple at this temperature T , corrected to each integer temperature T 标 The potential value under , is calculated in two cases, including:

[0093] Case 1: When the thermocouple is of the type with an international temperature scale, the standard platinum resistance temperature T is converted to 铂 The potential value U of the thermocouple under T Corrected to the potential value U at integer temperature T标 , U T标 The calculation formula is:

[0094] , (1)

[0095] in, is the integer temperature T 标 Seebeck coefficient of the lower thermocouple;

[0096] Case 2: When the thermocouple is of other types (this type of thermocouple does not have an international temperature scale and has poor linearity), according to the current standard platinum resistance temperature T 铂 The Seebeck coefficients at the first two integer temperatures are iteratively updated based on the potential value at the previous standard platinum resistance temperature, and the potential value is corrected.

[0097] Specifically, for case 2, the current standard platinum resistance temperature T 铂 The Seebeck coefficients at the first two integer temperatures are iteratively updated based on the potential value at the previous standard platinum resistance temperature, and the potential value is corrected, including:

[0098] The first step is to use the current standard platinum resistance temperature T 铂 The potential value U of the thermocouple under T , the previous standard platinum resistance temperature T 铂-1 The potential value U of the thermocouple under T-1 、The first two standard platinum resistance temperatures T 铂-2 The potential value U of the thermocouple under T-2 , the previous integer temperature T 标-1 and the first two integer temperatures T 标-2 , calculate the potential value of the first corrected integer temperature and the potential values ​​of the first two integer temperatures of the first correction , the calculation formula is as follows:

[0099] (2)

[0100] (3)

[0101] Step 2: Update the first two integer temperatures T according to formula (4) 标-2 The Seebeck coefficient S under T标-2 ,

[0102] (4)

[0103] Step 3: Update the first two integer temperatures T according to formula (5) 标-2 The potential values ​​of the first two integer temperatures under the second correction ,

[0104] (5)

[0105] Step 4: Repeat steps 2 to 3 until S T标-2 No longer changes, and the potential value of the last correction in the third step formula (5) is used as T 标-2 The potential value U at integer temperature T标-2 .

[0106] In one embodiment, the calculation formula for the sum of the residuals is:

[0107] (6)

[0108] Where v is the sum of the residuals, i is the i-th temperature within the current 10°C range, and f is the thermoelectric characteristic conversion function of a certain order polynomial.

[0109] In one embodiment, a thermocouple probe is placed in a standard normal temperature wind tunnel, and a static deviation calibration test of the thermocouple is performed at normal temperature and a preset airflow velocity to obtain a static deviation database, including:

[0110] Step 21: Place the thermocouple probe under the standard normal temperature wind tunnel, with the fairing facing the center of the incoming flow. Insert the cold end of the thermocouple and the standard platinum resistor into the ice-water mixture. The standard platinum resistor in the ice-water mixture will show the value T 冷铂 As the freezing point error μ,

[0111] (7)

[0112] Step 22: Compare the temperature measured by the thermocouple at room temperature with the temperature measured by the standard platinum resistance thermometer after correcting the freezing point error to obtain the static deviation λ of the thermocouple. The calculation formula is:

[0113] (8)

[0114] Where T1 is the reading temperature value after the thermocouple is corrected for the freezing point error, and F is the best-order thermoelectric characteristic conversion function in the current temperature range.

[0115] During specific implementation, the preset air flow velocity may be set to an air flow velocity of 15 m / s.

[0116] In one embodiment, the step of performing a temperature correction coefficient calibration test on a thermocouple to obtain a temperature correction coefficient database includes:

[0117] Step 31: Calculate the temperature correction coefficient at different total airflow temperatures and Mach numbers. ;

[0118] Step 32: Based on the temperature correction coefficient The temperature correction coefficient database is constructed based on the correspondence between the Mach number and the total airflow temperature. The temperature correction coefficient database is stored in a two-dimensional array matrix. The rows and columns of the two-dimensional array matrix are divided according to the Mach number and the total airflow temperature. Each matrix unit stores the temperature correction coefficient under the Mach number and the total airflow temperature. , the piecewise linear fitting under the same Mach number is Function, the piecewise linear fitting under the same total temperature is Function, T * is the total temperature of the airflow, and Ma is the Mach number.

[0119] In specific implementation, for step 3, the temperature correction coefficient calibration test of the thermocouple is carried out under multiple different total temperature rise ranges and multiple different Mach numbers of airflow conditions, wherein the multiple different total temperature rise ranges are set to the total temperature rise range of 30°C, 40°C, 50°C, and 60°C, and the multiple different Mach numbers are set to the Mach numbers of 0.2, 0.3, 0.4, and 0.5. Therefore, in this embodiment, the temperature correction coefficient corresponding to each total airflow temperature and each Mach number is obtained. , based on multiple temperature correction coefficients Build a temperature correction coefficient database.

[0120] In specific implementation, for the total airflow temperature T * The standard temperature is indicated by a standard platinum resistor. If the marked platinum resistor is inconsistent with the thermocouple measuring point, it is necessary to simulate the heat dissipation temperature and calculate the total airflow temperature T * .

[0121] Furthermore, the temperature correction coefficient The calculation formula is:

[0122] (9)

[0123] Among them, T2 is the temperature value after correcting the freezing point error and static deviation, , k is the thermal insulation coefficient. In this embodiment, k is 1.4.

[0124] In one embodiment, the correction of the temperature measured by the thermocouple based on the thermoelectric characteristics database, the static deviation database, and the temperature correction coefficient database includes:

[0125] Step 41: Arrange total pressure and static pressure measurement points at the test site and calculate the current Mach number Ma i ;

[0126] Step 42: Convert the voltage value of the thermocouple at each measuring point into the temperature value T of each measuring point according to the thermoelectric characteristic database. i ;

[0127] Step 43: The temperature value T of each measuring point i Perform freezing point error correction to obtain the reading temperature value T of the thermocouple at each measuring point after the freezing point error correction. 1i , T 1i =T i +μ;

[0128] Step 44: According to the static deviation database, the reading temperature value T after the freezing point error of the thermocouple at each measuring point is corrected 1i Perform static deviation correction to obtain the corrected freezing point error and the temperature value T after static deviation at each measuring point. 2i , T 2i =T 1i +λ;

[0129] Step 45: The temperature value T after correcting the freezing point error and static deviation of each measuring point 2i , using the temperature correction coefficient database Function interpolation calculation of the temperature value T at each Mach number 2i Corresponding temperature correction coefficient ξ T2i ;

[0130] Step 46: Piecewise linear fitting of the temperature values ​​T at each Mach number 2i Temperature correction coefficient ξ T2i , get the temperature value T 2i The temperature correction coefficient is a function of the Mach number: ξ T2i =ξ(Ma);

[0131] Step 47: Enter the current Mach number Ma i , according to ξ obtained in step 46 T2i =ξ(Ma) function interpolation calculation to obtain the temperature value T 2i and the current Mach number Ma i Temperature correction coefficient value ξ under T2i，Mai ;

[0132] Step 48: Based on the temperature value T 2i and the current Mach number Ma i Temperature correction coefficient value ξ under T2i，Mai , for temperature T 2i Perform speed error correction to obtain the dynamic temperature value T3 of the speed error correction;

[0133] Step 49: Take the dynamic temperature value T3 corrected by the speed error as input and re-execute steps 45 to 47 to obtain the temperature value T3 and the current Mach number Ma i Temperature correction factor under , and according to the temperature correction coefficient Re-iterate to obtain the dynamic temperature value T4 of the secondary velocity error correction;

[0134] Step 410: If the absolute value of the difference between the dynamic temperature value T4 corrected by the secondary speed error and the dynamic temperature value T3 corrected by the speed error meets the temperature criterion, the dynamic temperature value T4 corrected by the secondary speed error is used as the final dynamic temperature value after error correction; if the absolute value of the difference between the dynamic temperature value T4 corrected by the secondary speed error and the dynamic temperature value T3 corrected by the speed error does not meet the temperature criterion, continue to iteratively obtain the temperature correction coefficient and the corrected temperature value in step 49 until the temperature criterion is met, and the final dynamic temperature value after error correction is obtained, and the final dynamic temperature value after error correction is used as the thermocouple temperature value T after data processing of each measuring point at the outlet. n ;

[0135] Step 411: Execute steps 42 to 44 on the original data of each measuring point at the inlet to obtain the thermocouple temperature value T of each measuring point at the inlet after data processing. 2进 , according to the thermocouple temperature value T of each measuring point at the outlet after data processing n And the thermocouple temperature value T of each measuring point at the inlet after data processing 2进 Obtain the temperature rise range ΔT of each measuring point. The calculation formula for the temperature rise range ΔT is:

[0136] ΔT=T n -T 2进 .

[0137] Furthermore, the calculation formula of the dynamic temperature value T3 of the speed error correction is:

[0138] ,

[0139] The calculation formula of the dynamic temperature value T4 of the secondary speed error correction is:

[0140] ,

[0141] Among them, ξ T2i，Mai is the temperature value T 2i and the current Mach number Ma i The temperature correction coefficient value under is the temperature value T3 and the current Mach number Ma i The temperature correction coefficient under , k is the insulation coefficient.

[0142] In one embodiment, a specific thermocouple error correction method is disclosed. A thermocouple probe is used for actual small temperature rise precision temperature measurement. Under a temperature rise range of no more than 60°C and a Mach number of 0.4 (the actual temperature rise range and Mach number are determined based on the requirements of the fan / compressor small temperature rise test), the inlet and outlet temperatures, i.e., the temperature rise range, are measured with high precision. The data is then processed according to the following specific steps:

[0143] Step 51: Arrange the total pressure and static pressure measurement points at the test site and calculate the current Mach number Ma according to formula (10) i ,

[0144] (10)

[0145] in, is the total pressure, P S is the static pressure;

[0146] Step 52: Based on the generated thermoelectric characteristic database of thermocouples, the voltage value U of each measuring point is converted to i Convert to the temperature value T of each measuring point i , that is U i →T i ;

[0147] Step 53: The temperature value T of each measuring point i Perform freezing point error correction to obtain the reading temperature value T of the thermocouple at each measuring point after the freezing point error correction. 1i , T 1i =T i +μ; μ is the freezing point error of the thermocouple, which is a fixed value;

[0148] Step 54: According to the static deviation database, the reading temperature value T of the thermocouple at each measuring point after correcting the freezing point error is obtained. 1i Perform static deviation correction to obtain the corrected freezing point error and the temperature value T after static deviation at each measuring point. 2i , T 2i =T 1i +λ; λ is the static deviation of the thermocouple, which is a fixed value;

[0149] Step 55: Temperature value T obtained in step 54 2i , using the temperature correction coefficient database Function interpolation calculation of the temperature value T at each Mach number 2i Corresponding temperature correction coefficient ξ T2i ;

[0150] Step 56: Piecewise linear fitting of the temperature values ​​T at each Mach number 2i Temperature correction coefficient ξ T2i , get the temperature value T 2iThe temperature correction coefficient is a function of the Mach number: ξ T2i =ξ(Ma);

[0151] Step 57: Enter the current Mach number Ma i , according to ξ obtained in step 56 T2i =ξ(Ma) function interpolation calculation to obtain the temperature value T 2i and the current Mach number Ma i Temperature correction coefficient value ξ under T2i，Mai ;

[0152] Step 58: Based on the temperature value T 2i and the current Mach number Ma i Temperature correction coefficient value ξ under T2i，Mai , for temperature T 2i Perform speed error correction to obtain the dynamic temperature value T3 of speed error correction. The calculation formula of T3 is:

[0153] (11)

[0154] Step 59: Take the dynamic temperature value T3 corrected by the speed error as input and re-execute steps 55 to 57 to obtain the temperature value T3 and the current Mach number Ma i Temperature correction factor under , and according to the temperature correction coefficient Re-iterate to obtain the dynamic temperature value T4 for secondary speed error correction. The calculation formula of T4 is:

[0155] (12)

[0156] Step 510: If the absolute value of the difference between the dynamic temperature value T4 corrected by the secondary speed error and the dynamic temperature value T3 corrected by the speed error is less than or equal to 0.01 degrees, the temperature criterion is met, and the dynamic temperature value T4 corrected by the secondary speed error is used as the final dynamic temperature value after error correction; if the absolute value of the difference between the dynamic temperature value T4 corrected by the secondary speed error and the dynamic temperature value T3 corrected by the speed error is greater than 0.01 degrees, the temperature criterion is not met, and step 49 is continued to iteratively obtain the temperature correction coefficient and the corrected temperature value until the temperature criterion is met and the final dynamic temperature value after error correction is obtained. The final dynamic temperature value after error correction is used as the thermocouple temperature value T of each measuring point at the fan / compressor outlet after data processing. n ;

[0157] Step 511: Execute steps 52 to 54 on the original data of each measuring point at the fan / compressor inlet to obtain the thermocouple temperature value T of each measuring point at the fan / compressor inlet after data processing. 2进, according to the thermocouple temperature value T of each measuring point at the outlet after data processing n And the thermocouple temperature value T of each measuring point at the inlet after data processing 2进 Obtain the temperature rise range ΔT of each measuring point. The calculation formula for the temperature rise range ΔT is:

[0158] ΔT=T n -T 2进 .

[0159] In one embodiment, a high-precision thermocouple data processing system is used to implement the above-mentioned thermocouple error correction method for small temperature rise measurement of an aircraft engine. Figure 1 As shown, it includes three major parts: a high-precision thermocouple probe, a high-precision small temperature rise acquisition hardware system consisting of a cold-end compensation circuit, a signal conditioning module, a digital-analog acquisition card, and a host computer acquisition software; a high-precision small temperature rise acquisition software system consisting of a high-precision thermocouple hotspot conversion and error correction program, a thermoelectric characteristic conversion database, a temperature correction coefficient database, and a static deviation database; and a Mach number test system consisting of a measuring point total pressure probe, a measuring point static pressure probe, and a digital pressure scanning valve.

[0160] Among them, the output signal of the high-precision thermocouple probe is connected to the ice bottle as cold-end compensation, and then connected to the signal conditioning module and the digital-analog acquisition card in sequence to complete signal conditioning and A / D conversion. The original digital signal formed is then connected to the host computer acquisition software for acquisition, display and output, and then the signal enters the high-precision thermocouple data processing program; the total pressure probe and static pressure probe are arranged at the combined thermocouple measuring point, and their output pressure enters the digital pressure scanning valve to complete the measurement and acquisition and output the pressure signal; the thermoelectric characteristic database, temperature correction database, static error database, and ice point error in the ice bottle are imported into the high-precision thermocouple data processing program, and combined with the temperature signal imported by the host computer acquisition software and the pressure signal imported by the pressure scanning valve for comprehensive calculation to complete the data compensation and correction.

[0161] The thermocouple probe needs to be calibrated for static error and temperature correction coefficient in a system based on a jet-type hot wind tunnel and a standard normal temperature wind tunnel. Figure 2 As shown, the system includes a jet hot wind tunnel 1, a jet hot wind tunnel measurement and control system 2, a high-precision thermocouple probe for the outlet 3, an ejector tube 4, a signal conditioning and data acquisition system 5, a host computer software 6, a standard normal temperature wind tunnel 7, a high-precision thermocouple probe for the inlet 8, and a standard normal temperature wind tunnel measurement and control system 9. Static error calibration is carried out in a standard normal temperature wind tunnel, and temperature correction coefficient calibration is carried out in a jet hot wind tunnel. The calibration Ma numbers are selected as 0.2, 0.3, 0.4, and 0.5, and the calibration temperature rise ranges are selected as 30°C, 40°C, 50°C, and 60°C. Temperature correction coefficient calibration tests are carried out at all Cartesian direct product points of Ma number and temperature, and a two-dimensional database of temperature correction coefficients related to Ma number and temperature is established.

[0162] The thermocouple probe can be used to measure the steady-state temperature under small temperature rise after generating its thermoelectric characteristics database, static error database, and temperature correction coefficient database. For the test and data correction process, see Figure 3 .

[0163] The static error database and temperature correction coefficient database obtained after calibration are shown in Tables 1 and 2. The verification and comparison results of the corrected temperature and standard temperature in the prototype test are shown in Table 3. It is clear that the measurement accuracy of the temperature rise range has been improved after the static error and temperature correction coefficient correction.

[0164] Table 1 Static temperature measurement deviation calibration test data of a K-type material prototype in a low-speed wind tunnel

[0165]

[0166] Table 2 Temperature correction coefficients of K-type high-precision galvanic probes under heating conditions

[0167]

[0168] In specific implementation, after calibrating the temperature correction coefficients for different Mach numbers and different temperatures, the average temperature correction coefficient is selected as the probe temperature correction coefficient.

[0169] Table 3 Temperature measurement deviation of K-type probes at the inlet and outlet of compression components

[0170]

[0171] The embodiments provided by the present invention have the following advantages:

[0172] 1. Separate static calibration greatly reduces the indexing error: The existing mainstream thermocouple temperature measurement data processing mainly calibrates several temperature points and calibrates the indexing error through the national standard indexing table. Since the thermocouple material, thermocouple batch, probe structure, welding process, etc. will affect the indexing error of the thermocouple, this data processing method still cannot avoid the indexing error of the temperature segment between temperature points. This embodiment statically calibrates the thermocouple separately and establishes a indexing table to construct the optimal thermoelectric characteristic function, which greatly reduces the indexing error; at the same time, it provides a standardized process for indexing calibration data processing. For thermocouple materials that do not have a national standard indexing table, the Seebeck coefficient can still be solved and the indexing calibration data processing can be performed;

[0173] 2. Considering thermal conductivity error, the temperature measurement accuracy is significantly improved: The existing commonly used thermocouple processing method only corrects the velocity error through the normal temperature re-temperature coefficient. At an airflow velocity of Mach number 0.4, the temperature measurement accuracy within a total temperature of 200°C is generally ±1.5°C to ±2.5°C. This level of temperature measurement accuracy is difficult to meet the requirements of fan / compressor temperature rise efficiency testing. The high-precision temperature measurement data processing method based on thermocouples described in this embodiment considers the temperature correction coefficient, which is related not only to the Mach number but also to the total temperature. It also performs two-dimensional interpolation calculations to correct the velocity error and thermal conductivity error, which can improve the temperature measurement accuracy to within 0.2°C, greatly improving the accuracy of the temperature rise efficiency test.

[0174] 3. Easy programming and integration with test systems: The method of this embodiment allows for importing a database into a software program to perform batch data correction. Furthermore, it can be embedded in an acquisition program and real-time display software to integrate with the test system, achieving real-time acquisition, processing, and waveform display. This makes it feasible from an engineering application perspective.

[0175] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A thermocouple error correction method for measuring small temperature rise of an aircraft engine, characterized in that: The method comprises: Under the condition that the temperature rise range is not greater than 60°C, a static calibration test of the thermocouple is performed in the preset temperature range to obtain a thermoelectric characteristic database. The static calibration test of the thermocouple is performed in the preset temperature range to obtain the thermoelectric characteristic database, including: step 11, placing the thermocouple probe and the standard platinum resistor in the oil tank, and connecting the cold end of the thermocouple to the ice point device and the acquisition system, turning on the oil tank heating power supply, setting the oil tank temperature to 0°C in the range of 0-100°C until it is stable, and recording the value of the standard platinum resistor at this time as the standard platinum resistor temperature T 铂 ; Step 12, immerse the thermocouple in the oil tank and obtain the potential value U of the thermocouple T , increase the current oil tank temperature setting value by 1℃, repeat steps 11 and 12, complete the calibration test of all temperature points in the range of 0-100℃, and obtain the temperature T of each standard platinum resistance 铂 And the potential value U of the thermocouple at this temperature T ; Step 13, according to each standard platinum resistance temperature T 铂 And the potential value U of the thermocouple at this temperature T , corrected to each integer temperature T 标 Step 14, according to the potential value U at each integer temperature T标 , fitting thermoelectric characteristic conversion functions of polynomials of order 1 to 5 for every 10°C, calculating the sum of residuals of the polynomial of the current order in the current temperature range according to the thermoelectric characteristic conversion function, and selecting the best order thermoelectric characteristic conversion function within the current 10°C range by comparing the sums of different residuals of polynomials of order 1 to 5, and finally obtaining the thermoelectric characteristic database of the thermocouple; Place the thermocouple probe in a standard normal temperature wind tunnel and conduct a static deviation calibration test of the thermocouple at normal temperature and a preset airflow velocity to obtain a static deviation database. The thermocouple probe is placed in a standard thermal wind tunnel. Temperature correction coefficient calibration tests are performed on the thermocouple under different total temperature rise ranges and different Mach number airflow conditions to obtain a temperature correction coefficient database. Thermocouple probes are used in actual small temperature rise measurements, and the temperature measured by the thermocouple is corrected based on the thermoelectric characteristics database, static deviation database, and temperature correction coefficient database.

2. The thermocouple error correction method for small temperature rise measurement of an aircraft engine according to claim 1, characterized in that: The correction is for each integer temperature T 标 The potential values ​​under When the thermocouple is of the type with an international temperature scale, the international temperature scale is used to convert the standard platinum resistance temperature T 铂 The potential value U of the thermocouple under T Corrected to the potential value U at integer temperature T标 , U T标 The calculation formula is: ， in, is the integer temperature T 标 Seebeck coefficient of the lower thermocouple; When the thermocouple is of other types, according to the current standard platinum resistance temperature T 铂 The Seebeck coefficients at the first two integer temperatures are iteratively updated based on the potential value at the previous standard platinum resistance temperature, and the potential value is corrected.

3. The thermocouple error correction method for small temperature rise measurement of an aircraft engine according to claim 2, characterized in that: According to the current standard platinum resistance temperature T 铂 The Seebeck coefficients at the first two integer temperatures are iteratively updated based on the potential value at the previous standard platinum resistance temperature, and the potential value is corrected, including: The first step is to use the current standard platinum resistance temperature T 铂 The potential value U of the thermocouple under T , the previous standard platinum resistance temperature T 铂-1 The potential value U of the thermocouple under T-1 、The first two standard platinum resistance temperatures T 铂-2 The potential value U of the thermocouple under T-2 , the previous integer temperature T 标-1 and the first two integer temperatures T 标-2 , calculate the potential value of the first corrected integer temperature and the potential values ​​of the first two integer temperatures of the first correction , the calculation formula is: ； Step 2: Update the first two integer temperatures T 标-2 Seebeck coefficient S under T标-2 , the update formula is: ； Step 3: Update the first two integer temperatures T 标-2 The potential values ​​of the first two integer temperatures under the second correction , the calculation formula is: ； Step 4: Repeat steps 2 to 3 until S T标-2 No longer changes, and the potential value of the last correction in the third step formula is used as T 标-2 The potential value U at integer temperature T标-2 .

4. The thermocouple error correction method for small temperature rise measurement of an aircraft engine according to claim 1, characterized in that: The calculation formula of the sum of the residuals is: ， Where v is the sum of the residuals, i is the i-th temperature within the current 10°C range, and f is the thermoelectric characteristic conversion function of a certain order polynomial.

5. The thermocouple error correction method for small temperature rise measurement of an aircraft engine according to claim 1, characterized in that: Place the thermocouple probe in a standard normal temperature wind tunnel and perform a static deviation calibration test of the thermocouple at room temperature and a preset airflow velocity to obtain a static deviation database, including: Step 21: Place the thermocouple probe under the standard normal temperature wind tunnel, with the fairing facing the center of the incoming flow. Insert the cold end of the thermocouple and the standard platinum resistor into the ice-water mixture. The standard platinum resistor in the ice-water mixture will show the value T 冷铂 As the freezing point error μ; Step 22: Compare the temperature measured by the thermocouple at room temperature with the temperature measured by the standard platinum resistance thermometer after correcting the freezing point error to obtain the static deviation λ of the thermocouple. The calculation formula is: ， Among them, T1 is the reading temperature value after the thermocouple corrects the freezing point error, F is the best order thermoelectric characteristic conversion function in the current temperature range, T 铂 is the standard platinum resistance temperature, U T is the standard platinum resistance temperature T 铂 The potential value of the thermocouple under the condition of , μ is the freezing point error.

6. The thermocouple error correction method for small temperature rise measurement of an aircraft engine according to claim 5, characterized in that: The temperature correction coefficient calibration test of the thermocouple is performed to obtain a temperature correction coefficient database, including: Step 31: Calculate the temperature correction coefficient at different total airflow temperatures and Mach numbers. ; Step 32: Based on the temperature correction coefficient The temperature correction coefficient database is constructed based on the correspondence between the Mach number and the total airflow temperature. The temperature correction coefficient database is stored in a two-dimensional array matrix. The rows and columns of the two-dimensional array matrix are divided according to the Mach number and the total airflow temperature. Each matrix unit stores the temperature correction coefficient under the Mach number and the total airflow temperature. , the piecewise linear fitting under the same Mach number is Function, the piecewise linear fitting under the same total temperature is Function, T * is the total temperature of the airflow, and Ma is the Mach number.

7. The thermocouple error correction method for small temperature rise measurement of an aircraft engine according to claim 6, characterized in that: The temperature correction factor The calculation formula is: ， Where T2 is the temperature value after correcting the freezing point error and static deviation, and k is the insulation coefficient.

8. The thermocouple error correction method for measuring small temperature rise of an aircraft engine according to claim 7, characterized in that: The method of correcting the temperature measured by the thermocouple based on the thermoelectric characteristics database, the static deviation database, and the temperature correction coefficient database includes: Step 41: Arrange total pressure and static pressure measurement points at the test site and calculate the current Mach number Ma i ; Step 42: Convert the voltage value of the thermocouple at each measuring point into the temperature value T of each measuring point according to the thermoelectric characteristic database. i ; Step 43: The temperature value T of each measuring point i Perform freezing point error correction to obtain the reading temperature value T of the thermocouple at each measuring point after the freezing point error correction. 1i , T 1i =T i +μ; Step 44: According to the static deviation database, the reading temperature value T after the freezing point error of the thermocouple at each measuring point is corrected 1i Perform static deviation correction to obtain the corrected freezing point error and the temperature value T after static deviation at each measuring point. 2i , T 2i =T 1i +λ; Step 45: The temperature value T after correcting the freezing point error and static deviation of each measuring point 2i , using the temperature correction coefficient database Function interpolation calculation of the temperature value T at each Mach number 2i Corresponding temperature correction coefficient ξ T2i ; Step 46: Piecewise linear fitting of the temperature values ​​T at each Mach number 2i Temperature correction coefficient ξ T2i , get the temperature value T 2i The temperature correction coefficient is a function of the Mach number: ξ T2i =ξ(Ma); Step 47: Enter the current Mach number Ma i , according to ξ obtained in step 46 T2i =ξ(Ma) function interpolation calculation to obtain the temperature value T 2i and the current Mach number Ma i Temperature correction coefficient value ξ under T2i，Mai ; Step 48: Based on the temperature value T 2i and the current Mach number Ma i Temperature correction coefficient value ξ under T2i，Mai , for temperature T 2i Perform speed error correction to obtain the dynamic temperature value T3 of the speed error correction; Step 49: Take the dynamic temperature value T3 corrected by the speed error as input and re-execute steps 45 to 47 to obtain the temperature value T3 and the current Mach number Ma i Temperature correction factor under , and according to the temperature correction coefficient Re-iterate to obtain the dynamic temperature value T4 of the secondary velocity error correction; Step 410: If the absolute value of the difference between the dynamic temperature value T4 corrected by the secondary speed error and the dynamic temperature value T3 corrected by the speed error meets the temperature criterion, the dynamic temperature value T4 corrected by the secondary speed error is used as the final dynamic temperature value after error correction; if the absolute value of the difference between the dynamic temperature value T4 corrected by the secondary speed error and the dynamic temperature value T3 corrected by the speed error does not meet the temperature criterion, continue to iteratively obtain the temperature correction coefficient and the corrected temperature value in step 49 until the temperature criterion is met, and the final dynamic temperature value after error correction is obtained, and the final dynamic temperature value after error correction is used as the thermocouple temperature value T after data processing of each measuring point at the outlet. n ; Step 411: Execute steps 42 to 44 on the original data of each measuring point at the inlet to obtain the thermocouple temperature value T of each measuring point at the inlet after data processing. 2进 , according to the thermocouple temperature value T of each measuring point at the outlet after data processing n And the thermocouple temperature value T of each measuring point at the inlet after data processing 2进 Obtain the temperature rise range ΔT of each measuring point. The calculation formula for the temperature rise range ΔT is: ΔT=T n -T 2进 。 9. The thermocouple error correction method for small temperature rise measurement of an aircraft engine according to claim 8, characterized in that: The calculation formula of the dynamic temperature value T3 of the speed error correction is: ， The calculation formula of the dynamic temperature value T4 of the secondary speed error correction is: ， Among them, ξ T2i，Mai is the temperature value T 2i and the current Mach number Ma i The temperature correction coefficient value under is the temperature value T3 and the current Mach number Ma i The temperature correction coefficient under , k is the insulation coefficient.

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