Evaluation method for uncertainty of throat area measurement, measurement method, readable medium

Abstract

The present invention relates to a method for evaluating the uncertainty of throat area measurement, a measurement method, and a readable medium. Among them, the evaluation method includes step A: establishing a measurement model and a calculation model; step B: evaluating the uncertainty introduced by different factors according to the calculation model; step C: combining the uncertainties introduced by the above factors to evaluate the uncertainty of the measurement of a single throat area. The beneficial effect of this case is that the result of the uncertainty is expressed in the form of area, which is not only intuitive but also convenient for direct comparison with the design tolerance of the throat area, so as to realize a reliable verification of the accuracy of the coordinate measuring method.

Description

Technical Field

[0001] The present invention relates to the field of measurement, and in particular to a method for evaluating the measurement uncertainty of the throat area of a turbine guide vane, a measurement method, and a readable medium. Background Art

[0002] The minimum flow cross-sectional area of the convergent channel through which the gas flows through the turbine guide vane is called the throat area of the turbine guide vane. The size of the throat area has a direct impact on the temperature before and after the turbine stage, the gas flow field, the flow rate, the thrust, the rotational speed, the fuel consumption rate, etc., and is an important parameter for the adjustment of the overall performance test of the aeroengine. Accurately measuring the throat area of the turbine guide vane is extremely important for correcting the overall performance index of the aeroengine. For a civil aeroengine in the development stage, the three-coordinate measurement method is generally used to measure the throat area. Civil aeroengine products have strict requirements in terms of airworthiness, safety, reliability, and economy, and thus have higher requirements for the measurement accuracy of the cold throat area of the turbine guide vane. It is necessary to verify the three-coordinate measurement method adopted before the production process is finalized.

[0003] Evaluating the uncertainty of the three-coordinate measurement method is an important means to verify whether it meets the design requirements. In the prior art, for the method of evaluating the measurement uncertainty of the cold throat area of the turbine guide vane, for example, the method proposed by Xu Kaiming et al. in the literature "Three-Coordinate Measurement of the Throat Area Value of Turbine Guide Vane Blades" (Xu Kaiming, Huang Zhiguo, Zheng Xinglin. Three-Coordinate Measurement of the Throat Area Value of Turbine Guide Vane Blades [J]. Silicon Valley, 2011, 000(002): 31-32.), the uncertainty evaluation result is not expressed in the form of area (its unit is a length unit), so it is impossible to directly compare the relationship between the uncertainty and the allowable error value of the throat area, and it is very difficult to verify the accuracy of the measurement method.

[0004] There is a need in this field for a method for evaluating the measurement uncertainty of the throat area, a measurement method, and a readable medium to achieve a reliable verification of the accuracy of the three-coordinate measurement method. Summary of the Invention

[0005] The object of the present invention is to provide a method for evaluating the measurement uncertainty of the throat area of a turbine guide vane.

[0006] The object of the present invention is to provide a method for measuring the throat area of a turbine guide vane.

[0007] The object of the present invention is to provide a computer-readable medium.

[0008] A method for evaluating the measurement uncertainty of the throat area of a turbine guide vane according to one aspect of the present invention includes: Step A. The measurement model S of a single throat area 0= W × H, where W and H are the equivalent width and equivalent height of the throat, respectively; according to this measurement model, the calculation model for the area of a single throat is S = S 0 + △S 1 + … + △S m , △S 1 、…、△S m are the measurement errors of the area of a single throat caused by different factors during the measurement process; Step B. According to the above calculation model, evaluate the uncertainty introduced by the different factors. Define the factor that causes measurement errors in the measurement of both the throat width and the throat height during the measurement process as the first factor, then the uncertainty caused by this first factor is u c (S) = c 1 u(W) + c 2 u(H). Define the factor that causes measurement errors in one of the equivalent width and equivalent height during the measurement process as the second factor, then the uncertainty caused by this second factor is where, the above Step C. The uncertainty of the measurement of the area of a single throat is where where, u c (S 0 ) is the uncertainty caused by measurement repeatability, u c (△S 1 )、…、u c (△S m ) are the uncertainties caused by different factors during the measurement process.

[0009] In one or more embodiments of the above evaluation method, it further includes Step D. Evaluate the uncertainty of the measurement of the total annular throat area of the turbine guide vane. The total annular throat area of the turbine guide vane is the sum of the areas of the single throats of the guide vane. The measurement model of the total annular throat area The calculation model of the total annular throat area is where the influence of each factor is the same for different single throat areas, where n is the number of single throat areas; the uncertainty of the measurement of the total annular throat area is where

[0010] In one or more embodiments of the above evaluation method, the uncertainty caused by measurement repeatability is type A uncertainty, and the uncertainties caused by different factors are type B uncertainties.

[0011] In one or more embodiments of the evaluation method, the different factors in the measurement process include the indication error factor of the coordinate measuring machine, the rotary error factor of the turntable, the end face runout factor of the clamping, and the radius compensation error factor of the contact probe.

[0012] In one or more embodiments of the evaluation method, the indication error factor of the coordinate measuring machine is the first factor, the rotary error factor of the turntable is the first factor, the radius compensation error of the contact probe is the first factor, and the end face runout factor of the clamping is the second factor.

[0013] In one or more embodiments of the evaluation method, the expanded uncertainty U of the single throat area measurement = k × u c (S), where k is the coverage factor.

[0014] In one or more embodiments of the evaluation method, the expanded uncertainty U of the full-ring throat area measurement 环 = k × u c (S 环 ), where k is the coverage factor.

[0015] A method for measuring the throat area of a turbine guide vane according to one aspect of the present invention includes: Step S1. Obtaining the uncertainty of the single throat area measurement or the uncertainty of the full-ring throat area measurement obtained by the evaluation method described in any one of the above; comparing the uncertainty obtained in S1 with the design tolerance of the throat area, and if the uncertainty is less than the product of the design tolerance and a coefficient, it is determined that the measurement method is reliable.

[0016] In one or more embodiments of the measurement method, the coefficient is 0.3.

[0017] A computer-readable medium according to one aspect of the present invention has a computer program thereon, and the program is executed by a processor to implement the following steps: Step S10. Obtaining the uncertainty of the single throat area measurement or the uncertainty of the full-ring throat area measurement obtained by the evaluation method described in any one of the above, and obtaining the design tolerance of the throat area; Step S20. Comparing the uncertainty obtained in S10 with the design tolerance of the throat area, and if the uncertainty is less than the product of the design tolerance and a coefficient, outputting a judgment result that the measurement method is reliable.

[0018] In summary, the progressive effects of the present invention include but are not limited to, proposing a relatively perfect method for evaluating the uncertainty of the single throat area and the full-ring throat area measurement. The result of the uncertainty is expressed in the form of area, which is not only intuitive but also convenient for direct comparison with the design tolerance of the throat area to achieve a reliable verification of the accuracy of the coordinate measurement method. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other features, properties, and advantages of the present invention will become more apparent from the following description in conjunction with the drawings and embodiments. It should be noted that the drawings are only examples and are not drawn according to the condition of equal proportion, and should not be used to limit the actual scope of protection required by the present invention, where:

[0020] Figure 1 is a schematic diagram of an evaluation method for the measurement uncertainty of a single throat area according to an embodiment.

[0021] Figure 2 is a schematic diagram of an evaluation method for the measurement uncertainty of the full-ring throat area according to an embodiment.

[0022] Figure 3 is a schematic structural diagram of a measurement model for the measurement of a single throat area according to an embodiment.

[0023] Figure 4A and Figure 4B are respectively schematic diagrams of the influence of the turntable rotation error factor on the measurement of the throat width and throat height during the measurement process of a single throat area according to an embodiment.

[0024] Figure 5 is a schematic diagram of the influence of the clamping end face runout factor on the measurement of the throat height during the measurement process of a single throat area according to an embodiment.

[0025] Figure 6 is a schematic diagram of a method for measuring the throat area according to an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following discloses various different embodiments or examples for implementing the described subject technical solutions. To simplify the disclosure content, specific examples of each element and arrangement are described below. Of course, these are only examples and do not limit the protection scope of the present invention. "One embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the present application can be appropriately combined.

[0027] Flowcharts are used in this application to illustrate the operations performed by the systems according to the embodiments of the present application. It should be understood that the operations before or below do not necessarily need to be executed precisely in sequence. Other operations can also be added to these processes, or one or several operations can be removed from these processes.

[0028] As Figures 1 to 3 shown in one embodiment, a method for evaluating the uncertainty of the three - coordinate measurement of the throat area of a turbine guide vane includes:

[0029] Step A: Establish a measurement model and a calculation model. Establish a measurement model. Analyze the simplified throat of the measured turbine guide vane as Figure 3 shown. The area measurement model of a single throat 10 can be derived as S 0 = W×H, where W and H are regarded as the equivalent width and equivalent height of a single throat. Based on the obtained measurement model, by analyzing the key influencing factors of the throat area measurement, it is found that the area of a single throat is affected by the width and height of the throat. Therefore, factors that affect the measurement results of the throat width and height will also affect the measurement result of the throat area. The calculation model of the single throat area is obtained as S = S 0 +△S 1 +…+△S m , △S 1 …, △S m are the measurement errors of the single throat area caused by different factors during the measurement process. The above - mentioned factors are the factors that affect the measurement results of the throat width and height. In some embodiments, the above - mentioned factors may be the indication error factor of the coordinate measuring machine, the rotary error factor of the rotary table, the run - out error factor of the clamping end face, the radius compensation error factor of the contact probe, but not limited thereto. When evaluating the uncertainty, the factors that affect the measurement results of the throat width and height are evaluated according to the type - B uncertainty. The indication error factor of the coordinate measuring machine, as the name implies, is introduced due to the indication error of the measuring machine, including the width measurement uncertainty introduced by estimating the indication error of the measuring machine and the height measurement uncertainty introduced by the indication error of the measuring machine. The rotary error factor of the rotary table includes the width measurement uncertainty introduced by the rotary error of the rotary table and the height measurement uncertainty introduced by the rotary error of the rotary table. The specific influence principle is as Figure 4A and Figure 4B shown. O is the center of rotation, the Y - direction is the circumferential starting reference direction, E 1 E 2 is the correct measurement width of the throat when it deviates from the circumferential starting reference, E 1 E 3 is the width of the throat measured according to the circumferential starting reference direction; H 1 H 2 is the correct measurement height of the throat when it deviates from the circumferential starting reference direction, H 1 H 3 is the height of the throat measured according to the circumferential starting reference direction. The measurement error model of the rotary error of the rotary table for the throat width and height is Where ΔW is the measured throat width error, ΔH is the measured throat height error, and α is the rotary table rotation error. The clamping end face runout factors include the width measurement uncertainty introduced by the clamping end face runout and the height measurement uncertainty introduced by the clamping end face runout. The specific influence principle is as Figure 5 shown. For the throat of the turbine guide vane, the clamping end face runout will cause the current throat to be tilted relative to the initial measurement coordinate system, and this tilt mainly affects the measurement of the throat cross-section height dimension. Figure 5 In the figure, OZ is the axis of rotation, OY is the circumferential starting reference direction, the plane containing OY and perpendicular to OZ is the reference plane, and H 1 H 2 is the correct measured height when the throat deviates from the reference plane, and H 1 H 3 is the measured throat height according to the reference direction. The error model of the tilt on the throat height measurement is where ΔH is the measured throat height error and β is the tilt angle. The contact probe radius compensation error factor, as the name implies, is introduced by the contact probe radius compensation error, including the width measurement uncertainty introduced by the contact probe radius compensation error and the height measurement uncertainty introduced by the contact probe radius compensation error. The specific evaluation model of the uncertainty will be described in detail later.

[0030] Step B. According to the calculation model, evaluate the uncertainty introduced by the different factors. Define the factor that simultaneously generates measurement errors in the measurement of both the throat width and the throat height during the measurement process as the first factor. For example, among the factors cited above, the CMM indication error factor, the rotary table rotation error factor, and the contact probe radius compensation error factor that simultaneously affect the measurement results of the throat width and the throat height are the first factors, and the uncertainty caused by this first factor is u c (S) = c 1 u(W) + c 2 u(H). For example, the standard uncertainty evaluation introduced by the CMM indication error is evaluated according to Type B evaluation. The width measurement uncertainty introduced by the CMM indication error and the height measurement uncertainty introduced by the CMM indication error are respectively evaluated, and then according to the positive correlation, the formula u c (S) = c 1 u(W) + c 2 u(H) is used to synthesize the area measurement uncertainty introduced by the CMM indication error; the standard uncertainty evaluation introduced by the rotary table rotation error is evaluated according to Type B evaluation. The width measurement uncertainty introduced by the rotary table rotation error and the height measurement uncertainty introduced by the rotary table rotation error are respectively evaluated, and then according to the positive correlation, the formula u c (S) = c 1 u(W) + c 2The area measurement uncertainty introduced by the rotational error of the u(H) synthesis turntable; the standard uncertainty evaluation introduced by the radius compensation error of the contact probe is evaluated according to type B. The width measurement uncertainty introduced by the radius compensation error of the contact probe and the height measurement uncertainty introduced by the radius compensation error of the contact probe are evaluated separately, and then according to the positive correlation, the formula u c (S) = c 1 u(W) + c 2 u(H) synthesizes the area measurement uncertainty introduced by the radius compensation error of the contact probe. Define the factor that causes measurement error to one of the equivalent width and equivalent height during the measurement process as the second factor. For example, among the factors listed above, the clamping end face runout factor that mainly affects the measurement of the throat cross-section height dimension is the second factor. For the standard uncertainty evaluation introduced by the clamping end face runout, it is evaluated according to type B. The width measurement uncertainty introduced by the clamping end face runout and the height measurement uncertainty introduced by the clamping end face runout are evaluated separately, and then according to the non-correlation, the formula synthesizes the area measurement uncertainty introduced by the clamping end face runout. The uncertainty caused by this second factor is wherein, the above-mentioned

[0031] Step C. Combine the uncertainties introduced by the above factors to evaluate the uncertainty of the measurement of a single throat area. The uncertainty of the area measurement includes the standard uncertainty introduced by the repeatability of the area measurement itself, which is evaluated according to type A uncertainty. When the number of repeatability measurements is less than 10 times, the range method is used to calculate the experimental standard deviation. When the number of repeatability measurements is greater than or equal to 10 times, the Bessel method is used to calculate the experimental standard deviation. The uncertainty also includes the above different factors, that is, the above first factor and the second factor, which are evaluated according to type B uncertainty. Since there is no correlation between the first factors, the second factors, and between the first factor and the second factor in the measurement of a single throat area, and there is also no correlation between the first factor, the second factor and the area measurement repeatability, the uncertainty of the measurement of a single throat area is where wherein, u c (S 0 ) is the uncertainty generated by the measurement repeatability, u c (△S 1 )、…、u c (△S m ) are the uncertainties generated by different factors during the measurement process. For example, if four factors such as the indication error factor of the coordinate measuring machine, the rotational error factor of the turntable, the clamping end face runout factor, and the radius compensation error factor of the contact probe are exemplified, then m = 4. In some embodiments, it also includes the evaluation of the expanded uncertainty U for the measurement of a single throat area. The formula U = k × u c(S), where k is the coverage factor.

[0032] Step D. For the evaluation of the uncertainty of the throat area measurement, it can also be the evaluation of the uncertainty of the full-ring throat area measurement, and the full-ring throat area is the sum of the areas of each individual throat. The measurement model of the full-ring throat area The calculation model of the full-ring throat area is where the influence of each factor is the same for different individual throat areas, S 环 = where n is the number of individual throat areas; the uncertainty of the full-ring throat area measurement is where In some embodiments, it further includes the evaluation of the expanded uncertainty U of the full-ring throat area measurement, and U = k × u c (S 环 ), where k is the coverage factor.

[0033] The beneficial effect of using the uncertainty evaluation method introduced in the above embodiments is that the evaluation result of the output uncertainty is expressed in the form of area, which is not only intuitive but also convenient for direct comparison with the design tolerance of the throat area, so as to realize the reliable verification of the accuracy of the coordinate measuring method.

[0034] As described above, as Figure 6 shown, the method for measuring the throat area of a turbine guide vane may include:

[0035] Step S1. Obtain the uncertainty of the individual throat area measurement or the uncertainty of the full-ring throat area measurement obtained by the above evaluation method;

[0036] Step S2. Compare the uncertainty obtained in S1 with the design tolerance of the throat area. If the uncertainty is less than the product of the design tolerance and a coefficient, it is determined that the measurement method is reliable. The coefficient can be 0.3. If the evaluated uncertainty is less than 0.3 * design tolerance, it indicates that the measurement method is reliable. If it is greater than or equal to 0.3 * design tolerance, it indicates that the measurement method has not passed the reliability verification, and the result obtained by this measurement method is unreliable and should not be considered in the subsequent process. It can be understood that the specific value of the coefficient is not limited to 0.3 and can be flexibly adjusted according to the need to verify the reliability.

[0037] According to another aspect of this case, in some embodiments, this case also provides a computer-readable medium, such as a storage medium, on which a computer program is stored, and when the program is executed by a processor, the following steps are implemented:

[0038] Step S10. Obtain the uncertainty of the single throat area measurement or the full-ring throat area measurement obtained by the uncertainty evaluation method introduced in the above embodiments, and obtain the design tolerance of the throat area;

[0039] Step S20. Compare the uncertainty obtained in S10 with the design tolerance of the throat area. If the uncertainty is less than the product of the design tolerance and a coefficient, output a judgment result that the measurement method is reliable, and the calculated value obtained from the calculation model of the single throat area or the full-ring throat area can also be output. Otherwise, output a judgment result that the calculated value indicates that the measurement method is unreliable.

[0040] Those skilled in the art can understand that the program can also be executed with additional steps, such as the steps that can be executed by the program in the above calibration method and measurement method.

[0041] In some embodiments, the storage medium can be integrated into the processor. The processor and the storage medium can reside in an application specific integrated circuit (ASIC). The ASIC can reside in a user terminal. In one or more embodiments, the processor and the storage medium can reside in the user terminal as discrete components.

[0042] Computer-readable media includes both computer storage media and communication media, which includes any medium that facilitates the transfer of a computer program from one place to another. The storage medium can be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is also properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of the medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where disk generally reproduces data magnetically, while disc reproduces data optically with a laser. Combinations of the above should also be included within the scope of computer-readable media.

[0043] In summary, the beneficial effects of the above-described embodiments are as follows: a relatively complete method for evaluating the uncertainty of the measurement of the single throat area and the full-ring throat area is proposed, and the result of the uncertainty is expressed in the form of area, which is not only intuitive but also convenient for direct comparison with the design tolerance of the throat area, so as to achieve a reliable verification of the accuracy of the coordinate measuring method.

[0044] Although the present invention is disclosed as above in the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. An evaluation method for the uncertainty of the throat area measurement of a turbine guide vane, characterized in that, it includes: Step A. Measurement model S of a single throat area 0 = W × H, where W and H are the equivalent width and equivalent height of the throat respectively; according to this measurement model, the calculation model S of a single throat area = S 0 + △S 1 + … + △S m , △S 1 、…、△S m are the measurement errors of a single throat area caused by different factors during the measurement process; Step B. According to the calculation model, evaluate the uncertainty introduced by the different factors. Define the factor that causes measurement errors in the measurement of both the throat width and the throat height during the measurement process as the first factor, and the uncertainty caused by this first factor is u c (S) = c 1 u(W) + c 2 u(H). Define the factor that causes measurement errors in either the equivalent width or the equivalent height during the measurement process as the second factor, and the uncertainty caused by this second factor is where, the above Step C. The uncertainty of the measurement of the single throat area is where where, u c (S 0 ) is the uncertainty caused by the measurement repeatability, u c (△S 1 ), …, u c (△S m ) are the uncertainties caused by different factors during the measurement process.

2. The evaluation method according to claim 1, characterized in that, It also includes step D. Evaluating the measurement uncertainty of the total annulus throat area of the turbine guide vane. The total annulus throat area of the turbine guide vane is the sum of the individual throat areas of the guide vane, and the measurement model of the total annulus throat area The calculation model of the total annulus throat area is where the influence of each factor is the same for different individual throat areas; where n is the number of individual throat areas; The uncertainty in the measurement of the total throat area is where 3. The evaluation method according to claim 1, characterized in that, the uncertainty generated by the measurement repeatability is type A uncertainty, and the uncertainty generated by different factors is type B uncertainty.

4. The evaluation method according to claim 1, characterized in that, the different factors in the measurement process include the indication error factor of the coordinate measuring machine, the rotary error factor of the turntable, the runout factor of the clamping end face, and the radius compensation error factor of the contact probe.

5. The evaluation method according to claim 4, characterized in that, the indication error factor of the coordinate measuring machine is the first factor, the rotary error factor of the turntable is the first factor, the radius compensation error of the contact probe is the first factor, and the runout factor of the clamping end face is the second factor.

6. The evaluation method according to claim 1, characterized in that, The expanded uncertainty U of the measurement of the single throat area is U = k × u c (S), where k is the coverage factor.

7. The evaluation method according to claim 2, characterized in that, The expanded uncertainty U of the full annular throat area measurement 环 = k × u c (S 环 ), where k is the coverage factor.

8. A measurement method for the throat area of a turbine guide vane, characterized in that, it includes: Step S1. Obtain the uncertainty of the single throat area measurement or the uncertainty of the full-ring throat area measurement obtained by the evaluation method according to any one of claims 1-7; Step S2. Compare the uncertainty obtained in S1 with the design tolerance of the throat area. If the uncertainty is less than the product of the design tolerance and a coefficient, it is determined that the measurement method is reliable.

9. The measurement method according to claim 8, characterized in that, the coefficient is 0.

3.

10. A computer-readable medium having a computer program thereon, characterized in that, when the program is executed by a processor, the following steps are implemented: Step S10. Obtain the uncertainty of the single throat area measurement or the uncertainty of the full-ring throat area measurement obtained by the evaluation method according to any one of claims 1-7, and obtain the design tolerance of the throat area; Step S20. Compare the uncertainty obtained in S10 with the design tolerance of the throat area. If the uncertainty is less than the product of the design tolerance and a coefficient, output a judgment result that the measurement method is reliable.

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