Hierarchical progressive geometric feature measurement method for turbine runner

Abstract

The invention discloses a hierarchical progressive geometric feature measurement method of a water turbine runner. The method comprises the following steps: S1, establishing a geometric feature hierarchical progressive evaluation system of the water turbine runner; s2, establishing a'global-local-detail 'multi-level progressive measurement strategy, including adopting global photogrammetry to measure reference features, adopting laser tracking to measure main features, and adopting a handheld scanner to measure detail features; s3, real-time data splicing and registration are implemented in the measurement process, and measurement data of different levels are unified to the same coordinate system through a feature point matching algorithm; and S4, performing measurement density adjustment based on the feature level and performing real-time evaluation and supplementary measurement on measurement data. According to the method, different measurement means and progressive measurement strategies are combined, the geometrical characteristic measurement task of the turbine runner can be efficiently and accurately completed, and the measurement efficiency and precision are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of hydropower station equipment detection, and in particular to a hierarchical progressive geometric feature measurement method for a turbine runner. Background Art

[0002] The turbine runner is the core component of a hydropower unit. The geometric accuracy of the runner directly affects the operating efficiency and safety of the unit. As hydropower units develop towards larger and more efficient operation, the geometric accuracy requirements for the runner are becoming higher and higher. However, the current runner measurement work faces multiple challenges.

[0003] First, the turbine runner has the characteristics of large size and complex curved surface. Its geometric features are distributed at different spatial scales. From the overall installation reference to the local curvature details, precise measurement is required. The traditional single measurement method is difficult to meet the measurement requirements of different features at the same time. It is often necessary to use multiple measurement tools for repeated measurement, which is not only time-consuming and labor-intensive, but also prone to data inconsistency. Secondly, the existing measurement methods lack systematicity and hierarchy, and often use a "one-size-fits-all" approach to uniformly measure the entire blade. This approach not only wastes measurement resources in non-critical areas, but also may lead to insufficient measurement accuracy in key feature areas. Especially for areas with drastic changes in curvature, if a uniform measurement density is used, it is easy to miss important features or have insufficient measurement accuracy. Furthermore, there are obvious differences in the importance and accuracy requirements of different geometric features on the runner. For example, the position accuracy of the installation reference surface directly affects the installation quality, while the accuracy of the local curved surface affects the local flow state of the water flow. Existing measurement methods often cannot perform targeted measurements based on the importance of different features, resulting in low measurement efficiency. Therefore, the hydropower industry urgently needs a runner measurement method that can systematically solve the above problems. Summary of the invention

[0004] In order to solve the current technical problems, the main purpose of the present invention is to provide a hierarchical progressive geometric feature measurement method for a turbine runner, which improves the measurement efficiency and accuracy of the turbine runner by performing graded measurements according to the importance of the geometric features of the runner, adopting corresponding measurement means and density, and performing real-time evaluation and supplementary measurement.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a hierarchical progressive geometric feature measurement method of a turbine runner, comprising the following steps: S1. Establish a hierarchical and progressive evaluation system for the geometric features of the turbine runner, classify the turbine runner in the order of reference features, main features and detail features, and formulate accuracy evaluation indicators for each feature; among which, the reference features include the installation reference surface and the positioning hole, the main features include the inlet edge profile and the outlet edge profile, and the detail features include the local curvature and surface roughness of the blade profile; S2. Establish a multi-level progressive measurement strategy of "global-local-detail", including using global photogrammetry to measure reference features, using laser tracking to measure main features, and using handheld scanners to measure detail features; S3. Implement real-time data splicing and registration during the measurement process, and unify the measurement data at different levels into the same coordinate system through feature point matching algorithm; S4. Adjustment of measurement density based on feature level and real-time evaluation and supplementary measurement of measurement data.

[0006] In S1, the global accuracy evaluation index is used for the reference feature, the key section error evaluation index is used for the main feature, and the local curvature deviation evaluation index is used for the detail feature. The measurement accuracy of each feature is determined accordingly. The reference feature requires flatness ≤0.1mm and positioning hole roundness ≤0.05mm; the main feature requires contour ≤0.05mm and continuity deviation ≤0.03mm; the detail feature requires curvature deviation ≤0.025mm and surface roughness Ra ≤3.2μm.

[0007] In S2, the method of using global photogrammetric fiducial features is as follows: A measurement coordinate system is established by evenly distributing coded targets on the installation reference surface of the rotating wheel, and a multi-view image matching algorithm is used to obtain the spatial positions of the installation reference surface and the positioning holes.

[0008] In S2, the method of measuring the main features using laser tracking is as follows: A laser tracker is used to automatically track the reflector to obtain the spatial point information of the entrance and exit edge contours. A continuous scanning mode is used to ensure the integrity of the contour, and multiple repeated measurements are used to improve data reliability.

[0009] In S2, the method of measuring detailed features using a handheld scanner is as follows: The strip scanning method is used to obtain the local curvature and surface roughness data of the blade surface, and the data integrity is ensured through multi-directional overlapping scanning.

[0010] In S4, circular point distribution is adopted for the reference features, contour tracking point distribution is implemented for the main feature areas, and local encrypted point distribution is implemented for the detail feature areas.

[0011] The method of using circular point distribution for reference features is to place coded targets as control points around the installation reference surface and positioning holes, and use circularly evenly distributed measurement points.

[0012] The method of implementing contour tracking point arrangement for the main feature area is to set the starting point of the entrance edge contour and the exit edge contour at 50~100mm away from the installation reference surface, take a measurement point at each end distance along the contour line direction, and increase the point spacing in the area where the curvature radius is less than 100mm.

[0013] The method of implementing local encrypted point distribution for detail feature areas is to distribute points at equal distances on the blade profile, and then adjust the point density according to the curvature value of each area, and encrypt the points in areas where the curvature is greater than the set threshold. In S4, the method for establishing real-time evaluation and re-measurement of measurement data is as follows: By comparing the actual point cloud density distribution of each measurement area with the theoretical point layout requirements, the data integrity and measurement accuracy are evaluated. When it is found that the measurement quality does not meet the standards, the point layout strategy of the corresponding area is adjusted and supplementary measurements are carried out until a complete turbine runner measurement model is obtained.

[0014] The present invention has the following beneficial effects: The present invention establishes a systematic geometric feature evaluation system by performing graded measurement according to the importance of the geometric features of the turbine runner, and ensures the reasonable allocation of measurement resources through feature classification and accuracy definition; The present invention adopts a progressive measurement strategy of "global-local-detail", and significantly improves the measurement efficiency and accuracy by complementing the advantages of different measurement methods; The present invention realizes intelligent adjustment and real-time evaluation of measurement density, and ensures the integrity and reliability of measurement data. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0016] Figure 1 Flow chart of the implementation of the present invention.

[0017] Figure 2 Schematic diagram of the turbine runner characteristics.

[0018] Figure 3 Schematic diagram of the layout of coded targets for the installation reference surface and positioning hole area of ​​the rotor.

[0019] Figure 4 Schematic diagram of laser tracker measurement.

[0020] Figure 5 This is a schematic diagram of the distribution of main feature areas.

[0021] Figure 6 Schematic diagram of the distribution of detail feature areas. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be described more clearly below in conjunction with the accompanying drawings and embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0023] See also Figure 1 As shown, a hierarchical progressive geometric feature measurement method for a turbine runner comprises the following steps: S1. Establish a hierarchical and progressive evaluation system for the geometric features of the turbine runner, classify the turbine runner in the order of reference features, main features, and detail features, and formulate accuracy evaluation indicators for each feature. Figure 2 The reference features include the installation reference surface and the positioning hole, the main features include the inlet edge profile and the outlet edge profile, and the detail features include the local curvature and surface roughness of the blade profile.

[0024] In S1, progressive accuracy evaluation standards are formulated for geometric features at different levels. The global accuracy evaluation index is used for the datum feature, the key section error evaluation index is used for the main feature, and the local curvature deviation evaluation index is used for the detail feature. The measurement accuracy of each feature is determined accordingly. The datum feature requires flatness ≤0.1mm and positioning hole roundness ≤0.05mm; the main feature requires contour ≤0.05mm and continuity deviation ≤0.03mm; the detail feature requires curvature deviation ≤0.025mm and surface roughness Ra ≤3.2μm.

[0025] S2. Establish a multi-level progressive measurement strategy of "global-local-detail", including using global photogrammetry to measure benchmark features, using laser tracking to measure main features, and using handheld scanners to measure detail features.

[0026] In S2, the method of using global photogrammetric fiducial features is as follows: A measurement coordinate system is established by evenly distributing coded targets on the installation reference surface of the wheel. The spatial positions of the installation reference surface and the positioning holes are acquired using a multi-view image matching algorithm to achieve high-precision measurement of the reference features and provide a unified spatial reference for subsequent measurements.

[0027] For details, see Figure 3 , using an industrial-grade camera and a 12mm wide-angle lens, coded targets are evenly arranged on the installation reference surface and positioning hole area of ​​the wheel. The resolution of the industrial-grade camera is 4096×3072 pixels, and 8 measuring stations are used to complete 360° surround shooting. Each measuring station obtains 15-20 images to ensure that each target is imaged in more than 3 images. The multi-view image matching algorithm achieves a measurement accuracy of 0.1mm.

[0028] In S2, the method of measuring the main features using laser tracking is as follows: A laser tracker is used to automatically track the reflector to obtain the spatial point information of the entrance and exit edge contours. A continuous scanning mode is used to ensure the integrity of the contour, and multiple repeated measurements are used to improve data reliability.

[0029] For details, see Figure 4 , using a laser tracker with a measurement accuracy of ±15μm+6μm / m, with a 0.5-inch spherical reflective prism, set up the equipment 2-3 meters away from the water wheel runner, using continuous scanning mode, the scanning speed does not exceed 10mm / s, to ensure the continuity and stability of data collection. Repeat the measurement of each contour 3 times, and take the average value as the final result. The laser tracker sets multiple measurement points around the runner for measurement.

[0030] In S2, the method of measuring detailed features using a handheld scanner is as follows: The strip scanning method is used to obtain the local curvature and surface roughness data of the blade surface. Multi-directional overlapping scanning is used to ensure data integrity and achieve high-density collection of detailed features.

[0031] Specifically, a handheld 3D scanner is used to measure detailed features. A structured light scanner with a resolution of 0.025mm is used, and a single scan accuracy of 0.025mm is used. A cross-scanning method is used to ensure an overlap rate of more than 60% between adjacent bands. In areas with drastic changes in curvature, the scanner distance is shortened to within 200mm to improve local measurement accuracy.

[0032] S3. Implement real-time data stitching and registration during the measurement process, and unify different levels of measurement data into the same coordinate system through feature point matching algorithm.

[0033] Specifically, the measurement data at different levels are unified into the same coordinate system through the feature point matching algorithm of key features such as targets and reflective balls to ensure the consistency and integrity of the measurement data.

[0034] S4. Adjustment of measurement density based on feature level and real-time evaluation and supplementary measurement of measurement data.

[0035] In S4, circular point distribution is adopted for the reference features, contour tracking point distribution is implemented for the main feature area, and local dense point distribution is implemented for the detail feature area to achieve accurate measurement of complex areas. Specifically, the main features adopt a progressive point distribution with a basic point spacing of 30mm and a curvature change of 15mm, and the detail features adopt a dense point distribution strategy with a basic point spacing of 20mm and a high curvature area of ​​5mm.

[0036] Among them, see Figure 3 In this embodiment, coded targets are arranged on the reference surface and around the positioning hole as control points, and a measurement point is arranged every 45° on the circumference to fully reflect the overall morphological characteristics of the reference feature.

[0037] join Figure 4 , 5 , and contour tracking point distribution is implemented for the main feature area. In this embodiment, the starting point of the contour line is set at 50mm from the reference plane, and a measurement point is taken every 30mm along the contour line. In the area where the radius of curvature is less than 100mm, the point spacing is increased to 15mm. Through this progressive point distribution strategy, about 100 measurement points are finally obtained on the inlet side and about 85 measurement points are obtained on the outlet side, which fully ensures the continuity and accuracy of the contour features.

[0038] See also Figure 6 , local encrypted point distribution is implemented for the detail feature area. This embodiment adopts equidistant point distribution on the blade profile, with a basic point spacing of 20mm, and then adjusts the point density according to the curvature value of each area, and encrypts the points in the area where the curvature is greater than the set threshold, with an encrypted point spacing of 5mm, to achieve high-precision measurement of complex surfaces and ensure that the detail feature curvature deviation index is ≤0.025mm.

[0039] In S4, the method for establishing real-time evaluation and re-measurement of measurement data is as follows: This embodiment evaluates data integrity and measurement accuracy by comparing the actual point cloud density distribution of each measurement area with the theoretical point layout requirements. When it is found that the measurement quality does not meet the standards, the point layout strategy of the corresponding area is adjusted, and supplementary measurement is performed until a complete turbine runner measurement model is obtained.

[0040] The method of the invention has been put into practical application in the maintenance of turbines in a large hydropower station. Practice has proved that the method can improve the measurement efficiency and accuracy of the geometric characteristics of the turbine runner by more than 10%. By establishing a systematic measurement system and adopting advanced measurement methods, the maintenance quality of hydropower units has been significantly improved, which has important engineering application value.

Claims

1. A hierarchical progressive geometric feature measurement method for a turbine runner, characterized in that: The following steps are involved: S1. Establish a hierarchical and progressive evaluation system for the geometric features of the turbine runner, classify the turbine runner in the order of reference features, main features and detail features, and formulate accuracy evaluation indicators for each feature; among which, the reference features include the installation reference surface and the positioning hole, the main features include the inlet edge profile and the outlet edge profile, and the detail features include the local curvature and surface roughness of the blade profile; S2. Establish a multi-level progressive measurement strategy of "global-local-detail", including using global photogrammetry to measure reference features, using laser tracking to measure main features, and using handheld scanners to measure detail features; S3. Implement real-time data splicing and registration during the measurement process, and unify the measurement data at different levels into the same coordinate system through feature point matching algorithm; S4. Adjustment of measurement density based on feature level and real-time evaluation and supplementary measurement of measurement data.

2. The hierarchical progressive geometric feature measurement method of a turbine runner according to claim 1, characterized in that: In S1, the global accuracy evaluation index is used for the reference feature, the key section error evaluation index is used for the main feature, and the local curvature deviation evaluation index is used for the detail feature. The measurement accuracy of each feature is determined accordingly. The reference feature requires flatness ≤0.1mm and positioning hole roundness ≤0.05mm; the main feature requires contour ≤0.05mm and continuity deviation ≤0.03mm; the detail feature requires curvature deviation ≤0.025mm and surface roughness Ra ≤3.2μm.

3. The hierarchical progressive geometric feature measurement method of a turbine runner according to claim 1, characterized in that: In S2, the method of using global photogrammetric fiducial features is as follows: A measurement coordinate system is established by evenly distributing coded targets on the installation reference surface of the rotating wheel, and a multi-view image matching algorithm is used to obtain the spatial positions of the installation reference surface and the positioning holes.

4. The hierarchical progressive geometric feature measurement method of a turbine runner according to claim 1, characterized in that: In S2, the method of measuring the main features using laser tracking is as follows: A laser tracker is used to automatically track the reflector to obtain the spatial point information of the entrance and exit edge contours. A continuous scanning mode is used to ensure the integrity of the contour, and multiple repeated measurements are used to improve data reliability.

5. The hierarchical progressive geometric feature measurement method of a turbine runner according to claim 1, characterized in that: In S2, the method of measuring detailed features using a handheld scanner is as follows: The strip scanning method is used to obtain the local curvature and surface roughness data of the blade surface, and the data integrity is ensured through multi-directional overlapping scanning.

6. The hierarchical progressive geometric feature measurement method of a water turbine runner according to claim 1, characterized in that: In S4, circular point distribution is adopted for the reference features, contour tracking point distribution is implemented for the main feature areas, and local encrypted point distribution is implemented for the detail feature areas.

7. The hierarchical progressive geometric feature measurement method of a turbine runner according to claim 6, characterized in that: The method of using circular point distribution for reference features is to place coded targets as control points around the installation reference surface and positioning holes, and use evenly distributed measurement points around the circle.

8. The hierarchical progressive geometric feature measurement method of a turbine runner according to claim 6, characterized in that: The method of implementing contour tracking point arrangement for the main feature area is to set the starting point of the entrance edge contour and the exit edge contour at 50~100mm away from the installation reference surface, take a measurement point at each end distance along the contour line direction, and increase the point spacing in the area where the curvature radius is less than 100mm.

9. The hierarchical progressive geometric feature measurement method of a water turbine runner according to claim 6, characterized in that: The method of implementing local encrypted point distribution for detail feature areas is to distribute points at equal distances on the blade profile, and then adjust the point density according to the curvature value of each area, and encrypt the points in areas where the curvature is greater than the set threshold.

10. The hierarchical progressive geometric feature measurement method of a turbine runner according to claim 1, characterized in that: In S4, the method for establishing real-time evaluation and re-measurement of measurement data is as follows: By comparing the actual point cloud density distribution of each measurement area with the theoretical point layout requirements, the data integrity and measurement accuracy are evaluated. When it is found that the measurement quality does not meet the standards, the point layout strategy of the corresponding area is adjusted and supplementary measurements are carried out until a complete turbine runner measurement model is obtained.

Images