A novel cooling hole inspection method for turbine blade using 3D reconstruction of stereo vision

2021 ◽  
Author(s):  
Yuqi Cheng ◽  
Wenlong Li ◽  
Cheng Jiang ◽  
Gang Wang ◽  
Wei Xu ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Turbine Blade ◽  
Stereo Vision ◽  
Heat Dissipation ◽  
Turbine Blades ◽  
Reconstruction Technique ◽  
Feature Points ◽  
Inspection Method ◽  
Reconstruction Methods ◽  
Cooling Hole

Abstract Cooling holes (number 100~200, diameter 0.3~1.2 mm) are important heat dissipation structures of a turbine blade in aero-engine. Due to the small sizes and similar contours of cooling holes, it is difficult to extract and match their features by traditional stereo reconstruction methods. This paper proposes a novel cooling hole inspection method for turbine blades utilizing 3D reconstruction technique of stereo vision, which combines the stereo vision principle with the invariance of cross-ratio. The feature points of contours are extracted and matched by calculating two intersection points of circular contours and a line through the center points of adjacent cooling holes. Additionally, the 3D points corresponding to the feature points are reconstructed, by which, the diameters of cooling holes can be calculated successfully. Moreover, measurement experiments verify the effectiveness and accuracy of the proposed method. The experimental results show that the average errors of the standard circle ruler and tiny hole sample are within 0.05 mm, which satisfies the inspection requirement of cooling holes.

3D Reconstruction of Underwater Natural Scenes and Objects Using Stereo Vision

2013 ◽  
pp. 957-978
Author(s):  
C.J. Prabhakar ◽  
P.U. Praveen Kumar ◽  
P.S. Hiremath
Keyword(s):  
3D Reconstruction ◽  
Stereo Vision ◽  
Light Propagation ◽  
Research Community ◽  
Natural Scenes ◽  
Reconstruction Technique ◽  
Challenging Problem ◽  
Light Rays ◽  
Intensity Images ◽  
Preprocessing Technique

Over the last two decades, research community of computer vision has developed various techniques suitable for underwater applications using intensity images. This chapter will explore 3D reconstruction of underwater natural scenes and objects based on stereo vision, which will be helpful in mine detection, inspection of shipwrecks, detection of telecommunication cables and pipelines. The general steps involved in 3D reconstruction using stereo vision are provided. The brief summary of papers for 3D reconstruction of underwater environment is presented. 3D reconstruction of underwater natural scenes and objects is challenging problem due to light propagation in underwater. In contrast to light propagation in the air, the light rays are attenuated and scattered, having a great effect on image quality. We have proposed preprocessing technique to enhance degraded underwater images. At the end of the chapter, we have presented the proposed stereo vision based 3D reconstruction technique to reconstruct 3D surface of underwater objects. Ultimately, this chapter intends to give an overview of the 3D reconstruction technique using stereo vision in order to help a reader in understanding stereo vision and its benefits for underwater applications.

Novel Focal Sweep Strategy for Optical Aerothermal Measurements of Film-Cooled Gas Turbine Blades With Highly Inclined Viewing Angle

2021 ◽  
Vol 144 (3) ◽  
Author(s):  
Hongyi Shao ◽  
Xu Zhang ◽  
Di Peng ◽  
Yingzheng Liu ◽  
Wenwu Zhou ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Flat Plate ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Turbine Blades ◽  
Viewing Angle ◽  
Sweep Method ◽  
Gas Turbine Blades ◽  
3D Point Clouds

Abstract The viewing angle for optical aerothermal measurements on turbine surfaces is often limited by the turbine structure, requiring the optical system to have a large depth of field (DoF). Although the DoF can be increased by decreasing the lens aperture, this approach is impractical as a large aperture is essential to maintain an acceptable signal-to-noise ratio (SNR). To solve these problems in the optical aerothermal measurements of film-cooled gas turbine blades, an approach combining the focal-sweep method and three-dimensional (3D) reconstruction is proposed. The focal-sweep method is used to obtain all-in-focus images at an inclined viewing angle, following which the two-dimensional image is restored through 3D reconstruction. Thus, 3D point clouds with both a large DoF and high SNR can be produced. The developed method was validated via flat-plate film cooling experiments using pressure-sensitive paint at three blowing ratios of 0.4, 0.8, and 1.2, as well as three viewing angles. The measured adiabatic effectiveness contours demonstrate that the proposed method can produce all-in-focus measurements at highly inclined viewing angles, albeit at the price of slightly higher noise. In flat-plate experiments, the maximum relative difference is measured to be 6% between results obtained by conventional method at normal view and the proposed method at highly inclined view. Furthermore, the proposed method was applied to the turbine blade cascade film cooling experiment at a highly inclined viewing angle, and successfully reconstructed the 3D point cloud of the cooling effectiveness at the curved turbine blade surface.

Defect detection on the curved surface of a wind turbine blade using piezoelectric flexible line sensors

2021 ◽  
pp. 147592172110261
Author(s):  
Sang-Hyeon Kang ◽  
Myeongcheol Kang ◽  
Lae-Hyong Kang
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Critical Role ◽  
Turbine Blades ◽  
Ultrasonic Inspection ◽  
Ultrasonic Waves ◽  
Wind Turbine Blade ◽  
Large Area ◽  
Long Distance ◽  
Inspection Method

Blades play a critical role in the wind turbine system. Therefore, their structural health monitoring is very important. Blades are damaged by sudden changes in wind load, cracks due to collision of foreign objects, and disasters, such as lightning strikes, hail, and typhoons. Moreover, blades are expensive to maintain. Defects or damages to wind turbine blades reduce the life span and power generation efficiency of the wind turbine and increase safety risks and maintenance costs. Therefore, it is very important to detect blade damage to prevent problems in the wind turbine. Ultrasonic inspection is suitable for blades made of composite materials. Piezoelectric ceramic, which is a typical piezoelectric element, has relatively high sensitivity compared to other sensors. However, it suffers from brittle fractures and thus difficult to apply to curved structures. To overcome the limitations of piezoelectric ceramics, a piezoelectric flexible line sensor that can be applied to curved surfaces was manufactured using the dice-and-fill method for a [Pb(Li0.25Nb0.75)]0.06 [Pb(Mg0.33Nb0.67)]0.06 [Pb(Zr0.50Ti0.50)]0.88O3 with 0.7 wt% MnO2 (PZTNMML) ceramic disc. Instead of a typical ultrasonic inspection method with limited surface contact, a laser capable of producing ultrasonic excitation of ultrasonic waves over a large area from a long distance was used. The possibility of detecting a defect on the wind turbine blade using a piezoelectric flexible line sensor and laser ultrasound was confirmed in this study.

Surface Reconstruction of Stamping Parts Based on Binocular Stereo Vision

2013 ◽  
Vol 415 ◽  
pp. 314-317
Author(s):  
Hui Yu Xiang ◽  
Baoan Han ◽  
Jia Jun Huang ◽  
Zhe Li
Keyword(s):  
3D Reconstruction ◽  
Surface Reconstruction ◽  
Stereo Vision ◽  
Curved Surface ◽  
Feature Points ◽  
Scatter Diagram ◽  
Binocular Stereo Vision ◽  
Binocular Stereo ◽  
3D Information

In order to realize the 3D reconstruction of stamping parts surface, this paper based on binocular stereo vision principle firstly introduces the model of the binocular cameras. Internal and external parameters of camera can be obtained by binocular calibration, taking the printed circle grid centers which are on the stamping parts as feature points, and then using the disparity image obtained by HALCON to reconstruct 3D information of the feature points. Finally, use Matlab to plot out the scatter diagram of feature points and the fitting curved surface diagram.

3D Reconstruction of Underwater Natural Scenes and Objects Using Stereo Vision

2012 ◽  
pp. 114-136
Author(s):  
C.J. Prabhakar ◽  
P.U. Praveen Kumar ◽  
P.S. Hiremath
Keyword(s):  
3D Reconstruction ◽  
Stereo Vision ◽  
Light Propagation ◽  
Research Community ◽  
Natural Scenes ◽  
Reconstruction Technique ◽  
Challenging Problem ◽  
Light Rays ◽  
Intensity Images ◽  
Preprocessing Technique

Over the last two decades, research community of computer vision has developed various techniques suitable for underwater applications using intensity images. This chapter will explore 3D reconstruction of underwater natural scenes and objects based on stereo vision, which will be helpful in mine detection, inspection of shipwrecks, detection of telecommunication cables and pipelines. The general steps involved in 3D reconstruction using stereo vision are provided. The brief summary of papers for 3D reconstruction of underwater environment is presented. 3D reconstruction of underwater natural scenes and objects is challenging problem due to light propagation in underwater. In contrast to light propagation in the air, the light rays are attenuated and scattered, having a great effect on image quality. We have proposed preprocessing technique to enhance degraded underwater images. At the end of the chapter, we have presented the proposed stereo vision based 3D reconstruction technique to reconstruct 3D surface of underwater objects. Ultimately, this chapter intends to give an overview of the 3D reconstruction technique using stereo vision in order to help a reader in understanding stereo vision and its benefits for underwater applications.

Structural Studies on the Eukaryotic Ribosome

1990 ◽  
Vol 48 (1) ◽  
pp. 256-257
Author(s):  
Adriana Verschoor ◽  
Ronald Milligan ◽  
Suman Srivastava ◽  
Joachim Frank
Keyword(s):  
Chick Embryo ◽  
3D Reconstruction ◽  
Single Particle ◽  
Mass Density ◽  
Particle Surface ◽  
Uranyl Acetate ◽  
Electron Microscopic ◽  
Eukaryotic Ribosome ◽  
Negative Stain ◽  
Reconstruction Methods

We have studied the eukaryotic ribosome from two vertebrate species (rabbit reticulocyte and chick embryo ribosomes) in several different electron microscopic preparations (Fig. 1a-d), and we have applied image processing methods to two of the types of images. Reticulocyte ribosomes were examined in both negative stain (0.5% uranyl acetate, in a double-carbon preparation) and frozen hydrated preparation as single-particle specimens. In addition, chick embryo ribosomes in tetrameric and crystalline assemblies in frozen hydrated preparation have been examined. 2D averaging, multivariate statistical analysis, and classification methods have been applied to the negatively stained single-particle micrographs and the frozen hydrated tetramer micrographs to obtain statistically well defined projection images of the ribosome (Fig. 2a,c). 3D reconstruction methods, the random conical reconstruction scheme and weighted back projection, were applied to the negative-stain data, and several closely related reconstructions were obtained. The principal 3D reconstruction (Fig. 2b), which has a resolution of 3.7 nm according to the differential phase residual criterion, can be compared to the images of individual ribosomes in a 2D tetramer average (Fig. 2c) at a similar resolution, and a good agreement of the general morphology and of many of the characteristic features is seen.Both data sets show the ribosome in roughly the same ’view’ or orientation, with respect to the adsorptive surface in the electron microscopic preparation, as judged by the agreement in both the projected form and the distribution of characteristic density features. The negative-stain reconstruction reveals details of the ribosome morphology; the 2D frozen-hydrated average provides projection information on the native mass-density distribution within the structure. The 40S subunit appears to have an elongate core of higher density, while the 60S subunit shows a more complex pattern of dense features, comprising a rather globular core, locally extending close to the particle surface.

scholarly journals Turbine Blade Three-Wavelength Radiation Temperature Measurement Method Based on Reflection Error Correction

2021 ◽  
Vol 11 (9) ◽  
pp. 3913
Author(s):  
Kaifeng Zheng ◽  
Jinguang Lü ◽  
Yingze Zhao ◽  
Jin Tao ◽  
Yuxin Qin ◽  
...  
Keyword(s):  
Temperature Measurement ◽  
Turbine Blade ◽  
Measurement Method ◽  
Turbine Blades ◽  
Target Surface ◽  
Maximum Error ◽  
Radiation Temperature ◽  
Average Error ◽  
Real Surface ◽  
Wavelength Radiation

The turbine blade is a key component in an aeroengine. Currently, measuring the turbine blade radiation temperature always requires obtaining the emissivity of the target surface in advance. However, changes in the emissivity and the reflected ambient radiation cause large errors in measurement results. In this paper, a three-wavelength radiation temperature measurement method was developed, without known emissivity, for reflection correction. Firstly, a three-dimensional dynamic reflection model of the turbine blade was established to describe the ambient radiation of the target blade based on the real surface of the engine turbine blade. Secondly, based on the reflection correction model, a three-wavelength radiation temperature measurement algorithm, independent of surface emissivity, was proposed to improve the measurement accuracy of the turbine blade radiation temperature in the engine. Finally, an experimental platform was built to verify the temperature measurement method. Compared with three conventional colorimetric methods, this method achieved an improved performance on blade temperature measurement, demonstrating a decline in the maximum error from 6.09% to 2.13% and in the average error from 2.82% to 1.20%. The proposed method would benefit the accuracy in the high-temperature measurement of turbine blades.

scholarly journals 3D Reconstruction with Single-Shot Structured Light RGB Line Pattern

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4819
Author(s):  
Yikang Li ◽  
Zhenzhou Wang
Keyword(s):  
3D Reconstruction ◽  
Moving Objects ◽  
Structured Light ◽  
Color Space ◽  
Reconstruction Technique ◽  
Single Shot ◽  
Line Pattern ◽  
Hsv Color Space ◽  
Phase Map ◽  
Line Segmentation

Single-shot 3D reconstruction technique is very important for measuring moving and deforming objects. After many decades of study, a great number of interesting single-shot techniques have been proposed, yet the problem remains open. In this paper, a new approach is proposed to reconstruct deforming and moving objects with the structured light RGB line pattern. The structured light RGB line pattern is coded using parallel red, green, and blue lines with equal intervals to facilitate line segmentation and line indexing. A slope difference distribution (SDD)-based image segmentation method is proposed to segment the lines robustly in the HSV color space. A method of exclusion is proposed to index the red lines, the green lines, and the blue lines respectively and robustly. The indexed lines in different colors are fused to obtain a phase map for 3D depth calculation. The quantitative accuracies of measuring a calibration grid and a ball achieved by the proposed approach are 0.46 and 0.24 mm, respectively, which are significantly lower than those achieved by the compared state-of-the-art single-shot techniques.

scholarly journals Thermal–Fluid–Solid Coupling Analysis on the Temperature and Thermal Stress Field of a Nickel-Base Superalloy Turbine Blade

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3315
Author(s):  
Liuxi Cai ◽  
Yao He ◽  
Shunsen Wang ◽  
Yun Li ◽  
Fang Li
Keyword(s):  
Thermal Stress ◽  
Temperature Gradient ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Nickel Base Superalloy ◽  
Barrier Coating ◽  
Thermal Stress Field ◽  
Nickel Base ◽  
Stress Damage ◽  
Superalloy Turbine Blade

Based on the establishment of the original and improved models of the turbine blade, a thermal–fluid–solid coupling method and a finite element method were employed to analyze the internal and external flow, temperature, and thermal stress of the turbine blade. The uneven temperature field, the thermal stress distribution characteristics of the composite cooling turbine blade under the service conditions, and the effect of the thickness of the thermal barrier coating (TBC) on the temperature and thermal stress distributions were obtained. The results show that the method proposed in this paper can better predict the ablation and thermal stress damage of turbine blades. The thermal stress of the blade is closely related to the temperature gradient and local geometric structure of the blade. The inlet area of the pressure side-platform of the blade, the large curvature region of the pressure tip of the blade, and the rounding between the blade body and the platform on the back of the blade are easily damaged by thermal stress. Cooling structure optimization and thicker TBC thickness can effectively reduce the high temperature and temperature gradient on the surface and inside of the turbine blade, thereby reducing the local high thermal stress.

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