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

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.

Advances in Aeroengine Cooling Hole Measurement: A Comprehensive Review

“…The experiment results indicate that the evaluation error in measuring diameters is within 0.05 mm. This method allows simultaneous measurement of multiple cooling holes, significantly enhancing measurement efficiency [51]. Li Lei from Xi'an Jiaotong University [52] developed a cooling hole measurement method based on microscopic image sequence topographical reconstruction.…”

“…Researchers have taken advantage of miniature-sized probes for in-depth micro-hole measurements, including fiber probe technology [41][42][43][44][45] and capacitive probe technology [46][47][48][49][50][51]. The working mechanism of this method is presented in Figure 10.…”

A novel deformation measurement method for rotating blade based on PSO-ILS image correlation matching and mismatch correction

“…The accurate measurement of the deformation field provides an important reference for the health quality assessment of aero-engine blades, and plays a guiding role in the blade manufacturing and assembly process [1,2]. The earliest used * Authors to whom any correspondence should be addressed.…”

An accurate novel circular hole inspection method for sheet metal parts using edge-guided robust multi-view stereo

“…Compared with a monocular system, a binocular system adds the external parameters of two cameras so that a circular hole can be reconstructed with a polar constraint, and the problems mentioned for a monocular system can be solved well [9][10][11][12][13][14]. Huang et al [9] developed a local line-angle contour segmentation model for measuring key dimensions on flat parts.…”

“…However, the rust and complex reflection affected the precision. Cheng et al [14] used a binocular system and developed a dedicated detection algorithm based on cross-ratio invariance for cooling holes on turbine blades, which had narrow applicability. ATOS is a commercial binocular structured light scanning device from the GOM company.…”