Research Progress on Detection Technology for Film Cooling Holes and Coating Defects of Turbine Blades
XIA Kailong 1 , GE Chao 2 , WANG Qiutong 2 , HE Qing 1, 2
1. Surface Engineering Research Institute, Chinese Academy of Agricultural Mechanization Sciences Group Co., Ltd., Beijing 100083, China；
2. Beijing JinLunKunTian Special Machine Co., Ltd. Beijing 100083, China
Abstract：In order to meet the long-life and high-reliability requirements of modern gas turbine engines, the development trend of high-performance turbine blades is presented as integrated designing and manufacturing of film cooling structure and thermal barrier coating for thermal protection. However, the gas film structure and its cooling efficiency could be affected by the microstructure defects produced in the process of film holes preparation and the dimensional deviations caused by the coating. The progress of coating first will also cause local sintering or even cracking of the coating, with femtosecond laser drilling afterwards. During blade service, due to the temperature gradient and edge effects, the stress concentration of coating on the edge is more easily occurred, leading to the initiation and expansion of cracks, which becomes the weakness of failure. At present, traditional measurement methods, including the plug gauge method, flow method, and microprobe method, cannot effectively evaluate the geometric parameters, shape characteristics and processing defects of the film holes. Among the various non-destructive testing methods applied to evaluate the quality of blades and coatings, active infrared thermography is qualified of the advantages of high-speed, versatility and effective quality control. In this paper, a high-efficiency and high-precision parameters measurement and defect evaluation methods for alloy and coatings around the holes are reviewed in conjunction with traditional non-destructive testing methods and the development of common air-cooling structures and their preparation processes are discussed. The research progress of the application of active infrared thermal imaging technology in the evaluation of film cooling holes is enumerated in detail. At the same time, the article summarizes the deficiency and the development orientation of the current technology, which is of great significance for improving the processing quality control level of the gas cooling structures and film holes.
2022, 
