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4. Study on crack propagation tendencies of non-repaired and repaired nozzles

Author

Fujii, Tomoharu and Takahashi, Takeshi

Subjects
Turbines -- Research, Science and technology
Abstract

A system designed to control and predict the length of cracks that generate in the first-stage nozzles of E and F class gas turbines was developed. This system consists of three programs for (1) inputting cracks, (2) displaying cracks, and (3) predicting cracks, and a database consisting of approximately 350,000 cracks generated in first-stage nozzles taken from past repair records of five power plants operating in Japan. The database also contains data on operating time and number of starts of gas turbines. The distinctive features of this system are described below. (1) The crack data can be entered on the nozzle drawing as a picture by using the mouse. (2) The accumulated data allows the sections of nozzles in which cracks have generated most frequently to be identified. (3) The correlation formula of cracks and operating time or number of starts can be obtained simply. (4) By entering the scheduled operating time or number of start-ups to the time of the next scheduled inspection in the correlation formula, the length of cracks in optional sections and propagating in optional directions can be predicted. Using this system, the statuses of cracks generated in non-repaired and repaired nozzles of E class gas turbines were compared. The comparison focused on 11 patterns with comparatively long cracks selected from the cracks propagating together with the increase in operating time or number of starts. The propagation of cracks covering a period of approximately two years, which corresponds to the inspection interval of power plants in Japan, was also compared. The results showed that the extent of crack propagation tends to increase with the increase in the number of repairs. Furthermore, the propagation of cracks in repair nozzles is about two times greater than that in non-repair nozzles. It was also found that the system could identify the sections in which the longest cracks are generated. [DOI: 10.1115/1.1650378]

Published
2004

16. Embedded planar power inductor technology for package-level DC power grid

Author

Kondo, Yuta, primary, Yazaki, Yuichiro, additional, Sonehara, Makoto, additional, Sato, Toshiro, additional, Watanabe, Tetsuro, additional, Seino, Yuto, additional, Matsushita, Nobuhiro, additional, Fujii, Tomoharu, additional, Kobayashi, Kazutaka, additional, Shimizu, Hiroshi, additional, Yanagisawa, Yuki, additional, Someya, Teruki, additional, Fuketa, Hiroshi, additional, Takamiya, Makoto, additional, and Sakurai, Takayasu, additional

Published
2015
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50. Evaluation of Applicability of Compact Excitation Light Source to Detection of Thermally Grown Oxide Layer in Thermal Barrier Coating for Gas Turbines.

Author

Fukuchi, Tetsuo, Eto, Shuzo, Okada, Mitsutoshi, and Fujii, Tomoharu

Subjects
LIGHT sources, THERMAL barrier coatings, THERMAL analysis, GAS turbines, CONTINUOUS wave lasers, OXIDES
Abstract

SUMMARY A compact, continuous wave laser was applied to detection of the thermally grown oxide (TGO) layer in a thermal barrier coating (TBC) for gas turbine high-temperature components by photoluminescence. Experiments were conducted using TBC specimens heated in air to artificially produce a TGO layer. For specimens heated at 1100 °C, the photoluminescence intensity increased with heating time, whereas for specimens heated at 1000 °C, the photoluminescence intensity did not increase beyond 100 h. The results indicate that the formation of the TGO layer is strongly dependent on the temperature. In addition, scanning electron microscope (SEM) observations of the specimen cross section confirmed the formation of the TGO layer after heating for 100 h at 1100 °C. The applicability of a compact laser to TGO layer detection allows the development of a simple TGO detection system, which can be used in screening for the detailed inspection of delamination. [ABSTRACT FROM AUTHOR]

Published
2015
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