적외선 열화상 계측기법을 적용한 가스터빈 블레이드 건전성 평가

Abstract

Key part of main equipment in a gas turbine may be likely to be damaged due to operation under high temperature, high pressure, high-speed rotation, etc. Accordingly, the cost for maintenance increases and the damaged parts may cause generation to stop. The number of parts for maintenance also increases, but diagnostics technology for the maintenance actually does not catch up with the demand. The surface of a blade is thermal-sprayed, using powder with main compositions such as Ni, Cr, Al, etc. in order to inhibit hot oxidation. Conventional regular maintenance of the coating layer of a blade is made by FPI (Fluorescent Penetrant Inspection) and MTP (Magnetic Particle Testing). Such methods, however, are complicated and take long time and also require much cost. In this study, defect diagnostics were tested for the coating layer of an industrial gas turbine blade, using an infrared thermography camera. Since the infrared thermography method can check a temperature distribution on a wide range of area by means of non-contact, it can advantageously save expenses and time as compared to conventional test methods. For the infrared thermography method, however, thermo-load must be applied onto a tested specimen and it is difficult to quantify the measured data. To solve the problems, this essay includes description about producing a specimen of a gas turbine blade (bucket), applying thermo-load onto the produced specimen, photographing thermography images by an infrared thermography camera, analyzing the thermography images, and pre-testing for analyzing defects on the coating layer of the gas turbine blade. In this investigation, we evaluated diagnoses of a defect concerning coating of land-base gas turbine using infrared thermography camera. In this camera method has a strong point which is able to save time and costs compared with former method. Because it can be long field acquire temperature distribution by using non-contact method. But it has a week point that method applies thermal load about inspection sample. Presently, Method used widely in detection of crack is ultrasonic inspection. But this method, There is problem in application in place that uneven surface. In order to check cracks on a blade coating of a gas turbine, a part with cracks in a waste blade disposed after having been used in the field was extracted to produce a sample. So we apply the method by a infrared thermography camera to the produced sample, the sample was heated by means of a halogen lamp. In this paper, we want to describe production of land-base turbine sample, a method of applying thermal load at produced sample, infrared thermography camera technique, an analysis technique of thermography, a defect analysis of coating of land-base gas turbine blades.