Turbine Blade Cooling Duct Of The Original Infrared Image Enhancement And Processing

Turbine blade including guide blade and work blade is one of the crucial heated end components of gas turbine engine to convert heat energy of burning gas to revolving mechanism kinetic energy. It is very atrocious for turbine blade to revolve rapidly under concussion by high pressure erosive burning gas. Because of the speciality of turbine blade materials, the complexity of manufacture processing and the high cost, several nondestructive techniques have been proposed and used for blades inspection tasks. Conventional nondestructive techniques can not be applied widely for something of disadvantage.In this dissertation , in order to meet safety requirements and improve efficiency and accuracy, thermal wave nondestructive testing technique is applied to inspect defects of turbine blades. Different four methods have been proposed, and as our knowledge, this is the first report in China about the latter two methods. Thermal wave nondestructive testing is different from traditional infrared nondestructive testing techniques, the surface and subsurface structure or defect information could be obtained through active thermal stimulation and analyzing the temperature map of specimen.In this dissertation, the optimization to methods above about thermal wave nondestructive testing system are illustrated and several key problems in testing experiments are mainly discussed. The main conclusions and contributions are as follows:1. The thermal wave nondestructive testing system for turbine blades of aircraft engine has been well designed. The installation and debugging tasks of the system have been accomplished. The controlling circuit, the most important part of the system, and the autocontrolling circuit for water temperature have been designed and tested.2. Characteristic of cooling channels jam has been analyzed, and then, four inspiring methods are presented: (i) inspire the blade by using constant temperature box and cool it by gas; (ii) inspire the blade by hot water and cool it by cold water alternately; (iii) inspire the blade by induction cooker and cool it by cold gas simultaneity; (iv) inspire the blade by steam and cool it by cold gas alternately. Furthermore, based on the experimental results, the advantages and disadvantages of the methods are described respectively.3. The obtained thermal images of turbine blade have been processed using image subtracting, gray changing, image smoothing, etc.4. Four factors (the capability of infrared camera, acquisition time of images, noises, surface emissivity) which have important influence on the experimental results are amply illustrated. Methods of solving these problems are presented.