飞机涡轮发动机叶片红外探伤技术研究

【作者】 陆佳佳；

【导师】 叶玉堂；

【作者基本信息】 电子科技大学 ， 光学工程， 2007， 硕士

【摘要】 涡轮叶片是燃气涡轮发动机关键热端部件，对发动机的推重比和安全性有直接影响。涡轮叶片材料构成特殊，制造工艺复杂，价格昂贵，因而在生产和维修过程中，一般采用无损探伤技术对其进行缺陷检测。传统无损探伤方法，如X光、超声等，都因存在某些不足(如X光检测成本高，存在辐射泄露问题)而不能在涡轮叶片缺陷检测中得到很好的应用。为了满足涡轮叶片缺陷检测中安全性的要求，提高检测效率和精度，本文采用红外热波无损检测技术对涡轮叶片的缺陷进行检测。红外热波无损检测技术不同于传统的红外检测方法。它通过主动控制激励热源和测量样件表面的温度场变化，来获得样件表面及内部的结构信息，从而达到检测的目的。这种检测方法既能够应用于金属材料，也能够应用于非金属材料，且具有检测速度快、观测面积大、无污染、结合数字图像处理技术可以实现定量检测等优点。本文主要围绕涡轮叶片缺陷红外热波无损检测系统硬件、软件研制和实验中的几个关键问题进行阐述。论文的创新点及完成的主要研究工作如下：(1)完成了航空发动机涡轮叶片缺陷红外热波无损检测系统的设计、安装及调试工作。完成了系统核心控制电路的设计和调试工作。通过计算机与单片机之间的通信来控制热图像采集、热像仪自动调焦、三维平台移动、360°精密电动旋转台旋转、标志电源和电磁阀开关等，实现系统的半自动控制。(2)在深入分析涡轮叶片热障涂层缺陷和冷却通道堵塞缺陷特点的基础上，结合红外热波无损检测技术，设计了不同的激励源和激励方式，完成了缺陷检测实验。(3)在热图像处理中，结合红外图像低亮度和低对比度的特点，通过仿生物学模型的脉冲耦合神经网络对图像进行增强，这种算法能够在增强图像亮度和对比度的同时，抑制图像中的椒盐噪声。(4)总结实验中表面发射率、噪声干扰、激励方式和热像采集时刻等四个因素对实验结果的影响，深入分析了原因并提出了相应的解决方法。更多还原

【Abstract】 Turbine blades are the crucial heated end components of gas turbine engine, which have directly impact on the thrust-to-weight ratio and safety of engine. 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. For conventional in nondestructive testing methods, such as X-ray radiography and ultrasonics, there are some drawbacks for blade inspection. The application of X-ray technology is restricted by the radiation leakage problem and high expenditure on maintaining X-ray system.In this dissertation, in order to meet safety requirements and improve efficiency and accuracy, thermal wave nondestructive testing technique has been used to test defects of turbine blades. Thermal wave nondestructive testing is different from traditional infrared nondestructive testing techniques. The surface and subsurface structure information of specimen may be obtained through controlling the stimulation media actively and monitoring the temperature distribution of specimen. Both metal and non-metal material defects can be inspected using the technique. This method has superiorities, including high testing efficiency, large visual field, quantitative analysis based on digital image processing and no radiation.In this thesis, the hardware circuits and the software system of thermal wave nondestructive testing system are illustrated and several key issues in testing experiments are mainly discussed. The main research content and innovation 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, has been designed and tested. The system is semi-automatically controlled, and automotive controlling the image acquisition of infrared image sensor, auto-focusing of infrared image sensor, moving of 3-D platform, rotating of 360°accurate electric driven table and electric valves have been realized through data communication between PC and single-chip microcomputer.(2) Different heat medias and stimulation methods have been used and vast defects testing experiments have been done, based on in-depth analysis of defects characters of thermal barrier coatings and cooling ducts of turbine blades.(3) Pulse coupled neural network, which is a model derived from a neural mammal model, has been established to enhance image. The experiment results show that the algorithm can enhance contrast and brightness of image effectively and remove noise in images efficiently, especially for the infrared image with low contrast and brightness.(4) The influences of four factors (surface emissivity, noises, stimulation methods and acquisition time of images) on the results of experiments are amply analyzed. Methods of solving these problems are presented.更多还原