Study On Temperature And Displacement Detection Technique For Turbine Blades

With the continuous progress of automobile manufacturing industry, aviation and power industry, how to monitor operational parameters of rotary such as turbine engine is the hot researching problem for all industries. In this paper, a novel technique for turbine blades is presented to measure temperature and axial displacement simultaneously with a single sensor probe, by using non-tangent measurement method. Based on the basic principle of fiber-optic sensor, the measurement systems are discussed, which is suitable for the conditions of high temperature, strong electromagnetic interference and narrow space. In this project, the main elements for sensors, optical transmission system and signal processing system are discussed. Especially, a concentric multi-circle fiber bundle is used in the sensor probe, which is designed on the basis of the required temperature measurement range and displacement measurement range.The first part of the paper introduces the merits and faults of several kinds of radiation-type fiber-optic pyrometers. Based on the principle of colorimetry measurement, a fiber-optic temperature sensor is selected, in view of its high measurement accuracy and practicability. Then the paper expounds the determination of operating wavelength, which relies on the required temperature measurement range and the measurement accuracy of the fiber-optic pyrometer. Using the colorimetry measurement, the advanced circuits can monitor the change of temperature intelligently. And the measurement result can be close to the turbine blades'true temperature.In succession, for dynamic surface measurement, a new reflective intensity-modulated displacement sensor with a simple and reliable structure is proposed in detail, which shares a sensor probe with the fiber-optic temperature sensor. So it provides economical space for turbine blades. Then the mathematical model for the sensor head is constructed, and the reflectiveintensity modulation is analyzed. In order to eliminate the problem of different reflectivity factor, provide a high sensitivity and avoid the unstability of the light transmission system created by the illuminant receiving outside disturbance, double optical paths detecting technique is adopted in this project. By using such technique, the result shows that optical fiber displacement sensor's sensitivity problem to temperature can be well eliminated.The two-way signals from temperature and displacement system are disposed by electrophotonic detector, amplifier and singlechip ADuC848, which can complete A/D and ratio disposal, as well as communicating with PC. At last, the experimental model is constructed to examine and certify the approach.