Research And Development On Active Emissivity Detection System

The aeroengine of the aircraft often comes across the heat and temperature problems. To avoid damage of the temperature, thermal analysis is needed. And the surface emissivity of the aeroengine is the most important key parameter in thermal analysis and the primary reason for developing and choosing the thermal insulation.This thesis introduces the detection principles of the active emissivity test system, and describes the overall design of the active online emissivity measuring system, combining with measuring model. And, based on the type selection of the infrared sensor and emitter, the thesis introduces the structure design of the sensor, software and hardware. This thesis mainly deals with the software development, including the data acquisition system based on the PLC and the information processing platform based on VC6.0(the computer system). The PLC mainly expound the type selection of the smart module, software design and the fault tolerance algorithm. The computer system mainly expound the function and module design of the software, including software structure, timing control, data stream and the user interface design. The upper and PLC communicates with each other by RS-485, using the protocol formulated by the combination the Modbus protocol and the nonsequenced protocol.According to the requirements of the function and system performance of the active emissivity testing system ,the detection principles and the design of the electronic system, the thesis discusses the temperature compensation algorithm ,in order to compensate the error caused by the operating temperature change of the infrared sensor. The rationality and validity of the temperature compensation algorithm has been verified by a large number of tests in the later period. After that, by using the emissivity known templates, many experiments have been done to get values of module parameter C for each probe, and set the C value in the information processing platform to do the parameter confirmatory experiments. The results show that the consistency of the measurement system is high, and the measurement error does not exceed the scope of system requirements. The system successfully passed the acceptance of Party A.