Aircraft Icing Type Detection Based On Oblique End-face Fiber Optic Technology

Aircraft icing goes for aviation dangerous weather. Severe status of icing could causemajor accident of flight. Taking the microstructure into account, ice falls broadly into threetypes, i.e. glazed, rime and mixed ice. Different types of ice do different harm to flight. Toavoid the harm, the premise is to detect aircraft icing state timely and accurately. Atpresent, mainstream ice sensors ignore the impact of multifarious ice types on sensorcharacteristics, bringing biggish and intractable system error to ice thickness measurement.Consquently, the research on ice type detection is of great significance to improve the icethickness measurement accuracy and implement grading warning to aircraft icing.This thesis first proposes novel technique of oblique end-face fiber optic ice sensor.Single oblique end-face fiber optic ice sensor, double oblique end-face fiber optic icesensor and compound double oblique end-face fiber optic ice sensor are designed and theirprinciples of ice type detection are respectively discussed in terms of optical intensitydistribution. It is demonstrated how to figure out the slant angles of fiber bundles. Second,to detect the output signal of the sensors, digital accumulation solution is proposed, andthe corresponding circuit consists of drive circuit, photoelectric conversion circuit,differential-operational amplifying circuit, MCU circuitry and low-pass filter circuit. Thedesign of MCU softfare is also discussed. Finally, to test the performance of the sensorand the circuit, icing simulation experimental setup is devised and icing experiments areconducted on the single oblique end-face fiber optic ice sensor.The experimental result proves that single oblique fiber optic ice sensor can detect icetype exzactly, which lays foundation of aircraft icing type detection technology and itsengineering application.