Non-contact Icing Detection System Design And Experiment Research

Icing on a rotor has a great impact on the safety and performance of the helicopter, it will cause severe airplane accident and personal injury. The extensive researches in the icing detection field were held in foreign countries, the domestic research is relatively backward. Abundant of information both at home and abroad is reviewed. The non-contact detection technology based on active infrared laser is put forward in this thesis.The basic principle and method of the non-contact icing detection technologies were expounded in the paper. Aiming at the characteristics of the rotors, the influence of the torque and waving to the measuring system is analysed. The infrared laser detector is used to emit light to the under surface of the rotor actively, the reflected infrared light was received, converted, amplified and noise filtered, then the useful signal was extracted. Using the difference of the received energy signal between the icy and the non-icy area, the judgment of the rotor surface is icy or not is realized, and the icing range on the rotor along the string direction can be calculated. According to the principle of the system, the infrared laser source and photoelectric detector were chosen, and the preamplifier, programmable gain amplifiers, synchronous integrators, the subtractor circuit, the threshold comparator and DSP processing system and other major functional module circuit were designed.On the basis of the realization of the hardware and software function, many static experiments were performed. Through the study of the infrared transmission characteristics both on icy surface and non-icy surface, the difference of the output of the signal processing circuit between the icing state and the non-icing state were observed and analysed. The infrared transmission characteristics of many various materials were also studied and the suitable simulate icing material was found for the dynamic experiments. The impact of incident angle and distance changes were observed, then the according countermeasures were put forward preliminarily to overcome the torque and waving. Many dynamic tests were also preformed. The result showed that the scheme designed in the paper were feasible and effective, it can be used on the helicopters.