The Design Of Leaking Detection System Based On Optical Fiber Macro-bending Coupling Effect

Autonomous Underwater Vehicle(AUV) is under a tremendous pressure at the time of sailing,so underwater vehicle requires a good water pressure resistant performance and sealing performance. Generally the water tightness tests can not truly simulate the environments of underwater sail,so it is necessary to increase water leakage test at launching experiments or in actual navigation in order ti improve the water tightness tests for the design of the structure. In order to provide complete and reliable test data for underwater structures,the system needs to provide accurate reports of leaking state and leaking station.Currently,the reports for water leakage sensors specifically for underwater devices can hardly be seen.so independent research is very necessary for developing the water leakage sensor specifically for underwater devices.According to the proposed project specifications and design requirements, the paper designs the overall scheme of the system and describes in detail the working principle of leak detection system. The system uses a modular design, and completes the design of water leakage sensing unit, weak signal acquisition unit, addressing positioning unit and other features modular units. Considering the complexity of the underwater environment, and combining with the current development of leak detection technology, we designs a optical fiber macro-bend leakage sensor based on the principle of the optical fiber macro-bend coupling effect; Addressing positioning unit control the 256 sensor heads to sequentially cycle work through a circular increasing address code sending by FPGA and positioning addressing circuit. In the proposed leakage sensor constructed as a precondition, we complete the design of weak signal acquisition module, and the leakage station and the leakage position can decide by the output result of this module. Ultimately, this design realizes the leakage state detection of the 256 location with steps of 50 mm, the measuring length can reach 12.8m,and the leaking positioning accuracy can realize ±5mm.Finally, the paper complete the functional testing of sensor head and the whole system of the leak detection system.The results show that the stable performance of the design to meet the design requirements.