Research On The Key Technology For Blade Tip-timing Fiber-optic Sensor

The vibration of high speed rotating blade plays an important role on the safety of rotating machinery,so it's urgent to implement real-time monitoring of the blade and prevent the accidents before they happen.The blade tip timing fiber optic sensor is applied to the vibration monitoring system due to its high sensitivity,high electromagnetic interference ability and high reliability.In this paper,several key technologies for blade tip-timing fiber-optic sensor are studied systematically,such as establishing mathematical model based on the fiber optic probe of one translated fiber and six receive fiber,the guidance simulation and trial production of fiber optic sensor and the analysis of the factors which causes the measurement error.The main contents is shown as follows:1.In the project of blade tip-timing fiber optic sensor structure,the one translate fiber and six receive fiber probe structure is designed and the corresponding mathematical model is established.Besides,the numerical simulations are accomplished.considering a series of rules of the influence on intensity modulation property caused by multimode fiber parameters.2.In the precondition of outgoing light for the Gaussian beam,the mathematical model which reflects the effect of the convex reflected surface on intensity modulation property is built.The influence rule of the change of the radius of surface on intensity modulation is studied.3.The optical path structure of the blade tip-timing fiber-optic sensor is designed.The optoelectronic devices used in the measurement system are determined,and then the processing technology of probe head surface is explored,aiming at the conditions when the probe heads are covered by some dust and oil particles.4.The blade tip-timing fiber-optic sensor has been trial-produced.The measurement results are compared with those obtained by a different probe head with different fiber optic structural parameters,and the simulation results are verified by the experiments.Secondly,the influence of installation on intensity modulation is researched and the best installation position is determined;Thirdly,the properties of coated probe head studied by the static and dynamic experiments.5.The source of measurement error of the blade tip-timing fiber-optic sensor is analyzed,The causes of measurement errors are indicated and the methods of eliminating errors are proposed.At Last,the rise time of the pulse signal characteristics is analyzed,and the relationship between the rise time of the pulse signal and the rotational speed is revealed.