双圈同轴光纤束传感器三维空间输出特性研究
Three-Dimensional Output Behavior of Displacement Sensor of Two-Circle Reflective Coaxial Fiber Bundle

针对航空发动机的实际故障特点，首先,分析了对航空发动机涡轮叶片三维叶尖间隙、包括叶尖表面径向间隙、轴向与周向倾角三维参数的变化信息进行光纤传感检测的需求；然后，针对拟采用的光纤传感器形式——双圈同轴光纤束传感器在反射面相对传感器端面存在径向间隙、空间倾角的情况下建立了三维空间输出调制函数模型，设计了接收光纤虚像端面与入射光斑的交叠面积补偿算法以及接收光纤虚像端面的平均光强修正算法；其次，对建立的传感器输出特性数学模型在反射面平行、仅存在轴向倾角、轴向周向均存在倾角这3种情况下分别进行了仿真计算,并与相同探头参数下的实验结果进行了对比分析；最后，对不同光纤传感器参数下的输出特性进行了仿真。结果表明，新建立的双圈同轴光纤束传感器三维空间输出特性数学模型不仅从理论角度还原出了传感器在反射面三维空间参数变化下的输出特性，还能指导不同三维空间位移测量应用下的光纤传感探头设计工作。
Based on the characteristics of failures inside an aero-engine turbine, we introduced a three-dimensional fiber-optic tip clearance measuring method using the displacement sensor of a two-circle reflective coaxial fiber bundle. Next, we built a three-dimensional modulation function for the sensor when there was radial clearance and inclination in both the axial and circumferential directions of the reflector. We also built a compensation algorithm for the overlapping area between the receiving fiber and light spot, and a correction algorithm of average light intensity on the surface of the virtual image of the receiving fiber. Then, we obtained the simulation results of the three-dimensional modulation function when the reflector was parallel or declining relative to the probe, and compared them with the experimental results. Finally, we simulated output behavior with different design parameters of the sensor. We concluded that the newly built three-dimensional modulation function of the two-circle reflective coaxial fiber bundle not only reproduced the real output behavior of the sensor, but also provided theoretical guidance in the design process of the fiber-optic probe based on any measuring requirement for three-dimensional displacement.