流速/温度共采的光纤布拉格光栅涡轮流速传感器

FBG turbine flow rate sensor for acquiring flow rate and temperature simultaneously

为实现敏感元件仅为单一光纤光栅流速传感器的多参数同时测量,提出了一种流速/温度共采的光纤布拉格光栅(FBG)涡轮流速传感器。该传感器通过涡轮实现流体冲击力对光纤光栅中心波长的频率调制,解决光纤光栅温度应变的交叉敏感,理论计算得到其流速检测灵敏度为2.91·10-2 m/(s·Hz-1)。为测试传感器的性能,搭建了传感器测试系统,并选取光纤动态解调仪解调的光纤光栅中心波长动态信号作为试验原始数据。应用快速傅里叶变换(FFT)法分析试验数据,得到传感器流速的检测下限为0.541 7m/s,检测灵敏度为2.57·10-2 m/(s·Hz-1),检测精度为25mm/s,略小于理论计算值,其主要原因在于圆管内流体的流速并非均匀分布的匀速运动,管道内壁对流体具有一定的黏滞力。应用经验模式分解分析原始数据获取其趋势项信号,得到该传感器的温度灵敏度为10.6pm/℃,检测精度为0.5℃。

To measure multi-parameters at the same time by a flow sensor with only one Fiber Bragg Grating（FBG） as the sensitive element, a novel FBG turbine flow rate sensor was proposed. This sen- sor uses a power element turbine to achieve a fluid impact force to modulate the frequency of FBG cen- ter wavelength and to overcome the cross-talking of temperature and strain effectively. The theoretical calculation of flow rate detection sensitivity is 2.91·10.2 m/（s · Hz^-1 ）. To measure the properties of this sensor, a sensor measurement system was established, meanwhile the FBG center wavelength dynamic signal demodulated by a fiber dynamic demodulator was chosen to be the experiment origin data. A Fast Fourier Transform（FFT） was used to analyze the experiment data of the sensor. The re- sult shows that the flower limit of flow rate is 0. 541 7 m/s and the flow rate detection sensitivity is 2.57·10-2 m/（s· Hz^-1） with the detection accuracy of 25 mm/s, which are lower than the calculat- ed values. It suggests that the main reason of these phenomena is that the flow rate of fluid in thetransmission pipeline is not an even distributed uniform motion and the pipeline inner wall has some viscous forces on the fluid. Empirical mode decomposition was used to analyze the original signal. The experiment data indicate that the temperature detection sensitivity of this sensor is 10.6 pm/℃ and detection accuracy is 0.5 ℃.