Sánchez-Botello Xavier, Roig Rafel, de la Torre Oscar, Madrigal Javier, Sales Salvador, Escaler Xavier
IFLUIDS, Universitat Politècnica de Catalunya, 08028 Barcelona, Spain.
Floating Power Plant A/S, 4941 Bandholm, Denmark.
Sensors (Basel). 2023 Jul 26;23(15):6695. doi: 10.3390/s23156695.
The structural dynamic response of hydraulic turbines needs to be continuously monitored to predict incipient failures and avoid catastrophic breakdowns. Current methods based on traditional off-board vibration sensors mounted on fixed components do not permit inferring loads induced on rotating parts with enough accuracy. Therefore, the present paper assesses the performance of fiber Bragg grating sensors to measure the vibrations induced on a rotating shaft-disc assembly partially submerged in water resembling a hydraulic turbine rotor. An innovative mounting procedure for installing the sensors is developed and tested, which consists of machining a thin groove along a shaft line to embed a fiber-optic array that can pass through the bearings. At the top of the shaft, a rotary joint is used to extract, in real time, the signals to the interrogator. The shaft strain distribution is measured with high spatial resolution at different rotating speeds in air and water. From this, the natural frequencies, damping ratios, and their associated mode shapes are quantified at different operating conditions. Additionally, the change induced in the modes of vibration by the rotation effects is well captured. All in all, these results validate the suitability of this new fiber-optic technology for such applications and its overall better performance in terms of sensitivity and spatial resolution relative to traditional equipment. The next steps will consist of testing this new sensing technology in actual full-scale hydraulic turbines.
需要持续监测水轮机的结构动态响应，以预测初期故障并避免灾难性故障。当前基于安装在固定部件上的传统外置振动传感器的方法，无法足够准确地推断旋转部件上所受的载荷。因此，本文评估了光纤布拉格光栅传感器在测量类似于水轮机转子的部分浸没在水中的旋转轴 - 圆盘组件上所引起振动方面的性能。开发并测试了一种用于安装传感器的创新安装程序，该程序包括沿着轴线加工一条细槽以嵌入可穿过轴承的光纤阵列。在轴的顶部，使用旋转接头实时将信号传输到询问器。在空气和水中以不同转速测量轴的应变分布，并具有高空间分辨率。由此，在不同运行条件下对固有频率、阻尼比及其相关振型进行了量化。此外，很好地捕捉到了旋转效应引起的振动模式变化。总而言之，这些结果验证了这种新型光纤技术适用于此类应用，并且相对于传统设备，其在灵敏度和空间分辨率方面具有整体更好的性能。接下来的步骤将包括在实际全尺寸水轮机中测试这种新型传感技术。
