A fibre-optic grating sensor for the study of flow-induced vibrations

A fibre-optic Bragg grating sensor for flow-induced vibration measurement is described. The sensor is based on monitoring shift in the Bragg wavelength of a fibre Bragg grating. The fibre Bragg grating, when bonded onto a structure, can measure local;axial strain variation of the structure. The sensor was used to measure the flow-induced vibrations on a circular cylinder in a cross-flow. The measured strain epsilon is consistent with the transverse structural bending displacement Y obtained from a laser vibrometer in terms of the natural frequency of the fluid-structure system and the vortex shedding frequency. The experimental data further indicated that epsilon and Y are linearly correlated when the bending displacement is small. It is expected that the fibre Bragg grating sensor, because of its physical uniqueness, has an important role to play in the study of fluid-structure interactions. (C) 2000 Elsevier Science S.A. Ail rights reserved.