Non-Invasive Acoustic Monitoring of Gas Turbine Units by Fiber Optic Sensors

Abstract

In this article, we study the possibility of gas turbine unit (GTU) monitoring using interferometric fiber optic sensors. We used the Mach–Zehnder interferometer (MZI) scheme, which can be easily implemented and simply installed on the turbine, and also allows us to solve the problem of phase unwrapping conveniently. In this research, the following main steps were carried out: an experimental scheme based on the MZI was assembled, and its sensitive arm was fixed on the GTU under study; data on various operation modes of the GTU was collected; the data were subjected to frequency FFT analysis, based on which the main rotational speeds of the turbine were identified. With FFT analysis, we also demonstrated multiples harmonics, which appear in the case of GTU after operating time, caused by the number of blades. The possibility of GTU monitoring and analysis using a non-invasive compact fiber-optic sensor is demonstrated: spectral analysis is used to detect the rotor speed, as well as the presence or absence of high-order multiple frequencies indicating blade and bearing defects, which are determined by the number of GTU’s blades and rolling bearing used as turbines rotor supports.

Classification of Events Violating the Safety of Physical Layers in Fiber-Optic Network Infrastructures

“…Another option is to measure vibrations using interferometers. The most commonly used techniques employ the Mach–Zehnder interferometer (MZI), which can be used, for example, to secure gas turbines [ 13 ]; the Michelson interferometer (MI), which is commonly used for perimeter security [ 14 ]; or the Sagnac interferometer (SI), which is also used for perimeter security [ 15 , 16 ]. The use of the MZI and MI requires the use of reference fibers [ 17 ], which can be complex to implement in real infrastructures.…”

Activation Function Dynamic Averaging as a Technique for Nonlinear 2D Data Denoising in Distributed Acoustic Sensors

“…Together with other reflectometric methods that study slowly changing physical quantities in new materials and structures [17][18][19][20], distributed acoustic sensors for flaw detection problems form a complete understanding of the object's behavior in a wide range of external conditions [21,22]. Thus, in [21], distributed acoustic monitoring was used to study the operating regimes of a gas turbine. The nature of useful data and noise visually largely coincides with the images obtained in [13,14].…”

Characterization of sensitivity of optical fiber cables to acoustic vibrations

“…Arrangements using the MZI for acoustic sensing are used for example, it is possible to use microfiber MZI 23 which again requires a special fiber, or to use conventional fibers for acoustic monitoring of gas turbines 24 . It is also possible to use the open cavity and the collimators in the sensing arm of the MZI for sound sensing 25 .…”