Combined frequency and phase domain time-gated reflectometry based on a fiber with reflection points for absolute measurements

This work presents a detailed review of the development of distributed acoustic sensors (DAS) and their newest scientific applications. It covers most areas of human activities, such as the engineering, material, and humanitarian sciences, geophysics, culture, biology, and applied mechanics. It also provides the theoretical basis for most well-known DAS techniques and unveils the features that characterize each particular group of applications. After providing a summary of research achievements, the paper develops an initial perspective of the future work and determines the most promising DAS technologies that should be improved.

Section: Das In the Engineering Sciences (Andrey A Zhirnov And Konsta...mentioning

confidence: 99%

Section: Conclusion (Yuri a Konstantinov And Ivan A Lobach)mentioning

confidence: 99%

Scientific Applications of Distributed Acoustic Sensing: State-of-the-Art Review and Perspective

Gorshkov

Yüksel

Fotiadi

et al. 2022

“…Pressure, temperature, deformation, and vibration constitute the most important parameters of the working process in a model SRM chamber. Currently, only a limited number of FOSs are able detect these values [ 28 , 40 , 41 ]. The available data suggests the following requirement: an expected total measurement time of less than 10 seconds; typical oscillation frequencies of intra-chamber processes starting from tens of Hz, increasing to hundreds of kHz.…”

Section: Theorymentioning

confidence: 99%

Study of Intra-Chamber Processes in Solid Rocket Motors by Fiber Optic Sensors

Zhirnov

Stepanov

Sazonkin

et al. 2021

In this study, an experimental study of the burning rate of solid fuel in a model solid propellant rocket motor (SRM) E-5-0 was conducted using a non-invasive control method with fiber-optic sensors (FOSs). Three sensors based on the Mach–Zehnder interferometer (MZI), fixed on the SRM E-5-0, recorded the vibration signal during the entire cycle of solid fuel burning. The results showed that, when using MZI sensors, the non-invasive control of solid fuel burnout is made possible both by recording the time of arrival of the combustion front to the sensor and by analyzing the peaks on the spectrogram of the recorded FOS signal. The main mode of acoustic vibrations of the chamber of the model SRM is longitudinal, and it changes with time, depending on the chamber length. Longitudinal modes of the combustion chamber were detected by MZI only after the combustion front passed its fixing point, and the microphone was unable to register them at all. The results showed that the combustion rate was practically constant after the first second, which was confirmed by the graph of the pressure versus time at the nozzle exit.

“…One important parameter of such FOSs is their acoustic sensitivity threshold, that is, the minimum acoustic or vibration impact that the system can register. Several methods have been proposed to increase the acoustic sensitivity of FOSs, such as the use of a special cable with improved acoustic sensitivity [24][25][26][27][28], several photoreceivers together with special data-processing algorithms [29,30], and a special optical fiber with weak fiber Bragg gratings (wFBGs) recorded in a fiber with a known periodicity [31][32][33][34]. One possibility for increasing the SNR was investigated by using two probe pulses simultaneously [35][36][37][38], including with a certain polarization configuration [39,40].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity Improvement of Phi-OTDR by Fiber Cable Coils

Stepanov

Zhirnov

Koshelev

et al. 2021

We present a theoretical and experimental study in which we increased the sensitivity of a phase-sensitive optical time-domain reflectometer (phi-OTDR). This was achieved by constructing coils in the sensor cable, which increased the total amplitude of the impact on the fiber. We demonstrate this theoretically using the example of a phase-sensitive reflectometer model and practically in testing grounds with a buried nearby conventional sensor and a sensor with coils. The sensitivity increased 2.2 times. We detected 95% of events when using coils, versus 20% when using a straight cable. The suggested method does not require any modifications to the device.