Intrusive and non-intrusive microflow measurement based on distributed optical fiber acoustic sensing

Distributed optical fiber acoustic sensing has become a research hotspot in the field of microflow monitoring due to its simple structure and wide monitoring range. In this paper, a new method of modal frequency analysis is proposed based on the dynamic pressure of pipeline flow. Theoretical analysis and simulation results demonstrate that the pressure has an exponential relationship with the flow rate. Secondarily, an experimental system of intrusive and non-intrusive flow measuring based on distributed acoustic sensing is designed. With the flow rate range of 0.258–0.349 m/s, experimental result shows that the excellent exponential relationship between dynamic pressure and flow rate can be obtained by using the intrusive monitoring with the frequency band of 450 Hz-550 Hz and the non-intrusive monitoring with the frequency range of 750–850 Hz, respectively. The intrusive method has a better fitting and relative measurement error, with the degree of fitting verified up to 0.99432 and the optimal relative measurement error less than 1%.