High-Precision Flow Rate Measurement Based on Distributed Optical Fiber Acoustic Sensing

We have numerically and experimentally investigated the flow rate measurement of the pipeline based on the optical fiber. Employing the large eddy simulation (LES) model, we have quantitatively analyzed the pressure fluctuation of the pipe wall caused by the turbulent flow in the pipeline. The simulation results have shown that the standard deviation of pressure fluctuation was quadratic with the flow rate. We have verified the theoretical model by using a distributed optical fiber acoustic sensing (DAS) system in the flow rate range from 0.61 m/s to 2.42 m/s. The experimental results were consistent with the simulation results very well. Furthermore, to improve the measuring error at the low flow rate, we have employed the composite adaptive denoising algorithm to eliminate the background noise and system noise. The final results have shown that the minimum goodness of fit was improved from 0.962 to 0.997, and the variation of the quadratic coefficient significantly decreased by 93.25%. The measured flow rate difference was only 0.84% between different sensing points in repeated experiments.