A Multi-Path Ultrasonic Transit Time Flow Meter Using a Tomography Method for Gas Flow Velocity Profile Measurement

摘要

A velocity profile is the distribution of velocities in the axial direction over a cross-section of circular pipe.In this study,a new ultrasonic flow meter with a modified multi-path configuration,namely,a tomographic ultrasonic flow meter is proposed for the measurement of the flow velocity profile.The flow meter consists of a set of transmitting transducers and a set of receiving transducers placed at different positions on the pipe surroundings.This configuration produces an ultrasonic path in various directions and positions for the flow detection.Transmitting transducers,in sequence,propagate the ultrasound wave to all receiving transducers,and the axial velocity in each ultrasonic path is measured.The average velocity is calculated by using the weighting method.Using the theoretical flow profiles,the tomographic ultrasonic flow meter is simulated in asymmetric flow and compared to both the diametrical and quadrature configurations.The filtered back projection method is employed to reconstruct a flow velocity profile.In the reconstruction process,the flow velocity obtained in each ultrasonic path is used as the projection data.An experiment is also performed in a circular pipe for measuring the air flow velocity profile,in order to validate the proposed flow meter.