shows the relationship between the flow velocities on individual sound paths and the cross-sectional mean flow velocity downstream of the single-elbow pipeline, which is described using the division of sound path flow velocity and the cross-sectional mean flow velocity. It can be seen that the flow velocities on different sound paths nonlinearly depend on both the Reynolds number and the upstream straight pipe length. In addition, the differences between the four sound paths are more significant, while the Reynolds number is low.