Phase-Locked Particle Image Velocimetry Visualization of the Sound Field at the Outlet of a Circular Tube

The shedding process and acoustic flow formation in the region of outlet of a cylinder duct has been investigated by means of the particle image velocimetry (PIV) technique. The research work on the behavior of the sound field at outlets of waveguides addresses issues of importance to industrial applications. The obtained results can be used in a number of industrial applications involving pipes, ducts and tubing. In our investigation the acoustics flow fields are measured with a phase-locked PIV system with high sampling rate and large internal memory block using DAVIS v. 8.11 software. A cross-correlation method, in conjunction with the FFT analysis, is used as a vector processing algorithm. A series of PIV vector maps was used to evaluate the acoustic velocity field at the open end of circular tube throughout the acoustic cycle for frequencies of 700 Hz and 1400 Hz. Six phase steps were assumed for one frequency cycle and the characteristic signal was extracted from the velocity data step and shown graphically.