PIV of swirling flow in a conical pipe with vibrating wall

TL;DR

This study investigates how wall vibrations affect swirling flow in a conical pipe using PIV, revealing improved flow symmetry and reduced velocity fluctuations under different vibration frequencies.

Contribution

It is the first detailed experimental analysis of swirling flow in a conical pipe with vibrating walls, highlighting flow symmetry improvements and fluctuation reduction.

Findings

Presence of an intermediary recirculation cell

Vibration improves flow symmetry

Velocity fluctuations decrease significantly

Abstract

Swirling flows in conical pipe can be found in a number of industrial processes, such as hydrocylone, separator and rotating machinery. It has been found that wall oscillations can reduce the drag in water channel and pipe flows, but there is no study of a swirling flow combined with a vibrating wall in conical pipes, though there are many applications of such combination in engineering processes. A two-dimensional particle image velocimetry (PIV) is used to measure the swirling flow field in a water conical pipe subjected to a periodic vibrating wall for a Reynolds number 3800. The flow velocity statistics are studied under different vibration frequencies corresponding to Strouhal numbers from 60 to 242. The instantaneous axial and vertical velocity in one vibrating period, the mean velocities, and Reynolds stresses were obtained. The results show the existence of an intermediary recirculation cell in the middle of the pipe. They also show that the vibration improves the symmetry for the swirling flow while decreasing dramatically the velocity fluctuation.