Session: 10.3.2 - Turbulent Flows II

Paper Number: 158151

158151 - Investigating the Wake Structure Behind a Perforated Cylinder 

Abstract: 

This study experimentally investigates the flow past a wall-mounted cylinder with a row of perforated holes, immersed in a fully developed boundary layer, using a Particle Image Velocimetry (PIV) system. The perforated wall-mounted cylinder serves as a model for a pin fin commonly used in automotive and aerospace cooling devices. With the increasing demand for more compact and efficient cooling systems, this study explores the impact of perforations on the flow dynamics in the near wake of a circular cylinder.

Time-averaged flow statistics, including mean velocities, Reynolds stresses, and vorticity, are used to characterize the wake flow field along the vertical center plane when the perforations face directly into the incoming flow (0° orientation). The incoming flow was a fully developed boundary layer, and the Reynolds number based on a cylinder diameter of 25.4 mm and a maximum velocity of around 0.29 m/s, falls within the subcritical regime. Additionally, PIV measurements were performed along the same vertical center plane when the cylinder perforations were oriented at 30° relative to the incoming flow. This configuration was analyzed to evaluate how altering the orientation of the perforations modifies the wake structure and flow behavior.

The time-averaged velocity fields reveal that the recirculation zone in the near wake is smaller for the 0° orientation compared to the plain cylinder under the same flow conditions. This reduction is attributed to the jets emanating from the perforations, which interact with the recirculating flow. In contrast, the 30º orientation produces a wake structure similar to the plain cylinder but with smaller recirculation zone. Analyses of the Reynolds stresses and vorticity distributions further demonstrate the effects of the jets on the near wake, highlighting the stronger jet interactions near the wall. The study also explores flow dynamics in off-center vertical planes to provide a more comprehensive understanding of how perforation orientation influences wake behaviour.

Presenting Author: Maria Gudisey University of Windsor

Presenting Author Biography: