Influence of the porosity pattern on the aerodynamics of a square plate

TL;DR

This study experimentally investigates how different porosity patterns on square plates influence their aerodynamic behavior, particularly stall characteristics, using wind tunnel tests and PIV measurements.

Contribution

It provides new insights into how porosity pattern details affect stall behavior, which was not previously well understood.

Findings

Porosity pattern influences stall occurrence.

Edge porosity details are critical for stall behavior.

Porous plates exhibit different aerodynamic coefficients than solid plates.

Abstract

The evolution of the normal aerodynamic coefficient of 19 configurations of square plates with various porosity patterns, ranging from solid plate to homogeneous porous plate, is experimentally characterized. The variation of the porosity pattern is obtained by partially covering the holes of a commercial fly-swatter using adhesive tape. Evolution of the normal aerodynamic coefficient is assessed from the measurement of the angular position of the porous plate, placed as a freely rotating pendulum swept by a flow in a wind tunnel. These angular measurements are also supported by PIV measurements of the structure of the wake. We show that the porosity pattern determines whether or not an abrupt stall occurs. In particular, the details of the porosity pattern on the edges of the plate are decisive for the existence of abrupt stall.