Abstract
The purpose of this paper is to characterize and to estimate the recirculating length behind an aerodynamic profile in ground effect with Gurney Flap. The flow characterization at high Reynolds numbers was performed by means of numerical analysis. A correlation between the size of the recirculation length and the frequency of vortex shedding was studied. The vortex shedding has a characteristic frequency, which, in this work, is correlated to the size of a recirculation length defined by the authors. The numerical investigation methodology applied to the profile with Gurney Flap, was previously developed on the well-documented test case of the flow around a cylinder at high Reynolds. The case was chosen to investigate and to validate the numerical approach with experimental data.
Highlights
Classical studies have been performed on the frequency of vortex shedding by Strouhal [1] and Rayleigh [2], according to various Reynolds numbers
A remarkable impulse to understand the phenomenon was given by Theodore von Karman [3], who analyzed the stability at various wakes configurations at different Reynolds numbers
In this paper the von Karman vortex shedding is studied in two cases: a cylinder and a profile with Gurney Flap in ground effect
Summary
The wake behind 2D and 3D bluff bodies has been a topic of interest for engineers over many years but it still remains a difficult case for both experimental and numerical applications. In this paper the von Karman vortex shedding is studied in two cases: a cylinder and a profile with Gurney Flap in ground effect. It has been observed that changes in Reynolds number affect recirculation zone size: by increasing it, the instability intensity leading to the shear layer curl (the formation of the first vortex that draws the separate fluid layer on the opposite side) increases. The results of this study led to the conclusion that this device modifies the Kutta-Joukowski condition for a wing profile operating under subsonic conditions This condition requires that the flow from both surfaces mix in the wake, referring to Figure 2, the stagnation point (S2) moves to the trailing edge (because of the shorter distance ran by point B), creating an anti-clockwise vortex.
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