Abstract
This paper is dealing with an experimental study to show the influence of the geometric characteristics of the vortex generators VG son the thickness of the boundary layer (∂) and drag coefficients (CD) of the flat plate. Vortex generators work effectively on medium and high angles of attack, since they are "hidden" under the boundary layer and practically ineffective at low angles. The height of VGs relative to the thickness of the boundary layer enables us to study the efficacy of VGs in delaying boundary layer separation. The distance between two VGs also has an effect on the boundary layer if we take into account the interference between two pairs of VGs. The effect of the changing in (h- the height of vortex generator, d- the average distance between tow vortex generators) on the thickness of the flat plate boundary layer and the drag coefficients has been studied for triangular vortex generator. The measurements of the vortex generator have been changed to determine the optimum boundary layer thickness and the change in drag coefficients. An experiment was done at an average free stream velocity, (U∞,) of 28 m/s. The experiment was conducted in the wind tunnel UTAD-2 University (NAU) Kiev, Ukraine.
Highlights
Vortex generators (VGs) are used as flow control devices to provide a certain amount of delay separation of the boundary layer as well as weaken the harmful effects of strong local secondary flows
The objective of this research is an experimental study of the dependence of the drag coefficients and the boundary layer thickness of a flat plate on many geometric characteristics of the VGs. 32 models of VGs configured in different geometric dimensions to get the optimum geometric measurements, which is equivalent to the lowest value of drag coefficients
The influence of the geometric characteristics of the vortex generators on the drag of a flat plate and the thickness of its boundary layer is given in the (Table 3 and 4) and presented in the form of graphical methods (Figures 5, 6, 7 and 8)
Summary
Vortex generators (VGs) are used as flow control devices to provide a certain amount of delay separation of the boundary layer as well as weaken the harmful effects of strong local secondary flows. Most of the previous scientific research used a VG as a passive flow control device that modifies the boundary layer fluid motion, which brings momentum from the outer flow region into the inner flow region of the wall-bounded flows (Storms et al.,1994), delaying the separation of the boundary layer (Manolesos et al, 2015). Their implementation may produce overload drag at the body where they are placed. Li et al, (2019) got the results of the effect of VG height in the boundary layer
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