Drag coefficient of a finite length circular cylinder with plates

Аuthors

Le V. H.^*, Frolov V. A.^**, Germamo A. Y.^***

Samara National Research University named after Academician S.P. Korolev, 34, Moskovskoye shosse, Samara, 443086, Russia

*e-mail: halevan@mail.ru
**e-mail: frolov_va_ssau@mail.ru
***e-mail: germamo@mail.ru

Abstract

The problem of determining the drag coefficient of an isolated cylinder in a three-dimensional case has been studied in many works. Theoretical and experimental studies show that flow characteristics (including drag coefficients of cylinder of various elongations) depend not only on the flow regime (or Reynolds number as in the two-dimensional case), but also on the elongation of the cylinder. It was found that due to the tightening along the flow regime, in the region of Reynolds numbers corresponding to laminar flow, the drag coefficients of a low aspect ratio cylinder are less than those of a large aspect ratio cylinder. In the region of Reynolds numbers corresponding to turbulent flow, the drag coefficient of the cylinder almost does not change and does not depend on the elongation. Calculations show that the effect of reducing the drag coefficient in the two-dimensional case of a cylinder-plate system can reach up to 60%. It is practically important to conduct an experiment in a wind tunnel in order to find out whether this tendency is maintained for a three-dimensional flow and to what extent the drag reduction effect is realized in this case. In this work, the authors present the result of determining the drag coefficient of an isolated cylinder of finite elongation and a combination of cylinder with plates, obtained in the wind tunnel ADT-3 of Samara University. The effectiveness of the method for reducing the drag of a cylinder by installing a flat plate at the rear and deflectors at the front near its surface at Reynolds number Re=8.4∙104 is shown. The experimental result shows that the drag reduction of system cylinder with plates reaches 28% compared to the isolated finite elongation cylinder. It has been established that the effect of reducing drag in a three-dimensional flow is weaker than for the two-dimensional case.

Keywords:

drag reduction, aspect ratio, ADT-3 wind tunnel, cylinder-plate system, drag coefficient, low subsonic speeds

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