FLOW AROUND MODIFIED CIRCULAR CILYNDERS

Abstract

The flow around a circular cylinder has awaken the attention of different
researchers since the historic Strouhal's work of 1878. Ever since, many
experimental and numeric works have been carried out in order to
determine the relationship between the vortex shedding frequency and the
flow regime. Recently, a number of studies have been developed using
several small modifications in circular cylinder. In this work a circular
cylinder modified with a longitudinal concave notch, has been tested in
order to determine the relationship between the non-dimensional vortex
shedding frequency (Strouhal number) and the Reynolds number has been
determined to Reynolds up to 600. Additionally a modified circular
cylinder with a longitudinal slit also has been tested in order to determine
the Strouhal-Reynolds relationship in several attack angle configurations.
The experiments have been carried out in a vertical low turbulence
hydrodynamic tunnel with 146x146x500 mm of test section operating in
continuous mode. Flow visualization by direct liquid dye injection has been
utilized in order to produce vortex images. These images have been
captured in still chemical photography for different Reynolds numbers. A
hot-film probe has been adequately positioned in the vortex wake to
determine the vortex shedding frequency and consequently the Strouhal
number.