STRUCTURE OF A TURBULENT WAKE BEHIND A CRUCIFORM CIRCULAR CYLINDER (1ST REPORT, THE MEAN VELOCITY FIELD).

Abstract

The mean velocity field of a turbulent wake behind a cruciform circular cylinder which is composed of two sufficiently long circular cylinders is examined experimentally. The measurements were performed for the surface pressure distributions on the cruciform circular cylinder and the mean velocity profiles in the wake at a number of downstream stations in a wide range of x/d equals 3 to 594. It is revealed that the decay rate of centerline velocity defect is considerably slower, while the rate of growth of the half-width for the y equals z plane of the present wake is very close to that of a two-dimensional wake. In the center region of the wake of the cruciform shape, secondary flows are observed and the magnitude of the flow is measured. The drag coefficient of the cruciform circular cylinder almost agrees with that of the equivalent two-dimensional circular cylinder.