Velocity Characteristics of the Flow Around Disks and Cones

Abstract

A direction-sensitive laser-Doppler anemometer was used to measure the aerodynamic characteristics in and around the wake of disks and cones located in the center line of a jet exiting from a tube. The tube inner diameter was 42 mm; the maximum jet velocities were 8.2 and 10.6 m/s; and disks and cones of 10 and 15 mm diameter were located at 10 and 75 mm from the jet-exit plane. Profiles of the axial and radial mean velocity components and rms values of the three fluctuating components of velocity and shear stress were obtained. The measurements indicate for disks and cones of 10 mm diameter, recirculation lengths of 1.35 d and 1.60 d, respectively. The recirculation lengths increase with baffle diameter are independent of initial velocity and slightly decrease with the increase of the distance from the jet exit to the baffle. The turbulence intensity in the recirculation region is never less than 30 percent and strongly anisotropic. Periodic oscillations corresponding to a Strouhal number of 0.18 were found.