A characterization of the near field of a two dimensional wake by photon correlation
Abstract
Measurements of mean velocities, turbulent intensities, and various length scales have been made in the near field region of the turbulent wake behind a stationary and a rotating (500 rpm) two-dimensional circular cylinder. In the experiments, the free stream velocity was kept constant at 5.9 m/s, and the Reynolds number was 50,000; the free stream turbulence was approximately 5 percent. The measurements were carried out using a laser velocimeter with a frequency shifting phase modulator and a photon correlation processing scheme. It is shown that the recirculation region extends approximately one diameter downstream and that the momentum thickness increases for the rotating cylinder, indicating an increase in drag. The mixing width undergoes compression in the recirculation region behind the cylinder for both the fixed and rotating cases. The Taylor microscales in the near field are unaffected by the cylinder rotation.
- Publication:
-
Applications of Laser-Doppler Anemometry to Fluid Mechanics
- Pub Date:
- 1982
- Bibcode:
- 1982alaf.symp....1C
- Keywords:
-
- Circular Cylinders;
- Flow Measurement;
- Near Fields;
- Rotating Cylinders;
- Turbulent Wakes;
- Two Dimensional Flow;
- Angular Velocity;
- Autocorrelation;
- Computational Fluid Dynamics;
- Flow Velocity;
- Free Flow;
- Laser Doppler Velocimeters;
- Photons;
- Reynolds Number;
- Taylor Instability;
- Fluid Mechanics and Heat Transfer