An Experimental Investigation of the Near Wake of a Circular Cylinder.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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The near field region of the turbulent wake behind a rotating and nonrotating two dimensional circular cylinder is documented. U component mean velocities, turbulent intensities and velocity autocorrelation functions are measured at various downstream locations. From the autocorrelation functions, Taylor time microscales, longitudinal integral time scales and energy dissipation rates are computed. The measurements are performed for the flow over a circular cylinder at omega 0 RPM and omega is approximately 500 RPM. The free stream velocity and Reynolds number, based on cylinder diameter, are respectively 5.9 msec and approximately 50,000. The turbulent measurements are made with a laser velocimeter using a frequency shifting phase modulator and the photon correlation processing scheme. Naturally occurring contaminant is augmented with vaporized kerosene to increase the magnitude of scattered light. Results are presented for the effects of varying omega, frequency shifting, particle concentrations and detector optics pinhole size on the turbulent quantities. Author
- Test Facilities, Equipment and Methods
- Fluid Mechanics