The measurement of vortex induced effects in flow past stationary and oscillating circular and D-section cylinders

Experiments were performed in a wind tunnel on 3-inch diameter circular and D-section cylinders. A detailed investigation of the vortex shedding frequency, displacement amplitude, and the phase angle between the fluctuating pressure and the displacement signals of both circular and D-section cylinders was made in the "capture" region. These phenomena were investigated under various damping levels using magnetic dampers. Fluctuating surface pressures on a circular cylinder were measured along one half of the circumference at 11 sections selected along the span. The resulting sectional fluctuating lift coefficients as well as the total lift coefficients were obtained by integration for several wind speeds for both stationary and oscillating cylinders. Interesting to note are the vortex line inclination angles obtained from fluctuating surface pressure correlation. Using linearized hot wire anemometers, spanwise wake velocity correlation functions were measured and correlation lengths computed.