Direct measurements of oscillating lift on a rigid square section cylinder in a turbulent stream

Measurements of the fluctuating lift caused by vortex shedding have been made on a square section two-dimensional body. The measurement technique involved the direct measurement of force by a strain-gauged force transducer beam. Various turbulence levels and model span-to-width ratios were used. The results agree broadly with previous measurements for the force and its correlation at low turbulence levels, but show a surprising increase in the correlation of force with increasing turbulence intensities. This is in contrast to previous measurements, made in less direct ways, and implies that a long two-dimensional square-section body could feel a higher overall fluctuating force at high turbulence levels than with no turbulence present.