Transverse vibration behaviour of cylinders in line

Abstract

Wind tunnel investigations of cylindrical aeroelastic models arranged in a row (as in steel stacks) have been carried out. The test were performed in a turbulent flow boundary layer wind tunnel. In this series, the variables were the number of cylinders (maximum four), their spacing, and the angle of attack. For each cylinder, the amplitude of the transverse vibrations and the pressure coefficients of the transverse lift were measured. Measurements of amplitude relative to that of an isolated cylinder show the great influence of the cylinder spacing on the downstream cylinders. Spacings less than three times the cylinder diameter led in some cases to amplitude magnification factors of 2 for some of the cylinders in the line. The measured pressure coefficients show differences with design recommendations for the transverse-lift amplification factor. Further tests with a fixed leading cylinder were carried out to study the stabilising effect on the downstream cylinders. Results from these tests show that the fixing is only effective in reducing the vibrations of the second cylinder.