Aeroelastic Instability of Prisms in Turbulent Flow

Lateral oscillations of square and rectangular prisms resulting from its aerodynamic instability (often called galloping oscillations) are analyzed theoretically and studied experimentally in turbulent flow with a vertical profile of mean wind velocity. It appears that these vibrations exist even in a highly turbulent flow, but are somewhat less intense and more random in character than in a smooth flow. The possibility of a universal representation of galloping oscillations for bodies having different mass and damping has been shown earlier in smooth flow. The experiments described extend this concept to include turbulent flow. Such a universal representation of the galloping response of square and rectangular cantilevered prisms is derived directly from wind tunnel experiments. The results for example can be used to predict the aeroelastic instability of buildings of square cross section in either open country or urban areas. The effect of aeroelastic instability on excited oscillations in the region of stability is also investigated.