Forced vibration of a fully immersed pipe aspirating water: A theoretical investigation

This study investigates the forced vibration of a fully immersed pipe aspirating water under horizontal excitation at the top end. In the dynamics of aspirating pipes, the hydrodynamic force acting at the inlet plays an important role in stability, natural periods, and damping ratios. Under top-end excitation, this force also acts as an excitation force, leading to a significant increase in the first-mode amplitude with internal flow velocity. The shifts in the peak frequencies of higher modes and the effect of the drag coefficient on these responses are also systematically examined. Comparison of the first-mode response with experimental results shows good agreement between theory and experiment. These results demonstrate that the inlet force, whose validation has been difficult through stability analysis alone, can be validated under top-end excitation. This effect may also be an important consideration in the practical engineering design of water intake pipes.