The Hydro-VENUS is an energy harvester exploiting the flow-induced oscillation of a pendulum-like blade. In this study, the effects of the angular amplitude and non-dimensional flow velocity on the energy harvesting performance of the Hydro-VENUS are investigated through water channel tests. A semi-elliptical cross-section blade with the cross-sectional aspect ratio of 6 is employed in these tests. The experimental results revealed that the maximum power coefficient is obtained at specific angular amplitude and non-dimensional flow velocity. The approximate solution for the power coefficient is theoretically provided considering non-linearity of hydrodynamic forces acting on the blade. This theoretical approach revealed that the power coefficient is determined by tip speed ratio of the blade and the maximum power coefficient is obtained at specific tip speed ratio.

View full abstract

The wind characteristics of downbursts are significantly different from those of turbulent boundary layers. The non-stationarity, especially caused by a severe moving downdraft and strong divergent outflow near the ground, causes serious damage to buildings. The present paper investigates the characteristics of downbursts and its effects on buildings, based on an experiment with three kinds of jets, i.e., a pulsed jet, a moving jet and a pulsed moving jet, using a moving jet simulator that we have developed. The effects of non-stationarity of downbursts on the wind pressures and forces acting on buildings with three different sizes and six different heights are discussed. Finally, an evaluation method of downburst-induced wind loads on buildings is proposed based on the experimental results.

View full abstract