Counter-Rotating Type Tidal Stream Power Unit Moored by Only One Cable

The authors have proposed that a counter-rotating type tidal stream power unit mounted rigidly on a pile, and outputs of the power unit and forces acting on the pile were investigated experimentally at a previous paper, A single propeller makes the pile undertake a reaction force orthogonal to the stream direction. On the contrary, proposed counter-rotating propellers do not require undertaking the reaction force of the pile, because the rotational torque is counter-balanced in the unit. This advantage means that the unit can be moored by only one cable. Continuously, this paper proposes such a power unit with tandem propellers, and experimentally investigates a behavior of the unit floating in a water channel. The vibrations of the power unit are induced from not only the individual but also the interacting rotations of the front and the rear propellers.

九龙江北溪水闸上下游河床冲刷变化及原因分析

该文利用2006-2021年多个不同年份实测地形资料,对比不同年份九龙江北溪水闸南、北港拦河闸上下游横断面和闸中纵断面地形,分析河床冲刷变化,结合实测水文泥沙资料分析拦河闸下游河床冲刷变化原因。结果表明:近年来北溪水闸南、北港拦河闸上下游河床整体均有所冲刷,闸下游河床冲刷变化明显大于闸上游;闸下游河床2018年以前冲刷变化较显著,2018年以后冲刷变化较缓和。分析认为,拦河闸下游低水位下跌、潮动力作用增强、上游来沙量减小及河口采砂、航道疏浚等是导致拦河闸下游河床刷深的主要原因。