Study on the Scale Effects of Water–Sediment Characteristics in a Trapezoidal Desilting Channel with a Swirling Flow Generator

Abstract To clarify how scale effects alter the water–sediment characteristics of trapezoidal desilting channels with a swirling flow generator (TDCSFG) from model to prototype scale, this study combines numerical simulation with experimental validation. It systematically investigates the water–sediment movement laws and sediment discharge efficiency of TDCSFGs at three scales (1:1, 5:1, 10:1) under varying operating conditions, including the relative depth, flow velocity, sediment concentration, and sediment gradation. The results show that large-scale TDCSFGs perform better overall, with the 10:1 scale model showing the best performance under most operating conditions, especially at high flow velocities and under inflows containing a high proportion of fine particles. In contrast, variations in incoming sediment concentration have a negligible impact on sediment discharge efficiency. This study confirms that large-scale TDCSFGs combine low water consumption with strong operational adaptability, making them a promising and reliable technology for practical engineering applications such as water diversion from sediment-laden rivers and sediment discharge in hydropower station forebays.