Abstract: Restricted by hub layout and topography, many fish passage projects need to set up 180° turning section. Previous studies have found that the 180° turning section is prone to generate large recirculation area and hence affecting the upstreaming efficiency of fishes. Vertical rectifier plates are commonly used along the side walls of the turning section to improve the flow pattern of the turning section. Different from previous studies, we propose an arrangement scheme of adding a bulkhead along downstream direction to guide fish in the turning section. Numerical simulation of the flow field in the turning section demonstrate that the bulkhead arrangement makes the mainstream area basically centered, the recirculation area reduced, aspect ratio increased, and the flow area with different velocity values in the turning section formed.

Key words: vertical slot fishway, 180° turning section, numerical simulation, hydraulic characteristics;flow pattern