Field target dimensions of flow constrained by a transverse dam

Abstract

Construction and operation of channel control structures in valley rivers require carrying out a comparative study of their operation during design operational periods. The goal of this work is to set target dimensions for flow deformed by the transverse blind dam in field conditions, on the dam 30 in Amudarya river: The length of upstream and downstream vortex zones, boundaries between the core and intensive turbulent mixing zones, vortex zone boundaries, and their comparison with experimental data. Locations of the sections are set based on the possibility to accomplish the goal, in the headrace, where flow natural condition is maintained, in contraction zone, and within the borders of downstream vortex zone. Sections were fixed with landmarks and leveling instrument Vegal 24 was installed there. Zone boundaries and vortex lengths were set with the use of floats directly from the riverside of the use of boats. Design relationships obtained from the results of laboratory experiments were used to determine the length of upstream vortex zone, contraction area, downstream vortex zone, boundaries of hydraulically homogeneous zones, which were then compared with the field data. It was also set, that coefficients characterized flow spreading beyond the contracted section were equal to C 2 =0.186 and C 3 =0.545 as compared to 0.11 and 0.16 in the theory of turbulent jets. The length of vortex zones is shorter by 11.9% to 26.8%, which shows how much the distance between dams must be decreased in the system.