Evaluation of hydraulic performance of Nazanin dam side channel spillway

Abstract EN

Flow in the side channel spillway is very complex due to discharge changing along the side channel called spatially varied flow (SVF).

a physical model for Nazanin dam side channel spillway, which has been designed by hidroconstructia company with scale ratio 1:40 constructed in the laboratory to evaluate the flow characteristics in the spillway.

the flow depth at several locations along centerline, right and left side of the spillway were measured for discharges ranging from (2.56 – 33.45) l/s.

the performance of the spillway includes determination of discharge coefficient of the side weir, height of side walls for the spillway components and energy dissipation at the downstream of stilling basin.

furthermore, water surface profile was computed in the trough channel using one dimensional (1d) solution.

the analysis of the data collected from physical model showed that at higher flow rates the discharge coefficient was reduced and side weir can pass extra 18% of the discharge presented in the design report.

overtopping was observed clearly over transition, chute channel and stilling basin side walls.

the stilling basin could not dissipate energy efficiently.

it also observed that the percentage of energy dissipation rate was inversely proportional with the discharge.

furthermore, it was found that the 1d solution adequately predicted the water surface profile in the trough channel.