ارزيابي افت انرژي جريان از روي سرريزهاي پلكاني با استفاده از مدل فيزيكي

Evaluation of energy dissipation on stepped spillways by physical modeling

In a stepped spillway, the spillway face is provided with a series of steps from near the crest to the toe. The energy dissipation caused by the steps reduces the size of the energy dissipator, generally provided at the toe of the spillway. Stepped spillways have been built in the past but it appears to be renewed interests in them because of significant cost savings. This paper presents the results of hydraulic laboratory study on the characteristics of flow in large models of stepped spillways with 45-degree slopes. For the four stepped spillways the number of steps was selected as 5,10,15,20,35 and 50. The 7aʹ spillway was smooth( without step). Results showed that the steps significantly increase the rate of energy dissipation on the spillway face. The relative energy loss for stepped spillways was from 53.4 to 95.7 percent. For smooth spillway the relative energy loss was between 17.2 and 70.8 percent. It has been demonestrated that increasing number of steps results in higher energy dissipation with identical total head in upstream.