عنوان مقاله [English]
Stepped spillways are consist of some steps, which started from top crest of weirs to the down stream of spillways. These structures is used now because of their efficiency in dissipating energy of flow, and their benefits in economical aspects. This kind of spillways are also used in agriculture because of air entrance along them and natural purification of water. This study was carried out to find a mathematical model for estimating the relative dissipation of energy by making 10 physical models of stepped spillways in a laboratory flume. The models were built up to 31 steps, and data was collected by passing many different discharges through them. Effective parameters such as: a, N, Hdam, Yc, and (h, l) were obtained by data analysis and then some important and effective dimensionless parameters for geometric optimization of the stepped spillways were found using a dimensionless technique and analyzing the results. There was a relation between the relative dissipating energy and some dimensionless parameters like yc/h, Hdam/yc. Results showed that the best physical model for dissipating the energy was 15 step spillway. Finally, the geometric optimized formula were proposed for mentioned spillway by analyzing the obtained parameters.